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Use of organic manures for soil amendment has gained renewed attention with growing concerns about sustaining soil productivity. A greenhouse study was carried out to determine the influence of different soil amendments, namely poultry manure (PM), cattle manure (CM), and sulfur (S), on soil P status. The application rates were 0, 4, and 8 t ha-1 for PM; 0, 20, and 40 t ha-1 for CM; and 0, 0.75, and 1.5 t ha-1 for S treatments. Individual additions of PM and CM unlike S significantly affected phosphorus (P) concentrations in soils. The highest Olsen P and total P (TP) were with the highest PM (8 t ha-1) and CM (40 t ha-1) treatments. The addition of PM increased Olsen P to 59.2 mg kg-1 and TP to 761 mg kg-1. For the CM treatments, the highest Olsen P (66.5 mg kg-1) and TP (713 mg kg-1) concentrations were with the highest CM treatments (40 t ha-1). While PM additions decreased the bioavailability factor, CM increased it. Increasing S treatments decreased soil pH (8.0 to 7.8) but not statistically significantly. Application of S significantly increased EC (801.6 to 1163.4 µs cm-1). While the applications of CM increased shoot P concentrations unlike root P concentrations, PM and S did not significantly influence plant shoot or root P concentrations. Plant shoot P concentration was higher compared to root P concentration as expected due to the transformation of P from root to shoot. Poultry manure had no effect on plant length or weight. However, they were significantly increased by increasing additions of CM and S. The study indicated that CM addition is more effective on soil Olsen P and plant P concentrations as well as plant growth compared to PM and S. There are controversial results in the literature depending on the nature of amendments, plant systems, and specific soil properties. Therefore, more research is needed on manure as a soil amendment.
Sönmez et al. (Fri,) studied this question.