Influence of Cover Crop Planting and Termination Time on Rainfed Corn Production in Western Nebraska.

Cover crops (CC) are becoming popular across the United States and producers in semi-arid regions are questioning whether their incorporation is justifiable. Benefits of CC are potential increase in soil fertility, reduced soil erosion, and weed suppression. However, in dryer environments, CC can use excessive soil water, which may significantly reduce grain yield of subsequent crops. The objective of this study was to evaluate the impact of CC selection, planting and termination time on biomass production, soil moisture levels, and subsequent corn development and productivity. Treatments consisted of three planting times (3, 6, and 9 weeks after wheat harvest) and four CC termination times: i) winter-sensitive mixture, ii) winter-hardy mixture terminated 3 weeks before corn planting, iii) winter-hardy mixture terminated at corn planting, and iv) no CC. Cover Crop biomass was collected during fall 2016 and spring 2017. Corn was planted early to mid-May 2017. Soil moisture readings were recorded at corn planting from 0-20 cm deep. Corn biomass was collected at V6 growth stage. The experiment was conducted in a randomized complete block design with four replications. The study was established at two locations in western Nebraska (North Platte and Grant, NE). Preliminary results showed that CC planting time has an impact on total biomass accumulation in the fall, but did not have much of an impact on spring biomass accumulation. Soil moisture readings at corn planting time showed similar values for all treatments in North Platte, although at Grant there was significant reduction in soil water content where the winter-hardy CC were late terminated. Corn biomass accumulation at V6 was lower when CC were terminated late, especially in Grant. Results from this study will help us improve the recommendations for CC selection, planting and termination time under rainfed cropping systems of semi-arid environments in the Great Plains.