Evaluasi Kesesuaian Lahan Mineral dan Gambut untuk Peremajaan Tanaman Kelapa Sawit (Studi Kasus pada Beberapa Kebun Plasma di Provinsi Riau) - I Gusti Putu Wigena; D. Subardja; Andriati Andriati (Indonesian Center for Agriculture Land Resource Development, 2013)
Abstrak. Kesesuaian lahan sangat berkaitan dengan potensi perkebunan kelapa sawit plasma yang mampu berproduksi secara optimum dan berkelanjutan sehingga sangat diperlukan baik untuk pembangunan kebun baru maupun peremajaan (replanting). Untuk itu, dilakukan penelusuran kegiatan karakterisasi lahan mineral dan gambut serta evaluasi kesesuaiannya untuk peremajaan tanaman yang sudah tidak produktif di beberapa kebun plasma selama periode 3 tahun dari 2007-2009. Semua kebun bermitra dengan PTPN 5 yaitu kebun plasma Sei Pagar Kabupaten Kampar Kiri dengan agroekosistem gambut dangkal (<300 cm), Sei Galuh Kabupaten Kampar Kanan dengan agroekosistem gambut dalam (500-1200 cm), dan Sei Tapung Kabupaten Rokan Hulu dengan agroekosistem tanah mineral kering masam, Provinsi Riau. Gambut dangkal mendominasi kebun kelapa sawit plasma di Sei Pagar, memiliki kelas kesesuaian lahan cukup sesuai (S2), pembatas retensi unsur hara (nr) dengan produktivitas rata-rata > 24 t tbs ha-1 th-1. Selain itu, ditemui juga lahan berbahan induk alluvial masam bergambut yang memiliki kelas kesesuaian lahan cukup sesuai (S2), pembatas ketersediaan unsur hara rendah dan retensi unsur hara (ns,nr), dengan produktivitas rata-rata >20 t tbs ha-1 th-1. Gambut dalam terdapat di kebun plasma Sei Galuh, memiliki kelas kesesuaian lahan sesuai marginal (S3), pembatas perkembangan perakaran, ketersediaan unsur hara rendah, dan retensi unsur hara (rc,ns,nr) dengan produktivitas rata-rata <12 t tbs ha-1 th-1. Kebun kelapa sawit plasma di Sei Tapung didominasi oleh tanah mineral kering masam dengan topografi datar-berbukit, ada hubungan antara persentase lereng dengan kelas kesesuaian dan produktivitas kelapa sawit. Pada topografi datar (lereng 0-3%), kelas kesesuaian lahan cukup sesuai (S2), pembatas retensi unsur hara (nr), dengan produktivitas rata-rata >20,43 t tbs ha-1 th-1. Pada topografi berombak-bergelombang (lereng 3-8%), kelas kesesuaian lahan cukup sesuai (S2), pembatas retensi unsur hara dan bahaya erosi ringan (nr,eh), dengan produktivitas rata-rata >17,21 t tbs ha-1 th-1. Pada topografi berbukit (lereng>15%), kelas kesesuaian lahan sesuai marginal (S3), pembatas bahaya erosi, perkembangan perakaran, dan retensi unsur hara (eh,rc,nr) dengan produktivitas rata-rata <16,44 t tbs ha-1 th-1.Abstract. Land suitability evaluation has a significant correlation with the potential of smallholder oil palm plantation for optimum and sustainable production so that this activity become a prerequisite for both development of new plantation and replanting. Based on this reason, a review on the charachterization of mineral and peatland and its suitability evaluation for replanting of oil palm plantation on several smallholder oil palm plantation were conducted for the periode of 3 years, from 2007-2009. All plantation are under PTPN 5 partnership collaboration, namely Sei Pagar, Kampar Kiri Regency with shalow peat agroecosystem, Sei Galuh Kampar Kanan Regency with deep peat agroecosystem, and Sei Tapung Rokan Hulu Regency with mineral soil agroecosystem, Riau Province. The plantation areas are in Sei Pagar, dominated by shalow peatlands (<300 cm) with moderate suitability status (S2), and nutrients retention as a constraint (nr) and the average productivity is >24 t fruit bunches ha-1year-1. There is also found acidic clay alluvial as parent materials with moderate suitability status (S2), and root condition and nutrients retention (rc,nr) as constraints, and the average producitivity is >20 t fruit bunches ha-1 year-1. Deep peatlands (500-1200 cm) are located at Sei Galuh with marginal suitability status (S3), and root condition, nutrients supply, and nutrients retention as the constraint (rc, ns,nr), and average productivity <12 t fruit bunches ha-1year-1. Sei Tapung areas are dominated by upland acid mineral soils with plain-highly topography. In this location, and there is a significant correlation between slope degrees and land sutaibility status and oil palm productivity. On the plain topography (slope 0-3%), land suitability is a moderate (S2) and nutrients retention (nr) as constraint with average productivity >20,43 t fruit bunches/ha/year. The lands with undulating-rolling tofographiq (slope degree 3-8%), land suitability status was moderate suitable (S2), nutrients retention and slighty erosion hazard (nr,eh) as the constraints and average productivity is >17,21 t fruit bunches ha-1year-1. On the hilly topography areas (slope >15%), the lands are marginal suitability status (S3) with heavy erosion hazard, root condition, and nutrients retention as constraints, and average oil palm productivity is <16,44 t fruit bunches ha-1year-1.