Impact of rhizobial inoculum and inorganic fertilizers on nutrients (NPK) availability and uptake in wheat crop

Experiments were conducted to evaluate the effect of rhizobial inoculums and inorganic fertilizers on NP availability, soil microbial activity, wheat NPK concentration and uptake. These experiments were consisted of two factors, four inoculums (no, lentil, peas, and chickpeas) and two NPK doses (120:90:60 and 96:72:48 kg ha(-1)). Inoculums significantly increased plant total NPK concentration by 39, 57, and 37%, and their uptake by 66, 86, and 56%, respectively. Peas inoculum was most efficient in wheat NPK concentration and uptake. The interactive effect of inoculums and NPK demonstrated that peas and lentil inoculums with 20% less NPK had statistically better role than full NPK without inoculation. AB-DTPA extractible P and mineral N were progressively increased with incubation periods and exhibited significant differences between inoculated and uninoculated treatments during all incubation intervals for NP except at day 7 for N. Peas inoculum showed maximum mean net NP availability of 131.5 and 3.48 mg kg(-1) over 56 d of incubation, respectively. Significantly higher cumulative CO2 of 1429 mg kg(-1) with a net increase of 866 mg kg(-1) was recorded for pea's inoculums during 12 d of incubation interval. It is concluded that peas rhizobium could be used as a plant-growth-promoting rhizobacteria for wheat and other cereal crops.