Economic Optimum Nitrogen Fertilizer Rate and Residual Soil Nitrate as Influenced by Soil Texture in Corn Production

Abstract

Core Ideas A 12 site‐year study representing four soil surface textural group was conducted. Soil texture significantly influenced the economic optimum N rate (EONR). Overall, clay and loam soils showed lower EONR and higher optimum corn yield. Residual soil NO3–N (RSN) at EONR was higher in sandy soils. At ∆EONR higher than zero, RSN was lower in clay and loam soils. Soil texture has been reported to be a significant factor influencing economic optimum N rate (EONR) and residual soil nitrate (RSN). Therefore, this study aimed to (i) determine the impact of soil texture on EONR and (ii) investigate the interactive impact of N rate and soil texture on RSN in corn (Zea mays L.) production. The study was conducted over 12 site‐years in Quebec, Canada, and included six N rates (0–250 kg N ha−1) and four soil surface textural groups (clay, loam, sandy belonging to the gleysolic soil order [Sg] and sandy belonging to the podzolic soil order [Sp]). The quadratic plus plateau model, best described corn grain yield response and was used for predicting EONR. The EONR was greatest in the Sg soil (173 kg N ha−1) and lowest in the Sp soil (123 kg N ha−1), with the Sp grain yield being nearly 60% less than that predicted at other soil textural groups. The EONR in clay and loam soils was 144 and 164 kg N ha−1 with estimated grain yield of 12.7 and 12.0 Mg ha−1, respectively. The RSN content was greatest in Sg and Sp soils. The estimated RSN at EONR in Sp soil was lower than measured, indicating possible N losses in this soil. This study clearly demonstrated that soil texture should be major criteria on which static N rate recommendations are made to optimize corn grain yield and avoid RSN accumulation in the soil profile, particularly under wet conditions of Quebec.