Appropriate Application of Organic Fertilizer Can Effectively Improve Soil Environment and Increase Maize Yield in Loess Plateau

Fertilization has a significant impact on soil nutrients and microbiological properties, which, in turn, affect crop yield. However, the specific effects of organic and inorganic fertilizers on soil fertility and microbial characteristics in maize fields, as well as the key soil factors influencing changes in crop yield, remain largely unknown. A study was conducted over two years (2021-2022) to investigate the impact of various nitrogen fertilization rates and types on maize yield and soil properties in the Loess Plateau. Field experiments with five nitrogen levels (60, 90, 120, 150, and 180 kg N ha-1) and two fertilizer types (chemical and organic) were conducted. The optimal yield was achieved with 150 kg N ha-1, significantly surpassing that of other treatments by 4.5-45.7%. Compared with the organic fertilizers, the chemical fertilizers increased soil salt and catalase levels, with soil nitrate and ammonium content being higher at the jointing stage but lower at maturity. Organic fertilization improved soil potassium, organic matter, urease and phosphatase activities, and microbial populations. Yield correlated with several soil indicators, including salt content, nitrate, available potassium, and enzyme activities. Notably, soil nitrate also correlated with actinomyces quantity. A principal component analysis showed that the organic fertilizer was more beneficial to soil health than the chemical fertilizer. Consequently, this study recommends 150 kg N ha-1 of organic fertilizer for sustainable maize farming and soil health in China's northwest arid region, providing a theoretical framework for agricultural practices.