Effects of Austrian Winter Pea Winter Cover Crop and Nitrogen Rates On Grain Sorghum Yields.

A renewed interest in using winter cover crops to conserve soil and water, substitute for commercial fertilizer, and maintain soil quality has been growing in South Central Kansas. Research projects were established at the South Central Kansas Experiment Field to evaluate the effect of winter pea (Pisum arvense) and its ability to supply N to the succeeding grain sorghum ( Sorghum bicolor) crop yields when compared to commercial fertilizer. Winter pea is established in the fall, over winters, produces sufficient spring foliage, and is terminated prior to planting of a summer annual. Because winter pea is a legume, it can add N to the soil system. Effects of the cover crop compared with fertilizer N were limited and varied in the first year (1996), grain sorghum harvest. Limited growth of the cover crop due to weather conditions produced limited amounts of organic nitrogen (N). As the rotation continued through 2008, the first increment of N resulted in the greatest change in yield, and yields tended to peak at the 60 lb/a N rate treatment regardless of the presence or lack of winter pea.