Underseeded vs. Mid-Summer-Seeded Green Manures for Corn
In a Nutshell
Green manure cover crops best fit into extended and diversified crop rotations between the small grain and corn phases of the rotation. They can either be underseeded with a small grain crops in early spring or planted in the summer following small grain harvest. Farmer-cooperators Doug Alert & Margaret Smith and Vic Madsen compared corn following two green manure strategies: red clover or alfalfa underseeded with oats (US) vs. a mix of sunn hemp, sweet clover, red clover and radish planted in mid-summer after oat harvest (MSS).
Weed biomass in oats in mid-July was no different with or without the underseeding at both farms. By mid-October 2016, the US (red clover) produced more aboverground biomass than the MSS by almost 1,000 lb/ac at Alert/Smith’s. The opposite was true at Madsen’s: the MSS produced more biomass than the US (alfalfa) by approx. 800 lb/ac. Corn yields were no different between the two green manure treatments at both farms.