科研之友
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摘要
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 Quebec, Canada. The estimated exchangeable acidity (EEA) index was computed from the cation exchange capacity determined by the NH4OAc (pH 7.0) method (CEC-NH4OAc) minus the sum of Mehlich-III extractable non-acidic cations. The performance was high for IR-inferred CEC-NH4OAc 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-NH4OAc (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 CaCO3 kg(-1)), the EEA index using CEC-NH4OAc inferred within +/- 2.3 cmolc 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-NH4OAc. The IR spectroscopy can improve routine LR determination at low cost.
- 出版日期2016-4
