The Application of Fourier Transform Infrared Photoacoustics Spectroscopy (FTIR-PAS) for Rapid Soil Quality Evaluation
Authors: Ichwana Ichwana , Nasution Zulkifli , Munawar Agus Arip 
Published: May 2020

Abstrak. Tanah merupakan media tumbuh tanaman dan berperan dalam menjaga keseimbangan alam. Evaluasi kualitas dan kesuburan tanah menjadi hal penting dan merupakan pekerjaan rutin pada crop management system. Untuk memonitor dan menentukan kualitas tanah, beberapa metode telah diterapkan. Akan tetapi, metode tersebut berbasis pengukuran laboratorium yang melibatkan bahan kimia, memerlukan waktu yang lama dan kurang efektif pada aplikasinya. Infrared spectroscopy muncul sebagai salah satu teknologi yang cepat, simultan dan ramah lingkungan untuk digunakan dalam evaluasi kualitas dan kesuburan tanah dengan memprediksi nutrisi tanah yang utama berupa C, N, P dan K. Spektrum transmisi infrared (IR) diakuisisi pada panjang gelombang 1000-2500 nm dengan menerapkan metode photo-acoustic spectroscopy (PAS). Pendekatan metode Least square-support vector machine regression (LS-SVM) digunakan untuk memprediksi parameter nutrisi tanah. Hasil studi menemukan bahwa parameter C dan N pada tanah dapat diprediksi dengan sempurna karena C-N mengalami stretching akibat serapan gelombang IR. Sedangkan unsur nutrisi lain seperti P, K, Mg, Ca, S dapat diprediksi dengan maksimum residual predictive deviation (RPD) index maksimum 1.9. Lebih lanjut, lempung tanah, air tanah, dan mikroba tanah kemungkinan dapat diklasifikasi dengan baik dengan metode IR-PAS dan bantuan metode klasifikasi least-square discriminant analysis (LS-DA) dan cluster analysis (CA). Berdasarkan hasil studi, dapat disimpulkan bahwa teknologi FTIR-PAS dapat digunakan untuk real-time monitoring kualitas dan kesuburan tanah. The Application of Fourier Transform Infrared Photoacoustics Spectroscopy (FTIR-PAS) for Rapid Soil Quality Evaluation Abstract. The major function of soil is to provide fundamental natural resources for survival of plants, animals, and the human race. Soil functions depend on the balances of its structure and composition, well as the chemical, biological, and physical properties. It is become one important key aspect and routine activity in crop management system. To monitor and determine soil quality properties, several methods were already widely used in which most of them are based on solvent extraction followed by other laboratory procedures. However, these methods often require laborious and complicated processing for samples. They are time consuming and destructive. In last few decades, the application of infrared spectroscopy as non-destructive technique in determining soil quality properties (C, N, P and K) rapidly and simultaneously. Fourier transform infrared spectrum (FTIR) were acquired in wavelength range from 1000 to 2500 nm with applying photo-acoustic spectroscopy (PAS). Least square-support vector machine regression (LS-SVM) approach was then applied to predict soil quality properties. The results showed that C and N can be predicted accurately using FTIR-PAS whilst other parameters (P, K, Mg, Ca, S) can be predicted with maximum RPD index is 1.9. Moreover, soil clay, moisture and soil microbes were feasible to be detected by using FTIR-PAS combining with discriminant analysis (LS-DA) or cluster analysis (CA). It may conclude that FTIR-PAS technology can be used as a real time method  in monitoring soil quality and fertility properties.