Alleoni Luis R F, Brinton Scott R, O'Connor George A
Soil Science Dep., P.O. Box 09, University of Sao Paulo, Piracicaba, SP, Brazil 13418-900.
J Environ Qual. 2008 Jan 4;37(1):259-65. doi: 10.2134/jeq2006.0302. Print 2008 Jan-Feb.
Florida Spodosols are sandy, inherently low in Fe- and Al-based minerals, and sorb phosphorus (P) poorly. We evaluated runoff and leachate P losses from a typical Florida Spodosol amended with biosolids and triple superphosphate (TSP). Phosphorus losses were evaluated with traditional indoor rainfall simulations but used a double-deck box arrangement that allowed leaching and runoff to be determined simultaneously. Biosolids (Lakeland, OCUD, Milorganite, and Disney) represented contrasting values of total P, percent water-extractable P (PWEP), and percentage of solids. All P sources were surface applied at 224 kg P ha(-1), representing a soil P rate typical of N-based biosolids application. All biosolids-P sources lost less P than TSP, and leachate-P losses generally dominated. For Lakeland-amended soil, bioavailable P (BAP) was mainly lost by runoff (81% of total BAP losses). This behavior was due to surface sealing and drying after application of the slurry (31 g kg(-1) solids) material. For all other P sources, BAP losses in leachate were much greater than in runoff, representing 94% of total BAP losses for TSP, 80% for Milorganite, 72% for Disney, and 69% for OCUD treatments. Phosphorus leaching can be extreme and represents a great concern in many coarse-textured Florida Spodosols and other coastal plain soils with low P-sorption capacities. The PWEP values of P sources were significantly correlated with total P and BAP losses in runoff and leachate. The PWEP of a source can serve as a good indicator of potential P loss when amended to sandy soils with low P-retention capacities.
佛罗里达灰化土质地 sandy，原生铁铝基矿物含量低，对磷（P）的吸附能力差。我们评估了用生物固体和重过磷酸钙（TSP）改良的典型佛罗里达灰化土的径流和渗滤液中磷的损失。采用传统室内降雨模拟评估磷损失，但使用双层箱式装置同时测定淋溶和径流。生物固体（莱克兰、OCUD、米洛加尼特和迪士尼）代表了总磷、水溶磷百分比（PWEP）和固体百分比的不同值。所有磷源均以 224 kg P ha(-1) 的用量进行地表施用，这代表了基于氮的生物固体施用时典型的土壤磷施用量。所有生物固体磷源的磷损失均低于 TSP，且渗滤液磷损失通常占主导。对于莱克兰改良土壤，生物可利用磷（BAP）主要通过径流损失（占总 BAP 损失的 81%）。这种情况是由于施用泥浆（31 g kg(-1) 固体）材料后表面密封和干燥所致。对于所有其他磷源，渗滤液中 BAP 的损失远大于径流中的损失，分别占 TSP 总 BAP 损失的 94%、米洛加尼特的 80%、迪士尼的 72%和 OCUD 处理的 69%。磷淋溶可能非常严重，这在许多质地粗糙、磷吸附能力低的佛罗里达灰化土和其他沿海平原土壤中是一个重大问题。磷源的 PWEP 值与径流和渗滤液中总磷和 BAP 的损失显著相关。当将磷源施用于磷保留能力低的 sandy 土壤时，其 PWEP 可作为潜在磷损失的良好指标。
