Fertilizing with composted cattle manure to meet agro-environmental targets in continuous corn and corn–soybean agroecosystems in southern Quebec

Abstract

Balancing nutrient inputs from manure and supplemental inorganic fertilizers with crop requirements should achieve crop yield goals and agro-environmental targets. We asked if composted dairy cattle manure, alone or in combination with inorganic fertilizers, could sustain the corn and soybean yields, without increasing the residual soil nitrogen (N) and soil phosphorus (P) saturation of a sandy-loam soil in southern Quebec, Canada. Cropping systems were continuous silage corn and corn–soybean rotation, with each phase of the rotation grown every year, for 5 yr. Cropping systems were amended with compost at rates of 0, 15, 30, and 45 Mg (wet weight)·ha−1, and they received supplemental inorganic fertilizer to supply 200 kg N·ha−1·yr−1 to corn while assuring that corn and soybean received 45 kg P·ha−1·yr−1 and 125 kg potassium (K)·ha−1·yr−1 from compost and inorganic fertilizer. Crop yields were similar in compost-amended and inorganically fertilized plots. Corn yield was limited by N availability, and there was no P or K limitation in corn and soybean. Soil P saturation in the 0–15 cm layer exceeded the agro-environmental limit of 13.1% P/Al for a sandy-loam soil in Quebec, indicating that the P input exceeded crop uptake. Residual soil N concentration was affected more by the crop than the fertilizer source, with greater residual soil N in plots with higher grain production. Crop-induced priming can explain how N fertilizer cycles through the soil microbial community and is gradually mineralized during the growing season, and why crop senescence may trigger residual soil N release after harvest.