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TILLAGE AND RESIDUE IMPACTS ON MICROBIAL BIOMASS AND SOIL C AND N DYNAMICS UNDER DIFFERENT CROPPING SYSTEMS

Z. SHAH^1*, H. RAHMAN², M.A. SHAH², M. IQBAL³, U. PERVAIZ⁴ AND AMANULLAH⁵

Abstract: This study was aimed to investigate the impacts of tillage and residue management on soil microbial biomass-C (MBC) and –N (MBN), mineralizable N (MN), soil organic carbon (SOC), and total nitrogen (TN) in wheat (Triticum aestivum)-fallow, wheat-maize (Zea mays L.) and wheat-mungbean (Vigna radiata) sequences three year after establishment of the experiment. No-tillage increased SOC (16.20%), TN (17.07%), MBC (10.44%) and MBN (16.87%) over the tillage treatment. Crop residue return also increased microbial biomass and accumulation of C and N in soil over the residue removed treatment. Cropping intensity promoted microbial biomass and C and N dynamics over the system containing the fallow cycles. Among cropping systems, the legume-based system (wheat-mungbean) produced greatest SOC and TN in soil than cereal-cereal (wheat-maize) system and increased MBC and MBN in similar pattern. These results demonstrated that no-tillage, residue return and cropping intensity promoted the accumulation of soil organic matter that had beneficial impacts on soil fertility through enhancement of soil microbial biomass and supply of mineralizable nutrients particularly in the rain-fed farming system.

¹Department of Soil and Environmental Sciences, NWFP Agricultural University, Peshawar, Pakistan

²Department of Plant Breeding and Genetics, NWFP Agricultural University, Peshawar, Pakistan

³CCRI, Pirsabak, NWFP Agriculture Research System, Pakistan

⁴Department of Agriculture Extension Education, NWFP Agricultural University, Peshawar, Pakistan

⁵Department of Agronomy, N.W.F.P. Agric University, Peshawar, Pakistan

^*Corresponding author E-mail: zahirshah59@yahoo.com