Green Manure Comparison between Winter Wheat and Corn: Weeds, Yields, and Economics

Red clover (Trifolium pratense L.) and hairy vetch (Vicia villosa Roth) are leguminous crops (“green manure” hereafter), widely studied for their N2‐fixing contributions to cropping systems. Under certain circumstances they can provide weed control in cash crops. This study compared weed control, crop yields, herbicide use, and economic performance of these green manures in a no‐till winter cereal–green manure–corn (Zea mays L.) silage cropping sequence in central Pennsylvania. Red clover was interseeded into winter wheat (Triticum aestivum L.) or rye (Secale cereale L.), while hairy vetch and triticale (X Triticosecale) were planted after winter cereal harvest. Compared to hairy vetch, red clover provided continuous soil cover between the winter cereal and corn and two herbicide applications could not be applied (one in wheat and one prior to seeding hairy vetch) to the red clover, reducing herbicide active ingredient use by 28%. Weed infestation in wheat and corn did not differ between green manure systems, but corn yield following red clover averaged 3320 kg ha−1more, and 2012 wheat yield was 180 kg ha−1 greater in the red clover sequence. Corn after hairy vetch–triticale had lower corn plant population in 2012–2013. Yield differences in corn in 2012 probably resulted from population differences. Primarily because of red clover forage value, the red clover system resulted in greater net returns to management by US$1360 ha−1, and even without the forage harvest, the red clover system would have been more profitable due to lower production costs.Core Ideas As a green manure, red clover provided multiple benefits over hairy vetch and triticale. Red clover underseeded in winter grain, produced continuous cover, forage, and higher corn yield. Compared to hairy vetch and triticale, red clover controlled weeds with less herbicide. Red clover was more profitable than hairy vetch.