Year one (2014) of this project established 20 treatments with four replications in two research locations in Michigan. Year two (2015) continued the rotations/cover crops established in year one. Year two is the first crop year after the inclusion of wheat and/or cover crops in the rotation where their effects on agronomic, economic and soil health performance can be evaluated.
Preliminary Agronomic Results Yield results for the 2015 growing season are given for the SVREC site in Figure 3 and the Mason site in Figure 4. The effects of adding cover crops to continuous or two-crop rotations, or further increasing diversity by adding wheat with or without cover crops are often not easureable one year after the change.
The yield results from SVREC (Figure 3) confirm that after one year of changing the rotation there were no significant yield differences for corn, soybeans or wheat for the different treatments of previous crops and cover crop combinations.
The yield results for Mason:
• No difference for continuous corn with and without a cereal rye cover crop (treatments 1 vs 2)
• A 15 Bu/A increase for corn following soybeans with a cereal rye cover crop (treatment 7 vs 8)
• On average an over 70 Bu/A increase in corn yield following soybeans compared to continuous corn (treatments 1 and 2 vs 7 and 8).
• Corn following wheat with and without a cover crop yielded similar to corn following soybeans with and without a cover crop (treatments 17 – 20 vs 7 and 8).
• Corn following wheat with the oats and oilseed radish mix yielded over 56 Bu/A more than the average for the continuous corn treatments (treatments 19 vs 1 and 2). The other wheat and cover crop treatments were not different compared to continuous corn.
• There were no differences in yield between any of the soybean or wheat treatments.
The lower yields for continuous corn at the Mason site warrant further investigation and may not be attributable to rotation effects. The increase yield for corn after soybeans with a cereal rye cover crop and for corn following wheat with an oats and oilseed radish mix are promising, but requires multiple growing season to verify. The Mason site has experienced some ponding during rainfall events that could be impacting the results. We are continuing to evaluate the Mason data.
In general for the short-term, no conclusions can be made about cover crops and diversity one year after the change. Data from multiple growing seasons is required to evaluate the long-term affects on yield of increasing diversity with and without cover crops.
During the 2015 growing season, there were no observable differences in weed, insect or disease pressure with no differences in herbicide or pesticide treatment types, amounts or rates within cash crops.
Soil Health
Baseline soil samples were collected split and sent to Cornell University for soil health analysis (http://soilhealth.cals.cornell.edu/extension/test.htm) and retained for the Steinke laboratory for the 20 treatments from the two locations in 2014. Results from Cornell were received in 2015 and are summarized below:
• Soil health indicators were measured for physical, biological and chemical health.
• An overall quality score is computed from the individual indicator scores (less than 40% is regarded as very low, 40-55% is low, 55-70% is medium, 70-85% is high and greater than 85% is regarded as very high).
• The year one (baseline) average Cornell health assessment scores are given for the Mason Farm and the SVREC Farm in Table 1. The physical and biological scores for both location were very
low. Although chemical scores were very high, the overall quality score is low for these sites.
• With these low scores as our starting point, we are investigating if and which scores can be impacted through a year of cover crops, wheat and or wheat plus cover crops in the rotation.
Year two soil samples have been submitted to Cornell for analysis.
Next steps
• Economic evaluation of 2015 growing season
information will begin.
• Agronomic data analysis will continue on 2015 growing season data.
• Soil health results from 2014 and 2015 will be evaluated and samples for soil health from the 2016 growing season will be acquired.
• Year three of the study will be implemented beginning this spring. Field operations will be repeated for 2016 and data will be gathered for:
o Seeding rate (crop and cover crop)
o Cover crop density
o Fall and spring biomass
o Weed assessment (also for herbicide application)
o Disease assessment (also for pesticide application)
o Corn PSNT tests to determine
o Corn yield goal N application
o Cover crop N contribution
o Crop yields
o All equipment operations