Tillage and compost affect yield of corn, soybean, and wheat and soil fertility

Applying organic matter (OM) amendments to cropland reduces requirements for synthetic fertilizer and may eliminate yield differences between conventional and minimum tillage. The objectives of this research were to determine how tillage and composted swine (Sus scrofa L.) manure affected yield of corn (Zea mays L.), soybean [Glycine mar (L.) Merr], and wheat (Triticum aestivum L.) and soil concentrations of OM, P, and K. A corn-soybean-wheat/clover (Trifolium spp.) rotation, in all phases, was initiated in 1998 in plots that had been managed with moldboard plow (MP), chisel plow, or no-till since 1988. Moldboard and chisel plow increased corn yield in the first year of the study vs. no-till. Thereafter, tillage did not affect yield on plots that received compost. Tillage X compost interactions during the last 2 yr of the study increased no-till compost yield 11% vs. no compost. Soybean yield was similar in no-till and chisel compost plots during the study period and between MP and no-till in 3 of 4 yr. Tillage X compost interactions were observed in 2 of 4 yr that increased no-till compost yield 9% vs. no compost. Averaged across all crops and tillage, compost-amended soil had 63 g kg(-1) OM and 164 mg kg(-1) P vs. 56 and 55 in no compost. Corn and soybean producers can enhance yield with multiple compost applications and eliminate yield differences between conventional and no-till systems. Nevertheless, compost application for soil OM enhancement must be balanced with P input to minimize the potential for excessive soil P accumulation.