Effect of conservation agricultural practices and nitrogen management on growth, physiological indices, yield and nutrient uptake of soybean (Glycine max)

Abstract

A field experiment with soybean (Glycine max (L.) Merr.) under soybean–wheat (Triticum aestivum L.) cropping system was conducted during the rainy (kharif) seasons of 2014 and 2015 at the Indian Agricultural Research Institute, New Delhi, to assess the effect of conservation agricultural practices and nitrogen management on growth, physiological indices, yield and nutrient uptake of soybean. The experiment was laid out in a split-plot design with 4 conservation agricultural practices, viz. zero tillage without residue (ZT–R), zero tillage with soybean residue (ZT + SR), zero tillage with soybean and wheat residue (ZT + SWR) and conventional tillage without residue (CT–R), in main plots and 4 nitrogen-management practices, viz. 100% recommended dose of nitrogen (RDN) as basal (N1), 125% RDN as basal (N2), 100% basal + 25% top-dressing at flowering stage (N3) and 75 % basal + 25% topdressing at flowering stage (N4), in subplots. The results showed that growth parameters, physiological indices as well as nitrogen (209.2 kg/ha), phosphorus (20.2 kg/ha) and potassium (89.4 kg/ha) uptake were significantly higher in ZT + SWR than the other treatments. The ZT + SWR resulted in 14% and 11% higher grain yield and 22% and 21% higher profitability than ZT–R and CT – R, respectively. And among the nitrogen-management practices, N2, being at par with N3, showed significantly higher growth and better physiological indices at all the growth stages. However, significantly the highest nitrogen (201.8 kg/ha), phosphorus (19.6 kg/ha) and potassium uptake (88.2 kg/ha) were obtained with basal application of 125% recommended dose of nitrogen (N2). Significantly higher seed (1.96 t/ha) and stover yields (4.06 t/ha) were recorded with N2 than the other nitrogen-management practices