Impacts of Fertilization Optimization on Soil Nitrogen Cycling and Wheat Nitrogen Utilization Under Water-Saving Irrigation

Abstract

Scholars have proposed the practice of split nitrogen fertilizer application (SNFA), which has proven to be an effective approach for enhancing nitrogen use efficiency. However, the combined effects of SNFA on wheat plant nitrogen use efficiency, ammonia (NH3) emission flux, as well as the rates of nitrification and denitrification in different ecosystems remain unclear. Meanwhile, few studies have sought to understand the effects of the split nitrogen fertilizer method under water-saving irrigation technology conditions on nitrogen loss. The current study assessed soil NH3 volatilization, nitrification, and denitrification intensities, as well as the abundance of nitrogen cycle-related functional genes following application of different treatments. Specifically, we applied a nitrogen rate of 240 kg⋅ha–1, and the following fertilizer ratios of the percent base to that of topdressing under water-saving irrigation: N1 (basal/dressing, 100/0%), N2 (basal/dressing, 70/30%), N3 (basal/dressing, 50/50%), N4 (basal/dressing, 30/70%), and N5 (basal/dressing, 0/100%). N3 treatment significantly reduced NH3 volatilization, nitrification, and denitrification intensities, primarily owing to the reduced reaction substrate concentration (NO3– and NH4+) and abundance of functional genes involved in the nitrogen cycle (amoA-AOB, nirK, and nirS) within the wheat-land soil. 15N tracer studies further demonstrated that N3 treatments significantly increased the grain nitrogen accumulation by 9.50–28.27% compared with that under other treatments. This increase was primarily due to an increase in the amount of nitrogen absorbed by wheat from soil and fertilizers, which was caused by an enhancement in total nitrogen uptake (7.2–21.81%). Overall, N3 treatment (basal/dressing, 50/50%) was found to effectively reduce nitrogen loss through NH3 volatilization, nitrification and denitrification while improving nitrogen uptake by wheat. Thus, its application will serve to further maximize the yield and provide a fertilization practice that will facilitate cleaner wheat production in the North China Plain.

Using spatially variable nitrogen application and crop responses to evaluate crop nitrogen use efficiency

“…Site-specific prescriptions can lower N fertilizer rates based on knowing the TN distribution within a field, which can save producers money on fertilizer and prevent the overapplication of N that can contribute to pollution. This inference agrees with other studies that show reducing N fertilizer rates in areas of high TN (due to greater N mineralization) is an economically viable management strategy (Paustian et al 1997;Zhang et al 2009aZhang et al , 2009b.…”

“…Possible avenues of improving N mineralization estimates include use of remotely sensed soil moisture interpolated for depth effects, and upscaled modeling of soil climate based on rainfall and temperature patterns, along with soil mapping, and calibrated using growing soil climate observation networks. Overall, methods of accurately measuring N mineralization and immobilization require additional research, a fact that has been long recognized (Bremner and Mulvaney 1982;Wang et al 2009;Zhang et al 2009a).…”

Integrating NDVI, SPAD, and Canopy Temperature for Strategic Nitrogen and Seeding Rate Management to Enhance Yield, Quality, and Sustainability in Wheat Cultivation

“…However, NDVI’s predictive capacity appears to wane as the plant transitions to the heading stage, evidenced by the declining NDVI3 values across all nitrogen treatments. This trend is indicative of the plant’s physiological shift from vegetative growth to reproductive development and grain filling, as demonstrated by Zhang et al [ 32 ], who explored the impacts of optimizing fertilization on soil nitrogen cycling and wheat nitrogen utilization. Their findings underline the importance of adjusting nitrogen application to enhance wheat’s nitrogen uptake efficiency and reduce loss, shedding light on the relationship between nitrogen management and plant maturity stages [ 32 ].…”

The response of nutrient cycle, microbial community abundance and metabolic function to nitrogen fertilizer in rhizosphere soil of Phellodendron chinense Schneid seedlings

“…Using the extracted DNA as template, the relative expression abundances of microbial functional genes ( nifH , amoA-AOB , nirK and phoD ) involved in soil N and P cycling were detected by quantitative real-time PCR (qRT-PCR) which performed on the ABI StepOne instrument (ABI7500, Applied Biosystems, MA, USA) ( Lang et al, 2020 ; Kim et al, 2022 ; Zhang Z. et al, 2022 ; Li et al, 2023 ). All the primer sequences were listed in Supplementary Table 1 .…”