Evaluation of Nitrogen Release Characteristics and Enhanced Efficiency of a Novel Synthetic Slow-Release Nitrogen Fertilizer

Slow-release fertilizers are known as the excellent choice to conquer nitrogen losses; however, their slow-release properties and multifunctionality need comprehensive exploration and improvement. The current study aims to prepare a novel synthetic slow-release nitrogen fertilizer (NF) using urea, formaldehyde, and weathered coal powder as raw materials, and to investigate its nutrient release characteristics and enhancement effect on agricultural production. The characteristics of NF were investigated by fourier transform infrared spectroscopy, X-ray diffractometer, and thermogravimetry. The soil incubation, leaching, and pot experiments were conducted to evaluate the nitrogen release characteristics and crop growth effects of NF. The results showed that weathered coal powder addition did not change the main functional groups significantly but reduced the degrees of crystalline order and improved the thermal stability of NF. NF offered a gradually available nitrogen supply in the soil to minimize nitrogen leaching loss. The cumulative nitrogen leaching rate of NF was 39.8% lower than that of urea. Compared to conventional chemical fertilizers, NF improved the photosynthetic capacity and quality of eggplant, and the nitrate nitrogen content decreased by 64.7%. Moreover, NF enhanced soil fertility and avoided soil acidification. NF is a new synthetic slow-release nitrogen fertilizer with a stimulating effect and satisfactory slow-release effect, which can reduce nitrogen leaching loss and improve eggplant quality and soil fertility.