Reaction of IR20 rice to carbofuran and urea
1989
Salam, M.A. (Kerala Agricultural Univ., Karamana, Trivandrum, Kerala (India). Cropping Systems Research Centre)
The reaction of IR20 rice to combination of carbofuran and urea was studied at Tamil Nadu Agricultural University (TNAU) in summer (Feb-Jun) 1983. The objective was to examine the phytotoxic effects of carbofuran and its interaction with N. The experiment was laid out in a factorial combination of three levels of N (0, 60, and 90 kg N/ha as urea) and four levels of carbofuran (0, 1.0, 2.0, and 3.0 kg ai/ha) in a randomized block design with four replications. Soil at TNAU (11 degrees north, 77 degrees east, and 427 n above mean sea level) was a Vertisol (clay loam) containing 1.0% organic C, 99-8.0-254 ppm available NPK, 0.7 ppm OTPA-extractable Zn, with pH 8.2 and EC 0.3 ds/m. The crop was uniformly fertilized and kept insect free by spraying all plots with phosphamidon on a need basis, including plots treated with insecticide. Carbofuran was incorporated at planting to ensure minimum loss. N as urea was applied in three splits: 50% basal, 25% at tillering, and 25% at panicle initiation. Tiller production, leaf area index, root production, and grain yield increased with urea application up to 90 kg N/ha and with carbofuran application up to 1.0 kg ai/ha. Based on costs, the combination 90 kg N/ha and 1.0 kg ai carbofuran/ha was optimum. Costs were $2.5/kg carbofuran 3% granule, $0.5/kg N $0.2/kg rough rice, and $2.9/person (for labor).
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