**Rock Phosphate-Enriched Compost in Combination with Rhizobacteria; A Cost-E**ff**ective Source for Better Soil Health and Wheat (***Triticum aestivum***) Productivity**

**Motsim Billah 1, Matiullah Khan 2, Asghari Bano 3,\*, Sobia Nisa 4, Ahmad Hussain 5, Khadim Muhammad Dawar 6, Asia Munir <sup>7</sup> and Naeem Khan 8,\***


Received: 20 July 2020; Accepted: 9 September 2020; Published: 14 September 2020

**Abstract:** Organic materials from various sources have been commonly adopted as soil amendments to improve crop productivity. Phosphorus deficiency and fixation in alkaline calcareous soils drives a reduction in crop production. A two-year field experiment was conducted to evaluate the impact of rock phosphate enriched composts and chemical fertilizers both individually and in combination with plant growth promoting rhizobacteria (PGPR) on wheat productivity and soil chemical and biological and biochemical properties. The present study demonstrates significant increments in crop agronomic and physiological parameters with *Pseudomonas* sp. inoculated RPEC1 (rock phosphate + poultry litter + *Pseudomonas* sp.) over the un-inoculated untreated control. However, among all other treatments i.e., RPEC2 (rock phosphate + poultry litter solubilized with *Proteus* sp.), RPC (rock phosphate + poultry litter), HDP (half dose inorganic P from Single Super Phosphate-SSP 18% P2O5) and SPLC (poultry litter only); RPEC1 remained the best by showing increases in soil chemical properties (available phosphorus, nitrate nitrogen, extractable potassium), biochemical properties (alkaline phosphatase activity) and biological properties (microbial biomass carbon and microbial biomass phosphorus). Economic analysis in terms of Value Cost Ratio (VCR) showed that the seed inoculation with *Pseudomonas* sp. in combination with RPEC1 gave maximum VCR (3.23:1) followed by RPEC2 (2.61:1), FDP (2.37:1), HDP (2.05:1) and SPLC (2.03:1). It is concluded that inoculated rock phosphate (RP) enriched compost (RPEC1) can be a substitute to costly chemical fertilizers and seed inoculation with *Pseudomonas* sp. may further increase the efficiency of composts.

**Keywords:** available phosphorus; enriched compost; PGPR; poultry litter; rock phosphate; wheat
