NODULATION AND UPTAKE OF NITROGEN AND POTASSIUM BY GRAIN AND STRAW OF SOYBEAN [GLYCINE MAX (L.) MERRILL] AS AFFECTED BY POTASSIUM AND SPLIT APPLICATION OF NITROGEN

A field experiment on soybean (Glycine max (L) Merrill) under varied nutrient management and nitrogen application at different growth stages was conducted during khalif 2007 and 2008 to study the effect on nodulation and nitrogen and potassium uptake. The experiment was conducted in a randomized complete block design with four replications. The experiment comprised of three levels of nitrogen i.e 0, 30 and 45 kg N/ha applied at sowing and also its split application as basal dose and at pre flowering or pod filling stage. Split application of nitrogen in the treatments receiving 30 kg was done by applying 20 kg as basal and 10 kg at pre flowering or pod filling stage. Similarly 45 kg was split by applying 30 kg as basal and 15 kg at pre-flowering or pod filling stage. All these treatments were supplemented with two levels of potassium (0 and 30 kg K2O/ha). At 45 and 75 DAS (days after sowing) application of nitrogen had a non-significant effect on number and dry weight of nodules, whereas, at 105 DAS and at maturity it resulted in a significant reduction of these attributes than where no nitrogen was applied. Among different nutrient combinations 45 kg N ha(-1) applied at sowing recorded highest N uptake in both straw and grains at all the growth stages during both the years. At 45 and 105 DAS, maximum potassium uptake was recorded with basal application of 45 kg N and 30 kg K2O ha(-1). At maturity highest potassium uptake was recorded with application of 20 kg N ha(-1) at sowing and 10 kg N ha(-1) at pod filling along with basal application of 30 kg K2O ha(-1).