Evaluating Tradeoffs Between Forage Quality and Yield for Winter Cereals Grown as Forage Double Crops
In response to the increased frequency of extreme weather events, a growing number of farmers in the Northeast have become interested in harvesting winter cereal cover crops in the spring and then double cropping with corn silage to increase per acre crop yields and reduce feed imports. In the past three years of on-farm yield measurements, winter cereals harvested in May produced an average of 2 tons of dry matter per acre annually when properly managed. However, many factors, such as adverse weather, can prevent timely harvest, and recent discussions with farmers have revealed a strong interest in understanding what tradeoffs occur when winter cereals are harvested at different growth stages. In May 2014, we established sites at two research stations and we collaborated with extension educators and a crop consultant to collect forage samples at multiple winter cereal growth stages on three NY State farms. We sampled 18 cultivars across 4 winter cereal species (cereal rye, triticale, wheat, and barley), although each cultivar was not present at each site. Our preliminary results from the Musgrave Research Station indicate that cereal rye and triticale yields at each growth stage were not significantly different (P > 0.05). However, there was a significant interaction (P < 0.05) between cultivar and growth stage when comparing the relative forage quality (RFQ) of different cereal rye and triticale cultivars. Although the cereal rye and triticale cultivars produced an equivalent amount of biomass (yield), the RFQ of some cultivars decreased more slowly as growth stage advanced compared with other cultivars. These preliminary results suggest that winter cereal species selection, cultivar selection, and harvest timing are important management considerations that will affect the success of implementing these double cropping systems in the Northeast. Further statistical analyses of the data from all five sites will allow us to more thoroughly assess the tradeoffs between forage quality and yield, thereby fulfilling the objectives of this project.
1) Determine the forage quality and yield of four species of winter cereal cover crops (triticale, cereal rye, wheat, and barley) when harvested for forage at five different growth stages in the spring, from Feekes 7 through 10.5 (two nodes through heading). Yield has been calculated for all winter cereal species at each growth stage we sampled. Unfortunately, we were not able to collect biomass samples at all 5 targeted growth stages for all 18 cultivars across the 4 species. As the time between growth stages was as brief as 24 hours for some cultivars, it was not possible to scout all cultivars frequently enough at each site to collect samples at the originally proposed growth stages. However, we were able to collect enough samples for each cultivar to facilitate data analysis that will yield useful information and recommendations for farmers, extension educators, and crop advisers. Forage quality has been assessed for the triticale, cereal rye, and wheat samples, but the barley samples still require lab analyses.
2) Quantify tradeoffs between forage quality and yield across winter cereal species and cultivars and determine the timing and duration of optimal harvest windows prior to double-cropped corn for silage. Since all cultivars were not sampled at the same five growth stages, quantifying the tradeoffs between forage quality and yield will be more challenging than initially anticipated. In preparation for multiple oral presentations in November 2014, preliminary statistical analyses were conducted for a subset of the data. Once the forage quality lab work for the barley samples is complete, further analyses of these tradeoffs and harvest windows will begin.
3) Disseminate results and information about the potential of double cropping with winter cereal cover crops prior to corn silage to enhance farm productivity, reduce feed imports, increase profitability, and improve soil and water conservation. I presented the preliminary results of this project at three different conferences in November 2014: (1) Agronomy Society of America (ASA), Crop Science Society of America (CSSA), and Soil Science Society of America (SSSA) International Annual Meeting in Long Beach, CA; (2) Cornell University Cooperative Extension (CCE) Agriculture and Food Systems In-Service in Ithaca, NY; and (3) Northeast Region Certified Crop Adviser Training Conference in Syracuse, NY. Once all of the analyses are complete, additional presentations at grower conferences and publishing the summarized results as web-accessible reports will help stimulate greater dissemination of the findings throughout the state.
In April 2014, I developed an experimental design and sampling protocol for my collaborators to help ensure that all sites would be sampled consistently. In May, the research stations and on-farm field sites were identified, four blocks (replications) were flagged at each site, and sampling commenced. The sampling consisted of winter cereal growth stage identification, height measurement, and biomass harvest. Once collected, the forage samples were dried at 60°C, weighed to calculate yield, and then ground with a Wiley Mill (1-mm particle size). These ground samples were stored in plastic bags while I carried out fieldwork for my other research projects from June to August. In September, I hired a research assistant to help me prepare the samples for multiple forage quality analyses, including neutral detergent fiber (NDF), acid detergent fiber (ADF), ash content, crude protein (CP), and 48-hr in vitro digestible NDF (NDFD). Once the results of these forage analyses were received, I performed numerous statistical procedures using JMP Pro, RStudio, and MILK 2006 software on a subset of the data. In October, three oral presentations were created specifically for the different audiences at each conference I attended in November.
As previously mentioned, the work did not progress as expected. I did not anticipate how challenging it would be to monitor the rapid growth stage advancement for all of the cultivars at multiple sites. Complicating the logistical difficulty of this task was the highly variable soil characteristics at the Musgrave Research Station. Due to unforeseen drainage issues in the field, the maturity of some of the winter cereal replications were delayed by 2-3 weeks compared with the average growth stage of a given cultivar at any particular sampling date. As this variability was not limited to a single block or cultivar, the simple task of monitoring growth stage advancement was substantially more difficult.
These sampling challenges were certainly a good learning experience. Although we would not have been able to accomplish our objectives with a time-based approach, I quickly understood why most research that compares the forage quality of small grains is based on yield and forage quality over time, as opposed to specific growth stages. The only other deviation from the original proposal involved submitting my forage samples to Cornell-associated labs, rather than Cumberland Valley Analytical Services. We made this change in forage labs to provide more time for data analysis in preparation for my conference presentations.
In terms of remaining work, I still need to conduct forage quality analyses for the barley samples. However, the particularly harsh winter conditions in late 2013 and early 2014 damaged most of the barley. Consequently, some of the cultivars did not yield the minimum amount of dry matter required to complete all of the forage quality analyses. Once the lab work is finished on the barley samples, I can begin analyzing the full data set in order to address the objectives of this project.
Impacts and Contributions/Outcomes
Since I have not yet completed the statistical analysis for the full data set and presented the results, the impact of this project has not reached its full potential. However, the three presentations in November were great opportunities to introduce the benefits (and challenges) of growing and harvesting winter cereals for forage in double cropping systems. Since the audiences for two of the presentations, extension educators and crop advisers, work directly with farmers on a regular basis, the potential impact of the presentations is high. Once the data analysis is complete, I will present the findings at grower conferences and summarize the results in a CCE article, New York On-Farm Research Partnership report, and an agronomy fact sheet. These reports will encourage adoption of this management practice by highlighting the many benefits of winter cereal forages, which include limiting soil erosion and nitrate leaching, improving soil health, increasing per acre home-grown forage production, decreasing feed costs, reducing the greenhouse gas emissions associated with importing feed, enhancing farm profitability, and providing opportunities for manure application before seeding in the fall and after harvest in the spring. Presentation of the results will emphasize the practical importance of the tradeoffs that occur when selecting specific species and cultivars, and basing the timing of winter cereal harvest on growth stage. Since these published reports will be web-accessible, there is great potential to enhance agricultural sustainability in the Northeast through the practice of harvesting winter cereal cover crops for forage in double cropping systems. Coordinating winter cereal harvest with livestock nutrition will be of particular interest to dairy farmers, but farmers that produce forage crops will also find this research useful for improving crop management and farm profitability.
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