**8. Integrated application of RP, PSMs, and compost (bio-organo-phos)**

The PGPR include all the bacteria found in the rhizosphere, which directly or indirectly enhance plant growth. These may be involved in enhancing the availability of nutrient directly or through other indirect mechanisms like lowering the pH of rhizosphere. PSMs are the PGPR and can be utilized for enhancing the availability of P, which has a direct effect on nodulation. The combined application of RP-EC with PSMs could be helpful in improving the nodulation and the plant growth. There are few reports about their combined application. Shahzad and his co-workers [30] studied the effect of integrated use of plant growth promoting bacteria, and compost enriched with single super phosphate (SSP) for improving growth, yield, and nodulation of chickpea. Their results revealed that combined application of rhizobacteria and P-enriched compost resulted in an increase of 84, 97, and 79% in fresh biomass, number of pods plant−1 and grain yield, respectively compared to uninoculated control without compost. So PGPB along with SSP-enriched compost was found highly effective in improving growth, yield, and nodulation of chickpea as compared to their application alone.

A field experiment was conducted to study the impact of four different agro-industrial wastes inoculated with PSMs (*Aspergillus niger* and *Phanerochaete chrysosporium*) in increasing the availability of P from RP. From the results it was found that with the application of *Aspergillus niger*, 59.7, 42.6, and 36.4% of the total P present in the RP was released in the case of the application of sugar beet wastes, olive cake, and olive mill wastewaters, respectively which was suggested to be due to the secretion of organic acids. Overall, the growth and yield of the plants was increased with the combined application of RP, *Aspergillus niger* and different agroindustrial wastes, i.e. sugar beet wastes, olive cake, olive mill wastewaters, and dry olive cake [27]. Series of field and pot experiments were conducted in our lab to check the combined effect of RP, compost and PSMs in increasing the growth and yield of wheat. From the results, it was found that the combined application of RP-enriched compost with PSMs could serve as an alternate source of P for increasing the growth and yield of many crops, thereby leading to sustainable agriculture and cleaner environment [29]. Recently, we have conducted a series of pot and field experiments and their results have clearly shown better improvement in growth, nodulation, and yield of lentil compared to conventional use of chemical phosphatic fertilizers [31].
