Nitrogen leaching, recovery efficiency, and cotton productivity assessments on desert-sandy soil under various application methods

Poor fertilizer nitrogen recovery due to excessive N leaching in sandy soils often results in low cotton yield. The objective of the present study was to compare nitrate-N accumulation in the rootzone, leaching to plant uptake, and cotton yield under different urea application methods in a desert sandy soil. The study was conducted on southern oasis of the Taklamakan desert, China during cotton growing seasons of 2015 and 2016. Treatments included a control (no N-fertilization-C), conventional top-dressing of urea before flood irrigation (CTD), fertigation of soluble urea by drip irrigation (FD), and urea side-drilled in mud after flood irrigation (SDM). Results revealed that SDM and FD methods retained 4-fold and 3-fold, respectively, higher nitrate-N in 0-60 cm layer of the soil profile than CTD; the later had the most accumulation in 60-120 cm zone of the soil profile. However, greater nitrate-N accumulation in cotton root zone (0-60 cm) with SDM corresponded to aboveground cotton N uptake 6% and 41% higher than with FD and CTD, respectively. The highest N-leaching of 165 kg N ha(-1) occurred with CTD, being 61% and 70% higher than FD and SDM, respectively. Improved N-uptake under SDM corresponded to higher cotton biomass, boll density, boll weight, seed cotton and lint yield, and agronomic, physiological and recovery N-use efficiencies than FD and CTD methods. Together, the results indicate that flood irrigation followed by side-drilling of urea in mud is effective to improve yield, nitrogen recovery and use efficiency of cotton on sandy soils, where, the drip irrigation is not locally preferred.