Integrated Residue Management Systems for Sustained Seed Yield of Kentucky Bluegrass Without Burning

Final Report for SW03-021

Project Type: Research and Education
Funds awarded in 2003: $294,243.00
Projected End Date: 12/31/2007
Matching Non-Federal Funds: $31,040.00
Region: Western
State: Idaho
Principal Investigator:
Donald Thill
University of Idaho
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Project Information

Abstract:

Post-harvest grazing can remove 80%, or as much residue as burning, when the stocking density and grazing duration are adequate. Seed yield in post-harvest graze treatments were comparable to those in the full-load burn treatment, indicating post-harvest grazing is a potential non-thermal alternative for managing Kentucky bluegrass residue and sustaining seed production. About 43% fewer cattle are required with the bale-then-graze treatment compared to the full-load graze treatment. Switching to baling as a method of residue removal will require most farmers to purchase a baler and stacking equipment or have the residue custom harvested. A producer would need to harvest over 1,800 A before it would be profitable to purchase haying equipment versus having it custom harvested.

Project Objectives:

Develop livestock grazing systems and/or use of emerging biotechnology alternatives that optimize biomass turnover and maintain or increase bluegrass seed yield without burning.

Compare nutrient cycling efficiency in burned, mechanically managed and grazed bluegrass systems.

Investigate above ground insect pest and predator relationships in each bluegrass production system. Monitor diseases and weeds associated with the different treatments.

Examine the economic efficiency of each bluegrass production system including the associated production, price, and financial risk.

Identify potential key socio-cultural and economic costs and benefits of livestock grazing management practices or biotechnology alternatives versus current open-burning practices.

Disseminate information to growers, field consultants, extension educators, and scientific audiences.

Introduction:

Idaho ranks first nationally and accounts for 50% of the USA Kentucky bluegrass (Poa pratensis L.) seed production. In 1999, Idaho produced 36 million lb of bluegrass seed valued at $45 million from 60,000 A. Established bluegrass stands prevent erosion and nutrient loss to surface water, protecting soil and water quality. Sustained bluegrass seed productivity historically has relied on open-field burning of post-harvest residues that has been associated with significant air quality issues and public health impacts. Mandatory regulations that prohibit burning of bluegrass fields located in Idaho were implemented in February 2007. Alternative management systems must be developed that eliminate the need to burn bluegrass residues yet sustain productivity and economical seed yield, otherwise the viability of this economically and environmentally sound industry will be threatened severely. Residue management systems must be developed and tested in long-term, large-scale, on-farm trials that represent typical grower field conditions to properly assess treatment effectiveness on residue levels and impacts on grass seed production. This includes appropriate agronomic, ecological, environmental, economic, and sociological studies and analyses. Most alternatives to field burning require increased dependence on farm implements, fossil fuels, and herbicides, which are often associated with reduced grass seed yield. Integration of ruminant livestock enterprises (beef cattle or sheep) with grass seed production enterprises and/or use of emerging biotechnology alternatives for enhanced microbial in situ residue decomposition offers potential alternatives to field burning of grass seed residue that may sustain economic returns to the agricultural community.

Mechanical forces applied through ruminant animal utilization of grass seed residue include disruption of the sod via hoof action and physical particle size reduction via mastication during ingestion and rumination (feed particulate is commonly reduced to less than 0.3 inches for transit through the digestive tract). Grass seed residue is further reduced via microbial fermentation in the rumen and other fermentative organs of the hindgut. These mechanical and fermentative forces imposed by the ruminant animal may be managed to have the same net effect as open field burning of the crop residue. Successful integration of the livestock and grass seed enterprises therefore could serve to eliminate air quality problems associated with grass seed burning while securing an economic value from the grass seed residue

Numerous plant and animal interactions need to be quantified before feasible, integrated systems can be adapted. Timing or season of grazing and grazing intensity or utilization are factors that likely impact sod integrity and consequently sustainable grass seed production. Critical to the understanding of a viable integrated production system would be the evaluation of the nutrient content of the grazed or baled crop residue. Fall and winter-feed costs are commonly recognized as the largest operational expense for cow-calf enterprises and usually distinguish a high profit from a low profit enterprise. Grass seed residues would become available at the beginning of this critical grazing and feeding period. The suitability of grass seed residues as a nutrient resource for either mature, mid-gestation beef cows or fall-weaned calves (assuming protein and energy supplementation are provided) have the potential of having a positive impact of the profit potential of a cattle enterprise integrated with grass seed production.

When considering soil-plant systems, the presence of a litter layer is generally desirable. In addition to the conservation of moisture and protection against raindrop impaction and erosion (Stott et al., 1999), decomposition of the litter layer also serves as a major pathway of nutrient addition to the soil system (Schlesinger, 1991). Through a better understanding of the decomposition process, we can devise management strategies that reduce the negative impacts of the accumulation of agricultural residues while benefiting from the protection against erosion and increased nutrient return to the soil. Kentucky bluegrass requires a high N application rate. Currently N is often applied based on potential yields and precipitation (Mahler and Ensign, 1989). Over application of N fertilizer may result in nitrate contamination of groundwater and represents an economic loss to the grower. Leaving residues to decompose in the field ensures that some of the nutrients taken from the soil by plants are recycled. The release of nutrients from the residue should be considered when making fertilizer recommendations and may increase sustainability by reducing the dependence on inorganic fertilizers.

Billbugs (Coleopotera: Curculionidae) are a known pest of Kentucky bluegrass seed production systems, with the soil-dwelling larvae capable of destroying hundreds of acres after only a few years of infestation. Although billbugs have been shown to cause damage in bluegrass seed fields of the Grande Ronde Valley, OR (Walenta et al, unpublished data), little is known about their impact in north Idaho bluegrass systems especially those under non-thermal residue management practices. Billbugs occurring in the Inland Pacific Northwest include the bluegrass billbug (Sphenophorous parvulus Gyllenhal), the hunting billbug (S. venatus Say) and the Denver billbug (S. cicatristriatus Fabraeus) (Johnson-Cicalese et al. 1990). These species generally over winter as adults and produce offspring in the spring and summer, although the Denver billbug may also over winter in the larval stage. Adults feed on grass above ground but cause little damage. In contrast, the soil-dwelling larvae can cause considerable damage by tunneling through roots and by feeding on roots and crowns of turfgrass (Niemczyk and Shetlar 2000). Carabid beetles (Coleoptera: Carabidae) and spiders (Arachnida: Aranaea) are generalist predators that feed on a wide variety of crop pests. For example, Carabids have been shown to feed on wireworms, weevils and aphids in crop fields (Sunderland 2002) as well as grubs in turfgrass (Kunkel et al. 1999), while spiders have been shown to feed on aphids, moths and true bugs (Sunderland 2002, Nyffeler and Sunderland 2003). Little is known about the carabid or spider fauna of bluegrass seed systems of Idaho.

Cooperators

Click linked name(s) to expand
  • Don Crawford
  • Carl Hunt
  • Jodi Johnson-Maynard
  • Joe McCaffrey
  • Larry Van Tassell
  • J.D. Wulfhorst

Research

Materials and methods:

Field experiments were initiated on grower-cooperator farms in established Kentucky bluegrass stands previously burned every fall prior to implementing the treatments. Post-harvest residue management treatments were implemented during the late summer of 2003 in Lewis County, Idaho and 2004 in Latah County, Idaho (Hatter Creek Ranch). Both sites were seeded during the spring of 1999 with the variety ‘Palouse’ at the Lewis County site and ‘Kenblue’ at the Latah County site. The experimental design at both locations was a randomized complete block with four replications. Each plot was 400-ft long and 45- to 90-ft wide depending on treatment and the size of the experiment was about 25 A. At least one-half of each plot contained only main treatments, while the other part was used for smaller plot experiments (pest control and monitoring, nutrient cycling, emerging microbial biotechnology alternatives, etc.). Baseline seed yield was determined by harvesting and measuring seed yield by plot prior to implementing the residue management treatments in the fall. Residue management treatments were: full-load burn (historical practice); bale-then-burn; seed harvest (year 1) then chemical suppression-no seed harvest (year 2), chemical suppression-no seed harvest (year 1) then seed harvest (year 2); seed harvest (year 1) then mechanical suppression-no seed harvest (year 2), mechanical suppression-no seed harvest (year 1) then seed harvest (year 2); bale-then-mow-then-harrow (mechanical); bale-then-graze; and full-load graze. The alternate year treatments were abandoned after the second year because they performed poorly.

Granular fertilizer was broadcast in the fall to all plots scheduled to be harvested the following summer after all of the residue removal treatments were completed. Fertilizer was not applied to treatments that were not harvested the following year, i.e. chemical suppression/seed harvest and mechanical suppression/seed harvest. The Lewis County site received 445 lb/A of 30-8-6-6 as N-P-K-S and the Latah County site received 630 lb/A of 17-6-5-5 as N-P-K-S. Treatments were monitored for pathogens via disease surveys, and pathogens identified using standard morphological, physiological, and genetic identification techniques. Weed infestations were monitored and controlled as needed.

Seed yield was measured every year by plot using a field scale combine to harvest the seed and weigh pads were positioned under a seed trailer to measure yield. A seed sub sample was collected at harvest to determine clean seed weight, and gross seed yield was adjusted to clean seed yield. Residue management treatments were implemented immediately following seed harvest. A weather station recorded air and soil temperatures, precipitation, and total solar radiation.

The distribution of C, N, S, and P was determined in plots where residue was grazed immediately after seed harvest at the highest grazing intensity, full-load burned, baled-then-burned, or mechanically removed. Soils were sampled prior to the application of treatments to determine the initial soil properties. Three replicate soil samples were collected from the 0 to 4, 4 to 8, 8 to 12 and 12 to 24 inch depths within main plots following residue treatments. Total N, C, and S were measured using a dry combustion C/N/S analyzer. Inorganic (plant available) N was determined by extraction with KCl (Mulvaney 1996). Organic N was determined by subtracting the inorganic forms from the total N measured by the C/N/S analyzer. Available P was measured using the Bray-1 test (Kuo 1996) due to the acid nature of these soils.

Standing and non-standing (thatch) biomass was collected from the main plots just prior to swathing, and immediately following residue management treatments. Biomass measurements were made by removing all of the thatch with a wire rake from 3 randomly placed, replicate, 2.7 square foot quadrats within each plot. After removal of all non-standing biomass, the standing biomass was clipped approximately 0.4 inches from the soil surface and collected in a separate bag. The samples were returned to the laboratory, dried for 48 hr at 140 F, weighed, and corrected for mineral content by ashing sub samples in a muffle furnace at 932 F for a 4-hr period. Total C and N were measured from a composite of the three residue samples.
Forage quality of the post-harvest grazed residue was determined by plot from a composite sample of the residue collected from the same three 2.7 square foot quadrats per plot used to determine initial residue level. The forage quality of the baled residue was measured from a composite sample of 50 bale cores taken at random per plot using a hay probe. Kentucky bluegrass forage quality compositional measurements included dry matter (DM), crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), lignin, and 48 hr in vitro true digestibility (IVTD).

Each block within the experiment was cross-fenced and contained four 2 A grazing treatments and three 0.5 A burn and mechanical residue removal treatments. The fence was arranged so that beef cattle assigned to each plot had access to an available water source. Immediately after grass seed harvest, cattle owned by a cooperator were assigned to specific grazing treatments and were excluded from the non-grazed treatments. Cattle were managed daily (routine inspection, providing mineral supplement, checking available water, etc.). Periodic field inspections were conducted to visually evaluate degree of residue removal by the cattle and level of damage to the bluegrass plants by grazing and hoof trodding. At the beginning and at the end of each grazing period, weights of the cattle were obtained. Total mega calories of metabolizable energy harvested was determined based on body weight and on weight gain or loss of the animals during the grazing period. An economic value of the grazed residue was estimated based on the fair-market value of mega calories from locally produced conventional forages and grains. As an additional appraisal of energy harvested by the cattle, an estimate of digestibility of the grazed forage was determined.

Graze treatments were stocked at AU (animal unit) densities aimed at removing 80% of the post-harvest residue within 30 days post harvest. Cow/calf pairs were used to graze the post-harvest residue. An animal unit was defined as 1,000 lb. Calves and cows received an AU measurement based on their weight percentage of 1,000 lb. For example, a 500 lb calf received and AU of 0.5. Percent residue removal was determined by visual estimation. Cattle were fed 1.5 lb/d/AU of a 28% CP and 86% IVTD supplement in 2003 and fed 3 lb/d/AU of a 25% CP and 86% IVTD supplement in 2004 and 2005. Cattle were watered regularly and water consumption was measured by plot.

Total available digestible dry matter (IVTD x Kentucky bluegrass residue on a 100% dry matter basis) was determined by the amount of post-harvest residue times the percent IVTD. Dry matter intake (DMI), excluding supplement, was determined by the difference in the amount of ash free residue per plot before and after grazing plus plant regrowth during the grazing period. Animal unit DMI/d was estimated by the amount of residue removed over the number of days in the grazing period by the number of AUs grazing. Protein and IVTD intake per AU was determined by DMI/d times the percent CP and percent IVTD. The potential for Kentucky bluegrass residue to meet the minimum daily energy and protein intake requirements was estimated quantitatively from protein and digestible dry matter intake (National Research Council, 1996).

The forage value of Kentucky bluegrass was determined by comparing the forage quality of bluegrass to a referenced grass hay with 90% dry matter, 6.4% CP, 51% digestible dry matter, and the 20 yr historical monthly average price of $64.42/ton for grass hay in Idaho (Goering and Van Soest, 1970; National Agricultural Statistics Service, 2005; United States Department of Agriculture, 2005). Kentucky bluegrass residue was adjusted to a 100% dry matter basis to assign an economic value. This analysis assumed the economic value of CP and digestible dry matter energy was comparable.

The effects of Streptomyces hygroscopicus was examined when it was applied as a spore formulation to subplots within the Kentucky bluegrass field plots to determine if strain YCED9 enhanced the degradation rates of the lignocellulosic residues within the field and thereby enhanced bluegrass growth and maintained or increased seed yield in the absence of burning and/or in combination with other treatments.

The field application of S. hygroscopicus, YCED9 was done in April 2005 and 2006 to the following treatments: full-load burn, mechanical, bale-then-burn, bale-then-graze, and full-load graze. For replication, this was repeated over four different plots. Inoculation was done by mixing spores of strain YCED9 [100,000,000 colony forming units (cfu’s) in a whey carrier] into 1 gallon of water. The whey acts as a water soluble carrier and serves as an initial supplemental carbon source for the microbe as it begins to grow and colonize the grass residues in the field. The mixture was sprayed over the 10 by 30 ft plot at a rate of 0.26 gal/min. This gave total bacterial inoculant coverage of 1,000,000 cfu/1 square foot. When the fields were harvested, representative square samples (1 square foot) from the treatments were swathed by hand. The Kentucky bluegrass was dried and clean seed weight determined. Residue and seed yields were compared among each of the treatments and controls to determine what effects YECD9 inoculation had in comparison to the plots not inoculated with the microbe.

Pests and natural enemies were sampled by pitfall trapping in the plots. Pitfall traps were placed to the east of the centerline of each plot. Trap placement was stratified into north-south transects to prevent potential edge effects from neighboring plots on the east and west sides. The 400-ft long plot was divided into four-100-ft sections with one transect per section and one pitfall trap randomly placed along each transect. Pitfall traps were used to sample billbug, carabids and spider populations the week before and following the completion of a treatment. Traps were also used monthly during non-treatment periods to document the phenology and activity of these arthropods. When actively sampling, traps were left open for 3 d after which time their contents were collected and returned to the laboratory for processing. Sampling began on about May 1 and ended around October 15.

The economic analysis assessed the production, price, and financial risk associated with each of the seven bluegrass production systems. Cost and return (CAR) estimates were developed for each system. Ownership costs were allocated over the productive life of the assets required for each system using established capital recovery methods (AAEA 1998). A deterministic comparison of the profitability of the seven production systems was conducted using the CAR estimates, actual bluegrass seed, straw and livestock production yields, and actual output prices. To quantify production, price, and financial risk, a stochastic simulation model was developed using @RISK (Palisade 2000). The base model was the seven bluegrass enterprise budgets obtained from the CAR estimates. Empirical probability distributions for seed, straw and livestock yields were incorporated into the model to account for production risk. Historical bluegrass seed and livestock prices were obtained, and cyclical and long-term trends were modeled using harmonic regression technique tools (Van Tassell et al. 1989). Residuals from these trends were modeled and simulated to account for price risk from bluegrass seed and livestock prices. A planning horizon covering estimated bluegrass stand life under each production system was used in the stochastic simulation. The model was simulated for 1,000 iterations. Random draws from each price and yield distribution were obtained each year of the simulation while maintaining historical correlations (Palisade 2000). The appropriate yields from each system, along with input and output prices, were used to determine yearly income and cash flow. The net present value of each system was determined by summing the present values of the yearly income streams for each of the iterations. Net present values were compared using stochastic dominance techniques (Hardaker et al. 1997). Differences in net present values and other key economic indicators were examined using appropriate t-statistics and chi-square statistics.

An assessment in changes to lifestyle, production, and technology on the farm was determined. Sociocultural factors affected resource use, decision-making, and management practices (Butler and Carkner 2001). Multiple cycles allowed for longitudinal assessment of social change that accompanied technology adoption patterns and production changes. Understanding these types of social dimensions was critical for determining the overall success and implementation of change, adaptation, and evolution to alternative systems.

Data were analyzed with the general linear model procedure of SAS software (SAS Institute, 2001) with blocks and treatments as fixed effects. Data were tested for normality. Treatment effects were declared significant at P ≤ 0.05, and when ANOVA indicated, significant effects means were compared using a Least Significant Difference test (at P ≤ 0.05). Linear regression was used to determine the effect of post-harvest residue on seed yield (SAS 2000).

Research results and discussion:

Agronomic.

The alternate year seed harvest treatments (chemical fallow or mow then harvest) were dropped from the experiment after the second season because very few bluegrass panicles were produced during the seed harvest year.

There was a treatment by location interaction for residue removal, but not seed yield. Burn and graze treatments removed 78 to 87% of the post-harvest residue at Lewis Co. and 64 to 83% at Hatter Creek. The mechanical treatments removed 74% of the residue at Lewis Co. but only 34% at Hatter Creek. Bluegrass variety and environmental factors likely contributed to differences in residue removal response between locations. Mean seed yield across locations was 127 to 140% higher in the graze and burn treatments compared to the mechanical treatment. There was no treatment by year interaction for percent residue removal at Hatter Creek. The burn treatments removed 18 to 21% more residue than the graze treatments. Residue removal in the mechanical treatment was 1.8 to 2.4 times lower than the burn and graze treatments. There was a significant year by treatment interaction for seed yield; however, it was mainly due to greater seed yield in 2006 compared to 2005 except for the graze and mechanical treatments where seed yields were similar. Therefore, treatment main effects were compared. Full-load burn and graze treatments produced significantly more seed than the bale-then-burn, and all treatments produced 42 to 165% more seed than the mechanical treatment.

Forage Utilization.

Previous research indicates that the full load burn removes about 80% of the post-harvest bluegrass residue and non-thermal methods that remove at least 70% of the post-harvest residue have seed yields similar to full load burn. Post-harvest residue must be removed before October 1, because late residue removal can reduce the yield potential of Kentucky bluegrass in northern Idaho.

The livestock stocking density required to remove 80% of the post harvest residue in 30 days was calculated from the dry matter intake of cattle grazing the post harvest residue. Initial and remaining residue levels for the treatment by location and the treatment by year interactions were not significantly different between graze treatments, although tended to be higher in 2004 than 2003 or 2005 since the consumed residue tended to be higher for 2004. Mean residue consumed for the treatment by location and treatment by year interaction was 2.5 to 2.9 times higher in the full-load graze compared to the bale-then-graze treatment. Dry matter intake of residue per AU was not different between treatments and averaged 14.3 and 16.2 lb/d/AU in bale-then-graze and 22.7 and 21.0 lb/d/AU in full-load graze for the treatment by location and treatment by year interactions, respectively. The mean stocking density required to remove 80% of the post-harvest residue in 30 days was 1.5 to 1.75 times higher in the full-load graze compared to the bale-then-graze treatment. The required stocking density tended to be greater in 2004 than 2003 or 2005 due to more bluegrass regrowth during the grazing period in 2004. Full-load graze requires a greater stocking density since the baling operation in the bale-then-graze treatment removes about 50% of the post harvest residue. The lesser stocking density requirement in the bale-then-graze system might enable more Kentucky bluegrass acres to be grazed if the number of cattle available in an area is limited.

Forage Quality.

The forage quality (chemical composition) of Kentucky bluegrass residue was measured in the baled portion of the bale-then-graze treatment, the grazed portion of the bale-then-graze treatment, and the full-load graze treatment. Differences in forage quality can influence the supplement requirements and the monetary value of the forage. Minor differences in ash, CP, and IVTD occurred among treatments. The mean ash content of bales for the treatment by location and the treatment by year interactions (5.8 and 5.9%) was less than bale-then-graze (10.2 and 8.8%) and full-load graze (9.5 and 7.5%). The lower ash content in the bales was suggestive of less soil contamination in the bale samples (Kellems and Church, 2003). CP content varied among treatments in 2004 and 2005. The graze treatment had a higher CP content than the bales. Mean IVTD was significantly greater in the baled residue than in the bale-then-graze, but did not differ from the full-load graze treatment. ADF and lignin contents were not significantly different among treatments. In 2005, NDF was greater in the bale-then-graze compared to the bales, but was not different among treatments in 2004 or 2003.

The CP and IVTD intake was determined based on the post-harvest dry matter intake and its CP and IVTD content. Measuring the CP and IVTD intake allows for calculating feed supplementation. One AU consumed between 5.9 to 24 oz of CP/day and 4.2 to 10.8 lb of digestible dry matter (DDM)/day from the Kentucky bluegrass residue. Crude protein and DDM intake tended to be greater in the full-load graze than bale-then-graze most likely due to higher dry matter intake in the full-load graze. Greater dry matter intake in the full-load graze might have been due to easier consumption of the loose residue early in the grazing period compared to grazing short stubble following baling in the bale-then-graze treatment. There was greater intake, and thus less supplementation required in 2005 than in 2004 or in 2003. The CP and DDM requirements are greater in a lactating cow than a dry cow due to maintenance energy and protein requirements. The bluegrass residue met or exceeded the energy requirements for a dry cow in all treatments each year. In 2005, the Kentucky bluegrass residue in the bale-then-graze and full-load graze treatments exceeded the energy requirements for a dry cow and a cow in middle pregnancy. Little supplement was required (7.8-11.4 oz/d CP and 0.9-4.2 lb/d DDM) to meet the energy requirements of a lactating cow 3 to 4 months postpartum. Bluegrass variety and environmental factors may have an effect on the amount and quality of residue available for cattle consumption.

Forage Economic Value.

The forage economic value of Kentucky bluegrass was derived by comparing the forage quality of Kentucky bluegrass to grass hay with 90% dry matter, 6.4% CP, 51% digestible dry matter, and valued at $64.42 ton (Downing and Gamroth, 1999). The value assigned to the grass hay was derived from the average monthly grass hay price received in Idaho over the past 20 yr (National Agricultural Statistics Service, 2005). Kentucky bluegrass residue was adjusted to a 100% dry matter basis (dry matter) to assign an economic value. Kentucky bluegrass baled dry matter value was similar in 2003 and 2004 ($26.56 and $29.99/ton) but was 2.1 to 2.4 times higher in 2005 ($63.58/ton). It costs between $22.50 and $31.23/ton to rake, bale and stack Kentucky bluegrass dry matter at the edge of the field (Hinman and Schreiber, 2001; Van Tassell, 2002). Thus, the margin available for profit and trucking in 2003 and 2004 was low ($4.67/ton loss to $7/ton profit) compared to between $32 and $41/ton profit in 2005. The forage quality, and thus the forage value of the baled dry matter were much higher in 2005, which increases the margin available for profit. It is uncertain, but preliminary data suggest that fertilizer application might need to be increased in systems where the post-harvest residue is baled and removed from the field since macro (N, P, K, S, Ca, Mg) and micro (B, Fe, Mn, Cu, and Zn) nutrients are removed with the baled residue (Holman and Thill, 2005a). An increase in the amount of fertilizer required will increase the cost of fertilizing and reduce the margin gained from selling the baled residue. The per acre value of bluegrass residue was least for the graze component of the bale-then-graze treatment for all years. The forage value in the full-load graze treatment was $57 and $75/A higher than the value of the bales and grazing (bale-then-graze) in 2004, and $54 and $117/A greater in 2005. The full-load graze forage economic value in 2003 was lower ($4.54/A) than the value of the bales, but $38.50 greater than the graze component of bale-then-graze. The value of the Kentucky bluegrass forage will be offset further by the need to provide feed supplement, fencing, labor, and water.

Post-harvest grazing can remove 80%, or as much residue as burning, when the stocking density and grazing duration are adequate. Seed yield in post-harvest graze treatments were comparable to those in the full-load burn treatment for both environments, indicating post-harvest grazing is a potential non-thermal alternative for managing Kentucky bluegrass residue and sustaining seed production when at least 70% of the residue is removed. However, the long-term impact of grazing on stand productivity and profitability needs to be evaluated. Long-term, full-load grazing likely will be more profitable than bale-then-graze since the profit margin of baled Kentucky bluegrass is small, and the capital outlay to implement grazing (fence, water, etc.) on a per acre basis can be allocated over more AU in the full-load graze treatment compared to the bale-then-graze treatment. In addition, it is generally accepted that harvesting forage through grazing is less expensive than baling. However, 43% fewer cattle are required with the bale-then-graze treatment compared to the full-load graze treatment. The resources (fence, water, supplement, stocking density, and management) required to graze Kentucky bluegrass residue is important to consider since they might not be readily available or easily implemented in all situations. In particular, the high stocking density required to remove the post-harvest residue will likely limit the implementation of post-harvest grazing because of the limited number of cattle available in many bluegrass production areas. A cooperative grazing agreement between grass seed producers and livestock producers might improve the successful implementation of post-harvest grazing practices.

Residue.

Following the 2004 harvest at Hatter Creek, the initial non-standing residue levels were similar across the field and ranged from 1.8 to 2.0 t/A. Non-standing residue levels in all plots were lower in spring 2005 due to a combination of residue management in the fall and natural decomposition processes. Non-standing residue in the spring following the first harvest and application of treatments was significantly greater in the mechanical treatment (0.62 t/A) compared to that measured in all other treatments (0.05-0.32 t/A). Non-standing residue in the full-load graze and bale-then-graze treatments (0.27 t/A and 0.32 t/A, respectively) were statistically similar to that measured in the full-load burn treatment (0.17 t/A). Non-standing residue levels in spring 2006 were similar to those measured in 2005. The amount of non-standing residue in the mechanical treatment (0.65 t/A) was significantly greater than in all other treatments (0.06 to 0.17 t/A). Overall, non-standing biomass or thatch accumulation was significantly greater in the mechanical removal plots after the first application of treatments. This is consistent with reports of increased thatch and reduced yields when mechanical removal replaces burning in established bluegrass seed production systems. The amount of non-standing residue, in each year of the study was not significantly different between the full-load burn and graze plots suggesting that grazing with no residue removal may be a feasible alternative residue management practice in Kentucky bluegrass seed production systems.

Residue removal was determined by comparing post-harvest and post-residue management treatment biomass levels. In 2004 and 2005 residue removal was greatest in the full-load burn treatment and ranged from 92 to 93% of standing and 70 to 74% of non-standing biomass. The bale-then-burn treatment removed from between 81 and 93% of standing and 74 to 83% of non-standing residues. The percent residue removal in the full-load graze and bale-then-graze treatments was similar and ranged from 69 to 81% of standing to 54 to 64% of non-standing biomass. Consistent with the high levels of residue measured in spring, the mechanical treatment only removed 22 to 26% of the standing and 44 to 45% of the non-standing biomass.

Based on the nutrient content of standing biomass in each treatment and the percent residue removed, the potential loss of nutrients due to residue management was calculated. The removal of residue through baling in the mechanical treatment (22 to 26% removal) resulted in the loss of less than 1 lb/A each of calcium, iron, magnesium, phosphorus, sulfur and zinc. Potassium loss equaled 6.4 lb/A, while 5.8 lb/A of nitrogen were lost through baling. Burning of residue, which resulted in greater removal than baling, consumed 25.2 lb of potassium, 1.7 lb of magnesium, 3.6 lb of phosphorous, 2.4 lb of sulfur and 21.0 lb of nitrogen per acre. The fate of nutrients in the burn treatments is not as clear as in the baled plots. While nutrients in ash remaining after a fire are considered plant available, there is little direct evidence of ash layers increasing plant growth through fertilization effects (Daubenmire, 1968; Lloyd, 1972, Vogl, 1974). In addition, nitrogen, phosphorous and sulfur, all of which are known to be critical to Kentucky bluegrass seed production, are highly impacted by fire (DeBano et al., 1998) and are more likely to have been lost from the system. Similar to within the burn treatment, a portion of the nutrients that were consumed by cattle in the graze and bale-then-graze treatments may have been recycled and taken up by plants or stored in the soil for future plant growth.

While the results of our study provide an important first approximation of nutrient loss in each residue management treatment, more detailed nutrient budgets are required to design the most efficient and sustainable systems in regards to nutrient cycling. Nutrient losses are especially important to consider at this site. Potassium concentrations in the standing biomass averaged 1.3% by weight. This is below the critical range of 1.6 to 2% suggested for Kentucky bluegrass grown for forage (Marin and Matocha, 1973). Nitrogen concentrations in the aboveground biomass were also lower than those measured in a similar variety at a site in Kootenai Co., ID. The data suggest that both plant available nitrogen and potassium levels may be limiting yield at this site. Any losses of these nutrients through residue management, therefore, must be accounted for when making fertilizer recommendations.

Soil Properties.

Annual changes in the concentrations of important macronutrients were analyzed at the Hatter Creek site to determine if residue management treatments significantly influenced nutrient availability. Results from 2004 and 2005 indicate that ammonium (NH4+-N) concentrations in the first 60 cm (24 inches) of soil were severely depleted {< 2 mg/kg (1 mg/kg = 1 ppm) in 2004 and < 5 mg/kg in 2005} through plant uptake and/or leaching. No significant differences were detected among the residue treatments at any depth. Ammonium levels were somewhat higher (< 10 mg/kg) in 2006, likely due to the application of additional fertilizer in the early spring of this year. Nitrate concentrations tended to be low across all depths (<12 mg/kg in 2004, <6 mg/kg in 2005 and <4 mg/kg in 2006) with no significant differences among treatments within any year. Nitrate concentrations increased with depth in each year indicating loss below the root zone, especially in the full-load burn treatment in 2004 and 2005. Overall, inorganic nitrogen data suggest that nitrogen fertility may have contributed to the relatively low yields at Hatter Creek site. Nitrogen supply in the fall is a critical factor affecting Kentucky bluegrass seed production. Based on site-specific soil and climatic conditions nitrification and nitrate leaching may be favored during this critical period. These factors need to be balanced when determining fertilizer rates and timings to maximize growth and nitrogen loss beyond the root zone. In all three years, residue management treatment had no significant impact on inorganic nitrogen values when sampled following harvest. This may be due to the overall low values and the time during which soil samples were collected. More detailed sampling immediately following residue removal treatments is necessary to determine shorter-term effects. During the three years of the Hatter Creek study, plant available P levels in the first 10 cm (4 inches) of soil ranged from 43.5 to 60.9 mg/kg and were all above the recommended levels for bluegrass in northern Idaho. Despite the addition of phosphorous through supplemental cattle feed (3% N and 0.4% P) in the grazed plots, significant differences among treatments were not detected among treatments. Overall, the data suggest that the residue management treatments tested had no significant impact on post-harvest levels of plant available nitrogen or phosphorous after three years. Total organic carbon concentrations ranged from 1.5 to 1.9% prior to the application of the treatments. In year three of the Hatter Creek study (2006), significant differences were detected within the first 10 cm of soil. Within this depth, the mean organic carbon percentage within the bale-then-graze treatment (2.2%) was significantly higher than those in the mechanical (1.9%) and full-load graze treatments (1.7%). The mean organic carbon content in the full-load graze treatment was significantly lower than in the full-load burn treatment despite the fact that residue removal was similar in each of these treatments. This indicates that carbon storage in the soil is limited within the graze treatment by factors other than biomass removal/input to the soil. These factors may include differential decomposition processes and/or the degradation of soil physical properties leading to greater losses of soil organic carbon within the graze plots. Total nitrogen and sulfur concentrations followed similar trends to those described above for carbon but with no significant differences among treatments for any depth within any year. Significantly lower organic carbon content within the graze plots relative to the other treatments after three years is a concern. Although it was not measured as part of this study, soil compaction and the loss of aggregation in the graze treatment could enhance the decomposition of soil organic carbon stored in the soil. Depletion of soil organic carbon, a commonly measured indicator of soil quality, may lead to poor soil structure, water infiltration and storage, and nutrient supply/retention. Since soil organic carbon levels change over relatively long time spans, future longer-term study of the impact of grazing should be considered. In all cases, however, stocking rates necessary to remove residue must be balanced with the need to avoid soil compaction and the degradation of soil physical properties. Enhanced Residue Decomposition. In the Streptomyces-inoculated plots, residue decomposition rates were not significantly improved as compared to the non-inoculated plots, over the period of the field experiments. It would take another season’s worth of data to see any differences, if there are any. On the other hand, inoculation did reduce fungal population levels and diversity as compared to non-inoculated controls. These results indicate that Streptomyces inoculations might be useful in controlling fungal diseases that might appear in Kentucky bluegrass fields in the absence of field burning. Additional research over several more seasons is needed to confirm this potential. Pests. A total of 227 billbugs were collected over the course of the 2005 growing season, ranging between 0.12 to 2.0 billbugs/ trap/ treatment. The Denver billbug was the most common species captured during the study followed by the hunting billbug. No treatment effects (F = 1.34, df = 8, 24 P = 0.27) on billbugs (both species combined) were detected over the 2005 growing season. Correlation analysis revealed no significant relationships between billbug populations and other measured variables (e.g. carabids, spiders, seed yield and biomass) during the study. In contrast, a treatment effect was detected on July 18, 2005. During this single sample more billbugs (species combined) were found in the bale-then-graze and full-load graze treatments than in the Mow/Harvest and Chemical Fallow/Harvest treatments. Natural Enemies. Seventy four carabid beetles were captured over the 2005 growing season, ranging between 0.04 to 0.25 carabids/trap/treatment. No treatment effects (F = 1.34, df = 8, 24 P = 0.27) on carabids (combined group) or by functional guild were detected over the 2005 growing season. However, a significant treatment by date interaction effect on the Amara spp. (F72, 216 = 1.9, P < 0.01) was observed when seed predators were broken out by genus. This group was significantly more abundant in bale-then-graze and full-load graze treatments than in full-load burn on the first (P < 0.05) and third week (P < 0.05) of the 2005 study. Several significant correlations were found between carabids and independent variables during the study. Most notably, carnivorous carabids and all carabids combined were inversely correlated with non-standing biomass, respectively (carnivores: R = -0.36, P = 0.03; all carabids: R = -0.41, P = 0.01). Findings from this research indicate that pest and natural enemies responded more or less the same to Kentucky bluegrass nonthermal versus thermal residue management practices at Hatter Creek Ranch. The lack of treatment effects on billbugs is encouraging, suggesting that nonthermal alternatives to burning do not increase abundance of these pest species. In contrast, the lack of response of predators to nonthermal practices is surprising, as one might expect predators to be enhanced in nonthermal plots. Lack of differences between treatments during the study may be due to multiple factors. First, these results are based on a single year of sample data. Population and community structure of arthropods can change dramatically from year to year so these data may not provide a true picture of arthropod response to nonthermal treatments over years. Second, field burning may not significantly affect arthropod populations owing to temporal asynchrony between beetle phenology and burn events. In the Eastern US, activity of billbugs in turfgrass has been shown to occur from April-July with populations peaking in June, tapering off dramatically by August, and staying low for the remainder of the year (Johnson-Dicalese et al. 1990). A similar distribution pattern has been documented for many field inhabiting carabid species of northern Idaho (Hatten et al. 2007a) and for several weevil species as well (Hatten et al. unpublished). Indeed, during this study, billbugs peaked on July 2 and decreased after the second week of the same month. This phenological pattern results from the immigration of over wintering adults during spring, reproduction and offspring development from May-July (all the while feeding on bluegrass), and lastly the emergence of adults in July and early August. As field burning generally occurs in August or September, there is ample time for winged adults to disperse prior to field burning. Third, plot effects may have interfered with our results. The plots at Hatter Creek Ranch are quite large, but flying insects including weevils and carabids can easily move between plots potentially confounding treatment effects. Forth, sampling biases due to effects of vegetation structure on insect movement could have influenced trap catch during the study. Hatten et al. (2007b) found that the capture rates of pitfall trap for carabid beetles was lower in no-till wheat fields with dense crop residue on the soil surface than in conventional-tillage fields with bare soil. It is suggested that beetle movement may have been similarly affected in the nonthermal versus thermal systems at Hatter Creek Ranch. The negative correlations observed between total carabids and non-standing biomass during the study would appear to support this hypothesis. Moreover, trap catch of both billbugs and carabids was quite low during the study suggesting alternative sampling methods might be needed to improve relative abundance estimates in this system. Movement impedance might also explain the one date during the study in which billbugs were elevated in the bale-then-graze and full-load graze treatments. This sample date followed swathing of all treatments except the Mow/Harvest and Chemical Fallow/Harvest. These treatments were in their fallow year, which means that the grass height at the time of sampling was quite high. The low activity of billbug adults in these treatments could be due to hindered movement through the tall grass. On the other hand, if sampling biases occurred they were limited to specific groups because we found no significant correlations between seed predating carabids or the billbugs and vegetation biomass (standing or nonstanding). Sociological Survey. Final analyses were completed from the sociological data collected as a component within the project. Quantitative as well as qualitative data combined to enhance an understanding of attitudes and perceptions related to thermal residue removal practices, as well as alternative practices. Quantitative data resulted from a comprehensive general public telephone survey (N = 2,010) in 2004 with a 60% response rate that covered a 10-county area in the production region of study. The survey asked respondents about general air quality issues in their community, health-related impacts from air quality concerns, general perceptions of agricultural burning, and more specific items about the case of burning Kentucky bluegrass residue. Analyses were divided into two geographical schemes: 1) the first created five sub-zones to compare whether respondent views differed across the region; and 2) the second focused on county “type” to delineate whether size and character of the county’s population (‘urban’, ‘rural center’, or ‘open country’) had an affect on response patterns. Over the course of the project, 21 supplemental qualitative interviews were also conducted with various stakeholders within the issue. The analyses below present several of the key findings from these combined data. Related to one of the areas of interest in the project, the project team identified the rates of population change in the study region since 1990. The data indicate extremely high rates of in-migration in some of the areas, while others remain stagnant or experienced slight declines in population for the same period. These findings suggested the need to inquire about effects of newcomers vs. old timers and assess whether length of residence was a primary determining factor in overall attitudes about Kentucky bluegrass burning. Related to this pattern, the data show a relationship between length of residence and whether respondents preferred to continue to allow Kentucky bluegrass burning under current regulations, reduce burning, or eliminate the practice altogether. These data indicate two primary patterns. First, the large majority of respondents still favored continuing the right to burn bluegrass residue, and the least favored a total burn ban. Within categories of length of residence, length of residence does affect these views with longer-term residents tending to support continuing to burn more than shorter-term residents. In the survey, respondents were also asked their perception on the effect of the Idaho Smoke Management plan, cooperatively managed between State agencies and Nez Perce and Coeur d’Alene Indian tribes. Although the plan had only been in effect for one burn season prior to the data collection, the data indicate a sign of some perceived progress on the part of the public in relation to the Smoke Management Plan. Approximately one-third of all survey respondents indicated some health-related impact they perceived to be related to smoke from agricultural burning. Given this substantive level of self-reported impact, the research team cross-tabulated this with individuals’ preferences on burning bluegrass residue. The data demonstrate that even those who claim to be impacted by the smoke do not all prefer to end, or even reduce the amount of burning in relation to the agricultural production. Together, these data indicate a complexity of factors (population in-migration, environmental quality, agricultural production) that have an affect on public perceptions and attitudes for clean air. Although not reported here, the survey results showed that many residents understood the relationship and perceived a tradeoff of a loss of open-space in the landscape if the practice of bluegrass burning is eliminated based on local discourse about farmers selling the land if they lose those rights. The sociological components of this project remain complex, as ongoing litigation also led to a recent decision by the Ninth District Court of Appeals affecting the viability of the Idaho’s State Implementation Plan. During the last few months, this latest controversy has continued to generate conflict and negative perceptions between stakeholder groups involved in the debate over whether to continue to allow burning. Dissemination of Information. A web site was constructed and maintained. County extension educators and scientists disseminated information to growers, field consultants, and the public via extension field tours and presentations. Activities included field tours (annual Lewis or Latah County extension crop tours and special half-day field tours at critical phases of the research (e.g., fall grazing and prior to grass seed harvest) and presentations (winter extension meetings put on by field consultants and/or county extension educators). Publications included popular news articles and extension bulletins. Findings also were presented to scientific audiences in refereed publications and presentations. Literature Cited: Ayre, K. and G.R. Port. 1996. Carabid beetles recorded feeding on slugs in arable fields using ELISA. p. 411-418, In 1996 BCPC Symposium Proc. 66 Slug and snail pest in agriculture. American Agricultural Economics Association (AAEA). 1989. Commodity costs and returns estimation handbook. Ames, Iowa. Bolton, A., L.D. Incoll, S.G. Compton, and C. Wright. 1996. The effects of management of rotational set-aside on abundance and dispersion of slugs. p. 109-116, In 1996 BCPC Symposium Proc. 66 Slug and snail pest in agriculture. Butler, L.M. and R. Carkner. 2001. “Bridges to Sustainability: Links between Agriculture, Community, and Ecosystems. Pp. 157-73 in Interactions Between Agroecosystems and Rural Communities, ed. C. Flora. Boca Raton, LA: CRC Press. Chamberlain, K. and D. L. Crawford. 2000. Thatch biodegradation and antifungal activities of two lignocellulolytic Streptomyces strains in laboratory cultures and in golf green turfgrass. Can. J. Microbiol. 46:550-558. Daubenmire, R. 1968. Ecology of fire in grasslands. Advan. Ecol. Res. 5:209-266. DeBano, L.F., D.G. Neary, and P.F. Ffolliott. 1998. Fire’s Effects on Ecosystems. John Wiley & Sons, Inc., New York, NY. Doumbou, C.-L., M. K. Hamby-Salove, D. L. Crawford, and C. Beaulieu. 2002. Actinomycetes, promising tools to control plant diseases and to promote plant growth.Phytoprotection. 82(3):85-102. Downing, T., and M. Gamroth. 1999. Valuing Forages Based on Moisture and Nutrient Content. Pacific Northwest Extension Publication 259. Goering, H.K., and P.J. Van Soest. 1970. Forage fiber analyses. Apparatus, reagents, procedures, and some applications. USDA Agriculture Handbook No. 379. US Gov. Print. Office. Hardaker, J.B., R.B.M. Huirne, and J.R. Anderson. 1997. Coping with risk in agriculture. CAB International. New York, NY. Hatten, T.D., N.A. Bosque-Pérez, J.R. LaBonte, S.O. Guy and S. D. Eigenbrode. 2007a. Effects of tillage on the activity-density and diversity of carabid beetles in spring and winter crops. Environmental Entomology 36 (2): 356-368. Hatten, T.D., N.A. Bosque-Pérez, J. Johnson-Maynard, and S. D. Eigenbrode. 2007b. Tillage differentially affects the capture rate of pitfall traps for three species of carabid beetles. Entomologia Experimentalis et Applicata 124: 177-187. Hinman, H.R., and A. Schreiber. 2001. The effect of the “no-burn ban” on the economic viability of producing bluegrass seed in select areas of Washington State. Farm Business Management Report (Economic Report) EB1922E. Washington State University. Holman, J.D., and D.C. Thill. 2005a. Kentucky bluegrass seed production. University of Idaho Extension Publication 842. Johnson-Cicalese, J.M., G.W. Wolfe, and C.R. Funk. 1990. Biology, Distribution, and Taxonomy of Billbug Turf Pests (Coleoptera: Curculionidae). Environmental Entomology 19:1037-1046. Kellems, R.O., and D.C. Church. 2003. Livestock Feeds and Feeding. Fifth ed. Pearson Education, Inc., New Jersey. Kunkel, B.A., D.W. Held, and D.A. Potter. 1999. Impact of halofenozide, imidocloprid, and bendiocarb on beneficial invertebrates and predatory activity in turfgrass. Journal of Economic Entomology 92(4): 922-930. Kuo, S. 1996. Phosphorus, p. 869-920, In D. L. Sparks, et al., eds. Methods of soil analysis. Part 3. Chemical methods. Soil Sci. Soc. Am., Madison, WI. Lloyd, P.S. 1972. Effects of fire on a Derbyshire grassland community. Ecology 53. Mahler, R.L., and R.D. Ensign. 1989. Evaluation of N, P, S and B fertilization of Kentucky Bluegrass see in northern Idaho. Commun. in Soil Sci. Plant Anal. 20:989-1009. Martin, W.E., and J.E. Matocha. 1973. Plant analysis as an aid in the fertilization of forage crops. P. 393-426. In L.M Waslsh and J.D. Beaton (eds.) Soil testing and plant analysis. Soil Sci. Soc. of Am. Madison, WI. Mulvaney, R.L. 1996. Nitrogen-inorganic forms, p. 1123-1185, In D. L. Sparks, et al., eds. Methods of soil analysis. Part 3 Chemical Methods. Soil Sci. Soc. Am., Madison, WI. National Agricultural Statistics Service. 2005. Historical data. [Online] (verified July 20, 2005). National Research Council. 1996. Nutrient requirements of beef cattle. Seventh ed. National Academy Press. Niemczyk, H.D. and D.J. Shetlar. 2000. Destructive turf insects, 2nd ed. HDN Books, Wooster, OH. Nyffeler, M. and K.D. Sunderland. Composition, abundance and pest control potential of spider communities in agroecosystems: a comparison of European and US studies. Agriculture, Ecosystems and Environment 95(2-3): 579-612. Palisade. 2000. @RISK, advance risk analysis for spreadsheets. Palisade Corporation, Newfield, NY. SAS Institute, I. 2001. SAS/STAT user’s guide. Version 9.3. SAS Institute, Inc., Gary, NC. Schlesinger, W.H. 1991. Biogeochemistry: An Analysis of Global Change. 2nd ed. Academic Press, San Diego. Southwood, T.R.E. 1978. Ecological methods, with particular reference of the study of insect populations. 2nd Edition. John Wiley & Sons, New York. Stott, D.E., A.C. Kennedy, and C.A. Cambardella. 1999. Impact of soil organisms and organic matter on soil structure, p. 57-73, In R. Lal, ed. Soil quality and soil erosion. CRC Press, Boca Raton, FL. Stott, D.E., H.F. Stroo, E.T. Elliott, R.I. Papendick, and P.W. Unger. 1990. Wheat residue loss from fields under no-till management. Soil Sci. Soc. Am. J. 54:92-98. Sunderland, K. D. 2002. Invertebrate pest control by Carabidae, pp. 165-214. In J. M. Holland [ed.], The Agroecology of Carabid Beetles. Intercept Limited, Andover. Trejo-Estrada, S., I. Rivas-Sepulveda, and D. L. Crawford. 1998. In vitro and in vivo antagonism of Streptomyces violaceusniger YCED9 against fungal pathogens of turfgrass. World J. Microbiol. Biotechnol. 14:865-872. Van Tassell, L.W. 2002. Assessment of non-thermal bluegrass seed production. University of Idaho Research Bulletin 161. University of Idaho. VanTassell, L.W., J.R. Conner, and J.W. Richardson. 1989. The impact of range improvements on the success and survivability of producers in the Eastern Rolling Plains of Texas. Texas Agricultural Experiment Station Bulletin No. 1618, July. Vogl, R.J. 1974. Effects of Fire on Grasslands., p. 139-194, In T. T. Kozlowski and C. E. Ahlgren, eds. Fire and Ecosystems. Academic Press, Inc., New York, NY. Walenta, D.L., S. Rao, C.R. McNeal, B.M. Quebbeman, and G.C. Fisher. Sphenophorus spp., a complex billbug community infesting Kentucky bluegrass seed fields in the Grande Ronde valley of northeastern Oregon. Not Published. Oregon State University. Walker, D.J. et al. 1987. “Long-term productivity benefits of soil conservation.” In: STEEP-Conservation Concepts and Accomplishments, L.F. Elliot, ed., Washington State University, Pullman, WA.

Research conclusions:

Results demonstrate that grazing can be used as an effective tool to remove post-harvest residue in Kentucky bluegrass seed production systems. It is expected that growers in areas where adequate cattle are present will adopt this practice more in the future, especially considering current restrictions on field burning.

Switching to baling as a residue removal method tool will require most farmers to purchase a baler and stacking equipment or have the residue custom harvested. A producer would need to harvest over 1,800 A before it would be profitable to purchase haying equipment versus having it custom harvested.

Two species of billbugs (pest species) and numerous species of carabid beetles (natural enemies) occurring at the site and more importantly occurring in bluegrass seed production systems of northern Idaho were identified. It also was determined that billbugs do not appear to be enhanced by nonthermal versus thermal residue management practices. This is likely due to asynchrony between billbug phenology and timing of fire applications in thermal systems. Our results suggest that nonthermal residue management practices have little effect on pests or natural enemies relative to thermal management practices. Hence, we anticipate few management adjustments for control of these pest species. Research results from a concurrent study at Worley, ID., appear to corroborate these finding, indicating that nonthermal management systems do not aggravate billbug populations in Kentucky bluegrass seed production systems in northern Idaho.

The sociological components of this project remain complex, as ongoing litigation also led to a recent decision by the Federal Ninth District Court of Appeals affecting the viability of the Idaho’s State Implementation Plan (disallows all agricultural burning on non-tribal lands in Idaho). During the last few months, this latest controversy has continued to generate conflict and negative perceptions between stakeholder groups involved in the debate over whether to continue to allow burning.

The sensitivity of the suppression yield assumptions was tested by varying suppression yield distributions. Given the cost of suppression and the absence of seed production during the suppression fallow year, suppression techniques are not profitable unless yields can be increased by 25 to 50% over those assumed in the base conditions.

Participation Summary

Educational & Outreach Activities

Participation Summary

Education/outreach description:

Crawford, D. L. M. Kowalski, M. A. Roberts, G. Merrell, and L. A. Deobald. 2005. Discovery, development and commercialization of a microbial antifungal biocontrol agent, Streptomcyes lydicus WYEC108: history of a decade long endeavor. Society for Industrial Microbiology News. 55: 88-95.

Holman, J.D. 2005. Kentucky bluegrass (Poa pratensis L.) non-thermal and reduced thermal residue management and forage utilization. Ph.D. Dissertation, University of Idaho.

Holman, J., C. Hunt, and D. Thill. 2007. Structural composition, growth stage, and cultivar affects on Kentucky bluegrass forage yield and nutrient composition. Agronomy Journal. 99(1):195-202.

Holman, J., C. Hunt, J. Johnson-Maynard, L. Van Tassell, and D. Thill. 2007. Livestock use as a non-thermal residue management practice in Kentucky bluegrass seed production systems. Agronomy Journal. 99(1):203-210.

Holman, J., C. Hunt, and D. Thill. 2006. Post harvest affects on Kentucky bluegrass forage quality. In Annual meetings abstract [CD-ROM]. ASA, CSSA, and SSSA.

Holman, J., D. Thill, J. Johnson-Maynard, C. Hunt, L. Van Tassell, J.D. Wulfhorst, J. McCaffrey. 2006. University of Idaho Kentucky bluegrass seed production research update. Ag Equipment Power. Clinton Publishing, Inc. ISSN. 1535-9409.

Holman, J.D. and D.C. Thill. 2005. Kentucky bluegrass growth, development, and seed production. UI Ext. Bull. 843, p. 12.

Holman, J.D. and D.C. Thill. 2005. Kentucky bluegrass production. UI Ext. Bull. 842, p. 12.

Holman, J., J.L. Johnson-Maynard, J. Reed, and K.J. Umiker. 2005. Time of fertilizer application study p. 12. Department of Plant, Soil, and Entomological Sciences Kentucky Bluegrass Field Tour Report. June 9, 2005 Potlatch, ID.

Holman, J, D. Thill, J. Johnson-Maynard, K. Umiker, C. Hunt, and J. McCaffrey. 2005. Effect of reduced-burn and no-burn residue management on Kentucky bluegrass seed production. Proc. Western Soc. Crop Sci.

Holman, J.D., D.C. Thill, J.L. Johnson-Maynard, C. Hunt, J. McCaffrey, L. Van Tassell, J.D. Wulfhorst, D. Crawford, and J. Reed. 2004. A team approach to addressing a critical grass seed production issue. ASA/CSSA/SSSA Annual Meetings Abstracts (available on CD-ROM). October 31-November 4. Seattle, Washington.

Holman, J.D., C. Hunt, D.C. Thill, J.L Johnson-Maynard, and K.J. Umiker. 2004. The integration of livestock into Kentucky bluegrass seed production. ASA/CSSA/SSSA Annual Meetings Abstracts. (available on CD-ROM). October 31-November 4. Seattle, Washington.

Kentucky bluegrass website. http://agweb.ag.uidaho.edu/BlueGrass/

Min Jin Kang, Doctor of Philosophy (Ph.D.), Microbiology, Molecular Biology and Biochemistry. 2006. Characterization of Novel Members of the Streptomyces violaceusniger Clade and Characterization of Antibiotic Biosynthesis Genes from Streptomyces lydicus WYEC108. Ph.D. Thesis, University of Idaho, Moscow, ID.

Morgan Poloni, Master of Science (Non-Thesis M.S.), Environmental Science, May 2006. Thesis Project Title: Alternatives to Field Burning of Kentucky Bluegrass. University of Idaho, Moscow, ID.

Reed, J., D. Thill, and J. Holman. 2004. Herbicide suppression of Kentucky bluegrass stands in an alternate year production system. Proc. ASA-CSSA-SSSA.

Robertson, J.D., J. Johnson-Maynard, K. Umliker, and D. Thill.2006. Residue and nitrogen dynamics in northern Idaho Kentucky bluegrass seed. Proc. ASA-CSSA-SSSA.

Strap, J. L. and D. L. Crawford. 2006. Microbial ecology of Streptomyces in soil and
rhizospheres. In, Molecular Techniques for Soil and Rhizosphere Microorganisms.
J. E. Cooper and J. R. Rao, Editors. CABI Publishing Co., Wallingford, Oxfordshire,
UK. In Press.

Wolfley, J., L. Van Tassell, R. Smathers, J. Holman, D. Thill, J. Reed, 2006. Economic analysis of experimental thermal and non-thermal residue management systems for Kentucky bluegrass seed. University of Idaho Extension Bulletin. UI Bulletin 847. pp. 19

Wolfey, J., L. Van Tassell, D. Thill, and J. Holman. Evaluation of Non-thermal methods in the production of Kentucky bluegrass seed. 2006. Western Agricultural Economics Association Meetings, Anchorage, AK. June. Journal of Agricultural and Resource Economics 31,3.

Wulfhorst, J. D., Stephanie L. Kane, Larry W. Van Tassell, Beth Johnson, Romuald Afatchao, Katelyn Peterson, and Bernardo Alvarez. 2006. Public Attitudes and Perceptions of Air Quality and Bluegrass Seed Residue Burning in Northern Idaho. UI Res. 166.

Wulfhorst, J.D., L.W. Van Tassell, B. Johnson, John Holmon, and D. Thill. 2006. An industry amidst conflict and change: Practices and perceptions among Idaho’s bluegrass seed producers. Bul. 165, p.29.

Presentations:

Holman, J., D. Thill, J. Johnson-Maynard, J. McCaffrey, L. Van Tassell, J.D. Wulfhorst, C. Hunt. “University of Idaho Kentucky bluegrass field tour”. University of Idaho, Worley, ID. (May 23, 2006).

Holman, J., D. Thill, J. Johnson-Maynard, J. McCaffrey, L. Van Tassell, J.D. Wulfhorst, C. Hunt. “University of Idaho Kentucky bluegrass field tour”. University of Idaho, Potlatch, ID. (June 6, 2006).

Holman, J. 2006. Reduced and non-burn residue management alternatives in Kentucky bluegrass seed production fields. Sports Turf Magazine. March 22, 2006.

Johnson-Maynard, J.L., J.D. Robertson, K.J. Umiker, D.C. Thill, and J. Reed. 2006. Development of non-thermal residue management practices for northern Idaho Kentucky bluegrass seed production systems. p.12. Annual branch meeting of the Western Society of Soil Science, oral session abstracts. June 19-21. Park City, Utah.

Johnson-Maynard, J.L., K.J. Umiker, and D.C. Thill. 2003. Residue decomposition and nutrient loss in non-thermal Kentucky bluegrass systems. P. 59-60. Proceedings of the American Association for the Advancement of Science Pacific Division. Vol. 22. Part 1.

Johnson-Maynard, J.L., K.J. Umiker, and D.C. Thill. 2003. Non-thermal residue management and nutrient cycling in Kentucky bluegrass seed production systems. P. 87. Soil and Water Conservation Society 2003 Annual Conference Abstracts. July 26-30.

Roberston, J.D., J.L. Johnson-Maynard, D.C. Thill, K.J. Umiker, and J. Reed. 2005. Residue management and nitrogen dynamics in northern Idaho Kentucky bluegrass seed production systems. ASA/CSSA/SSSA Annual Meeting Abstracts (available on CD-ROM). Nov. 6-10. Salt Lake City, UT.

Thill, D.C., J.D. Holman, et. al. 2005. Integration of cattle as a non-thermal alternative to managing Kentucky bluegrass residue. Field Day, Aug. 31, Potlatch, ID.

Thill, D.C. 2005. Kentucky bluegrass field tours. Worley, Idaho, June 2; Potlatch, Idaho, June 9.

Umiker, K.J., J. Reed, J.L. Johnson-Maynard, D.C. Thill, and J. Holman. 2006. Early fall nitrogen application in Kentucky bluegrass for enhanced seed yield p. 24-30. University of Idaho Kentucky Bluegrass Field Tour Report. June 6, 2006. Potlatch, ID.

Van Tassell, Larry. “Economics of Alternative Bluegrass Production Systems.” Hatter Creek Kentucky Bluegrass Seed Field Day, Potlatch, ID. June 6, 2006.

Van Tassell, Larry and John Klein. “The Economic Efficiency of Bluegrass Production Systems.” Hatter Creek Kentucky Bluegrass Seed Field Day, Potlatch, ID. June 5, 2007.

Project Outcomes

Project outcomes:

Forage Economic Value.

The forage economic value of Kentucky bluegrass was derived by comparing the forage quality of Kentucky bluegrass to grass hay with 90% dry matter, 6.4% CP, 51% digestible dry matter, and valued at $64.42 ton (Downing and Gamroth, 1999). The value assigned to the grass hay was derived from the average monthly grass hay price received in Idaho over the past 20 yr (National Agricultural Statistics Service, 2005). Kentucky bluegrass residue was adjusted to a 100% dry matter basis to assign an economic value. Kentucky bluegrass baled dry matter value was similar in 2003 and 2004 ($26.56 and $29.99/ton) but was 2.1 to 2.4 times higher in 2005 ($63.58/ton). It costs between $22.50 and $31.23/ton to rake, bale and stack Kentucky bluegrass dry matter at the edge of the field (Hinman and Schreiber, 2001; Van Tassell, 2002). Thus, the margin available for profit and trucking in 2003 and 2004 was low ($4.67/ton loss to $7/ton profit) compared to between $32 and $41/ton profit in 2005. The forage quality, and thus the forage value of the baled dry matter were much higher in 2005, which increases the margin available for profit. It is uncertain, but preliminary data suggest that fertilizer application might need to be increased in systems where the post-harvest residue is baled and removed from the field since macro (N, P, K, S, Ca, Mg) and micro (B, Fe, Mn, Cu, and Zn) nutrients are removed with the baled residue (Holman and Thill, 2005a). An increase in the amount of fertilizer required will increase the cost of fertilizing and reduce the margin gained from selling the baled residue. The per acre value of bluegrass residue was least for the graze component of the bale-then-graze treatment for all years. The forage value in the full-load graze treatment was $57 and $75/A higher than the value of the bales and grazing (bale-then-graze) in 2004, and $54 and $117/A greater in 2005. The full-load graze forage economic value in 2003 was lower ($4.54/A) than the value of the bales, but $38.50 greater than the graze component of bale-then-graze. The value of the Kentucky bluegrass forage will be offset further by the need to provide feed supplement, fencing, labor, and water.

Economic Results of Suppression Treatments.

A stochastic simulation model was developed using cost and return estimates for the bluegrass seed production methods examined (mechanical, chemical suppression, and hay suppression) along with necessary rotation crops (spring and winter wheat). Prices of bluegrass seed, hay, and wheat were modeled using harmonic regression techniques to capture the inherent price cycles. On-farm bluegrass seed yields (mechanical treatment) were modeled using a log-linear function, and suppression yields were represented by empirical distributions conditional on mechanical treatment yields. Weibull distributions were used to model spring and fall wheat yields. The simulation model was used to report the economic feasibility of each treatment for the expected stand life. Because of unequal treatment lives, annual annuities from the net present values of the net returns to land, management and risk were developed.

Though mean net returns from all treatments were negative, the highest net returns per acre were realized from the mechanical treatment (-$11.41), followed by the chemical suppression treatment (-$22.30). The annual returns per acre for the mechanical and hay suppression treatments were close at -$28.03 and -$31.59 due to an assumed 15% seed yield reduction from the chemical suppression seed yields. This occurred because of limited stand density thinning by these latter treatments. The mechanical treatment also dominated all suppression treatments when compared by second-degree stochastic dominance. The mechanical treatment would have dominated the others by first degree stochastic dominance if not for the higher probability of extremely negative returns obtained from iterations when seed yields were low and stand establishments failed. Chemical suppression was preferred by all levels of risk aversion over the mechanical and hay suppression treatments as determined by first-degree stochastic dominance, while mechanical suppression was likewise preferred to hay suppression.

The sensitivity of the suppression yield assumptions was tested by varying suppression yield distributions. Given the cost of suppression and the absence of seed production during the suppression fallow year, suppression techniques are not profitable unless yields can be increased by 25 to 50% over those assumed in the base conditions.

Economic Results of Livestock Treatments.

Operating and ownership costs for the full-load burn, bale-then-burn, mechanical, bale-then-graze, and full load graze treatments were determined using data from the trials and interviews with farmers. Fertilizer and herbicide costs were consistent among treatments. Harvesting costs included cleaning and bagging. The highest operating costs were for the grazing treatments as a 3-strand high tensional electric fence was required ($4.33/A), livestock water needed to be provided ($3.76/head), and a 25% protein feed supplement was necessary ($5.57/head). The highest ownership costs were associated with treatments requiring baling, with the mechanical treatment also requiring a harrow operation. Bluegrass stand establishment was estimated at $330/A and was amortized over a 6 yr stand life.

Annual net returns and the net present value of the three returns were determined. Actual plot yields were used to determine returns per acre and bluegrass seed was valued at $1/lb. Baled straw yields ranged from approximately 1.5 to 2.5 t/A and was valued at $45/t. Two scenarios were examined for the livestock treatments: (1) the bluegrass seed producer does not receive a return from the livestock owner, and (2) the bluegrass seed producer receives $13/head/mo in return for grazing. All net returns were negative except for the bale-then-burn treatment in 2004. Low yields were the main culprit for the negative returns. The bale-then-graze treatment offered the highest average annual net return (-$180/A) and NPV (-$552/A) when the producer was able to benefit from a return on the baled residue and a $13/head return from grazing. The bale-then-burn was the next most profitable treatment, with an average annual -$234/A return and a -$636 NPV. The bale-then-burn was followed closely by the full-load burn treatment with an average annual return of -$224/A. Higher ownership costs and lower yields made the mechanical treatment one of the least financially preferable treatments.

The full-load burn treatment has been the most common residue treatment method among farmers in northern Idaho. Switching to a treatment that utilized baling as a residue removal method tool will require most farmers to purchase a baler and stacking equipment or have the residue custom harvested. An examination was made of these two alternatives to determine the number of acres required before it is profitable for the producer to purchase haying equipment. This analysis examined the breakeven acreage for yields of 0.75, 1.0, 1.5 and 2.0 t/A, because most custom operators charge by the ton. A producer would need to harvest over 1,800 A before it would be profitable to purchase haying equipment versus having it custom harvested. Breakeven acreage for yields of 1, 1.5, and 2 t/A were approximately 825, 225, and 125 A, respectively.

Farmer Adoption

Post-research farmer adoption has not been evaluated. A separate follow up survey will be required to determine adoption rate. The January 2007 ruling by the Federal Ninth District Court of Appeals on Idaho’s State Implementation Plan likely will confound survey results. The ruling resulted in an immediate ban on burning of residue on agricultural lands in Idaho, except within tribal reservation boundaries. Certain tribes will continue to allow burning of residue on agricultural lands within the boundaries of their reservation.

Our results suggest that nonthermal residue management practices have little effect on pests or natural enemies relative to thermal management practices. Hence, we anticipate few management adjustments for control of these pest species. Research results from a concurrent study at Worley, ID., appear to corroborate these finding, indicating that nonthermal management systems do not aggravate billbug populations in Kentucky bluegrass seed production systems in northern Idaho.

Recommendations:

Areas needing additional study

Post-harvest grazing can remove 80%, or as much residue as burning, when the stocking density and grazing duration are adequate. Seed yield in post-harvest graze treatments were comparable to those in the full-load burn treatment for both environments, indicating post-harvest grazing is a potential non-thermal alternative for managing Kentucky bluegrass residue and sustaining seed production when at least 70% of the residue is removed. However, the long-term impact of grazing on stand productivity and profitability needs to be evaluated.

Post-research farmer adoption has not been evaluated. A separate follow up survey will be required to determine adoption rate.

Research is needed to assess the effectiveness of sheep in removing post harvest bluegrass residue. Sheep producers in Idaho are being displaced from historical grazing lands in Hells Canyon and are looking for alternative grazing allotments.

While the results of our study provide an important first approximation of nutrient loss in each residue management treatment, more detailed nutrient budgets are required to design the most efficient and sustainable systems in regards to nutrient cycling.

During the three years of this study, interest among farmers into nitrogen management in Kentucky bluegrass seed production systems has increased, in part due to the steady increase in nitrogen fertilizer costs. This study was not designed to test fertilizer application rates/times. These types of studies, however, should be conducted in non-thermal systems.

Since soil organic carbon levels change over relatively long time spans, future longer-term study of the impact of grazing should be considered.

The results indicate that Streptomyces inoculations might be useful in controlling fungal diseases that might appear in Kentucky bluegrass fields in the absence of field burning. Additional research over several more seasons is needed to confirm this potential.

Insect sampling provided information on the abundance, phenology and composition of pest and natural enemies of Kentucky Bluegrass seed production systems in N. Idaho. However, we have some concerns regarding the sampling method (e.g. pitfall trapping), used in the Hatter Creek Farms study. It is our belief that the method underestimates arthropod relative abundance in grass seed systems, and it might yield biased estimates of relative abundance between treatments. Our finding of a negative correlation between carabid abundance and nonstanding biomass provides some evidence for this concern.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.