Pengembangan usahatani lahan kering berkelanjutan berbasis tembakau di sub-DAS Progo Hulu (kabupaten Temanggung propinsi Jawa Tengah)

Abstract

Due to inadequate soil and water conservation practices in farming activity at tobacco based farming systems, severe erosion and land degradation had been occuring in almost all upland agriculture in Progo Hulu Sub-watershed. This research was conducted : (1) to study land’s biophysic conditions and the characteristics of tobacco based farming systems, (2) to study and analyze the impact of various soil and water conservation practices on erosion, (3) to study and design sustainable conservation farming systems in tobacco based farming systems. The results showed that land use in tobacco-based farming systems at Progo-Hulu sub-watershed was generally (58.4%) suitable to its land capability and only 41.6% were not suitable. The predicted erosion on approximately 77.2% of lands were higher than local tollerable soil loss which need improvement of soil and water conservation techniques. Tobacco based farming systems was dominated by maize-tobacco (51.0%) and chili-tobacco (29.2%) cropping patterns; farmers income on this farming systems were higher than the income that can support worthed life living standard. The application of crop residue (tobacco stems) as mulch with rate of 7 ton/ha and 14 ton/ha combined with grassed bench terraces ((Setaria spacelata) controled erosion as much as 15-19% and 31-43%, respectively. Meanwhile, red bean-tobacco intercropping combined with crop residue mulch with the rate of 7 ton/ha suppressed erosion 13-20%. Sustainable tobacco-based farming systems can be developed in this area by practicing improved soil and water conservation technology with: (a) setaria grass to strengthen terraces + 7 ton/ha of crop residue mulch (RA-2) or red bean and tobacco intercropping + 7 ton/ha of crop residue mulch (RA-4) on 8-15% slope; (b) broadbase terraces + adequate slit pit (RA-5) on 15-30% slope; and (c) setaria grass to strengthen broadbase terraces + 14 ton/ha of crop residue mulch + adequate slit pit (R6) on >30% slope.

Fenomena kerusakan sumberdaya lahan atau degradasi lahan akibat erosi di daerah hulu DAS di Indonesia terus meningkat. Fenomena ini juga terjadi di Sub-DAS Progo Hulu, yang digunakan untuk usahatani lahan kering berbasis tembakau (UTLKBT). Akibat dari teknik budidaya yang kurang mengindahkan kaidah konservasi tanah dan air, pada kemiringan berbukit dan curam, serta curah hujan yang tinggi pada UTLKBT di Sub-DAS Progo Hulu telah menyebabkan terjadinya : (1) erosi yang parah, dan (2) degradasi lahan. Apabila dibiarkan atau tidak segera diperbaiki agroteknologinya, lahan yang telah mengalami proses degradasi tersebut akan menjadi tambah rusak, dan akhirnya menjadi lahan kritis dan mengancam keberlanjutan sistem UTLKBT di Sub-DAS Progo Hulu. Perencanaan sistem pertanian konservasi (SPK) yang komprehensif sangat diperlukan untuk mewujudkan UTLKBT berkelanjutan di Sub-DAS Progo Hulu. Oleh karena itu penelitian ini bertujuan : (1) mengkaji kondisi biofisik lahan dan karakteristik usahatani lahan kering berbasis tembakau di Sub-DAS Progo hulu; (2) mengkaji pengaruh teknologi konservasi tanah dan air (KTA) spesifik lokasi terhadap limpasan permukaan dan erosi; dan (3) merumuskan perencanaan sistem pertanian konservasi untuk mewujudkan sistem UTLK berkelanjutan berbasis tembakau di Sub-DAS Progo Hulu.