Aula, LawrenceOmara, PeterOyebiyi, Fikayo B.Eickhoff, ElizabethCarpenter, JonathanNambi, EvaFornah, AlimamyRaun, William R.2022-12-122022-12-122021Aula, L., Omara, P., Oyebiyi, F. B., Eickhoff, E., Carpenter, J., Nambi, E., ... & Raun, W. R. (2021). Improving winter wheat grain yield and nitrogen use efficiency using nitrogen application time and rate. Agrosystems, Geosciences & Environment, 4(1), e20148. DOI: 10.1002/agg2.2014810.1002/agg2.20148https://nru.uncst.go.ug/handle/123456789/6214Preplant nitrogen (N) application, which involves placing nutrients in the soil before seeding, has been an integral part of crop production systems for decades. Some producers are known to apply N at least 21 d before planting. This may increase N loss and lower grain yield. This study evaluated the effect of timing and rate of N application on winter wheat (Triticum aestivum L.) grain yield and N use efficiency (NUE). An experiment with a factorial arrangement of treatments was set up in a randomized complete block design with three replications. Treatments included four N rates (0, 45, 90, and 135 kg ha–1) with each applied 7 or 30 d before planting, and at Feekes 5 (FK5). Grain N was analyzed using LECO CN dry combustion analyzer. The difference method [Grain N from (fertilized plot – check plot)]/N applied was used to compute NUE. Nitrogen application rate significantly affected grain yield (P ≤ .01). Although the rate may be temporally and spatially variable, approximately 90 kg N ha–1 was required to obtain yields that differ markedly from the check. Midseason applied N (FK5) had similar yields to preplant applied N in two of four siteyears and significantly increased yield at one site in 2020. Out of two sites, the timing of N application had a substantial effect on NUE in both years (P ≤ 0.11). In this case, NUE was increased by as much as 9.5% for midseason applied N compared to 30 d before planting N application time.enWinter wheat grain yieldNitrogenNitrogen application time and rateArticle