Nitrogen management of furrow‐irrigated rice on clayey soils

Abstract

AbstractFurrow‐irrigated rice (Oryza sativa L.) (FIR) has garnered increasing attention in Arkansas and across the Mid‐South, as more than 15% of Arkansas’ rice crop now utilizes furrow irrigation water management. Because of this recent interest, little data exists on FIR production management. Studies were conducted from 2018 to 2020 to determine the optimum nitrogen (N) management program for FIR production on clayey soils. Nine N management strategies were studied in 2018 and 2019, including one‐ to four‐way applications and several rates, with one additional approach in 2020. Five site‐years were utilized where grain yield, milling yield, and total nitrogen uptake (TNU) were examined. Grain and milling yield were consistently maximized with a three‐way split consisting of 84 kg N ha–1 at V5–V6 (pre‐irrigation), 84 kg N ha–1 2 wk later, and 52 kg N ha–1 1 wk after the second application. Grain yield averaged 10,307–12,585 kg ha–1 while head rice yield averaged 52.2–62.1% under the 84/0/84/52 kg N ha–1 split. Total N uptake was greatest where three to four applications and/or a higher total N rate were utilized across all years, while a two‐way split or greater maximized TNU in 2020 alone. Recovery efficiency of nitrogen (REn) and agronomic efficiency of nitrogen (AEn) were generally higher with a greater number of split applications. Average REn for the 84/0/84/52 kg N ha–1 split was 34.4–50.6%. Results suggest that an additional 52–67 kg N ha–1 and/or additional N applications are warranted to maximize FIR production on clayey soils compared to recommendations in a traditional flooded system.