Phosphorus amounts and distribution in a Saskatchewan soil after five years of swine and cattle manure application

Qian, P., Schoenau, J. J., Wu, T. and Mooleki, P. 2004. Phosphorus amounts and distribution in a Saskatchewan soil after five years of swine and cattle manure application. Can. J. Soil Sci. 84: 275-281. Repeated application of animal manures to Saskatchewan soils has led to interest in the fate and distribution of residual manure P in the soil. The concentrations of soil phosphorus in various inorganic and organic fractions were investigated in soils sampled from long-term field research plots (Dixon, SK) with a 5-yr history of annual application of liquid swine manure or solid cattle manure at low, medium and high rates. The soil type at the research site is a loamy textured Black Chernozem (Cudworth Association). Annual rates of manure application over the 5 yr were based on the N contents in the manures and were equivalent to 0 (control), and approximately 100 (low), 200 (medium) and 400 (high) kg total N ha(-1) yr(-1) as manure. For comparison, urea alone was also applied at rates of 50, 100 and 200 kg N ha(-1) yr(-1). The total P concentration in the surface soil (0-15 cm) was significantly increased only by the addition of cattle manure and only in the medium and high rate treatments compared to the control. The most labile P fractions (Resin-P and NaHCO3-P) were also significantly increased with increasing rate of cattle manure addition. No significant increases in either soil total P or labile P fractions were observed in liquid swine manure treatments, which is attributed to the lower amount of P added with the swine manure treatment than the cattle manure treatment. Added P in the swine manure treatment more closely matched P removal in crop harvest compared to cattle manure treatment, which had more P added than was removed by the crop.