Angela Bastidas and Roger W. Elmore, University of Nebraska - Lincoln, Lincoln, NE
In the US Midwest, cover crop use has been limited by the relatively short growing season remaining after the primary crop is harvested. Increasing biomass production is critical for cover crop effectiveness; planting time is one of the most important factors to consider. In this study, we evaluated the impact of interseeding cover crops on corn at different corn developmental stages and assessed cover crop biomass production. The study was established under both rain-fed and irrigated conditions in Eastern Nebraska. Growth, development, leaf chlorophyll, plant height, stem diameter and yield were measured for corn; summer, fall and spring biomass – the following spring - were collected for 3 single-species cover crops (rye [Secale cereale L.], radish [Raphanus sativus L.] and hairy vetch [Vicia villosa Roth] and a 3-species mixture; soil temperature and soil water content were monitored. All corn measurements were affected when cover crops were planted at the same time as the corn; but we found no detrimental effects on corn when cover crops were planted at or after corn canopy closure (V8 corn stage). Rye seeded at corn planting negatively affected corn the most followed by the mixture and radish. Maximum cover crop biomass was produced during summer followed by spring while fall biomass was greatly reduced; cover crops planted at R6 corn stage (at physiological maturity) produced higher spring biomass than cover crop planted at V8, R5 or after corn harvest. Rye and the mixture produced the greatest biomass during both summer and spring; radish only produced measurable biomass during the summer since it did not overwinter. Soil temperature and water content were not affected by cover crop treatments. These results suggest the opportunity of intercropping cover crops into corn before harvest without affecting corn yield while allowing more biomass production.