Phosphorus dynamics in soils receiving chemically treated dairy manure.
Chemical treatment of animal manure with Al, Fe, and Ca salts appears capable of concentrating P in a smaller volume, thereby providing increased manure management options. However, little information is available on the fate of nutrients in soils receiving chemically treated manure. An incubation study (1 d to 2 yr) was conducted with three soils (Soils I, II, and III with 12, 66, and 94 mg kg(-1) Bray-1 P, respectively) and four manure treatments (one untreated and three chemical including Al-, Fe-, and Ca-treated) at two rates (12.5 and 25 mg P kg(-1)), and a control (no manure). Subsamples were analyzed for Bray-1 P and water-extractable phosphorus (WEP) after eight incubation time periods. Phosphorus distribution among different fractions (soluble and loosely bound; Al-, Fe-, and Ca-bound; organic P; and residual) was also determined after 1 d and 1 yr. Water-extractable P increased when soils received untreated or Ca-treated manure in proportion to P application rate. Water-extractable P, however, decreased (compared with control) for Soils II and III or slightly increased for Soil I with addition of Al- or Fe-treated manure. Water-extractable P decreased sharply between 1 d and 1 to 2 wk and then remained relatively constant or increased slightly up to 2 yr depending on treatment and soil type. Bray-1 P increased for all treatment types and soils in the following order: Ca-treated > Al-treated >/= untreated > Fe-treated > control. Within each treatment, Bray-1 P decreased between 1 d and 1 to 2 wk and then gradually increased for up to 3 mo (Soils II and III) or 6 mo (Soil I). Application of Al- or Fe-treated manure decreased P solubility with the effect being more pronounced in soils with high background P. Since the application of Ca-treated manure increased both WEP and Bray-1 P, it should be recommended for soils where the objective is to increase P availability. Several years of P input through fertilizer and manure contributed mainly to aluminum-bound phosphorus (Al-P) and to a lesser degree to other fractions. Only soluble and loosely bound P (all soils) and Al-P (Soil I) exhibited treatment-type effects after receiving chemically treated manure. The study results will help bridge the gap between our knowledge of chemical treatment systems for animal manure and the ultimate fate of P when the treated manure is land-applied.
Kalbasi
M
M
Biological Systems Engineering Department, 460 Henry Mall, University of Wisconsin, Madison, WI 53706, USA.
Karthikeyan
K G
KG
D000535:Aluminum / Q000737:chemistry; D000818:Animals; D002118:Calcium / Q000737:chemistry; D002417:Cattle; D007501:Iron / Q000737:chemistry; D008372:Manure; D010758:Phosphorus / Q000032:analysis* / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis; D012995:Solubility; D014873:Water Pollutants / Q000032:analysis
D008372:Manure; D012989:Soil Pollutants; D014873:Water Pollutants; D010758:Phosphorus; D000535:Aluminum; D007501:Iron; D002118:Calcium