faiz barchia

STABILITAS Ca, Mg, KTK TANAH DAN HASIL SAWIT PADA
LAHAN BERLERENG DI BENGKULU

Oleh
Muhammad Faiz Barchia

Abstract

The aim of this research to know stability of soil Ca, Mg, CEC, and yield of oil palm planted on acid mineral soil in Bengkulu with different slopping lands. The research was conducted on an oil palm estate in Putri Hijau, Bengkulu on September to December 2005. The estate lies on 75 m above sea level with rain of 3.027 mm yr-1, and physiographic of waving to hilly topographic, 0 – 45%. Area of the research was used 350 Ha.
Yield of oil palm was quite related to land slops in which fruit bunch weight (FBW) of the oil palm decreased with increase the land slops following linear equation; FBW = - 0.4279 (L) + 25.156 ; R2 = 0.8264. Soil Ca were stable in slopping land of 0 – 15% as next equation Soil-Ca = - 0.02 (L) + 2.9302; R2 = 0.1577; however, the soil Ca stability decreased with slops over 15% as equation, soil-Ca = - 0.1098 (L) + 7.3847; R2 = 0.8122. Likes soil-Ca, stability of soil Mg was high on the slops 0 – 15% as follow; soil-Mg = 0.0002 (L) + 0.3328; R2 = 0.001, but decreased in the soil with slops > 15%; following equation, soil-Mg = 0.0134 (L) + 0.9059; R2 = 0.7231. Stability of soil CEC relatively low on the slops of 0 -15%, likes follow; soil-CEC = - 0.0965 (L) + 5.1258; R2 = 0.3231, and unstable in the soil with slops of > 15%, as a next equation, soil-CEC = - 0.1193 (L) + 9.3062; R2 = 0.8805. The stabilities of plant nutrients in the soil with different slops affected level of oil palm yields in which on the slops of 0 – 8%, the FBW was means of 23.3 tons ha-1, relatively equal to yields of the FBW on >8 – 15% slops, namely about 22.4 tons ha-1; however, the FBW decreased sharply on the slops of > 15 – 30% with weight of 14.3 tons ha-1, oil palm productivity went down significantly on slops of .>30%, 9.8 tons ha-1. Expansion of oil palm estates on slopping lands with acid mineral soils should be based on conservation methods following environment view points.


Penelitian ini bertujuan untuk mengetahui stabilitas Ca, Mg, KTK tanah dan hasil kelapa sawit pada lahan berlereng di tanah mineral masam Bengkulu. Penelitian ini telah dilaksanakan di salah satu perkebunan kelapa sawit dalam wilayah Kecamatan Putri Hijau, Kabupaten Bengkulu Utara dari bulan September-Desember 2005. Lokasi penelitian terletak pada ketinggian sekitar 75 m dpl, topografi bergelombang sampai dengan berbukit, 0-45%, curah hujan rata-rata 3.027 mm tahun-1. Luas lahan penelitian 350 Ha.
Hasil sawit sangat ditentukan oleh kemiringan lereng dimana berat tandan buah segar menurun dengan semakin meningkatnya kelerengan dengan persamaan linear TBS = - 0.4279 (L) + 25.156 ; R2 = 0.8264. Ca tanah relatif stabil pada kelerengan 0 – 15% seperti persamaan Ca Tanah = - 0.02 (L) + 2.9302 ; R2 = 0.1577, tetapi kestabilannya sangat menurun pada lereng > 15% seperti persamaan Ca Tanah = - 0.1098 (L) + 7.3847; R2 = 0.8122. Juga stabilitas Mg tanah sangat tinggi pada kelerengan 0 – 15% seperti persamaan Mg Tanah = 0.0002 (L) + 0.3328; R2 = 0.001, dan menurun pada kemiringan > 15% seperti persamaan Mg Tanah = 0.0134 (L) + 0.9059; R2 = 0.7231. Stabilitas KTK tanah kurang stabil pada lereng 0 -15% seperti persamaan KTK Tanah = - 0.0965 (L) + 5.1258; R2 = 0.3231 pada lereng 0 – 15%, dan menurun tajam kestabilannya pada kelerengan > 15% seperti persamaan KTK Tanah = - 0.1193 (L) + 9.3062; R2 = 0.8805. Kestabilan hara tanah yang dipengaruhi kelerengan lahan akan menentukan tingkat hasil sawit dimana pada kelerengan 0 – 8%, berat TBS rata-rata 23.3 ton ha-1, dan hampir sama pada kelerengan >8 – 15% yaitu 22.4 ton ha-1, tetapi menurun tajam pada kelerengan > 15 – 30% dengan berat TBS, 14.3 ton ha-1, produktivitas lahan sangat rendah pada kemiringan .>30%, yaitu rata-rata 9.8 ton ha-1. Pengembangan lahan kelapa sawit pada lahan berlereng harus memperhatikan azas konservasi.