Why cereal rye?
In New York state, 330,000 acres of soybean were planted in 2016, which is a 2.5 increase since 2000. New York is also #3 in the country for number of organic farms. Organic soybean farmers are concerned about climate variability, reliance on tillage, and challenges with weed suppression. In what ways can cover cropped cereal rye help address these challenges in organic soybean farming? Does utilizing a cereal rye cover crop increase profitability of the system?
The benefits of cereal rye as a cover crop include: feasiblity for late fall planting, reduced winter soil erosion, plentiful biomass production, weed suppression, and possible use as forage.
Our experiment
This experiment compared different ways of managing a cereal rye cover crop to grow soybeans. We compared the effects of the different management practices on soil health indicators and soybean yield. The treatments were: 1) Plow down: incorporating rye into the soil in early spring, 2) Ryelage: harvesting rye for forage in later spring, 3) No-Till: roller crimping cereal rye just before soybean planting and leaving it as a surface mulch, and 4) No cover crop control.
Soybeans were planted in 2015, corn silage planted in 2016, and soybeans again in 2017. Hairy vetch was interseeded into the soybean at the third trifoliate stage, to provide a legume cover crop before the next season’s silage corn production.
We hypothesized that 1) Weeds will be suppressed by the cereal rye mulch as effectively as in the treatments using moldboard plow tillage and inter-row cultivation, 2) Soil health will be greater in the three cover crop treatments, 3) Crop yield will not differ among treatments, and 4) Partial profitability will be greatest in the Ryelage treatment.
Were our hypotheses supported?
Our first hypothesis was not supported; the No-till treatment had more weed biomass than the other treatments, but was still relatively low for organic production.
Our second hypothesis was supported; soil health was greater in the cover crop treatments than in the no-cover control. Soil health results showed significantly better infiltration and higher soil respiration in the No-till treatment compared to the No Cover treatment. The higher soil respiration and improved infiltration are likely due to the increased organic matter from the cereal rye residue at the surface. Additionally, the Plow Down treatment had significantly higher potentially mineralizable nitrogen compared to the No Cover and Ryelage treatments. This is because the Plow Down treatment had its cereal rye cover crop incorporated at a young stage, when the cover crop was highly concentrated in Nitrogen. No significant differences were observed in aggregate stability or active carbon.
Our third hypothesis was also supported. In 2015, there was no significant difference in soybean yield among the four treatments. However, in 2016 the No-till treatment yielded lower than the others, probably due to extremely dry conditions in June.
Finally, our fourth hypothesis was also supported. Preliminary results from a partial budget analysis show that harvesting cereal rye for ryelage and using tillage prior to growing organic soybean can maximize profitability.
