Teknik Penetapan Kebutuhan Air Bagi Tanaman Melalui Pengukuran Sifat Dielektrik Tanah

Hermawan, Bandi (2016) Teknik Penetapan Kebutuhan Air Bagi Tanaman Melalui Pengukuran Sifat Dielektrik Tanah. In: SEMIRATA BKS PTN WILAYAH BARAT BDANG PERTANIAN, 4-6 Agustus 2016, Universitas Malikussaleh.

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Abstract

Crop water use is usually determined by measuring the rate of evapotranspiration directly using the lysimeter or indirectly by calculating several climate variables. This research aimed to develop a technique for predicting changes in soil water content by measuring an insitu soil dielectrical property and used them to calculate the use of water by palm oil nursery in the polybags. Coarse-textured (loamy sand) and medium-textured soils (sandy loam) were treated with six manure doses (equaled to 0, 2,4,6,8 and 10 ton.ha-1), with three replicates respectively, therefore there were 36 polybags used in this study. The soil electrical property was presented by the electrical impedance (Z) and measured using instrument designed to transfer the electrical current at 1 kHz in frequency through a couple of wire inserted into the soil. The Z values (in kΩ) were measured every day to evaluate daily changes in soil water content at the planting media of palm oil nursery. Rainfall and added irrigation water were recorded as components in calculating water use by crops. Values of soil water content (θ, in g.g-1) were converted from Z values using a nonlinear regression model of θ = a.ebZ, where a and b were constants and determined by running a series of Z and gravimetrically θ measurements in the laboratory. Results showed that the proposed technique of predicting soil water content was able to calculate the water use by palm oil nursery accurately. Differences in soil water content among texture and manure treatments were also detected by this technique. Keywords: electrical impedance, palm oil, predicting model, soil water. Jumlah air yang dibutuhkan tanaman biasanya ditetapkan dengan mengukur laju evapotranspirasi tanaman secara langsung menggunakan lysimeter atau melalui penghitungan menggunakan beberapa variabel iklim. Penelitian ini bertujuan mendapatkan teknik pendugaan perubahan kadar air tanah melalui pengukuran sifat dielektrik tanah secara insitu untuk menghitung kebutuhan air bagi bibit kelapa sawit dalam polibag. Tanah dalam polibag dibedakan atas dua jenis tekstur (pasir berlempung dan lempung berpasir), enam dosis pupuk kandang (setara 0, 2, 4, 6, 8, 10 ton/ha) dan diulang tiga kali sehingga diperoleh 36 polibag. Sifat dielektrik tanah diwakili nilai impedensi listrik (Z) dan diukur menggunakan instrumen yang dirancang untuk mengalirkan listrik pada frekuensi 1 kHz melalui sepasang kabel yang diletakkan di dalam tanah. Nilai Z (satuan kΩ) diukur setiap hari untuk mengetahui perubahan kadar air tanah harian pada media tanam bibit kelapa sawit. Curah hujan dan jumlah air yang disiramkan dicatat sebagai komponen dalam penghitungan kebutuhan air bagi tanaman. Nilai kadar air tanah (θ, satuan g.g-1) diperoleh dengan mengkonversi nilai Z menggunakan sebuah model persamaan regresi non-linear θ = a.ebZ, dimana konstanta a dan b ditetapkan di laboratorium melalui serangkaian pengukuran Z pada sampel dengan tekstur. Hasil penelitian menunjukkan bahwa teknik yang digunakan mampu menghitung kebutuhan air bagi bibit kelapa sawit secara cepat selama dua bulan masa pertumbuhan dalam polibag. Perbedaan jumlah air yang dibutuhkan pada perlakuan tekstur dan dosis pupuk kandang juga terdeteksi dengan baik melalui teknik yang dikembangkan. Kata kunci: air tanah, impedensi listrik, kelapa sawit, model pendugaan.

Item Type: Conference or Workshop Item (Paper)
Uncontrolled Keywords: electrical impedance, palm oil, predicting model, soil water
Subjects: S Agriculture > S Agriculture (General)
Divisions: Faculty of Agriculture > Department of Soil Science
Depositing User: Mr. Bandi Hermawan
Date Deposited: 25 Jun 2020 06:25
Last Modified: 25 Jun 2020 06:25
URI: http://repository.unib.ac.id/id/eprint/21281

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