Effect of Fertilizer Nitrogen, Variety and Maturity on the Dry Matter Yield and Nitrogen Fractions of Corn Grown for Silage1

Abstract

AbstractThe effects of nitrogen fertilizer rates, variety and maturity on the dry matter yield and the amounts of total N, ethanol insoluble N and ethanol soluble forms of N (nitrate, free ammonium, amide and α‐amino acid) in three single cross corn varieties harvested for silage at early and late dent maturity were investigated on a sandy loam soil in northwest Wisconsin. Nitrogen was applied at 100, 200, and 300 kg/ha rates. Irrigated and non‐irrigated treatments were used, with these treatments having plant populations of 64,200 and 44,600 plants/ha, respectively. Considerable difference existed among varieties with respect to dry matter yield and content of the various N fractions. Nitrate N and total ethanol soluble N increased markedly at the fertilizer N rates beyond that required for maximum dry matter production. Harvesting at late dent maturity resulted in higher dry matter and protein yields and lower nitrate N and total soluble N levels. The results of this investigation indicate that application of excess amounts of fertilizer N to corn should be avoided to minimize accumulation of delterious soluble N compounds in silage corn.