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Abstract. Phosphorus (P) is a limited resource, and its efficient use is a main task in sustainable agriculture. Due to high costs of imported fertilizers, focus is now shifting to solutions that utilize local resources and biofertilizers. In a field experiment, the effect of combination of two inorganic phosphorus (P) fertilizer i. e. diammonium phosphate (DAP), single super phosphate (SSP), poultry manure (PM) and phosphate solublizing bacteria (PSB) on the on growth, yield, energy content and P utilization efficiency (PUE) of maize was evaluated in Typic Hapludolls acidic soil of Azad Jammu and Kashmir (AJK). Both inorganic P fertilizers when applied in combination with PM and inoculation with PSB significantly increased plant height, leaf area and chlorophyll content over control. Grain, dry matter, biomass yield and protein content increased by 48-99, 47-64, 48-75 and 61-104% over control. P uptake increased from 13 g kg-1 in control to 37 g kg-1 where DAP, PM and PSB was combined while increase in PUE was 7-24%. When applied in combination with PM, DAP+PM+PSB was the best treatment among P sources to be utilized.
Key words: phosphorus, yield, protein, P efficiency, PSB.
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Introduction. The total P% in soil accounts approximately for 0.04-0.10%, only 1.002.50% of which can be absorbed by plants, as most of the phosphorus in soils exists in forms unavailable for uptake by plants (Lin 1990). The low availability of phosphorus nutrition in soils has become the "limiting factor" for plant and root growth (Borch et al 1999; Kanako et al 2004; Saneoka et al 1989) especially after plants have gained sufficient nitrogen nutrition (Liang 1994; Woolmanse & Duncan 1980). Some 17.5 million tonnes of P is processed annually from world reserves of rock phosphates, of which approximately 85% is used in the production of fertilizers (Cordell et al 2009a). However, reserves of rock-P are finite with an estimated depletion of quality sources expected to occur within the next 50-80 years (Isherwood 2000). Indeed world commodity markets have already faced rapid and sharp increase in the price of phosphate rock in recent years i.e. an approximately 7-fold increase in the period between March 2007 and 2008 (Cordell et al 2009b).
The need to use renewable forms of energy and...