NITROGEN AND PHOSPHORUS CONTENT AND UPTAKE, SOIL NUTRIENT BALANCE AND SOYBEAN PRODUCTIVITY UNDER DIFFERENT LEVELS AND SOURCES OF PHOSPHORUS AND PLANT GROWTH REGULATORS IN SUB HUMID RAJASTHAN

Abstract

An experiment was conducted at Udaipur during kharif seasons of 2009 and 2010 on soybean crop involving twenty seven treatments i.e. three levels (20, 30 and 40 kg P₂O₅ ha^-1) and three sources (Single super phosphate or SSP; phosphorus rich organic manure or PROM and di-ammonium phosphate or DAP) of phosphorus in main plots and three plant growth regulators or PGRs (water spray, benzyl adenine 50 ppm and NAA 100 ppm) in sub plots of a split plot design having three replications. Results revealed that 40 kg P₂O₅ ha^-1, SSP and NAA recorded significantly higher pooled grain and stover yield equivalent to 25.95 and 37.37; 25.12 and 36.23 and 24.23 and 35.73 q ha^-1than their respective counterparts, respectively. The enhancements in grain and stover yields were associated with significantly higher pooled nitrogen and phosphorus uptake (kg ha^-1) equivalent to 243.96 and 24.79; 228.10 and 24.52 and 229.90 and 23.44 under 40 kg P₂O₅ ha^-1, SSP and NAA, respectively. Significantly higher pooled available soil N (298.24 kg ha^-1) andP₂O₅ (25.99 kg ha^-1) was recorded under 40 kg P₂O₅ ha^-1 but variations among different PGRs were indifferent. Significantly higher soil pooled soil N was recorded under PROM (294.93 kg ha^-1) but significantly higher pooled soil P₂O₅ was recorded under SSP (25.72 kg ha^-1).