Effect of Microbes and Vermicompost applied with different phosphorus levels on yield and phosphorus uptake of wheat and maize

Abstract

A series of experiments were conducted during 2018-2020 to investigate the inoculation effect of arbuscular mycorrhiza fungi (AMF), phosphate solubilizing bacteria (PSB) with vermicompost (VC) and different levels of phosphorus (P) on yield and P uptake of wheat and maize crops. In the first experiment soil samples were collected from the rhizosphere of wheat, berseem and pasture of 10 agriculturally important soil series of Peshawar valley and analysed for native status of AMF and PSB. Vermicompost was prepared from crop residues and earthworms and analysed for different physico chemical properties in the second experiment. In experiment 03, the PSB isolated from berseem and AMF spores isolated from sorghum rhizosphere were inoculated with vermicompost to maize under pot conditions. On basis of the highest soil AMF spores density and PSB population density, two out of ten soil series i.e. Pirsabaq and Tarnab were selected for further determination of the effect of these isolates on crop yield, N and P uptake by plants. In experiment fourth and fifth, the effect of inoculation with vermicompost was determined using different P levels on wheat and their residual effect on maize yield in same field layout. Results showed that the AMF spores in soil ranged from 10 to 28 per 10 g soil with dominant species of Glomus mosseae and Glomus intrardices, while PSB population density ranged from 1.8 ×106 to 3.2 ×108 colony forming unit (CFU) g-1 soil, mostly belonged to Bacillusand Diplo Bacillus genera. The prepared vermicompost consisted of 1.7% total N and 0.26% P contents. An experiment was conducted on the effect of AMF and PSB inoculated with vermicompost in Pirsabaq and Tarnab soil series on maize under pot condtion. In the Pirsabaq soil series, inoculation of AMF and PSB with vermicompost resulted in a maximum total dry matter production of 62.4 g pot-1, a 100 % increase above control. In treatments receiving 90 kg ha-1 P2O5 with AMF and PSB inoculation, maximum wheat grains yield was 3379 kg ha-1, up 76 %, and total dry matter yield was 8980 kg ha-1, up 49 % over control, wheat grains yield and total dry matter yield were statistically equal in treatments of 67.5 and 45 kg ha-1 P2O5, respectively, with vermicompost inoculated with AMF and PSB. Treatments receiving 90 kg ha-1 P2O5 had significantly greater plant P uptake of 18.5 kg ha-1 with an 89 % increase over control, which was statistically identical to treatments getting 67.5 and 45 kg ha-1 P2O5 with AMF and PSB inoculation and vermicompost application. The residual effect of 67.5 kg ha-1 P2O5 and AMF and PSB inoculation resulted in a maximum maize grain yield of 4285 kg ha-1, which was 38.5% higher than the control, which was statistically similar with maize grain yield recorded with residual effect of 90 and 45 kg ha-1 P2O5 with AMF and PSB inoculation and vermicompost, respectively applied to previous crop of wheat. With AMF and PSB inoculation by 90 kg ha-1 P2O5, maximum maize plant P absorption of 15.4 kg ha-1 was obtained with a 116 % increase over control, which was statistically similar with 45 and 67.5 kg ha-1 P2O5. Positive and linear correlations were noted for AMF soil spores density and root colonization for AMF with PSB population density in wheat and maize crops grown in pots as well as under field condition. Results suggested that inoculation of AMF and PSB with vermicompost and under different P levels have the potential to improve crop yield and nutrients uptake by plants on sustainable and environment friendly basis and may be recommended to minimize the dependence on chemical fertilizers.