Nutrient accumulation rates for wheat in the southeastern coastal plain

Abstract

Wheat (Triticum aestivum L.) production has increased in the southeastern Coastal Plains to provide many farmers with an increased mid‐year cash flow, and because breeding programs have improved disease resistance and increased yield potential for this crop. To determine if current fertilizer application rates were being utilized, nutrient accumulation rates for wheat grown on Norfolk loamy sand (fine‐loamy, siliceous, thermic Typic Paleudults) were quantified using mathematical splining. Wheat was sown in mid‐November at a rate of 100 kg ha^‐1 (288 seed m^‐2) in 190‐mm rows and fertilized with 84–30–56 kg ha^‐1 N‐P‐K for a 1986–87 crop, and with 120–16–31 kg ha^‐1 N‐P‐K for a 1987–88 crop. Aerial plant samples were collected seven or eight times between mid‐February (Feekes growth stage 5) and maturity in early June. Plant growth and N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, and Zn concentrations were measured. Aerial nutrient accumulation was calculated and described by splining with compound cubic polynomials. The accumulation patterns were similar to those previously identified for corn (Zea mays L.), with peak rates often occurring during both vegetative and reproductive growth stages. Total aerial N accumulation was approximately 120 kg ha^‐1 each year, with maximum accumulation rates of about 2.0 and 3.5 kg ha^‐1 day^‐1 in 1987 and 1988. Grain yield in 1987 and 1988 averaged 5,030 and 6,190 kg ha^‐1, respectively. Mathematical splining was an effective method for quantifying the aerial plant growth and nutrient accumulation rates. The results indicate that by using a split‐application technique to apply 80 to 120 kg ha^‐1 of N, the apparent N recovery was at least 65%. This study shows that Coastal Plain farmers can have both good yield and an environmentally sustainable wheat production program with similar management practices.