Guérin Julie, Parent Léon-Etienne, Abdelhafid Rahima
Department of Soils and Agri-Food Engineering, Université Laval, Québec, QC, Canada G1K 7P4.
J Environ Qual. 2007 May 25;36(4):975-82. doi: 10.2134/jeq2006.0424. Print 2007 Jul-Aug.
The P concentration in Norton Creek which drains cultivated Histosols in Quebec showed median concentration exceeding up to 14 times the environmental guideline of 0.03 mg total P L(-1). The aim of this study was to develop environmental and agronomic thresholds using soil tests to provide a tool for P management in Histosols. Soil samples were collected from Histosols across Quebec (82) and in fertilizer trials (66) to calibrate soil test methods against the degree of P saturation (DPS(OX)) using the acid-oxalate method and setting alpha(m) = 0.4, and the water-extractable P (P(W)) (Sissingh, 1971). The field trials on crop response to added P were conducted with carrots (8), potatoes (11), onions (10), Chinese cabbage (7), celery (10), and lettuce (20). Relative yields were computed as yield in control without P divided by highest yield with added P. The Mehlich III (M-III) P extraction was more closely related (r(2) = 0.73) to DPS(OX) than the Bray 1 method (r(2) = 0.62) and the Florida extraction method (r(2) = 0.53). The P/(Al+gammaFe) ratio as index of P saturation (IPS(M-III)) was the most closely related to DPS(OX) (r(2) = 0.88) setting gamma = 5. The critical P/(Al+5Fe) ratio of 0.05 at DPS(OX) = 0.25 and P(W) = 9.7 mg P L(-1) was validated by an independent study from North Carolina. The soil group (low- vs. high-IPS(M-III) soils) significantly influenced crop response to added P. Critical agronomic IPS(M-III) values were found between 0.10 and 0.15. Those environmental and agronomic benchmarks are instrumental for managing the P in vegetable-grown Histosols.
流经魁北克耕种有机土的诺顿溪中的磷浓度显示，其平均浓度超过环境指导值0.03毫克总磷/升达14倍之多。本研究的目的是利用土壤测试制定环境和农艺阈值，为有机土的磷管理提供工具。从魁北克各地的有机土（82个）以及肥料试验田（66个）采集土壤样本，采用酸-草酸盐法并设定α(m)=0.4，针对磷饱和度（DPS(OX)）以及水提取磷（P(W)）（西辛赫，1971年）校准土壤测试方法。对胡萝卜（8个试验）、土豆（11个试验）、洋葱（10个试验）、大白菜（7个试验）、芹菜（10个试验）和生菜（20个试验）进行了添加磷对作物响应的田间试验。相对产量计算为不施磷对照区的产量除以施磷最高产量区的产量。与布雷1法（r(2)=0.62）和佛罗里达提取法（r(2)=0.53）相比，Mehlich III（M-III）磷提取法与DPS(OX)的相关性更强（r(2)=0.73）。以P/(Al+γFe)比值作为磷饱和度指标（IPS(M-III)）与DPS(OX)的相关性最为紧密（r(2)=0.88），设定γ=5。来自北卡罗来纳州的一项独立研究验证了在DPS(OX)=0.25且P(W)=9.7毫克磷/升时，临界P/(Al+5Fe)比值为0.05。土壤组（低IPS(M-III)土壤与高IPS(M-III)土壤）对施磷作物响应有显著影响。临界农艺IPS(M-III)值在0.10至0.15之间。这些环境和农艺基准有助于管理种植蔬菜的有机土中的磷。
