Effects of Supplement Irrigation and Nitrogen Application Levels on Soil Carbon–Nitrogen Content and Yield of One-Year Double Cropping Maize in Subtropical Region

Abstract

Inappropriate irrigation conditions and nitrogen application can negatively affect soil carbon–nitrogen content and yield of maize, as well as can lead to underground water pollution and soil degradation. A two year (2018, 2019) field experiment was carried out to determine the effect of irrigation and N, alone and in combination on maize grain yield, grain nitrogen content, soil inorganic N and MBC of one-year double cropping maize (Zea mays L.) in a subtropical region. Split plot design was adopted, with main plots consisting of two water regimes: drip irrigation (drip irrigation to keep soil water content no less than 70% of maximum field capacity) and rainfed (no irrigation during growing period). Split-plot treatments consisted of five nitrogen application levels, including 0 (N0), 150 (N150), 200 (N200), 250 (N250), and 300 kg/ha (N300). The results of two-year field experiment showed that soil irrigation nitrogen interaction had a significant influence on the all measured parameters. In detail, soil NH4+-N and NO3−-N content, total nitrogen (TN), soil organic carbon (SOC) and grain nitrogen contents under the combined treatment of N250 and supplementary irrigation were higher relative to other treatments. Compared with rainfed, maize yield, thousand grains weight (TGW) and harvest index increased by 22.0%, 7.7%, and 15.2% under supplemental irrigation. Yield and TGW N300 were 287 kg/ha and 3.1 g higher than those of N250, and yield and TGW of N250 were 59.4% and 23.1% higher than those of N0, respectively. The yield of spring maize was 24.0% significantly higher than that of autumn maize. Therefore, we suggested that 250 kg/ha nitrogen application fertilizer combined with supplementary irrigation can improve soil fertility and annual maize yield in subtropical one-year double cropping region.

Melatonin and KNO3 Application Improves Growth, Physiological and Biochemical Characteristics of Maize Seedlings under Waterlogging Stress Conditions

“…The research of Arora and Bhatla [ 60 ] revealed that melatonin directly modulates the activity of NR, GS, GDH, and GOGAT in response to abiotic stress conditions. The increased activities of these enzymes were related to melatonin, which enhanced the antioxidant properties of GS and GOGAT [ 18 ]. In this study, we found that melatonin with KNO 3 enhanced enzyme activity and accelerated the nitrogen metabolism in maize seedlings under waterlogging stress conditions.…”

“…Nitrogen fertilizer application rates have recently increased significantly in Chinese intensive agricultural systems, mostly for crop production. Higher N fertilizer input increased crop yield, but it also reduced plant N usage efficiency, and excess N can have major environmental and human health repercussions [ 18 ]. As a result, maintaining crop growth and production while lowering nitrogen fertilizer ratios poses a significant challenge to agriculture for long-term survival [ 19 ].…”

Interactive Effects of Melatonin and Nitrogen Improve Drought Tolerance of Maize Seedlings by Regulating Growth and Physiochemical Attributes

“…Nitrogen (N) is the major source and a vital nutrient for plant growth and development because it affects the composition of proteins, nucleic acids, hormones, and other critical compounds [ 12 , 13 ]. To meet the agricultural demands of a growing population, synthetic N fertilizer application has increased dramatically in the last 50 years [ 14 ].…”

Irrigation and Nitrogen Fertilization Alter Soil Bacterial Communities, Soil Enzyme Activities, and Nutrient Availability in Maize Crop

“…However, the losses of N with high irrigation water as a result of leaching may need more fertilization. Furthermore, these changes in bacterial diversity could be explained by the quality and amount of irrigation water and root exudates (Sawicka et al, 2020;Wang et al, 2021c), which are the most important sources of nutrients for rhizosphere bacteria. Primary metabolites including amino acids, carbohydrates, and organic acids (Hou et al, 2020), secreted by the plants roots have a positive effect on C and N concentrations, as well microbial population (Frenk et al, 2015(Frenk et al, , 2018.…”