Increasing crop diversity in wheat rotations increases yields but decreases soil health

Demand for food is rising and the ability of any particular soil to support sustainable food production is dependent upon a variety of soil biochemical, chemical and physical soil parameters. However, the challenge is that the impacts of a new management practice on soil properties may take years to assess. In this field study, we investigated the effects of long-term cropping rotation treatments (established in 2001) on soil health indicators from soils under monoculture, 2-yr and 3-yr crop rotations with and without a cover crop. In particular, we compared soil heath indicators under eight cropping sequences including continuous winter wheat (Triticum aestivum L.) (WW), soybean (Glycine max L.)-winter wheat (S-WW), corn (Zea mays L.)- soybean-winter wheat (C-S-WW), and winter wheat-soybean-soybean (WW-S-S) all with and without red clover (Trifolium pretense L.) (RC) in the wheat phase of the rotation. We measured ten soil health indicators collected from the wheat phase of the rotation. Crop rotation had greater effects on soil health indicators than cover crop. After 17 years, crop yields were 23-28% greater for the 2-yr and 3-yr rotations than monoculture WW in the presence of red clover. In the absence of red clover, yields were 32-39% greater for the 2-yr and 3-yr rotations than monoculture WW. However, the soil health indicators were significantly greater for monoculture WW than the 2-yr and 3-yr rotations. These results suggest WW enhanced soil health while crop rotations with soybean negatively impacted most biochemical soil health parameters.