Effect of resource-conserving techniques on soil microbiological parameters under

Abstract

An experiment was conducted during 2000–07 to study the impact of 2 tillage intensities (bed planting and conventional), 3 levels of irrigation (sub-optimal, optimal and supra-optimal) in combination with 8 nitrogen management systems on the soil microbial properties under long-term maize (Zea mays L.)–wheat (Triticum aestivum L. emend. Fiori & Paol.) crop rotation. The mean value of soil respiration was 32% higher in bed planting over the conventional tillage. At sub-optimal, optimal and supra-optimal irrigation intensity, bed planting tillage recorded 47, 35 and 19% higher value respectively, of soil respiration over the corresponding treatments under conventional tillage. The highest dehydrogenase enzyme activity (129.05 mg tri phenyl formazone (TPF)/g soil/24 hr) was recorded in treatment where biofertilizer supplemented the 25% N requirement and the least was recorded where recommended dose of nitrogen was supplied as urea. Soils under bed planting method/zero tillage registered significantly higher dehydrogenase enzyme activity and microbial biomass carbon than the conventional tillage at all the 3 irrigation regimes, receiving different N sources. Soil microbial biomass carbon was significantly higher under bed planting method (13%) than the conventional tillage. At the 3 irrigation regimes, namely sub- optimal, optimal and supra-optimal no significant difference was observed in soil microbial biomass carbon. Application of N as organics significantly increased (41%) soil microbial biomass carbon over the soils receiving the recommended dose of nitrogen as urea. This study demonstrates the positive influence of conservation tillage (bed planting/zero tillage) method on selected biological parameters, especially, in soils receiving a combination of organic and inorganic N sources.