Bispyribac Sodium Persistence in Soil, Plant and Grain in Direct Seeded Rice and its Effect on Soil Properties

A field experiment on direct-seeded rice was conducted during kharif 2011 and 2012 at the College Farm, ANGRAU Hyderabad, to study the influence of different doses of bispyribac sodium 10% SC (10, 15, 20, 25 and 40 g a.i/ha) on physical, physico-chemical and fertility properties of the soil. Persistence of the herbicide in soil from application to harvest of the crop and the residues in plant samples at harvest were also studied. No significant changes in physical (texture, bulk density, particle density, pore space, maximum water holding capacity), physico-chemical (pH, EC, CEC, organic carbon) and fertility properties of the soil (available N, P₂O₅ and K₂O) were noticed at any of the applied doses. Bispyribac sodium dissipation in soil followed a first-order decay process. Half-life (DT₅₀) of bispyribac sodium was 13.10 days, 10.21 days and 9.93 days at 40 g/ha, 25 g/ha and 20 g/ha doses respectively. DT₉₀ values were also calculated. No detectable residues of bispyribac sodium were found in the straw or grain at the time of harvest.