Response of fodder sorghum (Sorghum bicolor) to different weed-management techniques and nitrogen levels

A field experiment was conducted during rainy (kharif) seasons of 2000-02 at Jhansi to know the response of fodder sorghum [Sorghum bicolor (L.) Moench] to nitrogen levels and weed-control techniques. Significant in- crease in green-fodder, dry-matter and crude-protein yields was recorded with successive increase in nitrogen up to 60 kglha. N at 60 kglha gave significantly higher green-fodder (45.2 tlha), dry-matter (8.26 tlha) and crude- protein yields (646.7 kglha) as well as nitrogen uptake (104.2 kglha), but at higher level showed no significant differences. However, 90 kg Nlha gave the highest net profit (Rs 15,850lha) and benefit : cost (B:C) ratio (1.55) compared with the remaining levels. Among weed-control techniques, broadcast sowing of cowpea (Vigna unguiculata (L.) Walp.) and application of atrazine @ 0.5 kglha were at par and gave significantly higher green- fodder (52.1 and 49.1 tlha) and dry-matter (8.9 and 9.06 tlha) yields than other techniques. Broadcast sowing of cowpea gave higher net profit.(Rs 13,80O/ha), B:C ratio (1.45) and significantly higher crude-protein yield (800 kglha) as well as nitrogen uptake (126.2 kglha) than others methods. Atrazine 0.5 kglha gave significantly lower weed density (25.6/m2), dry weight of weeds (0.30 tlha) and nitrogen uptake by weeds (4.0 kglha) than other techniques. This was closely followed by broadcast sowing of cowpea, registering 1 04.5/m2, 1.93 tlha and 16.3 kglha respectively. Interaction effects of nitrogen levels and weed-control techniques for green-fodder, dry-matter, crude-protein yields and nitrogen uptake of sorghum were also significant.