Rancang Bangun Alat Ukur Portable Berbasis Visual-Near Infrared (VIS-NIR) untuk Prediksi PH Tanah dengan Regresi Partial Least Square (PLS)

Kharisma, Adellia Refi (2026) Rancang Bangun Alat Ukur Portable Berbasis Visual-Near Infrared (VIS-NIR) untuk Prediksi PH Tanah dengan Regresi Partial Least Square (PLS). Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Kesuburan tanah sangat dipengaruhi oleh keseimbangan pH yang berperan penting dalam ketersediaan unsur hara bagi tanaman. Ketidakseimbangan pH dapat menghambat penyerapan hara dan menurunkan produktivitas lahan. Metode pengukuran pH tanah konvensional masih memiliki keterbatasan karena memerlukan kontak langsung dengan tanah serta berpotensi bersifat destruktif. Oleh karena itu, penelitian ini mengembangkan alat ukur pH tanah portabel berbasis spektroskopi Vis–NIR yang bersifat non-destruktif dan tanpa kontak langsung dengan sampel. Sistem dirancang menggunakan LED sebagai sumber cahaya, sensor spektral AS7265x, dan mikrokontroler ESP32 untuk akuisisi data spektral. Pengujian dilakukan pada tiga jenis tanah dengan variasi pH 3–9 yang diperoleh melalui penambahan larutan cuka dan kapur sirih, dengan lima kali pengulangan pada setiap kondisi. Data spektral dianalisis menggunakan metode regresi Partial Least Squares (PLS) untuk membangun model prediksi nilai pH tanah. Hasil penelitian menunjukkan bahwa model PLS menghasilkan nilai koefisien determinasi (R²) sebesar 0,5024 pada data training dan 0,4240 pada data testing seluruh repetisi. Penggunaan nilai rata-rata sampel meningkatkan performa model dengan R² sebesar 0,6544, RMSE sebesar 0,7027 pH, dan MAE sebesar 0,6518 pH. Evaluasi karakteristik statik alat ukur menunjukkan akurasi rata-rata sebesar 96,87%, linearitas sebesar 0,9795, serta rentang pengukuran pH 4,34–8,38 dengan span sebesar 4,04 pH. Hasil ini menunjukkan bahwa alat ukur pH tanah berbasis spektroskopi Vis–NIR mampu memprediksi pH tanah secara non-kontak dengan performa yang baik dan berpotensi diterapkan pada aplikasi pertanian.
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Soil fertility is strongly influenced by pH balance, which plays an important role in nutrient availability for plant growth. pH imbalance can inhibit nutrient uptake and reduce land productivity. Conventional soil pH measurement methods still have limitations because they require direct contact with the soil and may be potentially destructive. Therefore, this study develops a portable soil pH measurement device based on Vis–NIR spectroscopy that is non-destructive and does not require direct contact with the sample. The system is designed using LEDs as the light source, an AS7265x spectral sensor for capturing reflected spectra, and an ESP32 microcontroller for spectral data acquisition. Experiments were conducted on three types of soil with pH variations ranging from 3 to 9, obtained by adding vinegar and lime solutions, with five repetitions for each test condition. The acquired spectral data were analyzed using Partial Least Squares (PLS) regression to build a soil pH prediction model. The results show that the PLS model achieved a coefficient of determination (R²) of 0,5024 on the training data and 0,4240 on the testing data using all repetitions. Using the average values of each sample improved the model performance, yielding an R² of 0,6544, RMSE of 0,7027 pH, and MAE of 0,6518 pH. The evaluation of the static characteristics of the measuring device indicates an average accuracy of 96,87%, linearity of 0,9795, and a measurement range of pH 4,34–8,38 with a span of 4,04 pH units. These results demonstrate that the developed Vis–NIR-based soil pH measurement device is capable of predicting soil pH non-contact with good performance and has potential applications in agriculture.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Soil pH, Vis-NIR Spectroscopy, Partial Least Square, AS7265x, Portable measuring device.
Subjects:	Q Science > QC Physics > QC100.5 Measuring instruments (General) Q Science > QC Physics > QC451 Spectroscopy Q Science > QC Physics > QC457 Infrared technology. T Technology > T Technology (General)
Divisions:	Faculty of Vocational > Instrumentation Engineering
Depositing User:	Adellia Refi Kharisma
Date Deposited:	31 Jul 2026 04:28
Last Modified:	31 Jul 2026 04:28
URI:	http://repository.its.ac.id/id/eprint/140551

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