Pendugaan Erosi menggunakan Metode Universal Soil Loss Equation (USLE) di Perkebunan Kelapa Sawit

Abstract

Erosi tanah merupakan ancaman serius terhadap keberlanjutan perkebunan, terutama pada areal berlereng dengan curah hujan tinggi. Penelitian ini bertujuan menduga laju erosi dan mengklasifikasikan tingkat bahaya erosi (TBE) berdasarkan Permenhut No. P.32/Menhut-II/2009 di Blok H16 (34 ha, 7 unit lahan, 7 titik sampel) dan Blok H17 (17 ha, 4 unit lahan, 5 titik sampel) Pundu Nabatindo Estate, Kabupaten Kotawaringin Timur, Kalimantan Tengah. Penelitian dilaksanakan Desember 2025 hingga Februari 2026. Pendugaan erosi menggunakan persamaan Universal Soil Loss Equation. Erosivitas hujan (R) dihitung dari data curah hujan 10 tahun (2015-2024) menggunakan persamaan Lenvain (1975), erodibilitas tanah (K) dari nomograf Wischmeier dan Smith (1978), faktor panjang dan kemiringan lereng (LS) dihitung menggunakan persamaan Wischmeier dan Smith (1978), C berdasarkan persentase penutupan lahan, dan P mengacu pada tabel nilai P Arsyad (2010). Nilai R sebesar 2.329,15 MJ cm/ha/jam/tahun berlaku seragam. Nilai K berkisar 0,11–0,20 (H16) dan 0,10–0,19 (H17); LS berkisar 0,43–14,91 (H16) dan 0,64–3,77 (H17); C ditetapkan 0,048; dan P ditetapkan sebesar 1,0. Nilai erosi berkisar 9,39–178,67 ton/ha/tahun (H16) dan 11,64–55,46 ton/ha/tahun (H17). Berdasarkan klasifikasi TBE dengan kedalaman solum sedang (60–70 cm), lokasi penelitian di Blok H16 memiliki titik dengan TBE Ringan sebanyak 1 titik, Sedang 2 titik, dan Berat 4 titik; Blok H17 memiliki titik dengan TBE Ringan sebanyak 1 titik dan Sedang 4 titik.

Soil erosion is a serious threat to the sustainability of plantations, particularly in sloping areas with high rainfall. This study aimed to estimate soil erosion rates and classify the erosion hazard level (EHL) based on Minister of Forestry Regulation No. P.32/Menhut-II/2009 in Blocks H16 (34 ha, 7 land units, 7 sampling points) and H17 (17 ha, 4 land units, 5 sampling points) of Pundu Nabatindo Estate, East Kotawaringin Regency, Central Kalimantan. The study was conducted from December 2025 to February 2026. Soil erosion was estimated using the Universal Soil Loss Equation. Rainfall erosivity (R) was calculated from 10 years of rainfall data (2015–2024) using the Lenvain (1975) equation, soil erodibility (K) was determined using the Wischmeier and Smith (1978) nomograph, the slope length and steepness factor (LS) was calculated using the Wischmeier and Smith (1978) equation, the cover-management factor (C) was determined based on the percentage of land cover, and the support practice factor (P) was based on the P-factor values provided by Arsyad (2010). The R value of 2,329.15 MJ cm/ha/hour/year was applied uniformly across the study area. The K values ranged from 0.11–0.20 in H16 and 0.10–0.19 in H17; LS values ranged from 0.43–14.91 in H16 and 0.643.77 in H17; C was set at 0.048; and P was set at 1.0. Estimated soil erosion rates ranged from 9.39–178.67 tons/ha/year in H16 and 11.64–55.46 tons/ha/year in H17. Based on the EHL classification using a moderate soil solum depth (60–70 cm), Block H16 consisted of 1 sampling point classified as Light EHL, 2 as Moderate EHL, and 4 as Heavy EHL, while Block H17 consisted of 1 sampling point classified as Light EHL and 4 as Moderate EHL.