Effect of organic manures, inorganic fertilizers and biofertilizers addition on soil properties and productivity under onion (Allium cepa L.)

Abstract

A field experiment was conducted during rabi season of 2009 to find out the effect of integrated use of organic manures (farmyard manure and vermicompost), inorganic fertilizers and biofertilizers (phosphate solubilizing bacteria and Azotobacter) on growth, yield of and nutrient uptake by onion (Allium cepa L.) and nutrient build up in the soil. Application of 50% N through vermicompost + 25% N through urea + PSB + Azotobacter registered significantly higher yield of onion (74.85 q ha-1) and nutrient uptake (N, P, K and S) as compared to other treatments. After completion of experiment, the highest available N, P, K and S concentration (248.6, 19.7, 230 and 12.13 Kg ha-1, respectively) were recorded in the case of the treatment consisted of 50% N through vermicompost + 25% N through urea + PSB + Azotobacter (T6). Furthermore, the use of organic manures showed a significant improvement in soil physico-chemical properties (bulk density, water holding capacity, porosity, pH and EC) and residual nutrients concentration (N, P, K and S). Soil inoculation by P-solubilizers and Azotobacter alongwith FYM or vermicompost showed a remarkable increase in residual soil fertility status over the treatments which received FYM or vermicompost alone. The use of FYM and vermicompost has also showed a significant increase in soil fertility status over chemical fertilizers alone. The Azotobacter with organic manures can substitute the N requirement of plant to the extent of 25% without compromising with the yield, makes it a better integration in the present day context to sustain soil health and productivity to achieve better yield.