ASSESSMENT OF THE IMPACT OF DIFFERENT CROPPING SEQUENCES ON SOIL MICROBIAL POPULATIONS (BACTERIA, FUNGI, AND ACTINOMYCETES) AND ENZYMATIC ACTIVITY ACROSS VARYING SOIL DEPTHS IN WESTERN UTTAR PRADESH

Abstract

This investigation was conducted to evaluate the influence of different cropping systems and soil depths on soil microbial properties. Soil samples were collected from different cropping sequences at three depths: 0–15, 15 30, and 30–45 cm. The samples were analyzed for microbial populations (bacteria, fungi, and actinomycetes), microbial biomass carbon (MBC), and dehydrogenase activity. The results showed that both cropping sequence and soil depth significantly influenced soil microbial characteristics. All microbial parameters were recorded to be highest in surface layer (0–15 cm) and declined progressively with increasing depth due to reduced organic matter availability. Bacterial populations ranged from 3.6 × 10⁶ to 5.1 × 10⁸ CFU g⁻¹ soil, with the highest average values under maize–wheat and sugarcane–mustard–ratoon–rice systems. Fungal populations varied from 1.5 × 10⁴ to 8.2 × 10⁴ CFU g⁻¹ soil, while actinomycetes ranged from 1.7 × 10⁴ to 7.4 × 10⁴ CFU g⁻¹ soil, both recording maximum populations in the maize–wheat system. Microbial biomass carbon ranged from 223 to 385 µg g⁻¹ in surface soil, with the highest values under maize–wheat and sugarcane–cucumber cropping sequences. Dehydrogenase activity ranged from 62 to 81 µg TPF g⁻¹ day⁻¹, with maximum activity in the maize–wheat system. Overall, maize- and sugarcane-based cropping systems supported greater microbial abundance and activity than other cropping sequences.