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 collaborated with extension educators and a crop consultant to collect forage samples at multiple winter cereal growth stages on three New York State farms and two research stations. We sampled 18 cultivars across 4 winter cereal species (cereal rye, triticale, wheat, and barley), although each cultivar was not present at each site. We repeated this experiment in May 2015 at both research stations, and we expanded the number of collaborators and on-farm sites to refine our project results and enhance our deliverables.
Our 2014 preliminary results from the Musgrave Research Station in Aurora, NY, indicate that cereal rye and triticale yields were not significantly different (P > 0.05) at discrete growth stages. However, there was a significant interaction (P < 0.05) between cultivar and growth stage when comparing the relative forage quality of different cereal rye and triticale cultivars. Although the cereal rye and triticale cultivars produced an equivalent amount of biomass (yield), the relative forage quality of some cultivars decreased more slowly, compared with other cultivars, as growth stage advanced. 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 sites and both years 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 in 2015. As in 2014, we were not able to collect biomass samples at all five targeted growth stages for all cultivars and 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. We have been able to prepare all the 2015 samples for forage quality lab analysis, but unlike in 2014, we will not be able to run the analyses in a lab at Cornell. This change was unexpected, but we are close to selecting a lab that can analyze our samples using methods that match our approach in 2014.
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. Preliminary statistical analyses have been conducted for a subset of the data, and some nonlinear modeling approaches that we have explored appear to be well suited for describing our data. Once the forage quality lab work for the 2015 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 2014 preliminary results of this project at three different conferences in November 2014: (1) Agronomy Society of America, Crop Science Society of America, and Soil Science Society of America 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 March 2015, I created a brief summary of my preliminary results from 2014. This document was used as part of an “invitation to participate,” which was sent to extension educators, crop consultants, and farm advisers throughout NY. In April, I spent time coordinating with new collaborators on the project, making sure they understood the protocols and that they received all of the equipment necessary to complete the sampling. This also involved ordering the fabrication of additional quadrats for in-field biomass collection.
Using the same research design and sampling protocol that was established in 2014, all sites were flagged and sampled in May. The sampling consisted of winter cereal growth stage identification, height measurement, and biomass harvest. Once collected, the forage samples were dried at 55°C in forced-air ovens, weighed to calculate yield, and then ground with a Wiley Mill (1-mm particle size) in preparation for lab analysis. Due to the very high number of samples, grinding was not completed until October 2015.
Throughout the late summer and fall, I have been in contact with multiple forage analysis labs. It is important that we are able to work with a lab that uses comparable methods to those we used last year. As in 2014, the suite of analyses will include ash content, crude protein, neutral detergent fiber, acid detergent fiber, and 48-hr in vitro digestible neutral detergent fiber. This will allow us to calculate relative forage quality and make comparisons across species and cultivars.
As 2015 was the second year of this experiment, I was able to anticipate and prepare for some of the common challenges that our collaborators experienced the first year. For instance, I was able to notify our collaborators that some species or cultivars might be difficult to sample at the targeted growth stages due to very rapid maturation, depending on numerous environmental factors. Although this did not completely prevent missing some growth stages, it did appear to reduce the prevalence of missed stages. These more complete data sets will be helpful for our statistical analyses.
In 2015, some of the collaborators did not have access to ovens, and they were too far away from Cornell for me to drive to their location and pick-up the samples in person at each of the five sampling dates. This was an unexpected complication, but we were able to arrive at a reasonable solution: any collaborator that could not dry their samples was instructed to freeze their samples immediately after harvest. I was then able to pick up these forage samples at the conclusion of the experiment and dry them in ovens at Cornell. As freezing samples prior to drying can have an impact on forage quality analyses, this subset of data will be analyzed separately.
One of the greatest learning experiences in 2015 involved the large amount of communication that was required to coordinate with eight collaborators spread throughout NY State. Answering a wide variety of questions prior to the start of the experiment, sending equipment packages, troubleshooting winter cereal growth stage identification, and improvising when things didn’t go quite as planned was a really informative experience. Leading a collaborative team effort towards a common objective was challenging, but very rewarding.
We were able to follow the originally proposed plan quite closely with the exception of some collaborators freezing their samples prior to drying, and eventually having to send the ground samples to a commercial forage lab rather than completing the lab work at Cornell. Although these were unexpected changes, we were able to reach suitable solutions.
In terms of remaining work, I still need to send all of the 2015 samples to a lab for forage quality analyses. Once the lab work is complete, I can analyse the data, prepare some outreach materials, and present our findings at grower meetings and conferences.
Impacts and Contributions/Outcomes
Since I have not yet completed the statistical analyses 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 2014 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 those presentations was relatively high. Once the data analysis is complete, I will present the findings at grower meetings 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, and increasing per acre home-grown forage production, among many others. Presentations of the results will emphasize the practical importance of the tradeoffs that occur when selecting specific species, 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 if more farmers adopt this practice. 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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