Influence of biochar on weed control in dry direct seeded rice (Oryza sativa L.)
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Date
2019-06
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
A field experiment was conducted during the kharif season of 2018 at N. E. Borlaug Crop Research Centre of G.B. Pant University of Agriculture and Technology, Pantnagar, District Udham Singh Nagar, India to evaluate the effect of addition of biochar on weed dynamics and growth, yield and nutrient uptake of rice. The experimental soil was clay loam in texture, neutral in reaction, medium in organic carbon (0.72%), medium in available nitrogen ( 282.4 kg ha-1), high in phosphorus (25.2 kg ha-1) and medium available potassium (184.5 kg ha-1). The experiment consisting of 8 treatments viz., weedy check (WC), weed free (WF), Biochar @ 4.0 tonnes/ha along with Pendimethalin applied as PE @ 1.0 kg a.i./ha fb Bispyribac-sodium applied as PoE @ 25g a.i./ha at 20 DAS (BPB), Biochar @ 4.0 tonnes/ha along with Pendimethalin applied as PE @ 1.5 kg a.i./ ha fb Bispyribac-sodium applied as PE @ 25g a.i./ha at 20 DAS (BP1.5B), Biochar @ 4.0 tonnes/ha along with Pendimethalin applied
as PE @ 2.0 kg a.i./ha after sowing fb Bispyribac-sodium applied as PoE @ 25g/ha at 20 DAS (BP2.0B), Pendimethalin applied as PE @ 1.0 kg a.i./ ha after sowing fb Bispyribac-sodium applied as PoE @25g a.i./ha at 20 DAS (PB), Pendimethalin applied as PE @ 1.5 kg a.i./ ha
after sowing fb Bispyribac-sodium applied as PoE @ 25g a.i./ha at 20 DAS (P1.5B) and Pendimethalin applied as PE @ 2.0 kg a.i./ ha after sowing fb Bispyribac-sodium applied as PoE @ 25g a.i./ha at 20 DAS (P2.0B) was set out in randomized block design which was replicated thrice. E. colona and E. crusgalli were the two dominant grasses in the experimental field contributing 43.77and 17.02% at 60 DAS. T. portulacastrum, C. rotundus and C. iria were the pre dominant weed species during initial stages (40 DAS) contributing 17.25%, 25.57% and
11.76% respectively to the total weed population. Highest weed control efficiency was observed with P2.0B which was 6-8% more compared to BP2.0B up to 60 DAS. At later stages (80 DAS and harvesting), weed control efficiency was almost equal in both P2.0B and BP2.0B. Yield, yield attributes, total N, P and K uptake and soil chemical properties was differed significantly under various weed management approaches. Highest grain yield was obtained in weed free treatment which was only 7.38% higher than the herbicide treatment i.e. BP1.5B. Recommended dose of pendimethalin (1.0 kg/ha) along with biochar had 7.5 % reduced yield compared to 1.0 kg/ha pendimethalin without biochar amendment. Similar trend was observed in straw and biological yield. Higher dose of pendimethalin had reduced grain, straw and biological yield and setback on yield was more pronounced in non biochar amended soil. Grain straw ratio and harvest index remained unaffected due to treatments. Increasing the dose of pendimethalin to 1.5 kg/ha in biochar amended soil i.e. in BP1.5B total N, P and K uptake was increased by 19.4%, 24.64% and 12.78% respectively compared to current weed management practice i.e. PB. Biochar amended plots had higher organic carbon, available N, P and K content in soil. Addition of biochar decreased the B:C compared to without biochar treatments.
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