
%0 Journal Article
%A Redding, Matt R. 
%T Pig effluent-P application can increase the risk of P transport: two case studies
%J Soil Research
%D 2001/01/16
%V 39
%N 1
%P 161-174
%K run-off, leaching, phosphorus.
%R https://doi.org/10.1071/SR99112
%U https://www.publish.csiro.au/paper/SR99112 
%X Land application of piggery effluent (containing urine, faeces, water, and wasted feed) is under close scrutiny as a potential source of water resource contamination with phosphorus (P). This paper investigates 2 case studies of the impact of long-term piggery effluent-P application to soil. A Natrustalf (Sodosol) at P1 has received a net load of 3700 kg effluent P/ha over 19 years. The Haplustalf (Dermosol) selected (P2) has received a net load of 310 000 kg P/ha over 30 years. Total, bicarbonate-extractable, and soluble P forms were determined throughout the soil profiles for paired (irrigated and unirrigated) sites at P1 and P2, as well as P sorption and desorption characteristics. Surface bicarbonate (P B , 0&#8211;0.05 m depth) and dilute CaCl 2 -extractable molybdate-reactive P (P C ) have been significantly elevated by effluent irrigation (P1: P B unirrigated 231, irrigated 2906; P C unirrigated 0.030.00, irrigated 23.90.2; P2: P B unirrigated 7248, irrigated 39501960; P C unirrigated 0.70.0, irrigated 443287 mg P/kg; means.d.). Phosphorus enrichment to 1.5 m, detected as P B , was observed at P2. Elevated concentrations of CaCl 2 -extractable organic P forms (P OC ; estimated by non-molybdate reactive P in centrifuged supernatants) were observed from the soil surface of P1 to a depth of 0.4 m. Despite the extent of effluent application at both of these sites, only P1 displayed evidence of significant accumulation of P OC . The increase in surface soil total P (0&#8211;0.05 m depth) due to effluent irrigation was much greater than laboratory P sorption (&#62;25 times for P1; &#62;57 times for P2) for a comparable range of final solution concentrations (desorption extracts range 1&#8211;5 mg P/L for P1 and 50&#8211;80 mg P/L for P2). Precipitation of sparingly soluble P phases was evidenced in the soils of the P2 effluent application area. 
