Amendments of microbial biofertilizers and organic substances reduces requirement of urea and DAP with enhanced nutrient availability and productivity of wheat (Triticum aestivum L.)

Conventional biofertilizers (Azotobacter chroococcum and Bacillus subtilis; CBF), different doses of conventional chemical fertilizers (CCF) i.e. urea [(NH2)(2)CO3] and di-ammonium phosphate [DAP, (NH4)(2)HPO4] and combination of CBF and CCF were applied as different sole nutrient sources for the cultivation of wheat (Triticum aestivum L. c.v. PBW-343) in experimental plots of 2.0 x 2.0 M. The lower doses i.e. 1/4 and 1/2 of the recommended dose of CCF along with the CBF separately and in combination of these two were entrapped in an organic matrix (OM) consisting cow-dung, neem (Azadirachta indica) leaf powder and clay soil in ratio of 1:1:1 along with saresh (plant gum of Acacia sp.) as binder (15% w/w of dry mixture of the matrix materials; designated as super granules), were also applied as alternatives to the free/conventional forms of the various fertilizer treatments in the experimental fields. A combination of CCF and CBF increased nutrients availability and productivity of wheat more than the same fertilizers applied alone. The same fertilizers when entrapped in the above mentioned organic matrix further enhanced nutrients availability in soil as well as uptake in plants as measured on 30, 60, 90 and 120 days after sowing (DAS) in terms of nitrate, nitrite and ammonium in rhizospheric soil (0-15 cm) and in plant leaves as well as yield and productivity of wheat. The data indicate that even the lower dose of conventional chemical fertilizers in combination with microbial biofertilizers and organic matrix can be more effective for the enhanced productivity of wheat in sub-tropical agro-climatic conditions of wheat cultivating northern Indian regions. (C) 2014 Elsevier B.V. All rights reserved.