Molecular Soil Biology 2025, Vol.16, No.6, 314-324 http://bioscipublisher.com/index.php/msb 319 5.3 Effects on grain quality (enrichment of protein and micronutrients) In the Vertisol soil, when 5 t/ha of vermicomworm manure was used, along with green manure, combined with 50% NP fertilizer, and simultaneously treated with INM of Jivamrut and Azophos, the protein content of wheat grains was the highest, reaching 11.81%. The absorption amounts of nitrogen, phosphorus and potassium by wheat were 78.84, 20.52 and 77.82 kg/ha respectively, while under the lowest treatment, the absorption amounts of nitrogen, phosphorus and potassium were only 48.40, 10.38 and 48.80 kg/ha respectively, and the gap was relatively obvious. In terms of the amino acid composition of grains, the contents of methionine, cysteine and lysine varied between 1.36~1.45, 1.41~1.47 and 2.42~2.53 g/16 g N respectively (Gund et al., 2022). When 50% NPK was applied in combination with farmyard manure, or wheat straw and green manure were added simultaneously, the content of soil organic carbon increased, and the contents of available nitrogen, phosphorus, potassium and DTPA-Zn also increased accordingly (Walia et al., 2024). 5.4 Yield stability under different climatic and ecological conditions The INM experiment in the semi-arid area set up 5, 10, 15 and 20 t/ha farmyard manure (FYM) and used it in combination with different levels of NPK fertilizers. The experiment adopted a three-time irrigation method, which was carried out respectively at the seedling emergence stage, the tillering stage and the jointing stage. Under the condition of three irrigates, when 10 t/ha FYM was applied in combination with 80-60-40 kg of N-P2O5-K2O of ha-1, the grain yield of wheat was the highest, and the absorption of nitrogen, phosphorus and potassium by crops also reached the maximum. This treatment is relatively stable in different rainfall years and has a small impact on interannual rainfall variations (Ali et al., 2024). The wheat experiment on industrial wastewater irrigation compared different combinations of irrigation water and fertilization methods. When wastewater accounted for 25% and clear water 75% (IW1) in the irrigation water, and the fertilization method was 75% recommended chemical fertilizer plus 25% vermicomposted manure (INM2), the growth condition of wheat was the best. In two consecutive years, plant height, tillering number, leaf area index and grain yield all reached the highest levels (Kurmi et al., 2025). 6 Impact of INM on Soil Health and Sustainability 6.1 Soil fertility restoration and maintenance In the semi-arid pearl millet-wheat system, the application of different organic sources and NPs over 25 years resulted in a gradient increase in topsoil TOC within the range of 0.46–1.42%, with corresponding available N, P, K, and S reaching 194.7, 74.9, 761.2, and 54.6 kg/ha, respectively; the correlation coefficients between TOC and available N, P, K, and S were all greater than 0.77 (R² against N, P, K, and S were 0.769, 0.881, 0.758, and 0.914, respectively) (Kumari et al., 2024). In a 34-year rice-wheat trial in the Indo-Ganges Plain, the treatment of 50% recommended NPK + 50% FYM showed the best water-soluble aggregates and exchangeable, non-exchangeable, fixed, and total K states in both rice and wheat. Furthermore, the Fe and Zn activity pools increased to 984.8 mg/kg and 3.08 mg/kg, respectively, in the CFeOX fractionation, which were significantly higher than the full fertilizer treatment (Walia et al., 2024). A 31-year rice-wheat experiment further showed that the average annual C sequestration rate of the 50% NPK + 50% FYM treatment in the rice season and the 100% NPK treatment in the wheat season was 0.29 MgC ha-1 yr-1, higher than the 0.13 MgC ha-1 yr-1 of 100% NPK. Furthermore, organic carbon was positively correlated with permeability and water-stable aggregates, and negatively correlated with bulk density and soil strength (Sandhu et al., 2020). 6.2 Changes in soil organic carbon and nutrient availability In the continuous six-year experiment of pearl millet and wheat, when both farmyard manure (FYM) and chemical fertilizer (NPK) were applied simultaneously, there were significant increases in TOC, Walkley-black organic carbon, easily decomposable organic carbon (LBC), and microbial biomass carbon (MBC). Under the treatment of FYM+NPK, the LBC was 1.36 g/kg and the MBC was 273 mg/kg, both of which were higher than those treated with only FYM or only NPK. The positive correlation between LBC and MBC and wheat yield was the most obvious (Moharana et al., 2012). Under the integrated nutrient management of rice-wheat for 10 years, the green manure turning treatment provided the highest available nitrogen throughout the growth period, cumulatively reaching 962 μg cm-2, even higher than the 878 μg cm-2 of 100% chemical fertilizer application. The
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