Alkaline Hydrolyzable‐Nitrogen of Clayey Soils Reduces Supplemental Fertilizer Nitrogen Requirement of Rice in Arkansas. (1st November 2019)

• Record Type: Journal Article
• Authors: Fulford, Anthony M.; Roberts, Trenton L.; Norman, Richard J.; Slaton, Nathan A.; Greub, Chester E.; Davidson, Jarom T.
• Is Part Of: Agronomy Journal. Volume 111:Number 6(2019)
• Page Start: 3363
• Page End: 3373
• Publication Date: 2019-11-01
• Subjects: Agronomy -- Periodicals; 630
• DOI: 10.2134/agronj2019.05.0372
• Languages: English
• ISSNs: 0002-1962

Abstract

Abstract : The Illinois Soil Nitrogen Test (ISNT) and the Nitrogen Soil Test for Rice (N‐STaR) are alkaline hydrolyzable‐N (AH‐N) soil test methods that can potentially improve N fertilization of cereal crops by predicting a site‐specific fertilizer‐N rate; however, neither method has been evaluated for rice ( Oryza sativa L.) grown on clayey soils. The study objectives were to: (i) evaluate unfertilized (0 kg N ha −1 ) N uptake and yield response of rice to fertilizer‐N based on ISNT and N‐STaR soil test values of clayey soils sampled in 15‐cm increments to a 60‐cm depth and (ii) calibrate the fertilizer‐N rate required to achieve 95% relative grain yield (FN 95%RGY) with ISNT and N‐STaR. A significant and positive linear relationship ( P ≤ 0.001) occurred between AH‐N (ISNT or N‐STaR) and rice‐N response, regardless of sampling depth. Unfertilized N uptake, unfertilized yield (Yield0N ), or relative grain yield (%RGY0N ) regressed on AH‐N exhibited coefficient of determination ( r 2 ) values as great as 0.82, 0.59, and 0.78, respectively. The ability of AH‐N to be calibrated to FN 95%RGY was influenced by sampling depth with the greatest r 2 values occurring when clayey soils were sampled from ≤30 cm. The ISNT and N‐STaR explained as much as 90 and 95% of the variability in FN 95%RGY, respectively, at the 0‐ to 30‐cm depth. Alkaline hydrolyzable‐N soil test methods, such as ISNT and N‐STaR, provided an accurate indication of rice response to fertilizer‐N and have the potential to improve fertilizer‐N rate recommendations for rice grown on clayey soils. Core Ideas Inability to predict rice supplemental fertilizer‐N requirement limits usefulness of N recommendations. Sampling depth influenced correlation between alkaline hydrolyzable‐N and rice fertilizer‐N responsiveness. Alkaline hydrolyzable‐N accurately predicted supplemental N requirement across variously N‐fertile clayey soils.