Characteristics of Nitrogen Output during Typical Rainfall in Different Sugarcane Growth Stages in a Southern Subtropical Watershed

Abstract

Excessive fertilizer application, majorly nitrogen- and phosphorus-based fertilizers, in farmland has intensified environmental pollution of rivers, lakes, and other surface water bodies worldwide by agricultural non-point sources, especially the highly-mobile nitrogen. To solve nitrogen pollution in sugarcane areas, exploring the nitrogen output characteristics of agricultural watersheds in crop fields becomes necessary. Therefore, the objective of the study was to evaluate the characteristics of nitrogen output during typical rainfall events in different sugarcane growth stages in a southern tropical watershed in China. Dynamic monitoring of runoff and nitrogen concentration was carried out for four rainfall events and compared among four sugarcane growth stages (Establishment; Vegetative growth; Grand growth; Ripening) during the growing season of 2018 in the Nala watershed, Kelan Reservoir, Guangxi, China. The results showed that the total dissolved nitrogen flux of the 4 rainfall events ranged from 0.08 to 9.88 kg·hm−2 for the different growth stages. Nitrate nitrogen was the main component of the total flux, accounting between 75.7 and 92.1% of the total dissolved nitrogen while ammonium nitrogen accounted between 1.80 and 5.26% of the total flux for the 4 rainfall events. Total dissolved nitrogen and nitrate-nitrogen were significantly and negatively correlated with runoff (p < 0.05), while total dissolved nitrogen concentration did not correlate with runoff. The incipient scouring effect of total dissolved nitrogen and nitrate-nitrogen was not noticeable. The concentration of total dissolved nitrogen in the Nala watershed was inferior to class V water quality standard, indicating water eutrophication danger. The study showed that nitrogen nutrient inflow into the river was promoted by N-fertilization time and rainfall. Therefore, reasonably reducing N-fertilization dose and post-rain fertilization could effectively reduce nitrogen inflow into rivers and avoid the intensification of eutrophication in sugarcane areas. We recommend multiple years of studies to verify the possible impacts of differences in weather conditions.

Difference in the Contribution of Driving Factors to Nitrogen Loss With Surface Runoff Between the Hill and Plain Agricultural Watersheds

“…The N loss entering the water body is promoted by N‐fertilization time and rainfall. Rainfall is uncontrollable, while reasonably reducing N‐fertilization dose and post‐rain fertilization could be implemented based on modern agricultural technology (Ding et al., 2022; Guo et al., 2023; Sun et al., 2012; Zhang, Hou, et al., 2020). Unfortunately, due to higher evapotranspiration and extreme rainfall, higher drought or flood risks would be observed in different regions, which may amplify the effects of land use and fertilization (Aksoy et al., 2021; Amiri & Gocić, 2021; Law et al., 2022).…”

Design and Optimization of Sugarcane Spiral Fertilizer Applicator Based on Response Surface Methodology and Artificial Neural Networks

“…The yield and quality of sugarcane have a direct impact on the economic income of farmers and the country's overall economic interests [3,4]. Notably, the fertilization of sugarcane, a crucial aspect of its production, profoundly affects its growth and yield [5,6]. However, current traditional methods for sugarcane fertilization present several issues, such as uneven distribution of fertilizers, inadequate or excessive use of chemical fertilizers, and improper timing of fertilization.…”