Agronomic Effectiveness and Phosphorus Utilization Efficiency of Rock Phosphate Applied to Winter Wheat

Rock phosphate (RP) is an important natural source of P for plant nutrition, but the solubility and availability of P from RP is an issue in agricultural production systems. Integrated use of RP with various organic and inorganic byproducts has been reported to increase RP P use efficiency and stability of crop yields. A 2-yr (2010-2011 and 2011-2012) field experiment was conducted to examine the agronomic effectiveness and P utilization efficiency (PUE) of RP supplemented with wood ash, compost, and poultry manure with and without phosphate-solubilizing bacteria applied to rainfed wheat (Triticum aestivum L.) in the hilly region of Kashmir, Pakistan. The experiment was conducted in a completely randomized block design with factorial arrangement using three replications. Treatments included: control; RP; RP + wood ash (WA); RP + poultry manure (PM); RP + compost; control + phosphate-solubilizing bacteria (PSB); RP + PSB; RP + WA + PSB; RP + PM + PSB; and RP + compost + PSB. Results indicated that RP alone did not show significant effects on growth and PUE of wheat; however, the use of RP with PM and compost improved straw yield (21 and 22%), grain yield (52 and 50%), plant P uptake (73 and 84%), and PUE (95 and 103%) over the RP alone. Also RP + PM and RP + compost, when inoculated with PSB, resulted in a further increase in yield of 9 and 8%, P uptake of 28 and 29%, and PUE of 35 and 42%, respectively. These results demonstrate that use of PSB and organic amendments with RP could be a promising management strategy and viable technology to utilize both low-grade RP and organic materials efficiently for crop production and nutrient improvement in mountainous ecosystems.