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Agri‐environmental Thresholds using Mehlich III Soil Phosphorus Saturation Index for Vegetables in Histosols
Author(s) -
Guérin Julie,
Parent LéonÉtienne,
Abdelhafid Rahima
Publication year - 2007
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2006.0424
Subject(s) - histosol , environmental science , index (typography) , saturation (graph theory) , phosphorus , environmental chemistry , soil science , hydrology (agriculture) , agronomy , soil water , mathematics , soil organic matter , chemistry , geology , geotechnical engineering , biology , soil biodiversity , organic chemistry , combinatorics , world wide web , computer science
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 α 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+γFe)] M‐III ratio as index of P saturation (IPS M‐III ) was the most closely related to DPS OX ( r 2 = 0.88) setting γ = 5. The critical [P/(Al+5Fe)] M‐III 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.