Molecular Soil Biology 2025, Vol.16, No.4, 199-213 http://bioscipublisher.com/index.php/msb 2 03 to structural damage (Hu et al., 2022). Adding organic substances such as corn stover or biochar can significantly enhance soil aggregate stability and available water capacity, improve water distribution and drought resistance (Kim et al., 2016; Negiş, 2023). 5 Impact on Soil Chemical Properties 5.1 Nutrient consumption and enrichment (N, P, K, and trace elements) As a high-yield crop, corn has a great demand for major nutrients such as nitrogen (N), phosphorus (P), and potassium (K). Long term monoculture of corn can easily lead to soil nutrient consumption and imbalance. Continuous planting of corn can lead to a significant decrease in soil nutrient content such as total carbon, total nitrogen, available phosphorus, exchangeable potassium, and calcium with increasing planting years, especially in sloping areas and areas lacking fertilization management, where nutrient loss is more severe. Within 30 years, relevant nutrients can drop to about half of their initial values (Fujisao et al., 2020). The planting density and sowing date of corn also affect the distribution and residue of nutrients. An increase in density usually leads to a decrease in grain N, P, and K content, while soil residual N and K fluctuate with planting management (Djaman et al., 2024). Trace elements such as zinc and iron may also be deficient under high-intensity fertilizer and herbicide management, affecting crop quality and soil health (Afata et al., 2024). To alleviate nutrient consumption, scientific fertilization and crop rotation management have become key. Organic fertilizers, chemical fertilizers, and their combined application can significantly increase soil N, P, K content and crop yield, and the addition of organic fertilizers helps to slow down nutrient release and enhance soil buffering capacity (Mahmood et al., 2017; Adekiya et al., 2024; Jiang et al., 2024). Crop rotation and mulching (such as alfalfa maize rotation) can increase soil organic matter and available nutrient content, promote crop absorption of N, P, and K, enhance nutrient cycling and sustainability of the system (Zhang et al., 2022b; Mukhametov et al., 2024). 5.2 Soil acidification and alkalization trends In the corn planting system, long-term and large-scale application of chemical nitrogen fertilizers, especially ammonium nitrogen fertilizers, can lead to soil acidification and a decrease in pH value (Neelima et al., 2022; Khavkhun, 2024). The different types and amounts of mineral fertilizers can lead to soil acidification or alkalization. The application of certain fertilizers (such as diammonium phosphate and potassium sulfate) can lower pH, while calcareous fertilizers may increase pH (Khavkhun, 2024). Under the combined application of organic fertilizer and biochar, soil pH usually tends towards neutrality or slightly increases (Wu et al., 2023; Jiang et al., 2024). Acidified organic fertilizers like treated cattle slurry reduce nitrogen loss by lowering ammonia release, though their short-term effect on pH is limited and microbial diversity remains stable (Wierzchowski et al., 2021). In some cases, irrigation water or soil parent material may push the system toward alkalinization during long-term maize production. 5.3 Organic matter changes under different corn management systems Long term monoculture of corn, especially in the absence of organic inputs and sloping environments, leads to a significant decrease in soil organic matter (SOM) content, resulting in soil structure degradation and weakened nutrient supply capacity (Fujisao et al., 2020; Feng et al., 2022). In long-term positioning experiments in Northeast China, Laos and other places, continuous corn planting for 30 years resulted in a decrease of up to 50% in soil total carbon and total nitrogen content, which is closely related to yield decline (Fujisao et al., 2020; Feng et al., 2022). In flat land or fields with good organic management, the decline trend of organic matter is relatively slow, and it can even maintain stability. Management measures such as organic fertilizer, straw returning, biochar, and crop cover can increase soil organic matter and organic carbon content (Mahmood et al., 2017; Zhang et al., 2022b; Wu et al., 2023; Jiang et al., 2024; Xing et al., 2024). The combined application of fertilizers and biochar can increase soil organic carbon and total nitrogen content by more than 20%, and enhance microbial activity (Wu et al., 2023; Xing et al., 2024). The
RkJQdWJsaXNoZXIy MjQ4ODYzNA==