Long-Term Effect of Prescription-Based Fertilization on Culturable Soil Microorganisms and Carbon Dynamics in Northwest Himalayas.

The different approaches of fertilizer application can play an important role in altering soil biological properties, organic carbon retention, and its dynamics. The mechanisms implicit in the long-term accumulation and protection of soil organic carbon and improvement in soil biological environment, however, have not been well documented for maize crop cultivated in acid soils of the Northwest Himalayas. Based on a 13-year experiment, the effects of prescription-based fertilization on soil culturable microorganisms and soil carbon dynamics were investigated under a continuous maize cropping at Palampur, India. The experiment was initiated during 2007 in randomized block design (RBD) with 8 treatments which were replicated three times. The soil of the experimental site was acidic, having silty clay loam texture and classified taxonomically as "Typic Hapludalf." The surface soil samples from 0.15 m depth were drawn after the harvest of maize crop in 2019 for estimation of culturable soil microorganisms and carbon dynamics. Based on soil-test crop response approach, the application of 110 kg ha−1 nitrogen and 82 kg ha−1 phosphorus with 5 Mg ha−1 farmyard manure (FYM) for attaining the target yield of 4.0 Mg ha−1 of maize recorded significantly highest population of soil bacteria (40.7 × 105 CFU g−1 soil), fungi (57.0 × 105 CFU g−1 soil), actinomycetes (38.2 × 105 CFU g−1 soil), microbial biomass carbon (147.2 µg g−1), dehydrogenase enzyme activity (4.3 µg TPF g−1 hr−1), different fraction of organic carbon, i.e. very labile (4.6 g kg−1), labile (2.60 g kg−1), less labile (2.70 g kg−1), non-labile (2.94 g kg−1), soil organic carbon (8.9 g kg−1), total soil organic carbon (11.8 g kg−1), total carbon stock (16.1 t ha−1), carbon sequestration (3.24 t ha−1) and carbon sequestration rate (1.24t ha−1year−1) when compared with control plot. Based on the data associated with microbial soil environment and carbon dynamics, it was inferred that application of prescription-based fertilizers along with farmyard manure for a longer period not only improved population of soil culturable microorganisms but also enhanced soil carbon sequestration and minimized carbon di-oxide (CO2) emission to atmosphere. [ABSTRACT FROM AUTHOR]