Influence of Integrated Nitrogen and Weed Management Practices on Crop-weed Competition and Nutrient Depletion in Direct Seeded Rice

Abstract

A trial was conducted during 2019-20 and 2020-21 at BHU, Varanasi, to study the effect of integrated nitrogen and weed management on weeds in dry direct seeded rice. The main plot treatments consisted of four nitrogen management practices viz. Control (only P and K), RDF (100% RDN through inorganic), 75% RDN (Inorganic) + 25% through FYM, 75% RDN (Inorganic) + 25% through Vermicompost whereas five weed management practices viz. wheat residue as mulch (4 t ha-1) fb bispyribac Na 25 g a.i. ha-1 (2-4 leaf stage of weed), Pendimethalin 1 kg a.i. ha-1 fb bispyribac Na 25 g a.i. ha-1 (2-4 leaf stage of weed), Sesbenia up to 30 days (Brown manuring),  Two hand weeding (20 and 40 DAS) and Weedy check were allocated to subplots and replicated thrice. The maximum weed control efficiency was recorded with the control (only P and K) whereas 75% N through inorganic + 25% by FYM being statistically comparable with 75% N through inorganic + 25% by VC and 100% N from inorganic registered the lowest weed control efficiency. However, significantly lower weed index was noticed with the application of 75% N through inorganic + 25% by VC which was followed by 75% N through inorganic + 25% by FYM, 100% N from inorganic and control. In case of nutrient removal by weeds, significantly maximum nutrient content and depletion by weeds was noticed in N2 (75% RDN (inorganic) + 25% through FYM) over control nevertheless it remained statistically at par with N3 (75% RDN (inorganic) + 25% through VC) and N1 (100% RDN through inorganic). Among integrated weed management options, hand weeding at 20 and 40 DAS showed superiority over all the weed management practices. Application of wheat residue as mulch (4 t ha-1) fb bispyribac Na 25 g a.i. ha-1 (2-4 leaf stage of weed) recorded distinctly higher weed control efficiency and lowest weed index followed by Pendimethalin 1 kg a.i. ha-1 fb bispyribac Na 25 g a.i. ha-1. Nutrient content and removal by weed were lowest in wheat residue as mulch (4 t ha-1) fb bispyribac Na 25 g a.i. ha-1 (2-4 leaf stage of weed), whereas, it was recorded highest in weedy check.