Field experiments were conducted at Coimbatore, India with four dates of sowings in each of three seasons to determine the duration of phenological phases, heat unit requirements and evaluation of heat units to predict the developmental phases of Soybean (Glycine max [L.] Merr.). The variations in development of different phenological phases and maturity of Soybean due to season and sowing dates was manifested by varied accumulation of heat units calculated. There was a linear relationship between the number of days to flower initiation and cumulative day length. Growing degree days (GDD) were better predictors for development of phenological phases whereas maturity was controlled by Calender days and was closely followed by GDD. Photothermal units were the next best predictors for soybean developmental phases.

Field experiments were conducted during the summer season of 1994 and 1995 at Cotton Research Station, Srivilliputtur to study the effect of intercropping and foliar nutrition on the productivity of summer irrigated cotton. Cotton + blackgram raised in paired row system (2:1) produced higher mean seed cotton yield equivalent (1815 kg/ha), mean net return (Rs. 17,724/ha) and mean benefit cost ratio (1.96). Spraying DAP two per cent + KCI one per cent (1:1) solution was found more economical. Raising cotton + blackgram in paired row 2:1 ratio and spraying DAP two per cent + KCI one per cent (1:1) solution resulted in the highest net return of Rs. 20,225 and benefit cost ratio of 2.12.

Field experiments were conducted at the Agricultural College and Research Institute, Coimbatore to study the yield and economics of methods of weed control (hand weeding twice at 20 and 40 days after sowing (DAS), atrazine pre-emergence spray @ 0.5 kg ai/ha) and sowing (direct seeding and transplanting maize with 5 day old seedlings) and time of nitrogen application and their combined influence. Hand weeding twice at 20 and 40 DAS, transplanting of 5- day-old seedlings and application of nitrogen in three splits as 25% basal + 50% at knee high stage + 25% at tasseling stage recorded significantly higher yields, gross returns, net returns and benefit cost ratio.

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