Abstract
Minimum tillage and residue management are promising options to enhance soil organic matter (SOM), nutrient content and crop productivity but these practices have not been tested in the rice-jute system. The effect of soil disturbance practices, viz. zero tillage (ZT), strip tillage (ST), bed planting (BP) and conventional tillage (CT) at two residue retention levels (20% and 50%) was studied. The objectives were to assess the changes in SOM and nutrient content, the mineralization rate of SOM and the system productivity over three years in the rice-lentil/wheat-jute system. The field trials were done on a sandy loam soil (Cromic-Calcaric Gleysols) at Baliakandi upazila under Rajbari district. The land belongs to AEZ-12 (Low Ganges River Floodplain). The second crop between rice and jute was lentil for the 1ˢᵗ and 2ⁿᵈ years and wheat for the 3ʳᵈ year. Minimum tillage practices (ZT and ST) increased SOM, total nitrogen (TN) and extractable S & Zn contents in the upper 0-5 cm soil layer. At this soil depth, the soils were enriched after 3 years with SOM and TN content by 24 & 23%, 23 & 18%, 17 & 15% and 11 & 9% under ZT, ST, BP and CT practices, respectively, over the initial values. Accumulation of extractable P, S and Zn in the 0-5 cm layer of soil followed the sequence as ZT>ST>BP>CT practice. The 50% residue retention significantly increased SOM, TN and extractable P, K, S, Zn & B contents in 0-15 cm depth. Tillage practices significantly influenced soil bulk density (BD) at 0-5 cm soil depth after three crop cycles. Strip tillage markedly reduced BD compared to initial soil BD. The strip tillage and higher residue retention treatments conserved more soil water content (SWC) while producing the minimum penetration resistance (PR) values compared to other tillage practices and lower residue retention. Tillage practices significantly altered the grain yield of rice, lentil and jute fibre, but wheat yield remained unaffected. Higher residue retention increased the yield of all crops. Considering the mean rice equivalent yield (REY), ST and higher residue retention had significantly higher REY over other tillage practices and lower residue retention. Based on net return and benefit-cost ratio (BCR), strip tillage with 50% residue retention was economically more viable for crop production. The 3-year study suggests that ST coupled with higher residue retention could be a suitable tillage-residue management system for rice-jute based cropping in the sustenance of soil fertility, crop productivity and farming economy.