Identification and Evaluation of Potential Land Resources to Support the Development of Agricultural Commodities for Food Crops Zone

To support the goverment purpose to reach the food security, a land use study is needed. The aim of the research was  to provide  an  information  of  characteristics of  land  resources through the identification  and evaluation  of potential landresources and that suitable for food crops in Mamuju District South Sulawesi. The research method used landscape approach to mapping land units as the basis for preparing the soil map unit/DEM compared with field data survey. A case study was done in Mamuju District, West Sulawesi the results showed that the land in Mamuju for paddy covering was suitable enough of 115,250 ha and 54,883 ha of marginal fit, while for dryland crops were 106 978 ha was quite suitable and appropriate marginal was 82,592 ha. However, for cocoa fit enough land was 153,397 ha and corresponding marginal was 485,743 ha. Biophysical constraints were the erosion of land use/steep slopes, drainage, seasonal flooding, toxicity and nutrient retention. Direction of land use for agriculture in Mamuju for Rice crop area was 49,345 ha (6.23%), food crops rice and dry land was 10,680 ha (1.35%), dryland crops/crops was 101,785 ha (12.85%), perennial/Cocoa was 90,488 ha  (11.42%), and conservation land was 532,245 ha (67.18%).Keywords : Cland crops, land identification, soil evaluation [How to Cite: Nurdiyanto AP, Hikmatullah, Asisah, MB Saleh, and SD Tarigan. 2014. Identification and Evaluation of Potential Land Resources to Support the Development of Agricultural Commodities for Food Crops Zone. J Trop Soils 19: 53-61. Doi: 10.5400/jts.2014.19.1.53]  [Permalink/DOI: www.dx.doi.org/10.5400/jts.2014.19.1.53]  


INTRODUCTION
To support the government on accelerating the development of the national economy in the agricultural sector, increasing agricultural production of food crops and plantation crops are needed. Increased agricultural production can be done with intensification and extension programs which are strongly associated with the potential and the availability of land resources. Intensification program can be conducted in the areas that have agricultural production centers such as Java, while the extension program can be conducted outside the java island because it still has enough potential of land resources and a relatively low population density.
Sulawesi Island is an island that is potential as a priority area to develop food crops and to have a strategic role to support national food security. These areas should be directed as special areas that have ample potential land and undeveloped.
One of potential area is Mamuju, a regency of West Sulawesi province which is located at 1039'50 "-2054'52" south latitude and coordinate 172043'15 "-173054'03 'east longitude. Mamuju consists of 16 districts with a total area of 794,276 ha (BPS Prov Sulawesi Barat 2011).The population of the region was 336,973 people consisting of 173,413 men and 163,560 women.
The average rainfall in Mamuju station was 2635 mm, the rainy season falls between November / December to June, while the relatively short dry season occurs between July -October. In general, type of precipitation of Mamuju according to Schmidt and Ferguson was type A. This area is part of an active tectonic zone that many have complex geological processes, such as 54 Mamuju folds (folded), force (uplifted) and faults (faulted) and is part of the junction of three tectonic plates 1978). According to the 1:250.000 scale geological map sheet of Mamuju, rock formations of this area were formed from Quaternary, Tertiary and Pre-Tertiary. Based on field observations, soil parent materials can be divided into: deposition of alluvium, sedimentary rocks, granite intrusive rocks, volcanic rocks, and older metamorphic rocks (Table 1; Figure 1) The purpose of the study was to obtain a landuse information to provide a characteristics of land resources through the identification and evaluation of potential land resources and that suitable for food crops in Mamuju district, West Sulawesi.

Study Area
The study area was located on Mamuju District, West part of West Sulawesi Province, Indonesia ( Figure 1).

Materials
The material used in this study consisted of (1) digital Data resolution Landsat imagery and SRTM 30 m; (2)  The other materials were needed for field equipments consisted of compass, altimeter, GPS, Abney level, pH-meter, ArcView and ArcGIS program software for spatial analysis and data entry field observations.
Mapping method essentially uses the principles of landscape approach to mapping or land units (Marsoedi et al. 1997;Buurman and Balsem 1990) delineated from remote sensing imagery other data supported it. Land units were used as the basis for field observations. Therefore the availability of remote sensing image data was one important part of this study. Identification and evaluation of resource potential semi-detailed level of land began with desk work, then followed by field observations and data processing / preparation of maps. Application of GIS and digital analysis were used to speed up data processing and presentation of research results. To helped details and acceleration analysis of land units, an analysis relief was derived from Shuttle Radar Topography Mission (SRTM) data using ArcGIS software.
Activity analysis and delineation of land units were done on desk work and it was the main activity that must be done before the research field. Therefore, the preparatory activities for the analysis of land units were conducted more intensively, in order to facilitate field operations planning and preparation of soil maps in the field.

Preparation
Collection and compilation of data -Data collected from the research were reviewed and evaluated prior to completion of the relevant data and then did the data entry and ploted delineation of maps and observation points on the base map. Data compilation would be used as reference data or represent additional territory. Compilation of data was stored in databases and Horizon Site Description (SHD). In addition, the literature study were done to study the general physical condition of the environment and the availability of data supporting the survey area.
Preparation of base maps-digital-Base map used was derived from 1 : 50,000 scale Bakosurtanal / Badan Informasi Geospasial. If it was not available, the base map was created from 1:50,000 scale maps or topographic features.
Landsat image was scanned and then digitized by a few important attributes necessary maps. Preparation of Soil Map Unit Analysis-Analysis of digital data Landsat imagery and radar/SRTM was conducted to delineate the components of land units and land use right now. Land units consisted of the elements of Land Form, parent material, relief and slope, altitude, rate of incision and drainage patterns. For areas where no data available, it was done by using overlay delineation between Landsat imagery with digital elevation data, geological maps and map topographic features visually on a computer screen using ArcView. DEM data was used specifically detailed analysis of existing land units, using the slope parameter and the height difference was computerized processed by ArcGIS. Areas that can not be analyzed from the image delineation of land units were assisted by analysis of digital elevation/DEM, geological maps and RBI. Results delineation of land units and land use were transferred to the base map that had been adapted coordinate with remote sensing image data.

Fieldwork
Pre-survey -The event was held prior to the main survey in order to prepare the technical stuff as well as non-technical. Non-technical activities included consultation with local governments for confirmation and determination of the areas to be mapped; additional information, labor, and transportation/accessibility of the area etc. Technical matters such as conducting orientation and field observations were done to obtain an  overview of the study area. The information would be used as a basis to carry out an initial improvement of land units of analysis and implementation strategy of field operations. Main Survey-The survey included observations of main land units, and preparation of field maps terrain. Parameters observed included morphological characteristics. For areas that could not be reached, extrapolation based on similarity Landform, lithology, and relief was conducted. The procedure for morphological observation followed the guidelines for Land Observation (ISRI 2004). The composition of the soil units was estimated from observations transect (Steer and Hajeek 1979).
During the observations from the field, delineation improvements and land units map legend were carried out continuously, so that at the end of the field surveys it could already be formed. For land units were spread wide.
Preparation of Concept Maps Land -Concept maps were drawn towards the ground when the field work was completed. This map was the result of the analysis that had been corrected by the observation field. The maps contained legend of land, units Landform, parent material, relief, and slope and description of each unit area of the map (Hardjowigeno et al. 1993).

Data Processing
Data processing included interpretation of field data and laboratory data and field evaluation. Interpretation of data-data field observations and data analysis interpreted the characteristics and classification of land, land evaluation for agricultural commodities.
Land Evaluation-The evaluation of land, in principle, was done by caramatchingie by comparing the characteristics of the land with the growing requirements of plants (Djaenudin et al. 2003). Land suitability assessment methods in principle use the framework of FAO (1976) and CSR/FAO Staff (1983) and the process used the program Automated Land Evaluation System (Roositer and Van Wambeke, 1997). The system was capable of processing large amounts of data in a relatively short time. To support the needs of data which was complete, clean and had been stored in the database.
Preparation Guide Recommendations-Preparation of maps on agricultural development was done by matching the results of the evaluation of land in the overlay with existing maps and landuse maps status regional/spatial planning taking into account existing local commodity.

Evaluation
Evaluation and correlation intended as quality control was to maintain the quality of the mapping to match the rules or standards established soil mapping.

Form Region
Based on the interpretation of radar images / SRTM, Landsat imagery, geological maps, and map  topographic features Indonesia as well as field observations, the study area could be divided into 6 groups, namely Landform: alluvial group, group fluvio-marine, marine chains, chains karst, tectonics group and volcanic group.

The Land Use
Currently Mamuju land used for: 1) agricultural land, which consisted of rice, dry land farming, mixed farms, plantations and farms, 2) non-agricultural land, including upland forest, mangrove forest, scrub, grassland , sago swamps and neighborhoods (Table 2).

Land Evaluation
Evaluation is the process of land suitability assessments of an area of land for a specific use, in this case agricultural crops and perennial crops cocoa. Biophysical parameters used for land evaluation was the climate, terrain, and soil.
Land suitability assessment was conducted for each soil map unit to the level of class and subclass. The process of calculation was using a computerized program ALES (Automated Land Evaluation System). Evaluation results were presented in the form of tabular data.

Recommendation of Land Use for Agricultural Development in Mamuju District
The preparation of land use map direction for agricultural development based on evaluation of the suitability of land for food crops and cocoa, taking into account the general plan of the provincial spatial (spatial planning)/forest status, and current land use (existing landuse) using overlay technique maps. Suitable land which did not enter the protected area and had not been used, it could be used for expansion, while suitable land and had been used could be directed to agricultural intensification.
The land was quite suitable (S2 class) and the corresponding marginal (class S3) could be directed to the development of agriculture, while land that was not suitable (class N) was directed to conservation/ protection. To determine which choice was made priorities that was sorted from the first to crops, namely: (a) crop wetlands/wetland rice,     Figure 4).
In general, the study area could be grouped into three areas of development, namely: (a) Regions cultivation of food crops and perennial crops, (b) conservation area, and (c) other use. Agricultural cultivation area has been divided into arable land (existing landuse) for intensification and land for expansion (extensification). Existing landuse from the observations in the field showed that the land was generally flat to gentle sloping potential already cultivated, so that potential land for the purpose of practical agricultural expansion was not available, and if available, its range was narrow and scattered. Referrals/recommendations for the development of land use for food crops and cocoa crops are presented in Table 5 and land suitability and limiting factors for paddy, dry land crops, and annual crops are presented in Table 6 -8.
Referrals to the development of agricultural land use were specified as follows: (a) land for paddy crop area of 49.345 ha (6.23%) ; (b) for rice and corn / soy / vegetable 10.680 ha (1.35%); (c) for crops of corn / soybean / sweet potato / vegetable area of 101.785 ha (12.84%), and (d) for the cocoa / coconut area of 90.488 ha (11.42%). Land for conservation area 532.616 ha (67.19%), and the other uses 7.781 ha (0.98%).