Model Konservasi Tanah dan Air Berdasarkan Zona Agroekologi di Sub Das Gopgopan-Aek Sikorsikkorsik Kabupaten Toba Samosir

Abstract

Land resources in Gopgopan-AekSikorsikkorsik watershed must be managed properly because of the land condition in the criteria of degraded land. The use of land in Gopgopan –AekSikorsikkorsik watershed is dominated by farming, whereas farming carried out by farmers in this area hasn’t implemented soil and water conservation techniques yet. In Addition Gopgopan-AekSikorsikkorsik watershed which is the catchment area of Lake Toba until now is categorized in critical first priority class to be addressed. Some improvement efforts have been done by the government (through the National Movement of Forest and Land Rehabilitation) and LSM (SCBFWM activities funded by UNDP) however the results haven’t been showed so that another attempt is needed to resolve it. This study aims to: 1) analyze the suitability of the use of land in Gopgopan -AekSikorsikkorsik watershed based on Agroecology zone. 2) analyze the socioeconomic farmers in the Gopgopan –AekSikorsikkorsik watershed. 3) Design a model of soil and water conservation in accordance with the conditions of Gopgopan-AekSikorsikkorsik watershed. 4) Get the model for Soil and Water Conservation in Gopgopan AekSikorsikkorsik watershed. This study used research and experiment methods that consists of five phases. They are: 1) preparation and overlay map (type of soil map, topography, the land elevation and the use of land map), 2) the characteristic of biophysic land and farmers research, 3) land evaluation (the suitability of the use of land and the suitability of land evaluation), 4) designing the model of soil and water conservation, and 5) determining the model of soil and water conservation that is suitable in the region of Gopgopan- Aeksikorsikkorsik watershed. The results of the analysis showed that the Regional Gopgopan-AekSikorsikkorsik watershed, on the basis of physiographic land and the diversity of topography, has 4 agroecology zones named zones I, III, IV,V and it is dominated by zone III. The total area of land that is not in accordance with the directives of use of land is 2280.05 hectares, approximately 29.89% of the total Gopgopan-AekSikorsikkorsik watershed. Erosion hazard index in the Gopgopan-AekSikorsikkorsik watershed is classified as moderate to hazardous level. The characteristics of the farmers in the Gopgopan-AekSikorsikkorsik watershed are: a) the average of minimum land area for living well worth is 2 hectares, b) the dependence on land is classified as high, c) The type of plants cultivated is based on the simplicity of cultivation and market demand. Five model designs of Soil and Water conservation models are retrieved. a) Soil and Water Conservation Techniques with ridges, beds across the slopes with intercropping and crop rotation, with plant species I (Beans and Tomatoes) and V (Corn, paddy and cassava) + III (sweet potato, potato, turmeric, and ginger) and IV (Onion, red beans, peanuts and carrots) or V (Corn , paddy and cassava) + II (Chili, Eggplant). b) Soil and Water Conservation Techniques with bench terraces, beds across the slope with intercropping and crop rotation with the crop type, with plant species I (Beans and Tomatoes) and V (Corn, paddy and cassava) + III (sweet potato, potato, turmeric, and ginger) and IV (Onion, red beans, peanuts and carrots) or V (Corn , paddy and cassava) + II (Chili, Eggplant) . c) Soil and Water Conservation Techniques with Bench terraces+ mulch, with intercropping and crop rotation, with plant species I (Beans and Tomatoes) and V (Corn, paddy and cassava) + III (sweet potato, potato, turmeric, and ginger) and IV (Onion, red beans, peanuts and carrots) or V (Corn , paddy and cassava) + II (Chili, Eggplant) . d) Soil and Water Conservation Techniques with ridge terraces, beds across the slope with intercropping and crop rotation, with plant species I (Beans and Tomatoes) and V (Corn, paddy and cassava) + III (sweet potato, potato, turmeric, and ginger) and IV (Onion, red beans, peanuts and carrots) or V (Corn , paddy and cassava) + II (Chili, Eggplant). e) Soil and Water Conservation Techniques with bench terraces, ridge terraces + mulch, beds across the slope with intercropping and crop rotation with the crop type, with plant species I (Beans and Tomatoes) and V (Corn, paddy and cassava) + III (sweet potato, potato, turmeric, and ginger) and IV (Onion, red beans, peanuts and carrots) or V (Corn , paddy and cassava) + II (Chili, Eggplant). AHP is used in the Results of this analysis. The models of soil and water conservation techniques chosen are c and e models. e Model can technically be used on the land with a slope of 15-25% and c model can be used on the land with a slope of 8-15% in Gopgopan-Aek Sikorsikkorsik watershed.

Sumberdaya lahan di Sub DAS Gopgopan-Aek Sikorsikkorsik harus dikelola dengan tepat, karena kondisi lahannya termasuk pada kriteria lahan kritis. Penggunaan lahan di Sub DAS Gopgopan-Aek Sikorsikkorsik didominasi oleh perladangan, sedangkan usahatani yang dilaksanakan petani di kawasan ini belum menerapkan teknik konservasi tanah dan air. Selain itu Sub DAS Gopgopan-Aek Sikorsikkorsik yang merupakan daerah tangkapan air Danau Toba sampai saat ini dikategorikan prioritas dipulihkan daya dukungya. Beberapa upaya perbaikan telah dilakukan oleh pemerintah (melalui Gerakan Nasional Rehabilitasi Hutan dan Lahan) namun belum menujukkan hasil. Sehinga perlu upaya lain untuk mengatasinya. Penelitian ini bertujuan untuk : 1) Menganalisis kesesuaian Penggunaan lahan di Sub DAS Gopgopan-Aek Sikorsikkorsik berdasarkan Zona Agroekologi. 2) Menganalisis sosial ekonomi petani di kawasan Sub DAS Gopgopan-Aek Sikorsikkorsik. 3) Merancang model konservasi tanah dan air yang sesuai dengan kondisi Sub DAS Gopgopan-Aek Sikorsikkorsik. 4) Memperoleh model konservasi Tanah dan Air di Sub DAS Gopgopan-Aek Sikorsikkorsik. Penelitian ini menggunakan metode survei dan eksperimen yang terdiri dari 4 tahap yaitu 1) persiapan dan overlay peta (peta jenis tanah, topografi, ketinggian tempat dan peta penggunaan lahan), 2) survey karakteristik biofisik lahan dan karakteristik petani dan evaluasi lahan (evaluasi kesesuian penggunaan lahan dan evaluasi kesesuian lahan untuk komoditas yang dikembangkan), 3) merancang model konservasi tanah dan air, dan 4) menentukan model konservasi tanah dan air yang sesuai di kawasan Sub DAS Gopgopan-Aek Sikorsikkorsik. Hasil penelitian menujukkan bahwa Wilayah Sub DAS Gopgopan-Aek Sikorsikkorsik, atas dasar fisiografi lahan pada keragaman kelerengan terdapat 4 zona Agroekologi yaitu I, III, IV, V dan didominasi oleh zona IV. Total luas lahan yang tidak sesuai dengan arahan penggunaan lahannya adalah 2280,05 ha sekitar 29,89 % dari luas Sub DAS Gopgopan-Aek Sikorsikkorsik. Indeks bahaya erosi di sub DAS Gopgopan tergolong sedang sampai berat. Karakteristik petani di Sub DAS Gopgopan adalah: a)Rata-rata luas lahan minimum untuk hidup layak adalah 2 ha. b) Ketergantunga terhadap lahan tergolong jelek (tinggi). c) Jenis tanaman yang dibudidayakan berdasarkan kemudahan budidaya dan permintaan pasar. Diperoleh 5 rancangan model konservasi Tanah dan Air: a) Teknik Konservasi Tanah dan Air dengan Guludan, bedengan memotong lereng dengan pola tanam tumpangsari dan tumpang gilir dengan jenis tanaman (Buncis dan Tomat )dan V (Jagung, padi gogo dan ubi kayu) + III (ubi jalar, kentng, kunyit, dan jahe ) dan IV (Bawang merah, kacang merah, kacang tanah dan wortel ) atau V (Jagung, padi gogo dan ubi kayu) + II (Cabai Rawit, Cabai Merah, Terung). b)Teknik Konservasi Tanah dan Air dengan Teras bangku, bedengan memotong lereng dengan pola tanam tumpang sari/tumpang gilir dengan jenis tanaman I (Buncis dan Tomat) dan V (Jagung, padi gogo dan ubi kayu) + III (ubi jalar, kentng, kunyit, dan jahe ) dan IV (Bawang merah, kacang merah, kacang tanah dan wortel ) atau V (Jagung, padi gogo dan ubi kayu) + II (Cabai Rawit, Cabai Merah, Terung). c) Teknik Konservasi Tanah dan Air dengan Teras Bangku +mulsa, dengan pola tanam tumpangsari dan tumpang gilir dengan jenis tanaman I (Buncis dan Tomat) dan V (Jagung, padi gogo dan ubi kayu) + III (ubi jalar, kentng, kunyit, dan jahe ) dan IV (Bawang merah, kacang merah, kacang tanah dan wortel ) atau V (Jagung, padi gogo dan ubi kayu) + II (Cabai Rawit, Cabai Merah, Terung). d) Teknik Konservasi Tanah dan Air dengan Teras gulud bedengan memotong lereng dengan pola tanam tumpangsari dan tumpang gilir dengan jenis tanaman I (Buncis dan Tomat )dan V (Jagung, padi gogo dan ubi kayu) + III (ubi jalar, kentng, kunyit, dan jahe ) dan IV (Bawang merah, kacang merah, kacang tanah dan wortel ) atau V (Jagung, padi gogo dan ubi kayu) + II (Cabai Rawit, Cabai Merah, Terung). e) Teknik Konservasi Tanah dan Air dengan Teras bangku, bedengan memotong lereng dengan pola tanam tumpang sari/tumpang gilir dengan jenis tanaman I (Buncis dan Tomat )dan V (Jagung, padi gogo dan ubi kayu) + III (ubi jalar, kentng, kunyit, dan jahe ) dan IV (Bawang merah, kacang merah, kacang tanah dan wortel ) atau V (Jagung, padi gogo dan ubi kayu) + II (Cabai Rawit, Cabai Merah, Terung). Hasil analisis menggunakan AHP, model teknik konservasi tanah dan air terpiliih model c dan model e. Teknik konservasi tanah dan air model e digunakan pada lahan dengan kemiringan lereng 15-25% dan model c pada lahan dengan kemiringan lereng 8-15% di sub DAS Gopgopan-Aek Sikorsikkorsik.