Residual effect of nitrogen fertilizer and its influencing factors in farmland

The scientific evaluation of nitrogen fertilizer use efficiency is very important to guide agricultural production. The traditional nitrogen fertilizer evaluation scheme can only reflect the fertilizer use efficiency in the season applied, but ignore the residual effect of nitrogen fertilizer. The fate of fertilizer nitrogen, the amount, distribution, utilization and influencing factors of nitrogen fertilizer residues were reviewed in this paper. Based on the current research progress, the future research highlight and the implications of related research on agricultural management practice were proposed. In addition to being absorbed and utilized by crops in the season applied, the residual nitrogen in the soil can also continue to be absorbed and utilized by subsequent crops; the after-effect of nitrogen fertilizer should be taken into account when evaluating fertilizer efficiency. The recovery and utilization of residual nitrogen fertilizer are influenced by multiple factors such as its own migration and transformation, crop types, soil fertility conditions, climate environment and tillage management. In the production practice, the external factors that determine the recovery efficiency of residual nitrogen should be optimized. The potential practices include rotating deep root/high nitrogen absorption type crops and reasonable dense planting after long-term planting of shallow root/low nitrogen absorption crops, timely irrigation to conserve soil moisture in arid areas, customized fertilizer type according to the preference of crop nitrogen fertilizer, water and fertilizer integration technology to implement fractional fertilization, nitrogen application combined with microbial nitrogen conversion inhibitor in effectively improving the overall nitrogen utilization rate. Using ¹⁵N isotope tracer technology, integrating dynamic monitoring data such as residual fertilizer efficiency and soil nitrogen mineralization, combining multi-factor data such as crop type, expected management and target yield, as well as establishing a set of prediction and evaluation of residual fertilizer efficiency of nitrogen fertilizer and decision support model of nitrogen fertilizer reduction are of great scientific significance for guiding precise nitrogen fertilizer reduction and improving agricultural production efficiency in the future.