Effect of encapsulated herbicides on weed control, productivity and nutrient uptake of rice (Oryza sativa)

Abstract

Aim: To study the effect of season-long weed management using encapsulated herbicides on weed control, productivity and nutrient uptake of rice. Methodology: Field experiment was carried out with oxadiargyl encapsulated / loaded in zeolite, biochar, starch, water soluble polymer. It was compared with commercial formulation of oxadiargyl, butachlor, weed free check and weedy check. The experiments were laid out in randomized complete block design and replicated thrice. The physico-chemical properties of the experimental sites was sandy clay loam to clay loam in texture with pH ranging from 6.9 to 7.3, low organic carbon content, low available nitrogen, medium available phosphorus and potassium. Results: The lowest weed density and weed dry matter production of 47.3, 28.0 m-2 and 96.2, 32.8 kg ha-1 was observed in 2016 and 2017 respectively with the application of oxadiargyl loaded with zeolite at 20 DAT. Application of butachlor at 1.25 kg ha-1 fb hand weeding on 40 DAT and application of oxadiargyl loaded with zeolite recorded 86.7, 76.9 and 81.3, 72.8 percent higher grain yield in 2016 and 2017, respectively, as compared to weedy check. Higher N, P, K uptake was observed with application of butachlor at 1.25 kg ha-1 fb hand weeding on 40 DAT, which was comparable with oxadiargyl loaded with zeolite and oxadiargyl loaded with biochar during both the year. Interpretation: It can be concluded that oxadiargyl loaded with zeolite was more efficient in controlling weeds coupled with maximum growth and productivity under the constrained situation of manual weeding. Key words: Biochar, Encapsulation, Herbicides, Rice, Water soluble polymer, Zeolite