Weed strip management for minimizing soil erosion and enhancing productivity in the sloping lands of north-eastern India

摘要

Soil erosion and shifting cultivation are the major constraints to agriculture in the north-eastern region of India. Low acceptance of cost-intensive soil conservation technologies (e.g., terracing) calls for developing low-cost erosion control measures. Thus, a field experiment was conducted during the monsoon period of 2008 and 2009, in runoff plots on a land slope of 40% to test the hypothesis that weed cover, if properly managed, minimizes soil erosion and improves soil productivity. The treatments implemented in duplicates were: maize (Zea mays) under shifting cultivation (T-1), maize on contour lines (T-2), groundnut (Arachis hypogea) on upper and maize on lower half of treatment plot, with both on contour lines (T-3), groundnut on contour lines (T-4) and maize on contour lines with natural vegetation as buffer strips (T-5). The average sediment concentration of runoff water varied from 5.20 g L-1 (T-1) to 1.07 g L-1 (T-5) in 2008 and from 3.84 (T-1) to 0.89 g L-1 (T-5) in 2009. The soil loss ranged from 20.8 (T5) to 4.7 Mg ha(-1) (T5), with corresponding loss of 670-147 kg ha-(1) of SOC, 6.85-1.48 kg ha(-1) of available N, and 2.14-0.87 kg ha(-1) of available P. Weed strips and weed mulch on the upstream side of maize rows in T5 led to formation of stable mini-terraces promoting better plant and root growth. This study indicates cover management involving selective weed retention can reduce soil erosion, favourably modify land slope and promotes soil productivity.