ORGANIC AMENDMENTS MEDIATING SOIL MICROBIAL BIOMASS AND ENZYME DYNAMICS IN AN INCUBATION STUDY

Abstract

Organic amendments are widely recognized for their role in improving soil fertility and microbial functioning. This study evaluated the effects of different organic amendments—farmyard manure (FYM), poultry manure (PM), compost, and green manure (GM)—on soil carbon and nitrogen pools, microbial biomass, and enzyme activities under incubation conditions at the Soil Physics Laboratory, ISES, University of Agriculture Faisalabad. Results indicated significant improvements in total organic carbon (TOC), total nitrogen (TN), microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) with all amendments compared to the unamended control. GM recorded the highest increases in TOC (11.9 g kg⁻¹), TN (0.95 g kg⁻¹), MBC (312 µg g⁻¹), and MBN (62 µg g⁻¹), followed closely by PM. Enzyme activities, including dehydrogenase, urease, phosphatase, and β-glucosidase, were also strongly enhanced, with GM and PM showing the most pronounced effects. These results underscore the potential of organic amendments in mediating soil biochemical processes and sustaining fertility. Adoption of labile, nutrient-rich amendments, particularly GM and PM, may provide effective strategies to enhance soil microbial functioning, nutrient cycling, and long-term sustainability of intensive cropping systems.