A split-plot factorial experiment examined effects of tillage and winter cover crops on `Merit' sweet corn in 1994, 1995, and 1996. Main plots received tillage or no-tillage. Cover crops consisted of hairy vetch, winter rye, or a mix, and N treatments consisted of plus or minus inorganic N fertilization. The shoot N contents of vetch and mix cover crops ranged from 100 to 150 kg/ha, whereas N contents of rye were usually <50 kg/ha. In 1994 and 1995, vetch shoot N contents were 150 kg/ha, and corn yields following vetch were not significantly affected by addition of inorganic N fertilizer. In 1996, vetch N contents only equaled 120 kg/ha, and corn yields were significantly increased by addition of inorganic N. Supplemental N was also required to obtain maximum yields following mix and rye cover crops in all years, even though the N contents of vetch and mix cover crops were normally similar. Measurements of corn foliar N and available soil N were in agreement with the yield results. No-tillage did not significantly affect corn yields following vetch. However, no-till corn yields were reduced with rye (1995) and the mix (1995 and 1996) as a result of reduced corn plant population densities. Reliable tillage results were not obtained for 1994. It was concluded that a vetch cover crop could adequately supply N to sweet corn if vetch N content was at least 150 kg/ha. Sweet corn following rye or vetch/rye mix cover crops required additional N for optimal yields. Significant N in the mix cover crop was probably immobilized as the rye component decomposed. No-till sweet corn was grown successfully following vetch, but yields were often reduced with the mix or rye cover crops.
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