Phosphorus leaching in an acid tropical soil "recapitalized" with phosphate rock and triple superphosphate.
With high rates of phosphorus applied to increase "capital P" as a stock for plant uptake over several years, the question of P leaching is inevitable. We conducted an intact soil column experiment in the field to evaluate P leached from soils treated with triple superphosphate (TSP) and Gafsa phosphate rock (GPR) at 300, 600, and 900 kg P ha-1 with and without integration of cattle manure. The lysimeters, made from PVC tubes of 30-cm length, were inserted into the soil up to the 25-cm depth. The tubes were fitted with a resin bag containing a mixture of cation and anion exchange resin (50:50) at the lower end of the tube inserted into the soil. The tubes, arranged in a completely randomized design, were sampled randomly at 10-week intervals for 12 months. Phosphorus extractable from the top- and subsoil at the end of experiment and leached P were determined. More P was leached out from TSP (threefold) compared to GPR, and the amount of P leached increased with increasing rates of P fertilizer applied. Application of manure intensified the amounts of P leached from TSP, particularly at the 6-month sampling time. There was hardly any substantial P leached from the soil treated with GPR. Thus, for effective and efficient long-term P fertilizer management strategies, choosing the right P fertilizer source and monitoring P losses through leaching has to be done for enhanced fertilizer use efficiency and thus reducing P pollution of ground waters.
Gikonyo
Esther W
EW
Kenya Agricultural Research Institute, Kabete, Nairobi, Kenya. estgikonyo@yahoo.com
Zaharah
Abdul R
AR
Hanafi
Mohamed M
MM
Anuar
Rahim A
RA
D000818:Animals; D011756:Diphosphates / Q000378:metabolism*; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods; D005308:Fertilizers; D006863:Hydrogen-Ion Concentration; D008372:Manure / Q000032:analysis; D010710:Phosphates / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D063245:Plant Development; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis
D011756:Diphosphates; D005308:Fertilizers; D008372:Manure; D010710:Phosphates; D012987:Soil; D012989:Soil Pollutants; D010758:Phosphorus; C033414:superphosphate