Silage corn has been identified by the USDA-NRCS, Natural Resources Conservation Service, as one of the most significant sources of soil erosion and agricultural related water quality problems in the Northeast. Silage corn does not leave enough crop residue to provide cover over the winter or allow for adequate cover necessary for the effective use of conservation tillage practices in the spring. Runoff and leaching of fertilizer, manure and pesticides lead to water quality problems. These problems can be very costly to remedy and can lead to human health problems. Cover crops have long been used with row crops to reduce soil erosion, add organic matter and nitrogen, improve soil tilth, recycle nutrients, and for weed suppression. The use of cover crops specifically alfalfa is known to improve productivity by breaking up compacted soil layers caused by heavy farm equipment.
The establishment of cover crops immediately following the harvest of silage corn has been a problem due to the late harvest and short growing season in the Northeast. Aerial seeding of cereal rye and ryegrass during corn tasseling can be partially successful but is dependent on, adequate soil moisture and the degree of compaction and crusting of the soil surface. Interseeding cover crops, when the corn is 12-18 inches tall, after cultivation, and band application of herbicides is an option. This practice has had mixed results due to soil and weather conditions. Due to the limited use of cultivation and band spraying and a relatively narrow window of opportunity to cultivate and seed, this practice has not been widely accepted. An alternative establishment method needs to be developed which can be done efficiently and incorporated into existing operations using conventional equipment. A method is being developed to seed cover crops at time of corn planting.
The establishment of cover crops during corn planting has been prevented by incompatibility with commonly used residual pre-emergence herbicides. Now with the use of post emergence, low volume imidazolinone, herbicides such as Pursuit and conventionally bred corn hybrids (IMI or Clearfield) resistant to them, this option is now possible. The establishment of cover crops at corn planting overcomes some of the barriers of previous cover crop establishment methods. The system enables the farmer to get the cover crop on early when there are good soil moisture conditions for establishment. The cover crops then benefit due to some early growth prior to corn canopy closure and for rapid growth following corn harvest. Cultivation is not required to prepare a seedbed. The cover crops can be established using conventional seeding equipment allowing for uniform distribution and efficient use of seed (lower seeding rates and costs) resulting in better stands, or can be broadcast immediately following or during harrowing, or by conversion of insecticide boxes to drop seed at box level during the planting operation. This method is designed to be uncomplicated and to fit into existing operating procedures. The cover crop stands that can be produced by this method is far superior to past methods so that actual soil improvement, soil erosion reduction and water quality benefits may be actualized.
The goal of the project is to get several years worth of on farm research trials and demonstrations located around the states of New York, Vermont, and Pennsylvannia which can be used to educate farmers on this technique. I will utilize the facilities at SUNY Cobleskill, Empire Farm Days site and Aurora research farm, and farms located in the New York City, Skaneateles Watershed projects and Upper Susquehanna River Coalition in NY and Pennsylvania; as well as other locations in NY, Vermont and Pennsylvania.
There are two components to this work:
1) Education, demonstration, outreach and promotion of this technique to educate farmers, and agency personnel. A list of demonstration, outreach and promotion is listed in Appendix 11. This will also give us the opportunity to evaluate the system on different soil types, microclimates, corn planting dates and farm operations.
2) Research to quantify the benefits of the cover crop system from a soil and water quality perspective as well as some agronomic considerations. This information will be used to promote the benefits of this cover crop system to beneficiaries.
The establishment of cover crops following corn silage harvest is limited due to the short growing season in the Northeast. The establishment of cover crops at the time of corn planting takes advantage of good soil moisture, a prepared seed bed, and allows for the use of conventional seeding equipment. The establishment of cover crops during corn planting had been prevented by incompatibility with commonly used residual pre-emergence herbicides. Now with the use of low volume post emergence, imidizolinone, (IMI or Clearfield) herbicides such as Pursuit and corn hybrids conventionally bred to be resistant to them, this option is now possible. Herbicides are used to suppress the cover crops while controlling weeds without reducing corn yields.
The establishment of cover crops earlier in the season could allow for more top and root growth providing more soil erosion protection and water quality benefits compared to cereal grains planted following corn silage harvest in October. This increased growth could also provide for more nutrient uptake in the fall for nutrient management as well as soil and water quality benefits. Establishing cover crops at time of corn planting gives farmers in the Northeast the possibility of establishing legumes for cover cropping which is not possible following corn silage harvest, this would benefit nitrogen deficient systems. This system provides the farmers another time within their operation to establish cover crops. This project investigates the use of different cover crops, seeding rates, cover crop mixtures and herbicide combinations on corn yields and percent cover of the cover crops. This study indicated with adequate weed control and cover crop seeding rates there were no significant differences in corn yields between conventionally tilled silage corn with and without cover crops.
The effects of this cover crop system on soil and water quality was also investigated. The effects of the cover crops with and without two rates of manure application on phosphorus and sediment concentrations and runoff were investigated using rainfall simulation techniques on two dairy farms in Delaware County, NY (Kleinman et. al. 2005). Prior to dairy manure application, losses of P in runoff were primarily a function of erosion. Because all cover crops increased ground cover (up to 81% greater than the control), total P loads in runoff were significantly lower from cover cropped plots than from the non cover cropped controls. Despite concern that leaching of soluble P from the cover crops could enrich dissolved reactive P (DRP) in runoff, DRP losses from cover crops were generally not different from conventionally-cropped controls. Following manure application, runoff P losses increased by over an order of magnitude. Dissolved reactive P became the dominant form of P in runoff, due to contributions of readily soluble P in manure. There were no differences in performance between the cover crop species and the control. It was acknowledged that the intense level of rainfall simulation may have allowed for a greater amount of soluble P runoff than what could happen with more moderate rains washing the P into the soil.
A soil quality study was conducted after four years of this system comparing the soil physical and biological effects of the cover crops with conventional tillage and zone tillage. The cover crops evaluated were red clover, alfalfa and annual ryegrass, the annual ryegrass was evaluated under conventional and zone-till systems. Soil measurements include: bulk density, infiltration, wet aggregate stability test, pore size distribution, particulate organic matter fractions, percent decomposition and mineralizable nitrogen. There were significant differences for percent small aggregate stability and N-Mineralization with the best values being for the zone-till + annual ryegrass cover crop followed by the conventional tillage with annual ryegrass cover crop.
1) Out of 30 farmers that participated in cover crop demonstrations 15 will continue to apply cover crops on their own using this system on one field per year for three years after completion of the project.
Out of 35 farmers that participated 5 farmers put on significant acreage at there own expense. An additional 8 farmers tried a second or third demonstration on small acreage using the supplies provided by the SARE grant. Some of the problems with this system as reported by farmers is poor weed control for late germinating grasses like fall panicum and crabgrass, getting custom applicators to spray small acreages of imidizolinone herbicides and to spray them at the appropriate times. Applying a too heavy seeding rate is a common problem which can lead to additional competition from the cover crop.
2) Out of 25 farmers 5 will be willing to use their farms for a field day stop or write a testimonial on their experience with the system in a local SWCD or extension newsletter.
Eight farms were used for field days and extension tours. Empire Farm Days was used for 3 years giving opportunity for 1000’s of farmers to view the system. Tours were also given at Cornell’s Field Days in Aurora attended by farmers and agency personnel. Tours were given at Big Flats Plant Materials Center to many NRCS personnel as well as some farmers and other agency personnel. The Steve Stocking Farm which was used both in my grant as well as a farmer grant was featured in an article in the May 2005 publication “Farming: The Journal of Northeast Agriculture.”
3) Out of seven agency people involved in project 4 will instruct dairy farmers on their own on the use of this system resulting in cover crop plantings.
There were seven agency or consultants that instructed dairy farmers on this system. Due to the technical intricacy of the system this was more of a collaborative effort than a totally independent effort on their part. There continues to be an interest in the utilization of this system by other agency personnel based on continued contacts.
4) Research to be carried out according to procedures meeting discipline standards, statistically verifiable. The utilization of the research by NRCS to credit cover crop system for soil erosion reduction and P index.
Research on the effects of cover cropping for water quality benefits were successfully carried out in collaboration with Dr. Peter Kleinman from the USDA-ARS Pasture Systems and Watershed Management Research Laboratory at Penn. State. An article will be published in the November 2005 issue of the Journal of Soil and Water Conservation (Kleinman and Salon 2005). “Effect of cover crops established at time of corn planting on phosphorus runoff from soils before and after dairy manure application”. Research on the effects of cover cropping for soil quality benefits were successfully carried out in collaboration with Dr. Harold van Es from Cornell University. Additional soil biological lab work was done by Dr. David Wolfe from Cornell and Dr. Carol Franks at the National Soil Survey Center. Several studies looking at herbicide effects and seeding rate and mixture studies were conducted at the USDA-NRCS Big Flats Plant Materials Center.
This system has been written up in the cover crop specifications in New York. There has been discussions with personnel in charge of the RUSLE II data base, and they are willing to include this system as part of their alternative cropping systems. At present there is credit for intercropping which this system falls into and which is given more erosion control credit than fall applied cereal cover crops. Some states give credit in the P index for cover cropping but no additional credit has been given to this system to date. I have been contacted by several state water quality agencies as to the potential this system could have on their water quality programs.
This project was a research and demonstration/education project. The methods for establishing cover crops at time of corn planting were being investigated at the same time as trying to promote and introduce the technique to farmers. Therefore we were learning at the same time as educating. The utilization of on farm and other research facility locations allowed us to evaluate the system in a multiple amount of climates, soils, and management systems; and allowed for interaction with and demonstration for, many farmers and other scientists. The target audience was engaged by contacting Natural Resources Conservation Service (NRCS), Soil and Water Conservation District (SWCD) and Extension personnel as well watershed groups; New York City, Skaneateles and Upper Susquehanna River Coalition to identify farmers who would be interested in cover crops. Also Empire Farm Days a yearly three day farm show was used as an excellent location to have farmers observe the system and sign up for demonstration projects. I would volunteer to present and provide demonstrations for pre-planned meetings and field days by University, Extension and Conservation organizations.
Establishment of cover crops at time of corn planting studies at Big Flats Plant Materials Center 2000 – 2004
The plots are located in Big Flats, NY on Unadilla silt loam soils on a 0 – 3% slope at the USDA-NRCS Big Flats Plant Materials Center. In 2000 the field was plowed, disked and harrowed. The field was planted with a 97 day Pioneer corn hybrid 37J99 IR (imidizolinone resistant) on 6/5/00. The corn was planted at a rate of 28,000 kernels/ac and fertilized with 200 lbs/ac of 10-20-20 fertilizer through the planter. An additional 300 lbs/ac of 34-0-0 was broadcast on 6/26/00. The cover crops were hand broadcast on 6/5/00, immediately following the corn planting into 20×50 ft plots with 3 replications. The cover crops and planting rates were: common Dutch white clover at 8 lbs/ac; ‘Redstar’ red clover, and ‘Norcen’ birdsfoot trefoil at 10 lbs/ac, ‘Intrigue’ alfalfa, ‘Citadel’ perennial rye grass, and ‘Tetragold’ annual ryegrass at 15 lbs/ac. The herbicide treatments include: 1) Eradicane (5.0 pts/ac) pre-plant incorporated (PPI) on 6/1/00 + cultivation on 7/18/00, and 2) Eradicane (5.0 pts/ac) + Python (1.14 oz/ac) (PPI) on 6/1/00; 3) Pursuit (1.44 oz/ac) pre-emergence on 6/1/00 and 4) Pursuit (1.44 oz/ac) + Python (1.14 oz/ac) pre-emergence on 6/1/00. Treatments 3 and 4 were eventually harrowed prior to the corn and cover crop seeding due to rainfall and surface crusting. 5) Eradicane (5.0 pts/ac) (PPI) on 6/1/00 followed with Basagran (1½ pt/ac) post emergence spray on 6/29/00. Due to a quackgrass infestation all the following post emergence treatments received two ½ rates of Accent post emergence on 6/29/00 and 7/12/00 (.66 oz/ac is full rate). Along with the Accent, the post emergence treatments on 6/29/00 included 6) Pursuit (1.44 oz/ac), 7) Pursuit (1.44 oz/ac) + Buctril (1½ pt/ac), and 8) Pursuit (1.44 oz/ac) + Permit (.78 oz/ac). All post emergence spays were applied with a nitrogen based non ionic surfactant.
In 2001 the field was plowed, disked and harrowed. On 5/24/01 an 87 day Garst #8972 IT (imidizolinone tolerant) corn hybrid was planted. The corn was planted at a rate of 28,000 kernels/ac and fertilized with 160 lbs/ac of 10-20-20 through the planter. An additional 60 lbs of actual nitrogen as liquid was knifed in on 6/28/01. The cover crops were hand broadcast on 5/29/01 into 20 x 40 ft plots replicated 3 or 4 times (depending on herbicide treatment). Since there was a significant rain event prior to planting the cover crops the field was cultipacked following the seeding. The cover crops and the rates used were: ‘Arlington’ red clover, ‘Viking’ birdsfoot trefoil, ‘Amazon’ perennial ryegrass and ‘Tetragold’ annual ryegrass at 10 lbs/ac; ‘Cimmarron’ alfalfa at 12 lbs/ac and common Dutch white clover at 8 lbs/ac. there were also 4 mixes evaluated a) red clover, birdsfoot trefoil and perennial ryegrass b) red clover, birdsfoot trefoil and annual ryegrass c) red clover, white clover and perennial ryegrass and d) red clover, white clover and annual ryegrass. All of the legumes were seeded at a rate of 3 lbs/ac each and the ryegrasses were seeded at 4 lbs/ac. The mixtures were sprayed with Pursuit + Python at the rate described below. All of the covers had excellent establishment facilitated by a timely rainfall.
There were 5 herbicide treatments: 1) Eradicane (5.0 pts/ac) + Python (1.33 oz/ac) pre-plant incorporated on 5/22/01, 2) Pursuit (1.44 oz/ac) + Python (1.25 oz/ac) pre-emergence on 5/31/01; and post emergence treatments on 6/27/01 of 3) Pursuit (1.44 oz/ac), 4) Pursuit (1.44 oz/ac) + Buctril (1.0 pt/ac) and 5) Pursuit (1.44 oz/ac) + Basagran (2.0 pts/ac). All post emergence sprays contained a non ionic adjuvant with nitrogen.
In 2002 the field was plowed, disked and harrowed. On 5/10/02 a 99 day Garst #8966 IT (imidizolinone tolerant) corn hybrid was planted at a rate of 28,000 kernels/ac and fertilized with 160 lbs/ac of 15-15-15 through the planter. An additional 100 lbs/ac of actual nitrogen as liquid was knifed in on 7/03/02. The cover crops were hand broadcast on 5/15/02 into 20 x 40 ft plots replicated three times. The conditions were wet and the field was cultipacked following seeding. A cover crop seeding rate study was conducted, the seeding rates were: ‘Haygrazer’ alfalfa 8 and 15 lbs/ac; common Dutch white clove at 6 and 10 lbs/ac; and ‘Arlington’ red clover, ‘Tetragold’ annual ryegrass and ‘Aubisque’ perennial ryegrass at 8 and 12 lbs/ac. Pursuit (1.44 oz/ac) + Buctril (1.0 pt/ac) with a nitrogen based non ionic surfactant were applied post emergence on 5/23/02.
In 2003 the field was prepared as previously reported. On 5/09/03 a 95 day Golden Harvest #H6809 IT (imidizolinone tolerant) corn hybrid was planted at a rate of 28,000 kernels/ac and fertilized with 160 lbs/ac of 10-20-20 through the planter. The cover crops were hand broad cast into 20 x 40 ft plots replicated four times on 5/14/03. The conditions were wet and the field was cultipacked following seeding. The corn was side dressed on 6/19/03 with 200 lbs/ac 15-15-15 fertilizer. A cover crop seeding rate study was repeated using: ‘Aurelia’ Italian annual ryegrass, ‘Aubisque’ perennial ryegrass, ‘Tempus’ red clover and ‘Falcon II’ tall fescue at 8 and 12 lbs/ac, ‘Haygrazer’ alfalfa at 8 and 15 lbs/ac and Dutch white clover at 6 and 10 lbs/ac. Mixtures of red clover/white clover, red clover/alfalfa and annual/perennial ryegrass were also evaluated. The corn was sprayed with Pursuit (1.44 oz/ac) + Buctril (1.5 pts/ac) with non ionic and nitrogen adjuvant on 6/13/03.
A herbicide study was conducted to look at reduced rates of Accent and Pursuit; as well as Callisto, Permit and Lightning herbicides, the treatment combinations were: 1) Pursuit (1.44 oz/ac) + Callisto (6 oz/ac) pre-emergence , 2) Pursuit (.72 oz/ac) + Accent (.22 oz/ac) + Buctril (1.0 pt/ac) post emergence, 3) Pursuit (.72 oz/ac) + Accent (.22 oz/ac) + Buctril (1.0 pt/ac) post emergence, 4) Lightning (1.28 oz/ac) post emergence, 5) Pursuit (.72 oz/ac) + Permit (.78 oz/ac) + Buctril (1.0 pt/ac) post emergence and 6) Accent (.33 oz/ac) + Buctril (1 pt/ac) + Python (.5 oz/ac) post emergence. The pre-emergence herbicides were sprayed on 5/14/03; the post emergence herbicides which were sprayed on 6/13/03 included a nitrogen based non ionic surfactant. The cover crops were seeded at 10 lbs/ac except for white clover which was seeded at 8 lbs/ac.
In 2004 the field was prepared as previously reported. On 5/20/04 a 99 day Garst #8966 IT (imidizolinone tolerant) corn hybrid was planted at a rate of 28,000 kernels/ac and fertilized with 160 lbs/ac of 10-20-20 through the planter. The cover crops were hand broadcast on 5/21/04 into 20 x 40 ft plots replicated three times. The conditions were wet and the seed was cultipacked. The corn was top-dressed on 6/21/04 with 100 lbs/ac 34-0-0 fertilizer. The cover crops used were: common Dutch white clover at 8 lbs/ac, ‘Tempus’ red clover and alsike clover at 12 lbs/ac, Pioneer 53B60 alfalfa at 15 lbs/ac, hairy vetch at 20 lbs/ac, and ‘Aubisque’ perennial ryegrass, reed canarygrass, red fescue , KY bluegrass, ‘Manchar’ smooth bromegrass, ‘Climax’ timothy, ‘Falcon II’ tall fescue, and ‘Udder’ orchardgrass at 10 lb/ac rates. The herbicide combinations used were: 1) Pursuit (1.44 oz/ac) + Prowl (1.0 pt/ac) + Python (0.5 oz/ac) pre-emergence, 2) Pursuit (1.44 oz/ac) + Callisto (4oz/ac) + Dual (6oz/ac) pre-emergence, and 3) Pursuit (1.44 oz/ac) + Python (0.5 oz/ac) + Hornet (2 oz/ac) pre-emergence. The herbicides were sprayed pre-emergence on 5/25/04.
Methods: Cover crops corn herbicide studies 2001 – 2004
This project is set up to discover which cover crops are tolerant to registered corn herbicides and which can survive and provide adequate cover while the weeds are controlled. In most instances IMI or Clearfield corn hybrids are necessary to allow for the use of imidizolinone herbicides i.e. Pursuit. These studies evaluate potential herbicide combinations in small plots where corn yields are not measured. Promising treatments are then advanced toward larger plot size evaluations where corn yields are measured.
Preliminary work found that Eradicane pre-plant incorporated was used successfully on all leguminous cover crops, broadleaf weed control was inadequate and the cover crops needed more suppression. In 1996 Buctril herbicide was looked at for post emergence broadleaf weed control and cover crop suppression. It was found to be safe on the alfalfa and red clover but not on birdsfoot trefoil. The red clover can be set back by the Buctril depending on its stage of growth which can help prevent the red clover from competing with the corn. At the one trifoliate leaf stage the red clover can be killed by Buctril (1.0 pt/ac). A greenhouse study was conducted in cooperation with Dr. Nate Hartwig at Penn. State in 1999 evaluating 19 herbicide combinations. The greenhouse and three field studies conducted in 1998-2000 looking at the tolerance of cover crops to corn herbicides can be found in the 1998-2000 USDA-NRCS Big Flats Plant Materials technical report 1998-2000. We have continued our work in the field screening herbicides in 2001-2004.
In 2001 a Study was conducted to evaluate some pre-emergence and post emergence corn herbicide treatments on cover crops. This year the study was conducted without the interaction of a corn stand. The plots are located in Big Flats, NY on Unadilla silt loam soils on a 0 – 3% slope at the USDA-NRCS Big Flats Plant Materials Center. The plots were seeded on 5/14/01 by hand broadcasting seed, raking and rolling into 10×5 foot plots with 2 replications. The cover crops used included: common Dutch white clover (6 lbs/ac) , ‘Arlington’ red clover (8 lbs/ac) , and ‘Viking’ birdsfoot trefoil, (10 lbs/ac) and; ‘Tetragold’ annual ryegrass, ‘Citadel’ perennial ryegrass and ‘Cimmaron’ alfalfa at 15 lbs/ac. There were 8 herbicide treatments, their timing and rates are outlined in Table 1. The pre-emergence treatments were applied on 5/11/01 the post emergence treatments were conducted on 6/25/01. All post emergence treatments include non ionic surfactant and nitrogen. The herbicides were applied using a bicycle sprayer at 40 psi at a 20 gallons/ac rate of water sprayed at approximately 2 mph. The Eradicane pre-plant incorporated treatments were rototilled. Two rates of Eradicane + Python (1.16 oz/ac) were compared to test the maximum rate of Eradicane on cover crop species. Accent herbicide was investigated at 2 rates with a combination of herbicides (Table 1). When sprayed on 6/25/01 the weeds were 4-5 inches tall and around the 10 leaf stage; the alfalfa was at 5 trifoliate leaf stage, red clover 3 trifoliate, vetch 4-6 multiple leaf state and the ryegrasses had 5-6 tillers and 15 leaves. The spraying should have been done when the weeds and the cover crops were smaller. The plots were evaluated for vigor and weed control on 7/3/01 and for vigor again on 11/19/01.
In 2002 we evaluated Callisto, both pre and post emergence, Lightning, and Distinct herbicides in combinations. We also evaluated Pursuit (.72 oz/ac) + Accent (.33oz/ac) + Buctril (1.0 pt/ac). The cover crops were seeded on 5/16/02 as previously described in 2001 procedures with 3 replications in a completely randomized block design. The cover crops were seeded into Clearfield (imidizolinone tolerant), 99 day Garst #8966IT, corn planted on 5/10/02 at a population rate of 28,000 plants/ac with 160 lbs/ac of 10-20-20 fertilizer at planting with no topdressing or insecticide or planter box treatment. The cover crops used included: common Dutch white clover at 8 lbs/ac, ‘Tempus’ red clover, and ‘Viking’ birdsfoot trefoil at 12 lbs/ac; ‘Tetragold’ annual ryegrass and ‘Aubisque’ perennial ryegrass at 10 lbs/ac and ‘Cimmaron’ alfalfa at 15 lbs/ac. The herbicides were applied as previously described in 2001 procedures. There were 7 herbicide combinations evaluated, their rate and timing are displayed in Table 2. The pre and post emergence treatments were conducted on 5/28/02 and 6/21/02 respectively. When sprayed on 6/21/02 the weeds were 4-5 inches tall and around the 10 leaf stage. The alfalfa was at the 4-5 trifoliate leaf stage, red clover 3 trifoliate, white clover 2-3 trifoliate leaf stage and the ryegrasses had 5-6 tillers and 10-15 leaves. The spraying should have been done when the weeds and the cover crops were smaller. The cover crops were evaluated for percent cover on 10/18/02 and 5/27/03.
In 2003 we evaluated Permit herbicide and repeated some of the previous years herbicides reducing Accent to the 1/3 rate. The cover crops were seeded on 5/19/03 as previously described in 2001 procedures in 5 x 10 foot plots with 3 replications in a completely randomized block design. The cover crops were seeded into a Clearfield corn hybrid, 95 day Golden Harvest H6809IT, which was planted on 5/9/03 as described in 2002. The cover crops used included: common Dutch white clover at 8 lbs/ac, ‘Tempus’ red clover, and ‘Empire’ birdsfoot trefoil at 12 lbs/ac; ‘Aurelia’ Italian annual ryegrass and ‘Aubisque’ perennial ryegrass at 10 lbs/ac and ‘Hay grazer’ alfalfa at 15 lbs/ac. This year additional grasses investigated were: red fescue, ‘Falcon II’ tall fescue, hard fescue, ‘Udder’ orchardgrass, bluegrass, and ‘Manchar’ bromegrass at a 10 lbs/ac rate. The herbicides were applied as previously described in 2001 procedures. There were 12 herbicide combinations evaluated their rate and timing are displayed in Table 3. The pre and post emergence treatments were conducted on 5/22/03 and 6/17/03 respectively. When sprayed on 6/17/03 the weeds were 2-4 inches tall and around the 10 leaf stage. There was a predominance of field pennycress, which was controlled by all herbicide treatments. The alfalfa was at the 3-4 trifoliate leaf stage, red clover 2 trifoliate, white clover 1-2 trifoliate leaf stage and the ryegrasses had 5-6 leaves. The cover crops were evaluated on 7/11/03 for dry weight per 10 seedlings, on 10/6/03 for corn and cover crop vigor and on 11/21/03 for percent cover.
In 2004 evaluations were made to look at the effects of Prowl at 1.0 and 2.0 pts/ac and Dual Magnum at .5 and 1.0 pt/ac pre-emergence in combination with previous treatments for improved late season weed control and cover crop suppression. Hornet, Outlook and a Pursuit/Lightning herbicide combination were also evaluated. The cover crops were seeded on 5/25/04 as previously described in 2001 procedures in 5 x 10 foot plots with 3 replications in a completely randomized block design. The cover crops were seeded into corn which was planted on 5/19/04 as described in 2002. The cover crops used were: common Dutch white clover at 8 lbs/ac, ‘Tempus’ red clover and alsike clover at 12 lbs/ac, Pioneer 53B60 alfalfa at 15 lbs/ac, hairy vetch at 20 lbs/ac, ‘Aurelia’ Italian annual ryegrass at 6 lbs/ac and ‘Aubisque’ perennial ryegrass and reed canary grass at 10 lbs/ac and, red fescue , KY bluegrass, “Manchar” smooth bromegrass, “Climax” timothy, “Falcon II” tall fescue, and “Udder” orchardgrass at 8 lb/ac rates. The herbicides were applied as previously described. There were 18 herbicide combinations evaluated, their rate and timing are displayed in Table 4a. The pre and post emergence treatments were conducted on 5/25/04 and 6/23/04 respectively. The cover crops were evaluated on 8/5/04 for dry weight per 10 seedlings, and on 11/17/04 for percent cover.
Methods: Cover crop runoff phosphorus study
The study was conducted in the Cannonsville Reservoir Watershed, NY (42o21’N, 74o52’W), part of the New York City drinking water supply system. The watershed falls within the Glaciated Allegheny Plateau and Catskill Mountain Region.
Two fields were selected from adjacent farms in the watershed for trials of the simultaneous corn and cover crop establishment system (SCCC). Both fields had been in silage corn production for at least one year prior to the trials and both had long histories of receiving dairy manure as a source of nutrients. Dairy manure in the area is typically broadcast year round, and incorporated into the soil by moldboard and chisel plow during spring site preparation. At one site, trials were established on a moderately well drained Willowemoc soil (coarse-loamy, mixed, semi active, frigid Typic Fragiudept) in May, 2000. At the other site, trials were established on a somewhat-poorly drained Onteora soil (coarse-loamy, mixed, semiactive, frigid Aquic Fragiudept) in May, 2001. Trials were conducted with four replicate, 12 x 18 m2 plots for treatment in a completely randomized design. Slope gradients within the trial plots averaged 6 % at the Willowemoc site and 11% at the Onteora site. Perennial rye grass and red clover were grown as cover crop treatments at both sites. In addition, at the Onteora site, alfalfa was included. Adjacent areas under conventional corn silage production served as references to the cover crop treatments.
At both sites, imidazoline resistant corn varieties were planted in 30 inch rows prior to cover crop seeding. A Pioneer 37J99, 97 day corn was planted on 5/18/2000 at the Willowemoc site and a Garst 87 day hybrid was planted on 5/4/2001 at the Onteora site. All Willowemoc plots were fertilized with 200 lbs/ac of 20-5-20 and the Onteora plots were fertilized with 200 lbs/ac of 24-6-20 starter blend at corn planting. There were no additional manure or fertilizer applications during the crop establishment and growth phase of the study.
Cover crops were planted with a Brillion seeder within 10 days of corn planting. The Brillion seeder was calibrated to deliver 10, 12 and 15 lbs/ac for the red clover alfalfa and perennial ryegrass respectively. Observation of the resulting stands indicated a higher seeding rate was delivered. For both sites, Pursuit (imazethapyr) (1.44 oz/ac) and Buctril (bromoxynil) (1.5 pts/ac) herbicides were applied post emergence with non ionic surfactant plus nitrogen. Silage yield was determined by hand harvesting and weighing whole plants from two 15 ft of row within the center of each plot. Three representative plants were harvested from each 15 ft of row to determine dry matter content. Ground cover was determined on 11/14/2000 and 5/2/2001 at the Willowemoc site, and on 9/18/2001 and 4/16/2002 at the Onteora site. Ground cover was quantified within a 4 ft2 frame placed randomly at three locations within each plot and an average of these observations used to represent the entire plot.
Runoff plots were established at both sites within the larger cover crop plots developed for the cover crop trials. For each treatment, two pairs of 1 x 2 m2 runoff plots were installed with the long axis orientated down the slope.
Rainfall-runoff experiments were conducted once at the Willowemoc soil site in May 2001 (beginning 5/7/01), and twice at the Onteora soil site, in October 2001 (beginning 10/9/01) and April 2002 (beginning 4/23/02). Spring experiments were timed to occur shortly before annual cultivation so that they represented the maximum development of a cover crop stand. The fall experiment was conducted shortly after corn harvest, providing insight into differences that might be expected between the SCCC system where cover crops have already been established and a traditional cover crop scenario with no established cover crop prior to the fall seeding.
Rainfall simulations were conducted prior to manure applications with runoff collected and analyzed. Manure was then immediately applied at two rates to achieve 50 or 100 kg TP ha-1, the phosphorus and nitrogen corn removal rates respectively. Rainfall simulations were conducted 5 days later and runoff was collected and analyzed. For a detailed description of methods for installing runoff plots, the protocol for conducting rainfall simulation, collection and laboratory protocols and statistical analysis refer to (Kleinman et.al., 2005). Rainfall events of the intensity and maximum duration used in the National Phosphorus Research Project protocol exceed a 100-year return period in this region.
Methods: Cover crop soil quality study
In order to evaluate the effects of the cover crop system on soil quality a four year study was conducted. The soil quality study was conducted at Cornell University’s Musgrave Research Farm in Aurora NY (42 44’N, 76 39’W) on Lima silt loam soils (fine-loamy, mixed, active, mesic Oxyaquic Hapludalf). The corn silage was planted in early May using a 95 or 99 day Clearfield, Imidizolinone herbicide tolerant hybrid. 32,000 kernals/ac were planted in 30 inch rows using a Kinze planter with zone-till capabilities. At planting 241 lbs/ac of 10-20-20 fertilizer was applied, no insecticide or seed box treatments were used. 100lbs/ac of nitrogen as ammonium nitrate was surface applied as top dress each year. The herbicide treatment was Pursuit Python pre-emergence except in 2003 where Pursuit and Buctril was applied post emergence. The use of Pursuit and Python can cause corn injury if there is slow corn emergence and the Python should be reduced to half rate (.5 oz/ac) or an alternative herbicide treatment should be used. The cover crops were hand applied at or near planting. The cover crops used were alfalfa at 12 lbs/ac the first two years then at 8 lbs/ac. Red clover at 12 lbs/ac and annual ryegrass at 10 lbs/ac. Due to mortality of the annual ryegrass over winter, the second year the grass treatment was changed to 5 lbs/ac annual ryegrass and 5 lbs/ac of perennial ryegrass the last 2 years of the study. The first 2 years of the study the entire plot was plowed and disked 3 times and harrowed twice. After the second year the tilled fields were chisel plowed and disked. There was also a zone-till control and a zone-tilled annual cover crop treatment. The cover crops were cultipacked in following corn planting. Additional materials and methods information for each year is given in Table 5.
After four years of the study was completed the soil was sampled on 10/4/04. Soil measurements include: bulk density, infiltration, wet aggregate stability test, pore size distribution, particulate organic matter fractions, percent decomposition and mineralizable nitrogen, saturated hydraulic conductivity, porosity and core micro penetrometer. The methods used for these evaluations are outlined in Van Es H.M and R.R, Schindelbeck 2003, Van Es H.M 2006, and Wolfe D.W. 2005.
Kleinman P.J.A, P.R. Salon, A.N. Sharpley and L.S. Saporito, 2005. Effect of cover crops established at time of corn planting on phosphorus runoff from soils before and after dairy manure application. Journal of Soil and Water Conservation 60(6) 311 – 322.
Van Es H.M. et. al. Method for measuring aggregate stability using small rainfall simulator. Dept. of Soil and Crop Science. Cornell Univ., Ithaca, NY Research Series 2006. (in preparation).
Van ES, H.M. and R.R. Schindelbeck, 2003 Field procedures and Data Analysis for the Cornell Sprinkler Infiltrometer. Cornell University, Department of Crop and Soil sciences Extension Publication R03-01. 8 pages.
Wolfe, D.W. 2005. Approaches to monitoring soil quality. In: Uphoff, N. et. al. (eds.) Biological Approaches for Sustainable Soil Systems. CRC Press. Boca Raton, FL. Chap. 47 (in press).
Results: On farm trials 2001 – 2002
In the 2001 growing season 16 cover crop trials were planted, of these four were at research institutions (Cornell Aurora Research Farm, USDA-NRCS Big Flats Plant Material Center (BFPMC), SUNY Cobleskill, and Cornell Animal Science T&R Center) and 12 were on farms. Six of the sites had multiple species. The species of cover crops looked at were red clover, white clover, alfalfa, birdsfoot trefoil, hairy vetch, and perennial and annual ryegrass. Four of the sites were replicated trials. The 2001 growing season was extremely dry and resulted in some problems with the herbicide Python adversely affecting some corn and cover crop performance when used at the high end of the labeled rate. Out of the 16 sites this year 9 of them had cover crops which yielded as much corn as the control plots (17.0 tons/ac) and had excellent cover (70%), 3 had excellent corn yields with only fair covers. Four sites were adversely affected by the cover crop due to drought, high seeding rates and herbicide weather interaction. See Table 6 for a summary of the 2001 on farm corn yield data.
In 2002 we worked with 28 farmers and 4 research facilities setting up demonstrations and/or trials at 22 sites, see Table 7 for a summary of the 2002 on farm corn yields and cover crop data. Due to poor overall corn performance from drought conditions and other issues not all sites were measured for yield. The average corn yield for all of the cover crop treatments was 15.5 tons/ac compared to the control with 15.9 tons/ac. A study was conducted at 4 sites evaluating 2 seeding rates of alfalfa, red clover, white clover, and annual and perennial ryegrasses comparing corn yield and percent cover. See Table 8 for a summary of the corn yields and cover crop data for the 2002 seeding rate studies.
When evaluating the effects of different cover crop seeding rates on corn yields, the difference in corn yields appear correlated with percent cover of the cover crops when measured in the fall. In cases where there was little difference in corn yields between cover crop seeding rates there was also not much difference in the percent cover, see Table 8. The red clover and white clovers had the most difference between percent covers due to the seeding rate with the low rate reducing cover by 10%. The corn yields for the two different seeding rates were reduced an average of 2.5 tons/ac when going from the low to the high cover crop seeding rate. The low seeding rate average was 16.3 tons/ac compared to 16.0 for the control. The white clover does have a stoloniferous rooting system so some of the cover in the low rate could have been made up by this spreading habit later in the season. White clover can be very competitive at 10 lbs/ac, lower rates of white clover or a mixture of red and white clover should be investigated. Due to the tolerance of the alfalfa to many of the herbicides used in this program and its high water use it would be beneficial to reduce the alfalfa seeding rate even more or to include a reduced rate of herbicides like Accent or Banvel which would suppress the alfalfa. A mixture (total 8 lbs/ac) of alfalfa with red clover would reduce seeding costs, insure good cover and derive some of the benefits of the alfalfa tap root, while being less competitive than alfalfa alone. Annual ryegrass is more competitive than perennial ryegrass with a yield reduction from their low rates as compared to the control of 2.7 tons/ac and 1.0 ton/ac respectively. A mix of annual ryegrass and perennial ryegrass is preferred for a total of 8 lbs/ac. Some herbicide is needed to suppress the annual ryegrass. In no-till it has been reported that annual ryegrass can become a weed problem so careful management is recommended.
As in 2001 the pre-emergence treatment of Pursuit and Python has been shown to cause corn injury when there are conditions that inhibits rapid corn emergence even with Clearfield corn hybrids resistant to imidazolinone herbicides. When you have this injury to the corn or for any reason which delays canopy closure, the corn does not shade the cover crop quick enough and competition is evident. The use of Python with Eradicane pre-plant incorporated did not show this injury and conventional corn hybrids can be used, this limits your cover crop choice to legumes. Much research has shown that post emergence herbicide timing is very important with recommendations for mid post applications when the weeds are 2 – 3 inches tall. This is even more important in this system, depending on the herbicide used, since the cover crops won’t be adequately suppressed if they get too mature.
In 2003 we worked with 16 farmers and 4 research facilities setting up demonstrations and/or field trials at 16 sites. See Table 9, for a summary of 2003 corn yields and percent cover crop cover, averaged over all plantings. A study was conducted at two sites evaluating two seeding rates of: alfalfa, red clover, white clover and annual and perennial ryegrass. See Table 10, for the seeding rates, corn yields and percent cover of the cover crops for the seeding rate study. See Table 11 for a summary of the 2003 corn yields and percent cover of the cover crops for each of the individual plantings.
In 2003 there was a 1.3 tons/ac average reduction in silage corn yields (35% dry matter) from the use of the cover crops with 18.3 tons/ac, compared to the control for all sites with 19.6 tons/ac. The ryegrasses had a 1.5 tons/ac reduction. There is also typically a reduction in yields from post-emergence spraying when sprayed late compared to conventional pre-emergence systems. There was no corn yield benefit observed by lowering the cover crop seeding rates with both high and low rates averaging 18.5 tons/ac. In the seeding rate study the cover crop treatments resulted in a 2.6 tons/ac average reduction in corn yield compared to the control averaged for those sites. The corn yields with legume cover crops for both seeding rates averaged 19.5 tons/ac with a 2.1 tons/ac reduction compared to the control. Of the species tested in 2003, annual (ARG) and perennial ryegrass (PRG) were the most competitive. The corn yields with the ARG at both the 8 and 12 lb/ac rate was 15.9 tons/ac; the corn yields with a PRG cover crop was 18.4 and 17.6 tons/ac for the 8 and 12 lb/ac rate respectively compared to 20.4 tons/ac for the control. The percent cover in the fall at the 8 lbs/ac rate was 92 and 86 % for the ARG and PRG respectively. Some of the ARG cover was attributed to seed germinating from seed that was produced from the cover crop. It was observed that ryegrass seed production is possible when there is adequate sunlight which happens when the corn is being stressed and stunted with delayed canopy closure. Reducing the seeding rate further to the 6 or 8 lb/ac rate with good establishment procedures is an option to provide adequate cover.
In 2004 we worked with 18 farmers and 4 research facilities setting up demonstrations, field trials and research plots. In 2004 the plantings were conducted in New York, Pennsylvania and Vermont working with 5 extension agents 4 consultants and 1 SWCD employee. Some of these worked nearly independently with the farmers. Work increased in Pennsylvania with the support of the NRCS State Agronomist. In Pennsylvania we worked with an extension agent, a consultant, a SWCD employee, an ARS scientist and a Penn. State University farm manager with 6 farmers and 2 research facilities. See Table 12 for the on farm 2004 corn yields and cover crop data.
Results: Establishment of cover crops at time of corn planting studies at Big Flats Plant Materials Center 2000 – 2004
Results 2000: The corn silage yields (10/3/00) ranged from 15.4 to 19.4 tons/ac compared to 17.3 tons/ac for the control (Table 13 ). There was below average temperatures during the growing season in 2000. The average corn yields were reduced by the use of Python at the 1.14 oz/ac rate, pre-plant incorporated with Eradicane (16.8 tons/ac not counting the alfalfa treatment) this was apparent early in the growing season by visual observation, although the calculated yield was no less than the Accent/Pursuit treatment. Lower rates of Python .89-1.0 oz/ac have been used in the past with Eradicane with no apparent injury. The Eradicane/Basagran treatment (19.9 tons/ac) was the best treatment with an average of 89% cover (not counting the birdsfoot trefoil), which could be due to good pre-emergence control, followed by a post emergence clean up of the broad leaf weeds by the Basagran. The Accent treatments had the least percent covers across all cover crops. The perennial ryegrass (79.1%) and white clover (67.4%) had the best covers when average across all herbicide treatments on 11/14/00. The white clover is a good leguminous cover for erosion control due to its leaf retention over the winter. The annual ryegrass and the full rate of alfalfa were the most competitive to the corn. When the alfalfa seeding rate was reduced in half, corn silage yields went from 15.8 to 18.7 tons/ac with a drop in percent cover on 11/14/00 from 61.9 to 47.0 %. Most of these covers will be near or greater than 90% by May the following year. See Table 13, for a summary of 2000 corn silage yields and percent cover crop by the different herbicide and cover crop treatments.
Results 2001: The corn silage yields (9/19/01) were extremely low this year due to drought conditions with yields ranging from 7.2 to 12.2 tons/ac compared to 9.8 tons/ac for the control. When averaged over all of the cover crops and herbicide treatments there was an insignificant advantage of .65 tons/ac, for the controls over the cover crop treatments. The 2001 corn yield and percent cover crop data is summarized in Table 14. There was a reduction in red clover, white clover and birdsfoot trefoil percent covers from the Pursuit + Python pre-emergence treatments compared to the Pursuit alone. This was due to the drought reducing cover crop recovery from the Python herbicide at the 1.25 oz/ac rate. The alfalfa is more resistant to the Python than the other legumes and the annual ryegrass is more resistant to the Pursuit post emergence than the perennial ryegrass. When the annual ryegrass was seeded at the 4 lbs/ac rate in a mix the percent cover in November which was primarily the grass was at 70% indicating a reduction below the 10 lb/ac rate is warranted.
Results 2002: The corn silage yields from the cover crop seeding rate study ranged from 19.6 to 24.0 tons/ac compared to 23.4 tons/ac for the control. For the seeding rate study there was a trend but not a significant or practical difference between the (high vs. low) cover crop seeding rate and the percent cover of the cover crops. This indicates a reduction in seeding rates, to reduce seed cost, is warranted if care is given to facilitate good establishment. The perennial ryegrass had the lowest percent cover (50.0 and 38.3%) for the high and low seeding rates due to the stunting and mortality by the Pursuit herbicide. The corn yields did not correlate with the perennial ryegrass cover crop seeding rate, with the high cover crop yielding more than the low rate 24.0 vs. 19.9 tons/ac. The other cover crops, which had higher percent covers, were much closer in percent cover and corn yields, with yield differences for the high rate averaging just under 1 ton/ac less than the low rate. The corn yields with the alfalfa cover crop correlated to high and low seeding rates with 19.6 vs. 20.6 tons/ac with percent covers of 90 and 73.3% respectively, but the annual ryegrass had the opposite trend 21.0 vs. 19.6 tons/ac with percent covers for the high and low seeding rates of 97 and 90 % respectively. The 2002 data for corn yields and cover crop percent cover is summarized in Table 15.
Results 2003: Another seeding rate study was conducted in 2003, the corn yield and percent cover crop data is summarized in Table 16. The corn yields ranged from 13.1 tons/ac for the annual/perennial ryegrass mixture to 23.4 tons/ac for the control. Only the 8 lb/ac annual ryegrass rate (15.9 tons/ac) and the ryegrass mixture were significantly different from the control. The average yield with the other cover crop treatments was 22.6 tons/ac. Again as in 2002 there were no significant differences between corn yields between the high and low cover crop seeding rates, with the corn yields not always in the same ranking as the cover crop seeding rate or percent cover. There was only significant differences between the alfalfa (49 vs. 25%) and red clover (58.8 vs. 40 %) when evaluated on 11/20/03.
For the herbicide study in 2003, the annual ryegrass, perennial ryegrass and tall fescue had excellent cover 95%, 85% and 60% respectively for the Pursuit Callisto pre-emergence treatment with corn yields of 18.2, 19.3 and 20.8 tons/ac compared to the control with 20.9 tons/ac. The Lightning herbicide treatment was tested on legumes and provided 50 % cover and an average corn yield of 21.6 tons/ac compared to the control with 21.0 tons/ac. The Lightning post emergence treatment was late and experience has shown that early post emergence treatments can cause severe stunting and mortality to the legumes except for birdsfoot trefoil and hairy vetch. The other herbicide treatments which contained Accent were also only tested on legumes, these treatments provided 50 % cover with average corn yields of 21.4 tons/ac compared to the control ( 21.5 tons/ac) with no significant corn yield differences. The Pursuit, Permit plus Buctril treatment was tested on grasses and white clover. The white clover did well with 53% cover and a yield of 20.5 tons/ac compared to the ryegrasses which averaged around 90% cover. The annual ryegrass had a significantly lower yield of 13.4 tons/ac compared to the control and the perennial ryegrass both having 19.5 tons/ac. The annual ryegrass needs a herbicide to suppress it in this system. See Table 17 for a summary of the 2003 corn yields and percent cover crops.
Results 2004: The Pursuit, Prowl plus Python pre-emergence combination did not allow for sufficient legume survival, grasses were not evaluated due to preliminary results indicating their lack of tolerance to this combination. The Pursuit, Callisto plus Dual pre-emergence combination had no significantly different corn yields and allowed for significantly higher orchardgrass cover (78.3%) with 21.2 tons/ac corn yields. The perennial ryegrass produced 48.3% cover and corn yields of 20.5 tons/ac compared to 24 tons/ac for the control. Annual ryegrass was not tried and may have potential with this treatment. The Pursuit, Python plus Hornet pre-emergence treatment provided for excellent grass cover crop growth and comparable yields to the control, with average corn yields for all cover crops of 20.7 tons/ac compared to 22.1 tons/ac for the control. The seeding rate for the grass cover crops were at 10 lbs/ac and with perennial ryegrass, orchardgrass, tall fescue and reed canarygrass having greater than 80% cover on 11/18/04 the seeding rate could be reduced to 8 lb/ac. See Table 18 for a summary of the 2004 data for corn yields and percent cover crop.
Results: Cover crop corn herbicide study 2001 – 2004
The evaluation of the cover crops in 2001 was conducted on 7/31/01 and 11/19/01 without the stress of the shading and moisture competition from a corn canopy. This may have allowed for better recovery of the cover crops, therefore additional testing of promising treatments should be conducted under corn. The Eradicane at the higher rate 7.33 pts/ac had no detrimental effects on the legume cover crops, and had better weed control than the 5.0 pts/ac rate. There were still some escape lambsquarters and ragweed plants even with a full rate of Eradicane (7.33 pts/ac) + Python (1.16oz/ac). The ½ Accent rate (.33 oz/ac) + Python (1.0 oz/ac) or with Buctril (1.5 pts/ac) suppressed the legumes but except for the vetch they recovered. Grasses will not tolerate the ½ Accent rate. Past research has shown that birdsfoot trefoil is susceptible to Buctril. The Pursuit + Python (1.0 oz/ac) or Basagran (2.0 pts/ac) post emergence provided excellent establishment of all cover crops. See Table 1 for a summary of the 2001 data.
The evaluation of the cover crops in 2002 (Table 2) was conducted underneath a corn canopy on 10/18/02. The Callisto (8 oz/ac) pre-emergence was sprayed late when the legumes were in the cotyledon stage killing all of the legumes tested except for the alfalfa which out grew it and had 53% cover. The ryegrasses were not affected by the Callisto. When the Callisto was combined with the Pursuit pre-emergence, the perennial ryegrass was suppressed providing 45% cover on 10/18/02 compared to 91.7% for the annual ryegrass. The Lightning herbicide, a combination of Pursuit and Arsenal, suppresses the cover crops more than Pursuit. If Lightning is used late post emergence (LPO) the legumes will survive but not the grasses. Other studies have shown when Lightning is applied at early post emergence the suppression is excessive. Birdsfoot trefoil is the most resistant to Lightning, hairy vetch showed some resistance but needs additional study at early post emergence (EPO). Callisto (4 oz/ac) + Pursuit LPO allowed for all cover crops to grow except for red clover and hairy vetch. Callisto (4 oz/ac) + ½ rate of Accent (.33 oz/ac) LPO a non IMI corn hybrid treatment worked well on white clover, alfalfa, and birdsfoot trefoil with 95%, 85%, and 52% cover respectively on 10/18/02. This combination killed the grass cover crop, red clover, and hairy vetch. Callisto can not be used on red clover and hairy vetch and the ½ Accent rate can not be used on grass cover crops. The Pursuit (.72 oz/ac) + Accent (.33oz/ac) + Buctril (1.0 pt/ac) treatment worked well on red clover, alfalfa and white clover with 80%, 93%, and 100% cover respectively. The Distinct herbicide is similar to Banvel but with some reported grass activity it did not offer any advantage in grass cover crop suppression in this study. See Table 2 for a summary of the 2002 data.
The 2003 cover crop herbicide study was evaluated on 11/21/03 (Table 3). The fall legume percent cover ranked in order from most to least was white clover, red clover, alfalfa, birdsfoot trefoil, then hairy vetch. All of the grass cover crops tested this year were less competitive on the corn for all herbicide treatments then the ryegrasses and provided excellent cover. Their ranking in order of competitiveness was annual ryegrass, perennial ryegrass, tall fescue, orchardgrass, bromegrass, red fescue, bluegrass then hard fescue. The 1/3 Accent rate (.22 oz/ac) + Buctril (1.0 pt/ac) + Pursuit (1.44 oz/ac) allowed for the ryegrasses and tall fescue cover crops to grow providing an average of 65% cover on 11/21/03. Annual ryegrass was still too competitive. The ½ Accent rate (.33 oz/ac) with the above combination allowed only 42% grass cover, with greatly reduced seedling weights and is not recommended. The ½ Accent rate + Callisto (4 oz/ac) applied post emergence allowed for good percent cover of ryegrasses and tall fescue cover crops providing 78% cover without apparent corn competition. This is a non-imidizolinone (IMI) treatment. The Pursuit + Callisto (post) did not suppress the grasses as much as the ½ Accent rate + Callisto with average weights, on 7/11/03, of 13.1 vs. 6.3 grams of dry matter per 10 seedlings respectively. When the ½ Accent rate was combined with a full rate of Pursuit (1.44 oz/ac) + Buctril (1.0 pt/ac) grass seedling weight was reduced to 1.6 g. When the Accent was reduced to the 1/3 rate, average grass seedling weight increased to 5.5 g. The non-sprayed control grasses weighed 14.2 grams of dry matter per 10 seedlings. Pursuit (1.44 oz/ac) + Callisto (8 oz/ac) pre-emergence and Pursuit (1.44 oz/ac) + Buctril (1.0 pt/ac) + Permit (1.33 oz/ac) post emergence allowed for all grass cover crops to grow providing an average of 84% and 89% cover respectively on 11/21/03. The ryegrasses were too competitive and need some additional herbicide suppression. Of the cover crop grasses evaluated other than the ryegrasses the orchard grass and the tall fescue have the most potential for fall nutrient scavenging based on the amount of fall cover produced. See Table 3 for a summary of 2003 data for percent cover and seedling dry weights.
In the 2004 evaluation the best treatments for the legumes were: Pursuit (1.44 oz/ac) + Python (.5 oz/ac) + Prowl (1.0 pt/ac) pre-emergence; and Pursuit (1.08 oz/ac) + Lightning (.32 oz/ac) post emergence. The full rate of Accent (.66 oz.ac) + buctril (1.0 pt/ac) killed all cover crops; as did the Accent (.33oz/ac) + Buctril (1.5 pts/ac) + Dual (1.0 pt/ac), both were post emergence non imidizonlinone treatments. The latter treatment without Dual has worked for legume cover crops the Dual was added for later season annual grass control but did not allow for the legumes to grow. The Pursuit + Dual alone post emergence treatment was not tried.
The best treatments for the cover crop grasses from the 2004 evaluation year were: Pursuit (1.44 oz/ac) + Banvel (1.0 pt/ac) + Dual (1.0 pt/ac) post emergence; Pursuit (1.44 oz/ac) + Callisto (5 oz/ac) alone or with Prowl (1 pt/ac) pre-emergence, and Pursuit + Hornet (4 oz/ac) pre-emergence. The non imidizolinone treatment of Outlook (14 oz/ac) + Prowl (1.0 tons/ac) pre-emergence allowed for good growth of the cover crop grasses, this treatment is a low rate and may not provide adequate weed control. Some legumes survived this treatment as well. The non imidizolinone treatments of Dual (1.0 pt/ac) + Python (.89 oz/ac) pre-emergence did not allow the grasses to grow, there was limited survival for the red clover and alfalfa. Table 4a lists the 18 herbicide treatments evaluated in 2004. The 2004 data for the percent covers and seedling weights for all herbicide treatments are summarized in Tables 4b & 4c.
The grasses provide better cover in the fall than the legumes which tend to loose most of their leaves after a heavy frost. The annual and perennial ryegrasses, orchardgrass and to a lesser extent the tall fescue were tolerant to the shade and to the herbicides. The timothy, red fescue, bromegrass and Kentucky bluegrass were less shade and herbicide tolerant. The annual ryegrass was too competitive although there may be some opportunity to use higher rates of Dual with the annual ryegrass for better late season annual grass control.
Out of the legumes a mixture of white and red clover (4 lbs/ac plus 6 lbs/ac) would be the best choice or with a small amount (2 lbs/ac) of alfalfa. The alfalfa was the most competitive legume and was also the most herbicide tolerant. The white clover was more tolerant to herbicides than the red clover (i.e. Callisto pre and post emergence and Buctril post emergence), care needs to be taken not to seed white clover to heavily since it has more seeds per pound than either red clover or alfalfa. Hairy Vetch is not shade tolerant although it is tolerant to Lightning herbicide. Birdsfoot trefoil is slow to establish, the least competitive to the corn, and is tolerant to the full rate of Lightning; but is not that shade tolerant and its leaves fall off after frost and it is slow to regrow in the spring.
The biggest challenge is late season annual grass control. When taken off the research station we have found some of the herbicide combinations were not controlling late season crabgrass and fall panicum. Herbicide combinations which include small amounts of Dual may help in this regard.
A summary of some protocols:
Method #1: Clearfield Corn Hybrid
Conventionally till with final pass with harrow.
Plant cover crop with drill, Brillion or broadcasting prior to soil surface crusting, cultipacking if needed.
Plant corn as usual with Clearfield Hybrid (IMI corn i.e Pursuit Resistant).
Spray pre-emergence mix of Pursuit (1.44 oz/ac) and Python (.5 – 0.89 oz/ac) for grasses and legumes. For grasses use Pursuit plus Hornet (4.0 oz/ac) or Callisto (5-8 oz/ac). Dual at 6 oz/ac can be used for grasses. Python (.89 oz/ac) with Pursuit can cause stunting in corn during years where corn emergence is slow. Wait until corn is spiking before application or use .5 oz/ac.
Method #2: Clearfield Corn Hybrid
Prepare field and plant cover crop as above.
Plant corn as usual with Clearfield hybrid (IMI corn i.e Pursuit Resistant).
Spray post emergence mix of Pursuit (1.44 oz/ac) and other herbicides following label dependent on CC and weeds (i.e Buctril, Basagran, Python, Permit, Banvel, Callisto etc.). Use first three with grasses or legumes use second three on grasses only. Use non ionic surfactant with nitrogen.
Method # 3: Conventional Corn Hybrids
Prepare field and plant cover crop as above.
Spray Eradicane (5 pints/ac) + Python (1.0 oz/ac) pre-plant incorporated, follow-up with post-emergence legume tolerant herbicide if needed (Buctril or Basagran).
Incorporate Eradicane 3-4 inch deep criss-cross if possible. (Do not use Eradicane on grass cc). Plant normal corn hybrids as usual. Spraying post-emergence with 1/2 accent and Buctril has been used with red and white clover.
Cover crops: Note: it is important not to over apply seed
Red clover 10 lbs/ac do not use Callisto on red clover pre or post
Dutch white clover 6 lbs/ac can be used with Callisto.
Perennial ryegrass or other cool season grass 6-8 lbs/ac (Pursuit + Callisto Pre) (not with Eradicane)
Red clover + White Clover or alfalfa 6 + 4 lbs/ac ea.
Red clover + PRG 6 + 4 lbs/ac each
A table of herbicide/cover crop tolerances is given in appendix 10 c.
Results: Cover crop phosphorus runoff experiments
Yield and cover crop results:
At the site on Willowemac soils, in 2000, there were no statistical differences in corn yields between the control at 18.3 tons/ac and the red clover at 18.0 tons/ac, the corn yield was significantly lower from the perennial ryegrass cover crop treatment at 15.2 tons/ac. The percent covers as measured on 11/14/00 were 43%, 66% and 93% for the control, red clover and perennial ryegrass respectively. At the site on Onteora soils, in 2001, there were no significant corn yield differences between the control at 16.9 tons/ac, red clover at 16.4 tons/ac and the perennial ryegrass at 13.4 tons/ac, there were significantly lower corn yields from the alfalfa cover crop treatment at 9.0 tons/ac. The percent cover of the cover crops as measured on 9/18/01 was 10%, 85%, 91% and 81% for the control , alfalfa, perennial ryegrass and the red clover respectively. Some of the problems with the corn yields could be attributed to the higher than calibrated delivery of the cover crop seed from the planter as observed by a much higher density at planting as well as delays in weed control by the custom applicator.
Runoff properties prior to manure application:
Prior to manure application at the spring 2001 runoff experiment at the Willowemoc soil (exp#1) and the fall 2001 runoff experiment at the Onteora soil (exp #2) there was significantly more runoff from the control than from the cover crop treatments due to the reduced surface sealing and increased infiltration on the cover crop plots. There were no significant differences in the spring 2002 runoff experiment on the Onteora soil ( exp. #3) this situation was due to variation in runoff volume within individual treatments as well as elevated antecedent soil moisture. This situation resulted in a lack of statistical differences for this experiment for the other variables measured.
Averaged across experiments suspended solid loads were significantly greater from the control than the cover crop plots. The total P (TP) in runoff was largely a function of erosion as illustrated by generally strong relationships between total P and suspended solid concentration prior to manure application. There were statistically higher total P in the runoff from control plots from the first two experiments and a trend from the third. There were no statistical differences between cover crop species.
The dissolved reactive P did not differ significantly between treatments except for the exp #2 in the fall the second event had significantly higher dissolved reactive P (DRP) from the control plots.
Runoff properties following manure application:
Broadcasting dairy manure to soils over-rode differences in runoff P between control and cover crop treatments. Significant increases in runoff P (DRP and TP) loads and concentrations were observed for all cropping treatments when compared to before manure application. Much of the increase in runoff P was related to augmented DRP across all experiments the proportion of total P that was dissolved reactive P increased from 28% before manure application to 78% after manure application. It is possible under more natural rainfall conditions some of the DRP could infiltrate into the soil where it would then be protected by a cover crop. Tables, figures and more results and discussion for this study can be found in (Kleinman et.al. 2005).
Kleinman, P.J. A., P.R. Salon, A.N. Sharpley and L.S. Saporito, 2005. Effect of cover crops established at time of corn planting on phosphorus runoff from soils before and after dairy manure application. Journal of Soil and Water Conservation 60(6) 311 – 322.
Results: Cover crop soil quality study
In the soil quality study we compared soil quality indicators after four years of corn silage (2001 – 2004), with alfalfa, red clover and annual ryegrass cover crops conventionally tilled compared to a no cover crop conventionally tilled control and an annual ryegrass treatment with zone-till and a zone-till control without cover crop treatment. The average corn silage yields for 2001-2004 when grown with the conventionally tilled red clover, alfalfa, annual ryegrass and control; and the zone-tilled annual ryegrass and zone-tilled control were: 18.0, 17.4, 17.4, 17.5, 16.1, and 16.2 tons/ac 35% DM respectively. There were no statistical differences between corn yields when evaluated each year. The average percent cover in the spring for the red clover, alfalfa and annual ryegrass conventionally tilled and zone-till were 43.8, 60.8, 73.3 and 72.0 percent respectively. The yearly yields for the corn and percent cover crop are in Table12.
There were statistical differences in percent small aggregate stability between treatments. The percent small aggregate stabilities ranged from 16.8 to 37.0. The combination of zone-till plus annual ryegrass (ARG) cover crop was the best treatment as measured by small aggregate stability (37%), and that tilling with ARG cover crop had better values (30.6%) for these tests than zone-till alone (16.8%) or conventional tillage without cover crop (21.6%). There were no significant differences in percent small aggregate stability between the legume cover crops conventionally tilled and the treatments without cover crops with either conventional or zone-till. See Table 13 for a summary of soil quality tests statistically analyzed.
The N-mineralization rate (µg/gdw) was only measured for the ARG treatments and the non cover crop treatments, with conventional and zone-till. There were significant differences between treatments. The N-mineralization rankings of those treatments were the same as for the percent small aggregate stability test in descending order of ARG zone-till (6.88) , ARG conventional till (4.91), no cover crop conventional tilled (2.52) and no cover crop zone-till (1.77).
For the particulate organic matter (POM) 53µ and 250µ fractions, and percent large aggregate stability the trends indicated the best treatments were ARG zone-till, ARG conventional till followed by zone-till without cover crop and lastly conventional tillage with no cover crop.
Trends were observed in soil quality indicators improved by the addition of ARG in the zone-till system compared to the zone-till without cover crops for percent organic matter, decomposition rate and field infiltration rates. Some tests were still being driven by the annual tillage event these tests included bulk density, field infiltration, core penetration, and saturated hydraulic conductivity. See Table 14 for a summary of all soil quality data.
A farmer questionnaire and a methods fact sheet was made and distributed to farmers and conservation and extension agency personnel as a planning and application tool. A herbicide matrix of compatability of cover crops and herbicides was made available to extension personnel and consultants to assist in designing herbicide combinations. These are in Appendix 10 a,b,c.
In 2001, more than 500 farmers, agency personnel and consultants had the opportunity to hear about this project through SWCD and Watershed Council newsletters and field tours. Three sites were used for Field Day Tours with over 300 attendees. National Coverage of the project was covered in the No-Till Farmer Journal, the Conservation Technology Information Center national magazine and the NRCS national technology electronic newsletter. See Appendix 11a for a listing of all 2001 outreach and publicity.
In 2002, there were 15 meetings and demonstrations conducted with approximately 422 in attendance see Appendix 11b. Information was requested and sent out via email to 8 consultants or conservation and extension agency personnel outside of the region. A power point presentation, poster and a one page instruction sheet was created and used during the meetings to inform farmers and agency personnel about the technique and the project. Articles were written in SWCD and Cooperative extension newsletters as well as in two newspapers see Appendix # 3. An article describing the project was put on the National Plant Materials web site http://plant-materials.nrcs.usda.gov. A demonstration was again established at the Empire Farm Days site in Seneca Falls, NY. One poster was presented at the National SWCS meeting in 2002. Agency people have been involved in establishing demonstrations, an Extension Agent in Cumberland County Pa. establishing two trials on his own and four projects were conducted in Vermont with the St. Johnsbury Soil And Water Conservation District (SWCD) with assistance from the University of Vt. Cooperative Extension. Several NRCS and Extension agents in New York and Pa. have assisted in data collection and have attended field demonstrations.
In 2003, there were 13 meetings and demonstrations conducted with approximately 660 in attendance. These included Cornell’s Musgrave Research Farm Field Days, the Northeast Agronomy Society’s annual meeting and crop advisor training at the University of Vermont and Empire Farm Days in Seneca Co. NY. Presentations were given at major extension winter meetings in cooperation with the University of Vermont in Springfield and St. Johnsbury VT, Cornell University in Ithaca, NY, the Western NY Quality Forage Forum in Delevan, NY, the Agricultural Environmental Management for Comprehensive Nutrient Management Plan Development training session in Binghamton NY, and the NRCS East Region Technology Workshop (for NRCS technical specialist from the NE and Mid-Atlantic states) in Syracuse NY. These meetings attracted a diverse audience of extension agents, farmers, crop advisors, NRCS and SWCD employees. The power point presentation was expanded to include soil and water quality benefits and other cover cropping systems. See Appendix 11c for a listing of all 2003 outreach and publicity.
In 2004, there were 10 meetings and demonstrations conducted with approximately 1030 in attendance. The meetings concentrated on state level NRCS Agronomists and Plant Materials Personnel at two national meetings in Nebraska and Missouri. Information was also presented at the annual National Soil and Water Conservation Society and American Society of Agronomy meetings in Minnesota and Washington. See Appendix 11d for a listing of all 2004 outreach and publicity.
Additional Project Outcomes
Impacts of Results/Outcomes
Seven of the farmers conducting plantings in 2004 conducted plantings previously. Four were on their 3rd year. Six of these farmers increased their acreage and had bought their own corn, herbicides and cover crop seed. One of the farmers increased his acreage under the system to over 50 acres. Eight of the farms had field tours in conjunction with an extension agent and SWCD personnel. Farmers have figured out that they can mix the cover crop seed with their fertilizer and have it broadcast spread when fertilizing their corn. Another method we developed with a farmer is using the insecticide hopper with a minimum amount of adaptation as a seeder for surface spreading the cover crops in conventional tillage systems.
In many small demonstration projects the management of the small acreage by the farmer is sometimes delayed to get the majority of their field work done first. Custom spray applicators may not get to the field when it is ready this is especially true when spraying imidazolinone herbicides not compatible with conventional corn hybrids. This late spraying can impact on yields. There seemed to be a trend toward seeding at a higher rate than recommended, this was due to when calibrating for low seeding rates, drills are typically delivering more seed. This can be overcome by experience and using multiple settings in a field to learn which settings delivers the proper stand for future seedings. There is also a marketing problem with the Clearfield hybrid line (imidizolinone resistance) resulting in reduced investment and development of new hybrids with the Clearfield system especially for silage corn so there may become a hesitancy to choose these Clearfield hybrids over other corn hybrids with advanced genetics with increased yields and forage quality.
For those farmers we have worked with there has been an increase in awareness of the benefits of cover cropping. Some will benefit with this method of cover cropping while others may put more emphasis on the timeliness of their harvest and application of fall cover crops. This system may be useful in areas with highly erodible soils and as an option to increase or maintain the number of years of corn in a rotation to reduce or maintain soil losses while maintaining compliance with conservation programs.
Even with all of the outreach and work done many of the farmers do not seem willing to continue with this cover crop method. Although this is an alternative time of the year to establish a cover crop it is also a time when there are many other operations and management decisions competing for their time and attention. There is also a perceived or real risk of reduced yields with this system as compared to establishing a cover crop after the corn is harvested. This system takes more management and knowledge in weed control than a fall applied cover crop. It is also helpful if a farmer does his own spraying with this system.
Areas needing additional study
Continue to investigate herbicide combinations and techniques that can be used without the use of corn hybrids tolerant to imidizolinone herbicides. Work needs to be done for conventional hybrids as well as other herbicide resistant hybrids which look like they may have longevity in the market.
Work needs to continue with the Clearfield hybrid system using Lightening and Pursuit combinations and the use of the combinations of Pursuit, Accent, Callisto and Banvel at reduced rates to increase suppression on legumes and weeds. The use of small rates of Dual, and Prowl pre and post emergence with other post emergence herbicides need to be evaluated for increased suppression of cover crops and improved late season annual grass weed control.
White clover cultivars need to be evaluated to find highly stoloniferous varieties which can be seeded at lower rates at time of corn planting which will fill in during the growing season and prior to winter. Investigate the use of Pursuit plus Buctril with methylated crop oil (to suppress the alfalfa) on alfalfa at a couple of seedling stages too see if an alfalfa stand can be established under a corn crop without competing with the corn.