Chemical behavior of phosphorus over time in fertilized soils

• Main Author: Zhang, Tiequan.
• Other Authors: Mackenzie, A. F. (advisor)
• Format: Others
• Language: en
• Published: McGill University 1996
• Subjects: Soils > Phosphorus content.; Phosphatic fertilizers.; Corn > Fertilizers.
• Online Access: http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34486

Fertilizer P accumulates in soils, with potential for movement to waterways, causing eutrophication. Fertilizer P reactions in monoculture corn (Zea mays L.) production over time will determine environmentally sound soil management practices. Soil P changes over time were determined on a Chicot sandy clay loam (Grey Brown Luvisol) and a Ste. Rosalie clay (Humic Gleysol). Fertilizer P was added at 44 and 132 kg P ha$ sp{-1}$ and to the Chicot soil only, manure containing 60 kg P for the first five years. Mehlich-3 (M3) extraction, soil P fractionation, $ sp{31}$P NMR analysis, P in leaching water, and path analysis were measured. Added P increased M3 P more when manure was also added, and in clay soils. To increase M3 P by 1 kg ha$ sp{-1}$ required from 3.6 to 8.1 kg ha$ sp{-1}$ fertilizer P, and when "net" fertilizer additions were used, fertilizer required was from 1.8 to 5.3 kg P ha$ sp{-1}.$ Moderately labile organic P (Po) decreased at 0 added P. With P at the rate of plant removal, inorganic (Pi) and Po fractions were unchanged. Excess P increased labile P and resistant P through moderately labile Pi. More P remained in labile Pi fractions when manure P was added, or in the soil with the higher clay content. Soil organic P levels increased upon fertilization only in the sandy loam soil. Labile and moderately labile Po could be estimated using monoester phosphate values determined by $ sp{31}$P NMR. Inorganic P values in gravitational water increased above 0.05 mg P L$ sp{-1}$ when soil labile Pi increased above 108 mg kg$ sp{-1}$ in the sandy loam soil and 69 mg L$ sp{-1}$ in the clay soil. Thus soil P movement was related to inorganic P additions. Increased fertilizer P did not increase organic P leaching losses. Fertilizer P in corn production may result in groundwater eutrophication.