Premium
Lime Requirement Using Mehlich‐III Extraction and Infrared‐Inferred Cation Exchange Capacity
Author(s) -
Leblanc Michaël A.,
Parent Élizabeth,
Parent Léon E.
Publication year - 2016
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2015.07.0282
Subject(s) - cation exchange capacity , lime , chemistry , soil water , infrared spectroscopy , soil ph , soil test , environmental chemistry , soil science , analytical chemistry (journal) , environmental science , geology , organic chemistry , paleontology
Core Ideas Exchangeable acidity estimated from bases and CEC was related to lime requirement. CEC of Québec soils was inferred accurately from infrared spectroscopy. Model using CEC inferred within ±2.3 cmol c kg −1 was more accurate than the SMP buffer. Lime requirement (LR) to reach and maintain target soil pH levels could be determined using environmentally friendly methods to avoid buffer solutions containing toxic chemicals. Infrared (IR) spectroscopy can predict soil properties related to soil pH buffering capacity, potentially supporting LR models. The aim of this study was to develop IR‐based LR models across a wide range of soils in Québec, Canada. The estimated exchangeable acidity (EEA) index was computed from the cation exchange capacity determined by the NH 4 OAc (pH 7.0) method (CEC‐NH 4 OAc) minus the sum of Mehlich‐III extractable non‐acidic cations. The performance was high for IR‐inferred CEC‐NH 4 OAc predicted from mid‐infrared (MIR) and near‐infrared (NIR) spectra or computed from quantified organic C and NIR‐ and MIR‐predicted clay content (0.82 ≤ R 2 ≤ 0.91 in validation). The performance in cross‐validation of EEA using quantified CEC‐NH 4 OAc (0.81 ≤ R 2 ≤ 0.89) was higher than Shoemaker–McLean–Pratt (SMP) buffer (0.15 ≤ R 2 ≤ 0.77) for target pH H2O values between 5.5 and 6.5, and similar for a target pH H2O of 7.0. To support LR determination of cropping systems such as potato ( Solanum tuberosum L.) that requires low pH (<6.5) or to maintain adequate pH levels at low LRs (<1.5 g CaCO 3 kg −1 ), the EEA index using CEC‐NH 4 OAc inferred within ±2.3 cmol c kg −1 was found to be more accurate than the SMP buffer. Direct prediction of the EEA‐derived LR using NIR and MIR spectroscopy showed low performance (validation R 2 ≤ 0.48) compared with EEA computed from IR‐inferred CEC‐NH 4 OAc. The IR spectroscopy can improve routine LR determination at low cost.