Dairy Manure Compost Effects on Corn Silage Production and Soil Properties

Accumulation of dairy manure compost has created a need to identify alternative uses for this plant nutrient source. This field study determined compost effects on corn (Zea mays L.) silage production, nutritive value, and soil characteristics for three growing seasons following incorporation of dairy manure compost at 0, 35, 70, and 105 Mg dry matter (DM) ha -1 . Yields from subplots receiving annual split applications of supplemental inorganic N at 224 or 336 kg ha -1 yr -1 were not different. Compost at 35 Mg ha -1 with supplemental inorganic N fertilizer produced equivalent amounts of DM to that of conventional inorganic fertilizer (IF: 336-49-93 kg ha -1 , N-P-K) for the first 2 yr. By the third year, the IF treatment produced 17% more DM than the 105 Mg compost treatment (pooled across N rates). Corn silage nutritive values generally did not differ among compost and IF treatments. By the third year, compost applications >35 Mg ha -1 raised soil pH 2.3 units and increased electrical conductivity (EC) 50% compared to IF. Three years after compost application, soil P and K concentrations were still greater in plots receiving 70 and 105 Mg compost ha -1 compared to both the check and IF plots. Soil organic matter (OM) increased with compost rates over 35 Mg ha -1 the first season after application, but did not differ after the second season compared to IF. Compared to IF, dairy manure compost can improve soil nutrients for 3 yr; however, it can also increase soil EC and pH, which may be beneficial or detrimental.