Improving Nitrogen Fertilizer Use Efficiency in Subsurface Drip‐Irrigated Cotton in the Desert Southwest. Issue 6 (1st November 2019)

• Record Type: Journal Article
• Authors: Bronson, Kevin. F.; Hunsaker, Douglas J.; Meisinger, John J.; Rockholt, Sharette M.; Thorp, Kelly R.; Conley, Matthew M.; Williams, Clinton F.; Norton, E. Randall; Barnes, Edward M.
• Is Part Of: Soil Science Society of America Journal. Volume 83:Issue 6(2019)
• Page Start: 1712
• Page End: 1721
• Publication Date: 2019-11-01
• Subjects: Soils -- United States -- Periodicals; Soil science -- Periodicals; Periodicals; 631.4973
• DOI: 10.2136/sssaj2019.07.0210
• Languages: English
• ISSNs: 0361-5995

Abstract

Abstract : Declining water availability in the American Southwest continues to generate interest in efficient subsurface drip irrigation (SDI) for cotton ( Gossypium hirsutum L.) production. Fertigating urea ammonium nitrate (UAN) at low rates with high frequency is an important advantage of SDI. However, N fertilizer management guidelines specific to SDI cotton are lacking. A 3‐yr study was conducted on a Casa Grande sandy loam soil in Maricopa, AZ, to test a pre‐plant soil profile NO3 test algorithm and a canopy reflectance approach to manage in‐season N fertilizer for SDI cotton. Treatments included soil test‐based N management, reflectance‐based N management, and zero‐N at 100% evapotranspiration irrigation replacement. A second irrigation level of 70% evapotranspiration replacement included just the soil test‐based N and zero‐N treatments. The five treatments were replicated three times. Soil test–based N treatments received from 172 to 224 kg N ha −1, and reflectance‐based N amounts were 112 to 158 kg N ha −1 . Nitrogen recovery efficiency (RE) of UAN‐N was high, with 24 fertigations during 6 wk between first square and mid bloom ranging from 58 to 93%. The isotope dilution method estimated similar RE in 2017. Residual post‐harvest soil NO3 –N was notable only with 70% irrigation. Lint and seed yields were significantly reduced with the 70% irrigation treatment compared with 100% irrigation. The key result of this study is that reflectance‐based N management saved 17 to 112 kg N ha −1 without reducing lint yields compared with the soil test–based N treatment.