Mineralization and Leaching of Phosphorus from Soil Incubated with Surface‐Applied and Incorporated Crop Residue

Publisher Website
Google Scholar
Abstract
With the increasing use of conservation tillage, consideration of crop residue as a potential source of plant‐available P and mobility of this P in soil will be important from both agronomic and environmental standpoints. The effect of placement (surface or incorporation) of residue of six crop types (alfalfa, Medicago sativa L.; corn, Zea mays L.; oat, Avena sativa L.; peanut, Arachis hypogaea L.; soybean, Glycine max (L) Merr.; wheat, Triticum aestivum L.) on the mineralization and leaching of P from eight soils was investigated. Significantly greater (1.0% level) amounts of inorganic P were leached from surface‐applied compared to incorporated residues during the 84‐d incubation at 35°C, with the maximum amount leached after 28 d. The opposite was true for organic P, with greater amounts leached from incorporated residue than from surface‐applied residue. These amounts steadily decreased during the 84‐d incubation. Apparently, mineralization of residue P and movement within the soil was greater for surface‐applied compared to incorporated residue and was a positive linear function of available soil P content (r2 = 0.69–0.81). Any increase in soil P solubility caused by residue leachate would be expected to occur to a greater extent with an increase in available soil P. Leaching of mineralized P may be an important source of available P during initial crop growth.