Effect of different post-emergent herbicides on soil enzyme activity in cluster bean

Abstract

A field experiment was conducted during Kharif, 2016 at College of agriculture, Rajendranagar, Hyderabad, Telangana. The soil of the experimental site was sandy loam with pH, 8.02 and electrical conductivity, 0.35 dS m-1. The soil has low organic carbon (0.41%), available N (294 kg N ha-1), available P (30 kg P2O5 ha-1) and available K (204 kg K2O ha-1). The experiment was laid out in randomized block design with seven treatments replicated thrice. The treatments are T1: Pendimethalin (30% EC) @ 1.0 kg ha-1 (PE) followed by hand weeding twice at 20 and 40 DAS, T2: Pendimethalin (30% EC) 1.0 kg ha-1 (PE) followed by Imazethapyr (10% SL) 100 g ha-1 as post-emergence spray at 20-25 DAS, T3: Pendimethalin (30% EC) 1.0 kg ha-1 (PE) followed by Acifluorfen + Clodinafop propargyl (16.5 + 8% EC) 165 + 80 g ha-1 as post-emergence spray at 20-25 DAS, T4: Pendimethalin (30% EC) @ 1.0 kg ha-1 (PE) followed by Propaquizafop 2.5% + Imazethapyr 3.75% ME 50 g + 75 g ha-1 as post-emergence spray at 20-25 DAS, T5: Pendimethalin (30% EC) 1.0 kg ha-1 (PE) followed by Imazethapyr + Imazamox (70% WDG) 70 g (35 g + 35 g) ha-1 as post-emergence spray at 20-25 DAS, T6: Hand weeding (twice at 20 and 40 DAS) and T7: Control (unweeded). Soil samples were assayed for soil enzyme activity (dehydrogenase, urease, acid and alkaline phosphatase) at different intervals of observation viz., 1(24), 3(26), 8(31), 15(38) and 30(53 DAS) DAA. Soil enzyme activity was affected from 1DAA (24 DAS) to 15 DAA (38 DAS) due to the influence of herbicides but they recovered to normal from 15 DAA in post-emergence herbicide treatments. However they showed on par relation with hand weeded and controlled treatments.