Application of controlled release urea increased maize N uptake, environmental benefits and economic returns via optimizing the temporal and spatial distribution of soil mineral N

The creation of controlled-release urea (CRU) is a potent substitute for conventional fertilizers in order to preserve the availability of nitrogen (N) in the soil, prevent environmental pollution, and move toward green agriculture. This study’s main objectives were to assess CRU’s full application impacts on maize production and to clarify the connection between its nutrient release pattern and maize nutrient uptake. In order to learn more about the application effects of CRU on maize yields, N uptake and mineral N (Nmin) dynamics, the N balance of soil-crop systems, and economic efficiency in Dalian City, China, a series of 3-year (2018–2020) field experiments were carried out. There were 4 different treatments used in the experiment: no N fertilizer input (CK); application of common urea at 210 kg ha−1, the ideal fertilization management level for the site (U); application of polyurethane-coated urea at the same N input rate as U (PCU), and application of PCU at a 20% reduction in N input rate (0.8PCU). Our findings showed that using CRU (PCU, 0.8PCU) may considerably increase maize N absorption, maintain maize yields, and increase N use efficiency (NUE) compared to U. The grain yield demonstrated considerable positive correlations with TNK (leaf) in U and 0.8PCU but negative correlations with PCU, indicating that PCU caused excessive maize absorption while 0.8PCU could achieve a better yield response to N supply. Besides, PCU was able to maintain fertilizer N in the soil profile 0–20 cm away from the fertilization point, and higher Nmin content was seen in the 0–20 cm soil depth in various growth stages, particularly in the middle and late growing stages, optimizing the temporal and spatial distribution of Nmin. Additionally, compared to those in U, the apparent N losses rate in PCU was reduced by 36.2%, and applying CRU (PCU, 0.8PCU) boosted net profit by 8.5% to 15.2% with less labor and fertilizer frequency. It is concluded that using CRU could be an effective N fertilizer management strategy to sustain maize production, boost NUE, and increase financial gains while minimizing environmental harm.