This study analyzed the effect of fertilizers, farmyard manure (FYM), and lime on active soil organic matter (SOM) fractions and maize productivity in an acid Alfisol (Typic Hapludalf) of Palampur, Himachal Pradesh, India after three years of continuous maize cultivation (2019–2021). The experiment was laid out with eleven treatments comprising 100% NPK, 100% NPK with different combinations of FYM and lime, Natural Farming, and control. The increase in the active SOM fractions (water-soluble organic carbon, water-soluble carbohydrates, and soil microbial biomass carbon, nitrogen and phosphorus) was significantly higher with the application of 100% NPK, 10t FYM ha-1, and full dose of lime (4 t ha-1), recording 29–65% higher values compared to 100% NPK, with the greatest improvement observed in soil microbial biomass nitrogen. The integrated application of fertilizers, FYM, and lime significantly boosted productivity, increasing maize grain and stover yield by 2.1–2.7 times and 1.9–2.4 times, respectively over 100% NPK. Comparable yields were observed under both full and reduced lime application, indicating that lime dose can be reduced without compromising yield. Correlation analysis further confirmed that the active SOM fractions were significantly and positively associated with the yield (r: 0.888–0.943). Hence, proper soil management approach including the judicious use of fertilizers, FYM, and lime not only improves the SOM fractions but also ensures sustainable maize productivity, offering a mechanistic pathway for long-term soil fertility management in acid soils.
Mohapatra et al. (Sun,) studied this question.