After three years of investigating the influence of rotational diversity and/or cover crops on yield and soil health in continuous corn, continuous soybean and corn-soybean rotations:
? At the SVREC site:
? Year three corn yield was 19.9 bu/A higher when soybeans were added to the continous corn rotation, 30.1 bu/A higher when wheat and soybeans were added to the continuous the corn rotation and 10.2 bu/A when wheat was added to the corn-soybean rotation.
? Corn yield results suggest that the increases were probably more the result of diversity than cover crops.
? Year three soybean and wheat yields were not significantly different for any of the diversity and/or cover crop treatments.
? At the Mason site:
? Year three soybean yield was 16.8 bu/A higher when corn and wheat were added to the continuous soybean rotation, not different for the corn-soybean rotation, 17.5 bu/A higher for the corn-soybean-wheat with sorghum-sudangrass followed by cereal rye, 17.1 bu/A for the corn-soybean-wheat with red clover and not different for the corn-soybean-wheat with the oats and oilseed radish mix.
? Soybean yield results suggest that the increases were probably more the result of diversity than cover crops.
? Year three corn and wheat yield were not significantly different for any of the diversity and/or cover crop treatments.
Figure 6. Lisa Tiemann and Dean Baas present to farmers at the SVREC site during the 2016 MSU Ag Innovations Day.
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? Cornell soil health assessments indicate:
? For both the SVREC and Mason sites the overall quality scores remain low to medium with no clear relationships or trends between the overall scores and including diversity and/or cover crops for three years.
? The individual ratings for physical, biological and chemical parameters that contribute to the overall quality score did not show any clear relationships or trends from including diversity and/or cover crops for three years.
? Cornell suggest additional management changes in addition to the diversity and cover crops in the study including less tillage, manure, sod crops, etc. to correct the low ratings, in particular the low biological ratings. These changes are probably not economical, practical or of interest to farmers within the cropping regions studied.
? Longer term effects of diversity and/or cover crops can not be estimated with a single three year, one crop rotation cycle. While it is promising that significant yield differences emerged in year three for corn at SVREC and soybeans at Mason, we know building soil health is a slow process. A longer period under diversity and/or cover crops would be necessary to determine if soil health is improving, declining or remaining constant under the treatments studied.