Soil Physicochemical Properties as Influenced by Various Weed Management Practices in Winter Maize (Zea mays L.)

A field experiment was conducted in rabi season 2011-12 and 2012-13 at research farm of Bihar Agricultural College, Sabour, Bhagalpur, Bihar to assess the impact of various weed management practices on physico-chemical properties of soil in winter maize. Experiment consisted of nine treatments viz., acetochlor 90% EC at 1.25, 1.875, 2.5, 3.125 l ha-1, atrazine 50% WP at 2.0 kg ha-1, 2,4-DEE 38% EC at 2.65 l ha-1, weedy, weed free and acetochlor 90% EC at 5.0 l ha-1 laid out in randomized block design replicated thrice. Results indicated that bulk density, water holding capacity and moisture content of soil did not vary significantly at 45 DAS and harvest of maize due to acetochlor 90% EC and others. Soil pH, EC and organic carbon at 45 DAS and harvest did not differ significantly with acetochlor 90% EC and others. Total nitrogen, available P2O5 and K2O though varied significantly but there was not much variation among herbicides. Herbicide treated plots showed depletion of available N, P and K at harvest over weedy check due to higher nutrient removal by enhanced yield. Soil fertility status after harvest was recorded indicating a reduction in available N, P and K under weed free, acetochlor 90% EC @ 3.125 and 5.0 l ha-1 over initial and weedy check. Soil available N was lower in acetochlor 90% EC @ 5.0 l ha-1 and at par with its dose 3.125 l ha-1. Soil available P was lowest in acetochlor 90% EC @ 5.0 l ha-1, being at par with acetochlor @ 3.125 and 2.5 l ha-1 and was significantly lower over weedy check indicating highest soil available P which was at par with acetochlor 90% EC @ 1.25 and 1.875 l ha-1. Soil available K was lowest in acetochlor 90% EC @ 5.0 l ha-1 and similar to rest of its doses except 1.25 l ha-1. It showed parity to 2, 4-DEE 38% EC @ 2.65 l ha-1 and atrazine 50% WP @ 2.0 kg ha-1, which were significantly lower over weedy check. Weed free plot showed minimum soil available N, P and K.