Fallow Replacement Crops (Cover Crop, Annual Forage, and Short-Season Grain Crop) Impact on Wheat.

Producers are interested in growing cover crops and reducing fallow. Growing a crop during the fallow period would increase profitability if crop benefits exceeded expenses. Benefits of growing a cover crop have been shown in high rainfall areas, but limited information is available on growing cover crops in place of fallow in the semiarid Great Plains. A study from 2007–2014 evaluated cover crops, annual forages, and short season grain crops grown in place of fallow. In the first experiment (2007-2012) the rotation was no-till wheat-fallow, and in the second experiment (2012-2014) the rotation was no-till wheat-grain sorghum-fallow. Growing a cover, hay, or grain crop in place of fallow reduced the amount of stored soil moisture at wheat planting. On average, cover crops stored slightly more moisture than hay crops, but this soil moisture difference did not affect wheat yields. Soil moisture following grain crops was less than cover or hay crops, and this difference resulted in reduced wheat yields. These results do not support the claims that cover crops increase soil moisture compared to fallow. Wheat yield following the previous crop was dependent on precipitation during fallow and the growing season. In dry years (2011-2013), growing a crop during the fallow period reduced wheat yields, while growing a crop during the fallow period had little impact on wheat yield in wet years (2008-2010). Cover crops did not improve wheat yield. To be successful, the benefits of growing a cover crop during the fallow period must be greater than the expense of growing it; plus compensate for any negative yield impacts on the subsequent crop. Cover crops always resulted in less profit than fallow, while annual forages and grain peas often increased profit compared to fallow.