Perencanaan usahatani sayuran berkelanjutan berbasis kentang di DAS Siulak, kabupaten Kerinci, Jambi

Abstract

Established agricultural practices in upland vegetable growing areas in Indonesia are generally implementing up and down the slope cultivation with relatively high rates of fertilizers and pesticides applications. Combined with high rainfall intensity, these practices have contributed to high runoff and severe erosion and in turn gradually decreased land productivity and farmers income, thus unsustainable farming systems. The objectives of this research were : 1) to identify and describe existing conditions of the potato based vegetable farming systems, 2) to study soil conservation measures alternatives to control soil erosion and obtain optimal net farm income, and 3) to design potato based sustainable vegetable farming systems in Siulak Watershed, Kerinci District, Jambi Province. Land biophysical and farmers characteristics as well as agrotechnologies were identified through soil survey and farmers interview, while alternatives of soil conservation measures were studied through soil erosion plot experiments. Models of patato based sustainable vegetable farming system were formulated by simulation using Universal of Soil Loss Equation (USLE) model and multiple goal programming. Results of the research showed that up and down the slope vegetable farming practices and inadequate of soil conservation practices caused soil erosion rate of 39.25 - 229.14 ton/ha/year which was higher than the local soil tolerable loss (24.09 - 20.89 ton/ha/year), and net farm income was generally not enough to support life worthed living (Rp 28 000 000/year). Planting on ridges across the slope, or ridges constructed 15 degrees across the slope, or in ridges down the slope with a mound constructed across the slope in each 4.5 m distance and silt-pit, can be considered as alternatives soil conservation methods for vegetable farming systems. Potato based sustainable vegetable farming systems in Siulak Watershed could be accomplished by improving the cultivation practices by integrating the soil conservation methods (planting on ridges across the slope and mulch, or ridges down the slope with a mound constructed across the slope, mulch and silt-pit) into the existing systems. Potato based sustainable vegetable farming systems with the cropping pattern of potato-cabbage-tomato and recommended agrotechnologies performed the most optimum models in Siulak Watershed, Kerinci District, Jambi; this system generated soil erosion about 10.59 - 18.82 ton/ha/year and the net farm income about Rp 40 714 558 - Rp 52 745 652 per hectar per year on 0.44 ha farm area. Some farmers in Siulak Watershed have started applicating the recommended agrotechnologies right after the research was completed.

Hulu DAS Merao di Kabupaten Kerinci berada di dataran tinggi vulkan Gunung Kerinci dan sebagian dari hulu DAS Merao merupakan hutan kawasan lindung Taman Nasional Kerinci Sebelat (TNKS). Ketergantungan masyarakat di hulu DAS terhadap lahan cukup tinggi karena usaha pertanian merupakan sumber utama pendapatan sebagian besar masyarakat, terutama dari usahatani sayuran dataran tinggi. Pengelolaan lahan umumnya dengan agroteknologi yang tidak sesuai dengan karakteristik tanah dan kebutuhan tanaman. Daerah aliran sungai (DAS) Siulak di hulu DAS Merao merupakan salah satu sentra produksi sayuran dataran tinggi (terutama kentang) di Kabupaten Kerinci dan petani menanam sayuran tersebut dengan guludan searah lereng. Hal ini akan meningkatkan erosi dan mempercepat degradasi lahan akibat penurunan kualitas tanah dan pada gilirannya menyebabkan lahan kritis, terganggunya fungsi hidrologis DAS dan usahatani tidak berkelanjutan. Kajian mengenai usahatani konservasi untuk membangun model usahatani sayuran berkelanjutan berbasis kentang merupakan suatu langkah strategis, penting dan perlu segera dilakukan di DAS Siulak. Usahatani tersebut sekaligus sebagai upaya mengatasi perambahan dan alih fungsi hutan, mengembangkan potensi lahan dan wilayah sebagai sentra produksi sayuran terutama kentang, serta menekan dampak usahatani di DAS Siulak terhadap fungsi hidrologis DAS dan fungsi Danau Kerinci. Alternatif model usahatani sayuran berkelanjutan berbasis kentang di DAS Siulak adalah model usahatani sayuran berbasis kentang yang harus memenuhi kebutuhan hidup layak (KHL) petani, sekaligus mengendalikan erosi hingga lebih kecil atau sama dengan erosi yang dapat ditoleransikan (Etol) melalui penerapan agroteknologi spesifik lokasi, sehingga dapat diterima dan dikembangkan petani sesuai dengan sumberdaya yang dimiliki. Teknik konservasi tanah yang diintegrasikan di dalam model usahatani sayuran berbasis kentang di DAS Siulak dikaji melalui percobaan erosi petak kecil. Oleh karena itu penelitian bertujuan untuk : 1) mengkaji dan mendeskripsikan kondisi existing usahatani di DAS Siulak, 2) mengkaji alternatif teknik konservasi tanah yang dapat mengendalikan erosi dan memberikan produktivitas sayuran yang optimal di DAS Siulak, dan 3) merancang model usahatani sayuran berkelanjutan berbasis kentang di DAS Siulak.