Spatial Spread of Land Support Capability of Agriculture System in Pohuwato District Gorontalo Province Indonesia

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1 Proceeding International Maize Conference Spatial Spread of Land Support Capability of Agriculture System in Pohuwato District Gorontalo Province Indonesia Fitris S. Bagu Gorontalo University Introduction Land is one of natural resources, and it becomes an endowment that can be used for the needs of human life and all of the living things to support their life. Land can have several functions both as economically and as ecologically, so there must be any land assessment to evaluate land capability. Land condition, if it is seen from the aspect of land cover; sometime it has any dynamic changes because of the dynamic of use and man activity upon the land. Some significant factors that play the use of the land is such as land capability aspect. Land capability evaluation is land potency evaluation for the use of several agriculture system widely and do not talk about the function to some particular plants or some particular management (Sitorus 2004). The efforts of land use should consider some important aspects of land capability, so to get the balance between human economic purpose and natural resources balance, there must be an appreciation from several institutions that involve in land used to do land management and land cultivation by considering several aspect of land capability. The final goal that shall be achieved is the existence of sustainable land use, and the land is still productive. Sustainable productivity can only be achieved by cultivating the land based on its natural capability that is owned by that land. Land characteristics can be different from one location compare with other locations, land capability can be different too. Land capability classification is one form of land evaluation that can be done to give important input as guidance or recommendation to use the land and to manage land cultivation system. Land capability analysis can give significant consideration about land use based on physical characteristic and the capability of that particular land. This analysis also gives important knowledge about initial condition of the land and negative effect of land use, so in further it can be a device to plan and manage the cultivation of the land. By considering that condition, there must be some management effort and cultivation procedure that is suitable with the capability of the land. The management effort can be more concretely managed in the form of planning, managing, and also giving guidance and knowledge about land capability existing in Pohuwato District Gorontalo Province. Based on those reasons, there must be scientific research about spatial spread of land capability in Pohuwato District Gorontalo Province. According to important issues mentioned in the background of the problem, it can be framed that there are some problem of the research toward the management that is viewed from the aspect of land capability, those are: (1) What are the characteristics of land formation, slope, and land cover/land use (in land unit), (2) How is the land capability in Pohuwato District Gorontalo Province that can support the system of sustainable land used as agriculture? The research is expected to give several benefits, such as: (1) to study the characteristic of land formation, slope, and land cover/land use (land unit) in Pohuwato District, (2) to analyze land capability that can support the system of sustainable agriculture land use in Pohuwato District. It is expected that the research can bring some benefits, such as (1) to provide the information about land characteristic in Pohuwato District; (2) to give the information about the classification of land capability in Pohuwato District; (3) to give alternate input for stakeholders in making the decision especially the decision that correlates with land use, (4) based on the development of science, it can provide an additional knowledge in planning the land for agriculture science. Literature Review The Evaluation of Land Capability Land becomes a part of land extend that covers the understanding of physical environment including climate, topology/relief, hydrology and even natural vegetation 218

2 Bagu: Spatial Spread of Land Support Capability of Agriculture System in Pohuwato District Gorontalo Province Indonesia condition that potentially will influence toward land function and land use (FAO 1976).Landin broader meaning is included one which has been influenced by several human activities both in the past time and in the future (PPTA 1993). According to Senawi (2007), land capability valuation is actually a process to guess the natural resources of the land to maximize the function. Land capability is grouping activity into smaller categories or classifications. The classification of land capability in this research is based on Arsyad s criteria (1989). The Classification of Land Capability Every land, based on the character and limited factors that have functional potency that is different from one another. The evaluation of land capability is basically the evaluation of land potency to the function of several agriculture systems in broad sense, and it does not discuss its function for one particular commodity or its particular cultivation process (Sitorus 1985). The classification of land use is the systematical assessment and grouping into several categories based on some characteristics that become the potency of the obstacle in its function naturally (Arsyad 2006). The evaluation of land use that determines the classification of land capability is really needed by farmers to cultivate their land to have maximum economical result. The classification of land capability is grouping the land into special units based on its capability to the most intensive use, and the treatment given can be use sustainably and continually (Worosuprodjo 2007). based on its classification, land capability can be divided into three stages; those are class, sub class, and unit or cultivation unit. Classification structure of land capability based on obstacle factor is shown in Table 1. Based on the classification of land capability from Arsyad (2006), there are four classes (class I up to IV) that are suitable for agriculture process of food production and four classes (class V up to VIII) for perennial plants. The explanation of each classification of the land that is suitable for seasonal and annual plants is presented in this following explanation. Class I land. This land is categorized as very good class with flat surface and the slope is 0 3 %. This land is resistant toward the erosion, the texture is muddy and it is easy to cultivate. Land permeability is medium, and the drainage is good until medium. This land almost does not have any limiting factor in its use. Class I land is suitable for seasonal plants. Giving fertilizer and the efforts of good land structure maintenance is needed to keep the fertility of the land and increase its productivity. Class I land has one or more combination of the character and quality such as: (1) located in almost flat topography; (2) small threat of erosion, (3) having deep effective depth; (4) usually having good drainage system; (5) easy to cultivate; (6) good capacity in restrain the water; (7) fertile or responsive toward fertilization; (8) no flood threat; (9) under its area climate that is suitable to the growth of other plants. Class II land.it is suitable to every kind of agriculture function with little obstacle and threat that will damage the soil. The land has slight slope, deep, and smooth texture. It needs light conservation process for seasonal agricultural plants. The conservation processes are cultivation based on the contour, plants rotation, land cover plants, and other light cultivation processes. Land limitation or damage threat to Class II land is one of the combinations from these factors: (1) slight slope; (2) erosion sensitivity or medium erosion threat or having medium erosion; (3) effective depth is quite deep; (4) not really good soil structure and cultivation effort; (5) light until medium salinity or containing natrium that is easy to lose but having big possibility to appear again; (6) water surplus can be repaired with drainage but it still exists as limiting factor that has medium level; and (7) climate condition that is not relay suitable to the plants and cultivation. Table 1. Classification criteria of land capability. Factor Class capability I II III IV V VI VII VIII Soil texture (t): a. upper soil layer (40 cm) t2/t3 t1/t4 1/t4 (*) (*) (*) (*) t5 b. bottom layer t2/t4 t1/t4 tt1/t4 (*) (*) (*) (*) t5 Slope surface (%) io I1 I2 I3 (*) I4 I5 I6 Drainage d0/d1 d2 d3 d4 (**) (*) (*) (*) Effective depth ko ko K1 K2 (*) K3 (*) (*) Erosion condition e0 e1 e1 e2 (*) e3 e4 (*) Pebbles / rock b0 b0 b0 b1 b2 (*) (*) b3 Flood Oo O1 O2 O3 O4 (*) (*) (*) 219

3 Proceeding International Maize Conference Class III land. It is suitable to all kinds of agriculture function with some obstacles and threat that is bigger than class II land. This land often has fast permeability. Special treatment for its land preservative process is medium by making terraces, plants rotation, land cover and fertilization. Class II land has heavy limiting land that reduces its functional choice or needs special conservation action and both. Land limit that exists in class III land relay limits the period of its use for seasonal plants, cultivating period, plants choice, or combination of those limiting factor. Land limit or damage threat can be caused by one of these factors, such as (1) rather inclined slope or little wavy; (2) sensitive to erosion or having heavy erosion; (3) having great flood that can damage the plants; (4) having slow permeability in under soil surface; (5) shallow depth toward rocks, having hard soil surface, having breakable hard soil layer or having hard clay layer that limits the movement of root systems and water saving ; (6) too wet or still having saturated water quality after drainage; (7) low capacity of holding water; (8) medium salinity and natrium content; or (9) little hard climate obstacle. Class IV land. It has land limit and bigger damage threat than the other three previous lands that have been mention before. Its plants choice is also more limited. If it is used for seasonal plants, it needs more careful cultivation process and more difficult conservation action should be applied and maintained such as desk terrace, vegetation stream flow, limiting dams, and some actions to maintain the fertility of the soil and physical condition of the land. The land in this class cannot be used for seasonal plants and general agriculture plants. It is only suitable to grass plants, productive wood, herding savannah, conservation forest, or forest for protection.land limit or damage land threat in class Iv land is caused by one or some combinations of these factors: (1) inclined slope or mountainous landscape; (2) big erosion sensitivity; (3) the influence of former quite terrible erosion that happened previously; (4) shallow land; (5) low capacity in restraining water; (6) stagnate water that can cause heavy damage to the plants; (7) too much free water and saturation threat or continually stagnate water after the drainage; (8) salinity or water content. Class V land. Land in this category is not threatened by erosion, but it has other limiting land factors that cannot be eliminated practically, so it can limit the choice to cultivate the plants, and it is only suitable to grass, savannah, production forest, conservation forest and natural conservation for plants and animals. The land in this class has several limiting land factors that limit the choice of the plants and hampering land cultivation process for seasonal plants. This kind of land is located in flat topography or almost flat topography, but it is flooded by stagnate water, having flood often, rocky, or the climate is not really suitable or having limiting combination to that land. The example of class V land is (1) lands that often get flood, so it is very difficult to use the land as planting area for seasonal plants formally; (2) flat land that lies under normal climate, so it is impossible to produce agriculture plants normally; (3) flat land or almost flat land which has rocky landscape, and (4) flooded land that has improper drainage system and it is not suitable for seasonal plants but grass or hard plants can grow there. Class VI land. This land is usually located in steep slope if it is used as herding. If it is used as production forest, it has to be managed well to avoid erosion. There are some type of this land that has deep root area system but it is located in steep slope and it can be used as seasonal plants with heavy conservation treatment. Class VII land. It is not suitable to use as agriculture cultivation. If it is used as savannah of production forest, there must be a special treatment to avoid erosion with heavy effort treatment. Some kinds of land in class VII is deep and it is not sensitive toward erosion. If it is used as agriculture for food producing, there must be desk terrace making and supported by vegetative ways for land conservation besides fertilization. Land in class VII has several limiting land or heavy damage threat, and the damage cannot be lost. The areas are such as (1) located in very steep slope; (2) experiencing very heavy erosion; (3) very shallow root area and it is located in slope level 45-65%. Class VIII land. This area is not suitable to be used as agriculture production and people have to let this area in its natural condition under its natural vegetation. This land has slope level more than 90% or it is covered by hard rocks, and it has hard texture. Class VIII land is useful for protection forest, recreation place, or natural conservation. Limit or damage threat in this class can be (1) located in very steep slope; (2) rocky, or (3) very low capacity in restraining water. The example of this land area is dead land, sandy beach, rocky mountain, and peak of the mountain. Research Method Research Location and Time The location of the research is located is Pohuwato District Gorontalo province. The time of the research was during February 2010 February

4 Bagu: Spatial Spread of Land Support Capability of Agriculture System in Pohuwato District Gorontalo Province Indonesia Research Instrument There were several instruments used the research. They were: (1) land sample to be analyzed in the laboratory. (2) Indonesian surface map with scale 1 : 50,000 (year 1990). (3) the book of Gorontalo province in the form of numbers (in 2010) to gain secondary data. (4) the book of Pohuwato District in the form of number (in 2010) to gain secondary data. (5) government s Rule no 4 in 2011 about Geospatial Information. There were several tools used in this research. Those were: (1) stationary tools as supporting tools in the field. (2) notebook Acer, Intel Core 2 Duo, dan Software used were Microshop Office Word 2007 and Excel 2007, QM for Windows 2.0, Software SIG Arc Info 3.5.1, Arc View versi 3.3, dan ENVI 4.4 extensi edit tool, extensi xtool, extensi transform dan registry tool that were used in processing SIG and making map layout, (3) GPS (Global Position System) Garmin e-map, used as supporting tool to decide coordinate position in the field. (4) digital camera to take pictures as the documentation of the field, (5) printer Canon Ip 1300 to print the map as the result of the research, (6) soil drill used as soil taker tool and ph test in the research location and as determiner of land effective depth, (7) abney Level, used to test the slope level in every sample location. Laboratory tools to analyze the result were chamber glass, measuring glass, sieve tool, soaking basin, pipettes, crucible, oven, analytical scale, and other tools. Table 2. Coordinate spots of land sample taking location. Sample spot Land unit East longitude North latitude number code (BT) (LU) 1 S1IIKc S1IIHt S1IITg S1ISw F2Ikc F1Itg F1Ibk F1Itg F1Ikc S1Ibl S1Itg S1Irt S1Itg S1Itg S1Irt S1Itg S1VKc F1Ikc F1Ikc F1Itg Sources: RBI map (2010) and fieldsurvey(2010). Laboratory test toward soil sample covered several items, such as: 1. Soil texture, the score of soil texture was determined from the analysis result of the laboratory toward soil fraction comparison like mud, sand, and loam. 2. Permeability, the score of permeability was determined from the analysis result of the laboratory with some categories like slow class, quite slow class, medium, quite fast, and fast. 3. Salinity, salinity data was gained from the measurement of electrical conductor capability in the laboratory with electric conductivity mete that was determined in the for mm hos/cm. Research Method and Data Analysis The method used was land evaluation method with land unit approach. Land unit was chosen by considering the aspect of land slope, land formation, and land use. Map arrangement of land formation, slope map, land cover/ land use map were arranged by map interpretation RBI scale 1 : 50,000 in 1999, alos image June 2008, and field survey July until December 2010, while land capability map was achieved by RBI map interpretation in 1999, administration map in 2010, land unit map in Pohuwato District in 2010, and analysis result of LCLP (Land Classification and land Planning) in Land sample taking was done in 20 spots of locations by using stratified random sampling. Data analysis was done spatially by using Geographical Information System. Result and Discussion Land Unit Characteristic The characteristic and quality of every land unit could be achieved from direct measurement and observation in the field and also the analysis result of land sample in the laboratory. The result can be presented as follow: (1) surface slope: slope level in the research locations were various from 0-2% until > 40%, (2) erosion danger rate could be classified as heavy category until very heavy category, (3) land effective depths were various from 20-25, and > 90 cm, (4) kinds of soil: Brown Aluvial, Mediteran, Humus Gley, Renzina, Podzolic, Grumusol, Latosol, grey Aluvial, Podsolic, and Andosol, (5) kinds of rock were also various: Aluvium, volcanic Rock Pani, Tinombo Formation (volcanic rock Popayato), (6) land formations were deep alluvium hills, strong alluvium hill, flat land, and wavy land area. (7) rain rerocivity (A) were 221

5 Proceeding International Maize Conference from 323 until , (8) factors of plant variety and plant management (CP) were about 0.01; 0.2; 0.28; and 0.3, (9) slope factors (LS) were about 0.3; 0.4; 1.2; 4.25; and 9. (10) Land Erobility (K) was about 0.13; 0.16; 0.2; 0.21; and Land Capability Class The result of the research shows that land capability class in Pohutato District consists of class I, III-L, III-Lb, III-P, III-Pb, III-Pl, III-Plb, IV-L, IV-Lb, V-P, and VI-L. The spread of land capability class is showed in the Table 3. Table 3. Spatial spread of land capability in Pohuwato District. Subdistrict Land capability Width I III IV V VI Mangroves Lakes Forests (ha) Buntulia Dengilo Duhiadaa Lemito Marisa Paguat Patilanggio Popayato Popayato Barat Popayato Timur Randangan Taluditi Wanggarasi Luas (ha) Persentase (%) Sumber: Hasil Analisis 2010 Figure 1. Land capability map. 222

6 Bagu: Spatial Spread of Land Support Capability of Agriculture System in Pohuwato District Gorontalo Province Indonesia Conclusion The conclusion that could be achieved are, (1) the characteristic of land unit in Pohuwato District is various, (2) land capability class in Pohuwato District consists of I, III, IV, V, and VI. Land which has capability class I, III, and IV can be cultivated and used for agricultural activity, but the land with land capability V and VI are not suitable to use as agricultural area and seasonal plants because it is located on the slope with slope level more than %, so it is easy to get erosion and the depth of the land is very shallow. Land use for annual plants needs to use terrace system and it does not need to have intensive weeding. Referrences Arsyad, S Konservasi tanah dan air. IPB-Press. Bogor Arsyad, S Konservasitanahdanair.IPB-Press. Bogor FAO Aframework of land evaluation. Soil Buletin. No 32/IILRI. Pub No,22 Rome Italy. PPTA Petunjuk teknis evaluasi lahan. Departemen Pertanian. Jakarta. Senawi Optimalisasi penggunaan lahan untuk pengendalian erosi tanah permukaan di Sub DAS Wuryantoro. Disertasi. Fakultaseografi, Universitas Gadjah Mada. Sitorus, S.R.P Evaluasisumberdayalahan. Penerbit Tarsito. Bandung. Sitorus, M.L. and Nuraidi Analisis keragaman sifat-sifat tanah dan implikasinya terhadap pengelolaan lahan pertanian. Balai Penelitian Pertanian. Bogor Worosuprojo and Suratman Pemanfaatan sumberdaya alam berwawasan lingkungan. Makalah seminar tema membangun masyarakat Indonesia masa depan memasuki milenium III Fakultas Geografi Universitas Gadjah Mada. Jogyakarta. 223