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

2004 Annual 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

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


Team members established the 12 ha field experiment during spring 2004. In a 2003 preliminarily experiment, bale/burn, bale/graze, full load burn, full load graze, and mechanical treatments removed 87, 86, 84, 78, and 74% of the post-harvest residue, respectively. Baling removed 71% of the post-harvest residue. Seed yield was negatively correlated with the amount of residue remaining after the residue removal treatment the previous fall. Results suggest that residue removal alone does not promote regrowth of bluegrass, but rather residue removal and plant available nitrogen need to occur soon after harvest. Residue, insect, and soil samples were collected from both sites and are being analyzed.

Objectives/Performance Targets

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


A preliminary study was conducted during summer 2003 to determine proper cattle stocking rates for bluegrass residue utilization. Based on information learned from the preliminary studies, team scientists have made some modifications to the treatments contained in the proposal. The most significant change is that there will be no treatment that requires cattle tp utilize all post-harvest bluegrass residue. About 60-70% of the residue was removed by bailing immediately after seed harvest and before grazing. The period of time required for cattle to remove the entire amount of post-harvest residue was too long to allow for needed fall regrowth of the bluegrass plants. The long-term experiment was established during spring 2004 on a 12 ha site near Moscow, Idaho. Fencing materials were purchased and the fence installed during spring 2004 for enclosure treatments that will use cattle to manage bluegrass residue. The team held several planning meeting during the past year. Palouse (2003 experiment) and Kenblue (2004 experiment) produced about 6750 kg/ha of above-ground biomass. In 2003, bale/burn, bale/graze, full load burn, full load graze, and mechanical removed 87, 86, 84, 78, and 74% of the post-harvest residue, respectively. Baling alone removed 4,790 kg/ha of the post-harvest residue in 2003 and 3,262 kg/ha in 2004.
Seed Yield: A baseline seed yield was taken for each plot at both locations prior to establishing treatments. The baseline seed yield averaged 1188 and 627 kg/ha at the 2003 and 2004 sites, respectively. The 2003 site yielded less in 2004 than 2003 due to the dry fall conditions in 2003. Seed yield ranged from 267 to 460 kg/ha of uncleaned seed across treatments in 2004. Full load burn yielded 105 kg/ha less than bale/burn, and did not yield significantly different from the other treatments. Seed yield in the bale/graze treatment was statistically equal to bale/burn, and 125 to 194 kg/ha more than mechanical. Seed yield was negatively correlated with the amount of residue remaining after the residue management treatment (post-treatment residue) the previous fall. Burning Kentucky bluegrass residue releases K, P, Ca, N, and other nutrients into the soil. In the absence of burning, N might not be available in adequate quantities until it is applied. In 2003 Kentucky bluegrass initiated regrowth in the burn treatments one week after burning, but regrowth did not visibly occur in the non-thermal treatments until after fertilizer was applied, one month after the initial regrowth in the burn treatments. Plant regrowth occurred in all treatments in 2004 soon after harvest, but growth in the mechanical treatment was visually estimated to be 25% less than the growth in the full load burn treatment. These results suggest that residue removal alone does not promote regrowth of Kentucky bluegrass, but rather residue removal and plant available nitrogen need to occur soon after harvest. Applying an early application of nitrogen immediately following a post-harvest residue management treatment that removes 80% or more of the post-harvest residue might promote early fall regrowth and higher seed yield.
Forage Quality: Forage CP, NDF, ADF, lignin, and IVTM levels were not different between the post-harvest grazed and baled residue. In 2003, CP averaged 4%, NDF averaged 76%, ADF averaged 43%, lignin averaged 6%, and IVTD averaged 43%. In 2003, cow weights ranged from 400 to 700 kg and calf weights ranged from 104 to 317 kg. In 2004, cow weights ranged from 440 to 653 kg and calf weights ranged from 122 to 299 kg. In 2003, 2,497 and 6,687 kg/ha DM were available and 1,528 and 5,270 kg/ha DM were removed by grazing in the bale/graze and full load graze treatments, respectively. An additional 4,357 and 3,262 kg/ha DM were removed by baling in the bale/graze treatment in 2003 and 2004, respectively. In 2003, the residue composition prior to grazing was 52% standing stubble in the bale/graze treatment and 17% standing stubble in the full load graze treatment. In 2003, DMI d 1 AU-1 was 6.2 kg higher in the full load graze treatment compared to the bale/graze treatment, which had a DMI d 1 AU-1 of 4.3 kg. In 2003, one AU consumed 153 g d-1 CP and 1.7 kg d-1 IVTDM in the bale/graze treatment, and 333 g d-1 CP and 4.2 kg d-1 IVTDM in the full load graze treatment. Cattle grazing the Kentucky bluegrass forage will require protein and energy supplementation to meet their requirements. Water consumption was 78 L d 1 AU-1 in 2003 and 23 L d 1 AU-1 in 2004, a difference of 70%. The higher water consumption in 2003 was due to warmer temperature, drier fall conditions, and less plant regrowth. Water consumption and availability is an important factor to consider when grazing Kentucky bluegrass residue. At a cost of $0.098 kg-1 IVTDM, the baled residue was worth $195.9 ha-1 or $44.96 t-1, the bale/graze grazed residue was worth $64.5 ha-1, and the full load graze grazed residue was worth $222.3 ha-1. Although the Kentucky bluegrass residue has forage value and the graze treatments resulted in yields higher than the mechanical treatment, the net profit associated with each of the different alternative residue management systems needs to be evaluated.
Residue, Nutrients, and Insects: Residue samples were collected at the 2003 site in Lewis County post harvest and following all residue management treatments. Although the research plots were moved to Latah County in 2004, residue data from the Lewis County site helped to better focus our treatments at the new site. Residue samples from the Lewis Co. site were taken after harvest (8/10/04) and following all residue management treatments (10/5/04). These samples are currently being weighed and corrected for mineral content. A subsample of residue from each plot has been taken and will be analyzed for total C, N, and S in a CNS analyzer. Changes in residue amount and nutrient content between the two sampling dates will be used to determine the percent residue removal and nutrient loss due to each treatment. Soil samples from each treatment were collected following swathing and have been air-dried, gently ground, and sieved in preparation for analysis. This winter the soils will be analyzed for total C, N, and S, as well as plant available N and P. Data from the soil samples will provide background data that will allow us to determine changes in soil fertility due to residue management. The focus of this year’s work has been to establish the study plots at the Latah County site and to collect, sort, and initiate identification of ground beetles and spiders from pitfall traps across thermal and nonthermal treatments. Samples are being processed to provide specific taxonomic data. Over 192 samples were collected over three sample dates at the Lewis County site in 2003 and 144 samples per sample date at the Latah County sites over four sample periods during 2004. The samples have been sorted to remove the predacious beetles and spiders, which have been separately curated and await taxonomic determinations during spring and summer of 2005.
Microbial Formulations: Stable (long shelf life), water-mixable, and dry powder formulations of the microbial agent have been prepared and are ready for use in the field next spring. They are composed of S. hygroscopicus YCED9 spores in dry powder carriers (zeolite or powdered milk). They are currently being stored at 4 C. Their viability will be checked prior to use by dilution plate counting on an agar growth medium. The formulation that we will use in the spring contains S. hygroscopicus YCED spores [108 colony-forming units per gram (cfu/g)] in a sterile powdered milk carrier. It will be dissolved in water, and the resulting spore suspension will be applied as a liquid at an inoculation rate of 104 cfu/square foot, which is an application rate we have shown to work well in previous experiments in turf on golf greens, and in laboratory biodegradation experiments with turf thatch. Laboratory scale experiments are in progress through the winter months. In these experiments we are using actual Kentucky bluegrass field residues and soils sampled during last year’s Hatter Creek field season. We are comparing residue decomposition rates in non-sterile inoculated and uninoculated soil samples, and we are confirming the optimal application rate for inoculation of the microbial agent in the field next spring. The primary objective of these experiments is to confirm in advance of the field season that the planned inoculation rate will work well with actual bluegrass residues in the Hatter Creek field soil. The experiments are being run at flask scale, using 25 grams of soil per flask with 1 gram of bluegrass residue per flask. As in past research, experiments are being run for 60 days and replicate flasks are sacrificed at time zero and every 15 days thereafter. In Spring 2005, at the time of first grass sprouting and outgrowth, the microbial formulation will be inoculated into subplots within the larger plots that were subjected to various alternative treatments during 2004. This is the first opportunity we have had to apply the formulation because of the timing of the other treatments in the fall 2004, which were not completed until October, which was too late for us to have an early fall inoculation. Each subplot is 10-15 feet and is replicated within each of the four large main replicate treatment blocks. The alternative treatments within which we have inoculation sub-treatments include the control full load burn, mechanical removal, bale and burn, bale and graze, and graze only. The parameters that will be monitored during the field season include residue decomposition rates, fungal population levels, inoculation effects on bluegrass growth, and seed yield. Each parameter will be followed within the subplots from time zero (day of inoculation) and periodically throughout the spring, summer and fall. Data from the sub-treatments will be compared to data obtained from the respective non-inoculated treatments and the full load burn control. We anticipate that we will carry out a second inoculation of one-half of the subplots during the summer.
Socio-Economic: Recent literature has focused on farmer/non-farmer relations, especially at the rural-urban interface zones common to changes in many contemporary rural landscapes. The production of Kentucky bluegrass seed in northern Idaho occurs within a similar context due to the region’s residential growth over the last 10-15 years. As a result, our recent efforts within the project have continued both qualitative and quantitative data collection efforts within the fields of social and economic analyses. In January through March 2004, we administered a telephone survey to a stratified random sample of 4,165 adults across a ten-county region in northern Idaho. Sub-samples were divided along boundaries of five zones correlating to production and/or population impacts areas. A total of 2,010 surveys were completed, yielding an overall response rate of 60%. Still underway, preliminary data analyses have yielded descriptive statistics of individual measures as well as simple bivariate relationships. In response to whether bluegrass field burning would lead to water quality problems in local lakes and streams, relatively normal patterns of response were found across the sub-regions. Responses to whether a ban on bluegrass field burning would lead to increased residential development of farmland yielded greater differences among the zones on the northern end vs. southern end of the region, with the former indicating more perceived development. Related, the perception also exists to a greater extent within the northern regions that restrictions on grass seed field burning will lead farmers to switch to growing crops that could cause more windblown dust and soil erosion. Attendance at related community meetings, field tours, and public hearings also continued as data observations and outreach activities. Additional key informant interviews were conducted with various stakeholders in the region, including representatives of special interest groups that oppose the current thermal practices. According to key informants, some indicators show the smoke management plan is more organized than in previous years. However, different stakeholder groups continue to experience stress and anxiety related to the management structures in place, as well as the impacts to the airshed.
Information Dissemination: The bluegrass extension program is an integral component of the University of Idaho Kentucky Bluegrass Team for disseminating information to producers, industry representatives, government agencies, university personnel, students, and general public. In addition, the bluegrass extension specialist has been able to provide the team with anecdotal producer observations and input concerning bluegrass production and residue management. Information has been disseminated through numerous local and regional presentations, the Kentucky bluegrass list serve, mass media publications, extension reports, individual contacts, media interviews, field tours, conferences, and the bluegrass website ( Two extension publications: 1) the effect of residue management on Kentucky bluegrass production and 2) the effect of residue management on Kentucky bluegrass growth and seed production are currently in review. Information has been disseminated through Idaho Agriculture in the Classroom, producing an “Idaho Bluegrass Production” workbook, and leading a student tour of a bluegrass production field. Historical bluegrass yield and production data for the PNW has been compiled and reported on the bluegrass website. In addition to the website, a list serve, unit converter, contact list, and research database containing over 250 references has been established. A survey has been conducted of producers in Idaho and Washington to determine their bluegrass production information needs and preferred method of delivery. This information will be used to help focus research and extension objectives.

Impacts and Contributions/Outcomes

Increasing Producer Knowledge Base:
New residue management systems will be provided to grass seed growers that greatly reduce post-harvest burning of residue and improve air quality, while minimizing soil erosion.
Integration of plant and animal factors will create bluegrass residue management systems that are acceptable to the general public and are economically beneficial to both grass seed and livestock producers in northern Idaho and eastern Washington.

Eliminating the loss of nutrients from burning and residue removal will improve the on-farm nutrient balance and reduce dependence on inorganic fertilizers. Understanding the importance of nutrient release in agronomic residues will help us to develop more economically efficient fertilizer recommendations while further protecting water quality.
Maintaining or increasing the acreage of this perennial crop will protect against erosion, improving soil and water quality.
Information Dissemination:
Growers and industry representatives will have access to information through field tours scheduled at various times during the three year production cycle to demonstrate residue management effects on livestock and grass seed production.
Meetings will be conducted throughout the region and will include grass seed and livestock producers, as well as research and extension personnel.
A web site will be constructed and maintained to provide grass seed and livestock producers access to all information associated with grass seed production.
Results will be published in the appropriate professional journals and disseminated at professional meetings.
Number of Acres/Animals Impacted:
Approximately 24,300 ha of grass seed are produced in northern Idaho annually. It is estimated that producers will adopt the use of livestock to remove residue on 20% of the acres, or about 4,800 ha. With a stocking rate of 5 head per ha, this would impact about 24,000 head of cattle annually. In addition, another 30% will adopt mechanical residue removal plus enhanced microbial decomposition.
Actual Positive Economic Impact (Dollar Value) to Farm/Ranch Families and Communities:
Under current bluegrass production practices where field burning is not allowed, return per ha is reduced by as much as $398. If these proposed bluegrass production practices (livestock grazing and/or microbially enhanced decomposition) are successful, an adoption rate of at least 50% could be expected given that bluegrass burning may soon be outlawed in Idaho as it has already been in Washington. Given this adoption rate, direct revenue to grass seed producers in the region would increase by $4,981,800. Using a multiplier of 1.8, direct and indirect benefits to the region would be over $8.9 million from adoption of these practices in Northern Idaho alone, with the potential of increased benefits if producers in Washington and Oregon also adopt these practices. Additionally, assuming a 50% adoption rate in Northern Idaho, the economic value of reduced soil erosion from maintaining farmland in bluegrass production could equate to an additional saving of over $300,000 per year using erosion studies by Walker et al. 1987.
Beef cow-calf producers typically operate on an extremely narrow profit margin and often operate at a net loss. Consequently, cow-calf producers would be highly motivated to seek methods of reducing operating costs. Feed costs incurred during the fall and winter is the largest single cost for the cow-calf producer and often exceeds 50% of the total cost of production of a weaned calf ($180 to $250 per cow-calf unit). It is reasonable to assume that identification of prudent grazing practices could reduce fall/winter feeding costs by $40 to $60 per cow, thereby greatly widening the profit margin. We estimate that this benefit could be achieved from approximately 0.4 ha of grass seed residue and fall regrowth.
There will be measurable social and cultural impacts associated with the potential changes from moving to a non-thermal production system. Farmer, rancher, and community acceptance will increase with proper assessment of shifts in norms, customs, and practices related to a regional heritage and identity evolved in conjunction with burning practices.


Jodi Johnson-Maynard

[email protected]
Associate Professor of Soil Science
University of Idaho
PO Box 442339
Moscow, ID 83844-2339
Office Phone: 2088859245
J.D. Wulfhorst

[email protected]
Associate Professor of Rural Sociology
University of Idaho
PO Box 442334
Moscow, ID 83844-2334
Office Phone: 2088857645
Joe McCaffrey

[email protected]
Professor of Entomology
University of Idaho
PO Box 442339
Moscow, ID 83844-2339
Office Phone: 2088857548
Don Crawford

[email protected]
Professor of Microbiology
University of Idaho
PO Box 443052
Moscow, ID 83844-3052
Office Phone: 2088856001
Carl Hunt

[email protected]
Professor of Animal Science
University of Idaho
PO Box 442330
Moscow, ID 83844-2330
Office Phone: 2088856932
Larry Van Tassell

[email protected]
Professor of Agricultural Economics
University of Idaho
PO Box442334
Moscow, ID 83844-2334
Office Phone: 2088857869