Conserving end-of-season N with effective seeding dates for cover crops based on fall growing degree days

Final Report for LNE06-238

Project Type: Research and Education
Funds awarded in 2006: $85,953.00
Projected End Date: 12/31/2009
Region: Northeast
State: Massachusetts
Project Leader:
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Project Information


Our hypotheses were:
i. that fall-winter losses of N leaching in corn fields are avoidable, and can be reduced or prevented if cover crops are used, and are planted early enough to be effective, and
ii. that use of cover crops and nutrient management has economic benefit to the farmer, can be integrated into the cropping system through outreach and education, and is transferable to other regions.

To achieve the objectives research studies and on-farm field experiments were established for corn-cover crop planting date evaluation. These involve field studies demonstrating the effective date for fall establishment of cover crop after corn harvest for optimal N accumulation. However, because farmers are impacted by adverse weather conditions (e.g. excessive rain in two project years) they often have difficulty in meeting the cover crop planting dates for optimum end-of-season N accumulation and thus other approaches are needed. The project involved more than 25 farm studies with data collection and an evaluation of the corn-cover crop system, and more farmers in the review of management strategies for establishment of cover crops in standing corn at the time of topdressing N fertilizer, and field studies investigating the use of early planting of early maturing corn hybrids.

On-farm and research trials have shown early hybrids on average have similar yield and similar or improved quality compared to late season hybrids and if planted would help to ensure earlier planting of a cover crop. Early planting was shown to be very important for maintaining silage yields and quality and for achieving and as with early maturing corn hybrids an early harvest date. Six field studies across Massachusetts for establishing cover crops in standing corn in June at the time of fertilizer topdressing showed this practice was not viable and although farmers suggested use of helicopters in late August they realized this previous practice was cost prohibitive and not likely to return.

Results obtained from all of on-farm demonstrations were presented at farmers meetings, field days, and barn meetings. In these meetings collaborating farmers where on-farm demonstrations were conducted at their farm talked about their learning and the adjustments they made to their management practices. As a result of this project more than 10 farmers who were not planting cover crops before have started planting cover crops by making some adjustments in their management. Five farmers (with the total of 259 acres) are now using shorter season corn hybrids, 3 farmers (with total of 203 acres) are planting corn from 1-2 weeks earlier, 2 farmers (with total of 97 acres) is spreading manure while harvesting corn silage rather than spreading manure after the corn is harvested. One farm moved away from corn and seeded these fields (approx. 100 acres) to pasture and now raises beef rather than dairy cattle. We are also aware of 5 other dairy farmers (2 of them never planted cover crops before) who have made further management adjustments for earlier planting of cover crops in the 2010 growing season.

Cover crop growth and climatic data were integrated into a fall GDD model and incorporated into the economic considerations. All findings were and continue to be shared with and reviewed by farmers. The results are transferable to other farm locations/regions through the development of the GDD model. This work is being continued with other funds to make this information web accessible.


Well-established cover crops are effective in taking up residual soil nitrate after the harvest of corn or other crops, and nitrate released from applied manure. Preliminary experiments at the UMass Crop and Animal Research and Education Center Farm in 2004-05 demonstrated a seeding date of September 1 had greater cover crops growth and increased N accumulation compared to September 15 (or later) the recommended seeding date in this area for erosion control. Numerous studies have shown that effective cover crops prevent erosion and loss of reactive phosphorus in runoff from fall applied manure. Given that cover crops accumulate N they also minimize the nitrate leaching to ground water during the fall and winter months.

Cover crop seeding date is important for adequate canopy and root development before cool weather slows or stops growth. The ability of the cover crop to absorb nitrate from the soil is affected by the degree of colonization of the soil by roots. In most years, seeding dates after mid September will result in less than adequate leaf growth to reduce the erosive force of rain and runoff, and the small amount of root growth will not contribute much to stabilizing the soil or for nutrient accumulation. The mid-September seeding date as a standard for cover crops was established for their effectiveness for erosion control. Whether effective dates for erosion control are similar to effective dates for preventing leaching were unconfirmed. We now know that seeding one to two weeks earlier will significantly increase N accumulation. However, information on the effect of any delay in establishment of cover crops on nitrate leaching had not been determined.

Low fall temperatures are a major factor controlling growth and the potential effectiveness of cover crops planted at different dates for reduced impact on ground water quality. The responsiveness of rye growth to temperature lends the possibility of relating biomass and N accumulation to growing degree days (GDDs) as is used in maturity classification of corn hybrids.

Performance Target:

Our objectives are i. to determine critical seeding dates and a growing degree day (GDD) model for rye cover crops. ii. To evaluate methodologies for early establishment of cover crops, and iii. to demonstrate the economic benefit of adopting effective cover crops.

Of 20 dairy/livestock farmers who participate in on-farm studies and farm based outreach, 15 will use the developed assessment methods for cover crop effectiveness in recovering end-of-season nutrients, and 10 will make management decisions (changes) to ensure cover crops are effective for N uptake.


Click linked name(s) to expand
  • Thomas Akin
  • A. Masoud Hashemi
  • Timothy O. Randhir


Materials and methods:

Field experiments with four cover crop seeding dates (approx. Sept. 1 to Oct. 14) were established on dairy farms and at the UMass Crops Research and Education Center farm to determine effective dates for mopping-up end-of-season N. Twenty six farm sites, spanning four Massachusetts counties, participated in cover crop and other field studies with temperature data collection as appropriate to establish a growing degree model for rye cover crops. Recruitment occurred from farmers involved in nutrient management planning with UMass Extension and NRCS, from farmers participating in annual farm meetings, and from farmers showing interest in an interview survey.

Corn field sites were chosen on the basis of a long manure application history and fields receiving manure in both the spring and fall, as is the usual practice of farmers. Selected sites were fields with a high mineralization capacity for N, typical of corn fields on many dairy farms. The experimental design used for cover crop and other studies was a randomized complete block design with three or four replicates at each field site. Samples of cover crops were collected in mid to late October, November, December, and late-April to early-May. The spring date represented the last probable plowing dates for corn. Soil samples were also collected.

Temperature data collected was used to determine growing degree days [?(Average Daily Temperature – Base Temperature)] for specific growth stages of the rye cover crops relative to shoot and root development for the uptake of N and erosion abatement. Growing degree days were determined using an initial base or threshold temperature of 4.5 degrees C (40 degrees F) and this was varied to give the best growth model fit using regression analysis.

Two strategies were followed to assist farmers in achieving effective cover crop establishment for end-of-season nutrient uptake. The first approach was to use rye and other species for cover crop establishment into growing corn. This method was reported by sweet corn growers to be effective in establishing rye, annual ryegrass and smooth bromegrass when seeded in early June at the time of side/top-dressing corn with N fertilizer. The hypothesis was that cover crops seeded at this time would germinate and begin growth but the growth would be restricted by the shade from the corn crop. When the corn is harvested for silage, the earlier seeded cover crops would begin rapid growth in the enhanced light conditions. If effective this method advances the establishment time of cover crops by at least two weeks compared to cover crops seeded after corn harvest.

The second approach involved corn hybrid time of seeding studies on some farms where early maturity corn hybrids were compared to medium and late maturity hybrids for yield, ear development, relative feed value, and time of harvest maturity. The goal was to determine extent of yield reduction, if any, from early maturing corn hybrids, and to demonstrate how planting an earlier maturing hybrid might improve nutrient retention with earlier planting of cover crops. While this was an indirect approach, we believed growing late maturity corn hybrids has led to the late planting of non-effective cover crops. Measurements for corn yield included total biomass and ears, and stalk samples for N sufficiency. Corn maturity was recorded for each corn hybrid and the time gained for seeding cover crops.

During the initial recruitment of dairy/livestock farmers a face to face interview was completed on 34 dairy farms in Massachusetts. Each farm was visited and farmers completed a comprehensive survey on farm practices including data relevant to this project concerning cover crop and corn management. Each spring (2007, 2008, 2009) farmers were invited to attend one of two meetings (west and central Mass.) to develop the appropriate research methodology for on-farm studies and to review research approaches for more effective cover crops. This was a participatory process, with growers being encouraged to share their knowledge and experience.

An economic analysis was conducted using the collected farm experimental data using an approach that evaluated the risk aversion of farmers related to the alternative cropping practices for more effective cover cropping systems. From research results GIS maps for cover crop seeding dates relating to the GDD model were developed as decision aids for farmers, field agency staff, and agricultural educators. Each summer one or two on-farm meetings were held and research activities were discussed. Results were also presented in newsletters, at regional and national agronomy and soils meetings, and shared at CCA training meetings.

Research results and discussion:

Farmer Participation:

In the first year we met with USDA-NRCS partners in the spring to discuss how to recruit farmers for field studies and demonstrations. The goal was to have 10 to 15 farmers involved in the project by the first summer. This was achieved with 10 farm demonstrations established in 2006. In 2007, 11 additional farm studies were conducted, and in 2008 and 2009 five farm studies were conducted on farms including studies at the UMass Crop and Animal Research and Education Center Farm. Farmer participation in spring and summer meetings ranged from less than 15 in some to more than 60 in others. Overall the average would have been more than 25 in each of 10 farmer and agency meetings.

Farmer Survey Related to Cover Crops and Farm System Approach to Corn Silage Production and Nutrient Management:

The Massachusetts survey of dairy farm practices related to nutrient management was conducted to determine prevailing practices on 34 dairy farms in 2006. Farmers were interviewed at farm by an agronomist and a dairy specialist using a comprehensive survey form. More than 50% of farmers had participated in nutrient management planning (Fig. 1) and had thus been exposed to the role of cover crops in end-of-season nutrient conservation. While most famers used soil tests (96%) (Fig. 2) just over 50% had an analysis of manure with only 22% having done this in the last two years (Fig. 3). About 50% broadcast fertilizer prior to seeding corn and almost 70% use starter fertilizer (Fig. 1). Forty percent side or topdressed nitrogen but less than 30% used the PSNT to determine nitrogen need (Fig. 1). More than 75% of the soil samples were taken by fertilizer companies (Fig. 4) while manure sampling was mostly (76%) done by the farmer. Farmer opinions on manure usage showed application somewhat related to soil test results but most was applied without regarded to an N or P restriction. More than 75% of the farmers indicated they had not calibrated the manure spreader (Fig. 5).

Farmers indicated they seeded corn from late April through early June with the week of May 8 – 15 being the week when most was planted (Fig. 6). Silage corn harvest occurred from the beginning of September through early mid-October, with more than 50% harvested after September 15 (Fig. 7). Farmers indicated cover crop seeding dates were from September 15 through October 25 (Fig. 8). The surveyed farmers expressed an interest in learning more about BMPs and manure management.

The survey results and other interactions with farmers and students led us to develop our conceptual thinking, research and educational programs following a farm system approach to corn silage production and nutrient management. In this cover crops were an integral part, though often neglected in farm practice and in outreach education. The farm system approach involved consideration of corn planting time and planning for an early harvest, choosing early maturity corn hybrids, all elements of nutrient management planning relating to soil testing, fertilizer usage, and manure use efficiency, and early seeding of cover crops. The survey indicated more education on nutrient management is warranted and that farmers can make savings on fertilizer purchases and protect the environment if they implement certain proven practices.

Cover Crop Seeding Dates and Other Related Field Studies of the Farm Cropping System:

Data was collected from 7 site years of cover crop seeding date field studies, 15 experimental site years and earlier data comparing short-season and full (late) maturity corn hybrids, 5 experimental site years for corn planting date studies, and 6 experimental site years of under seeding cover crop species into growing corn. Data and results for field studies are discussed in the next main section. Farmers indicated in the survey and in farmer meetings that they had difficulty in achieving the desired early seeding date for cover crops because of farm logistics and delay corn growth due to wetter and cooler conditions than normal the last two years (2008, 2009). This led us to examine another approach of planting a cover crop at the suggested date for erosion control or earlier, and then to delay manure application until cooler (cold) temperatures in November/December for reduced ammonia volatility from surface applied manure.

The GDD model was developed using temperatures recorded for the experimental sites for cover crop seeding date studies. Different base (threshold) temperatures were evaluated to improve goodness of fit of the data from several years in the model. The base temperature of zero degrees C was determined to give the best fit. From the GDD model the loss of N with delayed seeding of cover crops was estimated for varying geographic locations and used as part of the economic analysis. Throughout the 3-4 year project period visits were made to farms involved in cover crop and corn planting studies providing research support for on-farm experiment evaluations and data collection.

Participation Summary


Educational approach:


Herbert, S.J., M. Hashemi, and S. Weis. 2008. Farm System Approach for Corn Silage Production and Nutrient Management. 2007 Massachusetts Agronomy Research report. 28:2-3.

Herbert, S.J., M. Hashemi, S. Weis, A. Farsad, and J. Carlevale. 2008. Cover crop Seeding dates and N Accumulation. 2007 Massachusetts Agronomy Research report. 28:5-6.

Herbert, S.J., M. Hashemi, and S. Weis, and A. Farsad. 2008. Comparing Early and Late Corn Hybrids. 2007 Massachusetts Agronomy Research report. 28: 6-7.

Herbert, S.J., M. Hashemi, and S. Weis. 2010. Planting Date and Hybrid Influence on Corn silage Yield and Quality. 2009. Massachusetts Agronomy Research report 30:19.

Herbert, S.J., M. Hashemi, and S. Weis. 2010. Planting Effective Cover Crops by Using High Yield Early Maturity Corn Hybrids for Silage. 2009. Massachusetts Agronomy Research report 30:19.

Farsad, A., S.J. Herbert, M. Hashemi, and T. Randhir. 2010. Developing an efficient Cover Cropping System for Maximum nitrogen Recovery in Massachusetts. 2009 Massachusetts Agronomy Research report. 30:14-15.


Herbert, S.J., M. Hashemi, and S. Weis. 2009. Planting Date and Hybrid Influence on Corn silage Yield and Quality. ASA-CSSA-SSSA. Nov. 1-5, 2009. Pittsburgh, PA

Herbert, S.J., M. Hashemi, and S. Weis. 2009. Planting Effective Cover Crops by Using High Yield Early Maturity Corn Hybrids for Silage. ASA-CSSA-SSSA. Nov. 1-5, 2009. Pittsburgh, PA

Farsad, A. Improved Measurement of Nitrate Leaching in Fall Planted Cover Crops. Northeastern Branch, Crops, Soils, and Agronomy Conference. July 12-15, 2009. Portland, Maine.

Farsad, A., S.J. Herbert, M. Hashemi, M. Ranjbar, and L. Chen. Automated N Leachate Measurement in the Field Using Equilibrium Tension Lysimeter. ASA-CSSA-SSSA. Oct. 5-9, 2008. Houston, TX.

Herbert, S.J., M. Hashemi, S, Weis, and T. Randhir. 2007. Managing Cover Crops for Maximum Nitrogen Recovery Following Corn. ASA-CSSA-SSSA. Nov. 4-8, 2007.New Orleans, LA.

Hashemi, M. and S.J. Herbert. 2007. Massachusetts Survey of Dairy Farm Practices related to Nutrient Management. 2007. ASA-CSSA-SSSA. Nov. 4-8, 2007.New Orleans, LA.

Herbert, S.J. 2007. Success and Failures of Early Cover Crops to Protect Water Quality. New England regional In-service training for Ag service Providers. Feb. 7-8, 2007. New Castle, NH.

Herbert, S.J. 2007. Massachusetts Farmer Evaluation of Use of Various Tests. New England regional In-service training for Ag service Providers. Feb. 7-8, 2007. New Castle, NH.

Herbert, S.J. 2006. Cover Crop Planting Date and Nutrient Retrieval. New England regional In-service training for Ag service Providers. Feb. 6-7, 2006. New Castle, NH.

Annual field days and farmer research group meetings:

Farmer Meeting, April 1, 2007. UMass Crop and Animal research and Education Center. South Deerfield, MA.
Farmer Meeting, April 3, 2007. Jordan Farm, Rutland, MA.
Farmer Meeting, March 31, 2010. Cooks Farm, Hadley, MA
Farmer Meeting, April 7, 2010. Talvy Farm, W. Brookfield, MA
Twilight Barn Meeting, July 12, 2007. Hosted by Robert and Martha Richardson. Warren MA.
Twilight Barn Meeting, July 31, 2008. Hosted by Templeton Development Center. Templeton, MA.
Twilight Barn Meeting, August 5, 2009. Hosted by Raymond and Pamela Robinson. Hardwick, MA.
Twilight Barn Meeting, August 18, 2010. Hosted by Wayne Goulet. Hadley, MA.
Annual Field Day, August 21, 2007. UMass Crop Research and Education Center. South Deerfield, MA.
Annual Field Day, July 16, 2009. UMass Crop Research and Education Center. South Deerfield, MA.
Annual Field Day, August 11, 2010. UMass Crop Research and Education Center. South Deerfield, MA.


Hashemi, M., A. Farsad, and S.J. Herbert. Growing effective cover crops for erosion control and end-of-season nitrogen accumulation. CDLE 10-2.

Additional Project Outcomes

Project outcomes:

Impacts of Results/Outcomes

Results from field studies and further activities are discussed in detail below.

Seeding Dates for Cover Crops:

Most farmers and extension and UDSA-NRCS staff have known the appropriate date for seeding cover crops based on achieving 30% cover prior to winter for control of soil erosion. In the Deerfield area of the Connecticut River Valley in Massachusetts the seeding date has been taken to be September 15. However, this seeding date for cover crops had been determined only for controlling water and wind erosion. Thus, seeding dates were based on plant canopy cover, not on root development for their nutrient accumulation. Growth of cover crops with varying seeding dates is illustrated in Figure 9.

Our research from 2004 to 2009 has indicated the seeding date for maximum biomass growth and N accumulation was two to three weeks earlier than the date for adequate soil erosion control (Figs 10-12). Based on these results most cover crops planted by farmers are not effective in accumulating end-of-season nitrogen because they are planted after the desired date. If nitrogen, for example, is not accumulated by a cover crop it will be lost during the fall as indicated by the lower soil N values for the no cover treatments during the fall (Fig. 13), and very low soil N values for rye and oat cover crops regardless of seeding date (early September or late October) after winter in early spring. Our earlier studies reported that cover crops planted in early September had 50% more nitrogen accumulation than cover crops planted in late September. Results from our studies in this project confirmed these earlier reports for both rye and oat cover crops and that rye retained more of the accumulated N through the winter than oat.

Early establishment dates for cover crops were confirmed in UMass and farmer studies as necessary for effectiveness for end-of-season N accumulation by cover crops and this translated into higher PSNT levels with earlier seeding (Fig. 14). Later seeding of cover crops even in heavily manured soils indicated N fertilizer was needed due to PSNT levels below the 25 ppm sufficiency level of nitrate-N for corn silage.

Accumulated GDD was calculated from Sept. 1st to Dec. 30th. The base temperature of zero degrees C was found to give the best fit for normalizing data based on GDD accumulation from different seeding dates in several experiments and years. It was determined that 1030 units (Base temp. 0 degrees C) were needed for maximizing rye cover crop growth. There appeared to be no benefit to greater GDD accumulation in terms of N accumulated. Data showing the relationships for biomass increase and GDD accumulation or loss, biomass and N accumulation with change in seeding date are given in Table 1. A delay in the planting date reduced N accumulation exponentially. Even a small delay in planting cover crop in fall reduced its efficiency for N accumulation dramatically. A small drop in GDD can lead to exponentially larger reduction in biomass and N accumulation.

Using the data from the 14 weather stations, we were able to estimate GDD and therefore could estimate biomass and N accumulation for each date of planting in any locations in the State. To increase the accuracy of our model and for better estimates a non-liner model calculated using the weather station data the GDD was based on temperature and the elevation and precipitation (R squared 96%). Thus, the estimate of GDD for each location was determined with greater accuracy.

GDD = f(temperature, elevation, precipitation), and Biomass = f(GDD), N uptake = f(Biomass)

In this way we can estimate potential N uptake for each location in the State, using the elevation and precipitation data and we can do that for any planting date from August 1st to October 31 or later. A digital map integrating temperature, elevation and precipitation was developed for the critical planting date zones based on GDD accumulation (Fig 15). Biomass and N accumulation for weekly interval planting dates. These maps are the basis of a decision making tool for the dairy farmers and to assist them in deciding the best practical cover crop seeding date. This tool is being finalized as a web-based decision aid.

Strategies for Earlier Seeded Cover Crops:

Previously cover crops have been inter-seeded in standing corn using helicopters. This is now probably not a viable option because of cost and absence of cost-share programs for such aerial seeding methods. In all of the inter-seeded cover crop studies rye seeded in June in the first year, with good growth in July, plant material was almost absent after corn harvest in late August to early September (Fig. 16). Based on this data and early July inter-seeding with similar results, this method was abandoned in later years. Farmers were encouraged to use other options of combine seeding of cover crops with the harvest operations or with the incorporation of manure.

Seven years of field studies at the UMass Research Farm have shown that yield of early hybrids was similar to late hybrids. The average yield weighted for the number of hybrids each year was 28.6 t/ac for early hybrids and 28.7 t/ac for the late hybrid group. In all maturity groups there are high and lower yielding hybrids of varying quality (Fig. 17). Hybrids were not always consistently high yielding at differing sites. However, planting early hybrids may increase nutritional quality without lowering silage yield.

Early seeding of corn and choice of an early maturing hybrid helps to ensure an earlier harvest date and greater chance of seeding a cover crop near to the optimum date for maximizing N accumulation. Several studies were established to demonstrate crop response to date of planting in relation to date of harvest (Fig. 18) and to maturity group of hybrid (Figs. 19 and 20). Any delay in planting tends to reduce total yield as well as grain contribution to yield and hence overall quality. A delay in planting reduced yield more than the differences in yield between early and late maturing hybrids (Figs. 19 and 20) with yield of early maturity hybrids being similar to late at varying planting dates for silage and ear yield.

Economic Analysis

From first day of August to the end of the Julian year, average weekly GDD was calculated (20 weeks) for 14 weather stations in and around the state of Massachusetts. For each week, using ArcMap and Interpolation techniques, a raster map was created. For maximum N recovery winter rye requires about 1050 GDDs (based on data from all cover crop experiments) which we call Critical GDD (CGDD). In mapping we looked for regions with similar CGDD (we assumed that a GDD range between 1000 and 1100 can be considered as CGDD). Regions with critical amount of GDD (CGDD) were extracted from each raster map to create the growing degree day map for Massachusetts. (Fig 15). Ideally, cover crops need to be planted earlier in the western part of Massachusetts compared to the east. This is because the west is higher in altitude and hence cooler than the ocean moderated eastern climate. It also means the growing season is shorter with later planting of corn in the western hills, meaning later corn harvest and less opportunity for planting cover crops on schedule for maximum N accumulation.

The effect of a delay in planting cover crops on GDD accumulation is shown in Table 1. The trend is linear for up to 4 weeks of delay in planting. More than 12% of GDD will be lost by each week of delay in planting. Four weeks delay will cause about 50% loss in GDD. The effect of a delay in planting cover crops on biomass loss had an exponential trend. Four weeks of delay will cause about 80% loss in biomass. A one week delay can reduce the biomass production by 29%.

Nitrogen accumulation is more important economically than biomass production. When the cover crop is planted on time, it can accumulate more than 100 lb N/ac. Nitrogen loss also has an exponential trend. One week delay in planting cover crops can reduce N uptake by 25% (about 27 lb N/ac loss). It again demonstrates the dramatic effect of planting date on cover crop efficiency. Four weeks delay in planting cover crops reduces N uptake by 74% (about 78 lb N/ac loss).

This delay in planting cover crop translates directly into economic loss. Assuming the price of each pound of N in fertilizer is about $0.52 (based on 2010 urea price) it is possible to save about $55 per acre by planting cover crops on time. This number comes from multiplication the price of each pound of N with the amount of N recovery. Economic loss due to delay in planting cover crop has also an exponential trend. More than 25% of the economic loss happens with just one week delay in planting cover crop.

Farmer Adoption

The results of the multi-year and multi-location comprehensive cover crop research project and associated research into the corn-cover crop system was presented to farmers who attended several annual field days, farmer research group meetings, and barn twilight meetings. A list of the events is presented in the above section of this report. Attendants were impressed with the potential nitrogen recovery (~ 120 lbs N/acre) by early planting of winter rye cover crop. However the short growing season is the major constraint to plant effective winter rye cover crop in Massachusetts. A combination of earlier planting of silage corn (late April-early May), when is applicable, along with using shorter season corn hybrids (90-95 days RM) provides a greater opportunity of planting winter rye by the first week of September. At UMass 10-years of corn hybrid trials have shown that on average, shorter season corn hybrids yield similar to full-season corn hybrids. Many farmers now have decided to select earlier maturity corn hybrids, at least for a few fields, which enables them to harvest corn silage earlier, and plant winter rye cover crop earlier for higher nutrient recovery. We are aware of 3 farmers that were not planting cover crops before for one reason or another and now have started planting cover crops. Six other dairy farmers have been able to plant cover crops earlier by using shorter-season corn hybrids and/or earlier planting of their silage corn. At least 5 farmers (2 of them never planted cover crops before) have decided to plant corn earlier and/or use earlier maturity corn hybrids for the 2010 growing season. Some of these farmers have noticed that their silage corn yields have been reducing possibly because of lower organic matter in their fields.

The short growing season was complicated by two consecutively wet growing seasons (2008 and 2009) which delayed planting on many farms with delayed crop maturity resulting in a delayed harvest and late planting of cover crops. To further extend the education related to this project we have selected 3 farms in Pioneer Valley, Central Massachusetts, and Southeast Massachusetts as pilot farms to demonstrate the potential N recovery by winter rye cover crop planted at various time and the effect on yield of subsequent corn, planted in the same fields. These three pilot farms will be used as demonstration sites for our educational workshops next year.

Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

Because farmers have time constrains related to length of the growing season, weather conditions, and soil conditions, we extended our research to see if ammonia losses from surface applied manure would be reduced with applications in cool temperatures. Applications made in November and December had much lower ammonia loss to the air than earlier applications in warmer temperatures. Applying manure late in the fall as a surface application to a earlier cover crop may be a strategy needed when cover crops cannot be planted at the ideal time. There is a need to see if the reduced ammonia loss transfers to greater nitrogen available to the crop the next growing season.

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