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

Abstract 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 (T 1 ) to 4.7 Mg ha −1 (T 5 ), 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 T 5 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.