Cover crop water use and impacts on subsequent wheat yields in the Central Great Plains

Authors: Nielsen, David; LYON, DREW - Washington State University; HERGERT, GARY - University Of Nebraska

Submitted to: Colorado State University Newsletter
Publication Type: Popular Publication
Publication Acceptance Date: 12/20/2014
Publication Date: 1/15/2014
Publication URL: http://prowers.colostate.edu/agro/agro_docs/Farm%20%20Ranch%20January%202014.pdf
Citation: Nielsen, D.C., Lyon, D.J., Hergert, G.W. 2014. Cover crop water use and impacts on subsequent wheat yields in the Central Great Plains. Colorado State University Newsletter. Vol 1:1-4.

Interpretive Summary: Cover crops have been demonstrated to provide a wide array of benefits to soils in various regions of the United States, but their use has not been thoroughly tested in the semi-arid environment of the Central Great Plains. This article reports on the results of an experiment with the objectives of determining if cover crops grown in a 10-species mixture used water differently than cover crops grown as single species and to quantify the effects of cover crop water use on subsequent wheat yield. At both Akron, CO and Sidney, NE cover crops grown as single species and as mixtures used water similarly and produced biomass with the same water use efficiency. Subsequent winter wheat yields were reduced due to the cover crop water use compared to where wheat followed a fallow period. The higher costs of growing a cover crop mixture compared with growing a single-species planting are not justified, as there appear to be no special benefits derived from the mixture.

Technical Abstract: Cover crops have been demonstrated to provide a wide array of benefits to soils in various regions of the United States, but their use has not been thoroughly tested in the semi-arid environment of the Central Great Plains. This article reports on the results of an experiment with the objectives of determining if cover crops grown in a 10-species mixture used water differently than cover crops grown as single species and to quantify the effects of cover crop water use on subsequent wheat yield. The study was conducted at Akron, CO and at Sidney, NE under a range of water availability conditions. The cover crop treatments consisted of single-species plantings of oats, peas, flax, or rapeseed, and a 10-species mixture of those same four crops plus lentils, vetch, clover, barley, safflower, and phacelia. At both Akron and Sidney cover crops grown as single species and as mixtures used water similarly and produced biomass with the same water use efficiency. Subsequent winter wheat yields were reduced due to the cover crop water use compared to where wheat followed a fallow period. Biological activity in the cover crop plantings was greater than in the fallow plot, but not different in the mixture than in the single-species plantings. The higher costs of growing a cover crop mixture compared with growing a single-species planting are not justified, as there appear to be no special benefits derived from the mixture.