Finding the Balance Between Corn Yield and Cover Crop Biomass.

In the US Midwest, fall-seeded cover crops are limited by the relatively short growing season remaining after the primary crop is harvested. There is the possibility of lengthening the cover crop growing season by modifying corn management to enhance cover crop productivity.  The objective of this study was to assess the effects of planting date (early and late), plant population (low, average and high) and corn maturity (80 to 115 days relative maturity, RM) on corn yield to allow different dates for cover crop establishment after corn harvest. The study was established in Eastern -rainfed- and South Central -irrigated- Nebraska during 2015 and 2016 growing seasons.  At each location, two blocks were established; one for measuring corn yield and one for planting a cover crop (rye [Secale cereale L.]) at different planting dates according to estimated harvest maturities of the different RM hybrids; fall and spring rye biomass were collected.  Corn yield was affected by plant population and RM (irrigated), and planting date and RM (irrigated and rain-fed), confirming the early planting is important for late-season hybrids under irrigated conditions and late planting is affecting negatively all hybrids under rain-fed conditions.  Shorter-season hybrids (95 and 105 RM) compared to the regionally used (111 RM or higher) may allow earlier corn harvest and cover crop planting without negatively impacting corn yield ultimately increasing cover crop biomass production. The 80 and 86 RM provide potential more cover crop biomass than later-season hybrids recognizing there may be a negative impact on corn yield.  Corn harvest maturity was spread out a month with the different management treatments, allowing 4 cover crop planting dates.  Cover crop biomass production was affected by planting date for both fall and spring, with highest production for the earliest planting date in both the fall and the spring.