Lebak Swamp Typology and Rice Production Potency in Jakabaring South Sumatra

The economic and regional development of Palembang has caused land conversion, which was originally as agricultural land and has been converted into non-agricultural activities. The research aimed to compare the typology of lebak swamps and potential rice production before and after the landfilling. Spatial data were obtained using Landsat imagery interpretation in 1987 and 2016. Attribute data was collected using questionnaires and sampling technique was done using disproportionate random sampling method. Typologies of lebak swamps consisted of lebak lebung, deep lebak, middle lebak, levee lebak, shallow lebak and dry land. After landfilling, dry land covers an area of 1,964 ha (72.73%), while the lebak swamp was decreased by approximately 736 ha (27.27%). Before landfilling, soil orders were found based on its dominance, namely Histosols, Entisols, Inceptisols and Gelisols. After landfilling, composition of soil order was dominated by Entisol, Inceptisol, Gelisols and Histosols. Before landfilling rice yields were produced about 3,240 tons of milled dry rice (MDR)/year, and rice production potency is now only about 506.25


INTRODUCTION
Lebak swamp (freshwater swamp or back swamp or inland swamp) is defined as a region or a plain located along left and right positions of the rivers and characterized by a poor drainage system (Sjarkowi et al., 2007;Zahri et al., 2018).It is mentioned as back swamp because the plain extends away from the sea or the rivers.In wet seasons, lebak swamp becomes flooded plains as it gets water overflow of major rivers and rainfall as well as its normally stagnant water is very difficult to drain.In dry seasons, the stagnant water shrinks because most of the water flows back into the river and the plains become dry.At dry seasons, lebak swamp will be planted by farmers to grow usually rice and cereals.Besides rice, lebak swamp is utilized for fishing activities, livestock and others (Armanto, 2014).
Lebak swamp in South Sumatra province cultivated as the agricultural area is less than 30% and is distributed along the Musi River and Ogan River.In achieving food self-sufficiency, lebak swamp is able to provide the highest rice productions (30%) compared to technically irrigated rice fields (27%), tidal rice fields (25%), and other rice fields (18%) of the total rice production in South Sumatra (Armanto et al., 2013).Lebak swamp for agriculture can still be improved, not only for rice production, but also for fisheries and plantations as well as other uses (Adriani et al., 2018;Wildayana, 2018a;2018b).
Jakabaring is an adjoining area directly and located in the southern part of Palembang and is mostly occupied by lebak swamp.Thus Jakabaring is a supporting area and at the same time experiencing direct pressure due to the population increase and economic development of Palembang and its surroundings.Thus land conversion in Jakabaring is very difficult to be avoided, and the government has developed some public facilities in this area, among other international sport center, super and hyper markets, shopping centers, residential centers and others (Wildayana, 2017;Junedi et al., 2017).
In the beginning Jakabaring belongs to lebak swamp area for agricultural purposes (Wildayana, 2014).In line with the economic development, Jakabaring has been allocated not only for agriculture, but also for non-agricultural areas.In order to utilize it optimally, it has been reclaimed by landfilling.The landfilling materials come originally from the Musi river, which consist of small rock, sand and mud soil.
We need to take some lessonlearnt from this case especially in terms of agriculture (Sarno et al., 2017;Ningsih et al., 2017).The lessons-learnt will help us to analyze and to examine with care when lebak swamp will be converted to other non-agricultural purposes (Wildayana, 2015).Therefore, this research aimed to compare lebak swamp typology and rice production potency before and after landfilling in Jakabaring South Sumatra.

METHODOLOGY
The research approach is done in two ways, namely for spatial data collection and data attribute.Spatial data were ob-tained using Landsat imagery interpretation in 1987 and 2016.The interpretation of the research area was supported by thematic maps, topographic maps of 1:50,000 scale, landuse maps with scale of 1: 250,000, swamp maps with scale of 1:500,000 and followed by calculation of area and distribution of natural phenomena by planimetric method (Figure 1).
The soil classification is based on the Soil Survey Staff (2014) manual book and the measurement of the rice production was done by plots of squares (size 10-10m) and multiplied by the whole planting area.The research method for attribute data was using field survey.Determination of sampling technique was done by using disproportionate random sampling.The total number of respondents (mostly farmers) was 120 respondents.Recording of respondent data was done by interview using questionnaire.Data attribute was processed and analyzed by using SPSS program and displayed in the form of narration, description and tables.

RESULTS AND DISCUSSION
Research results and discussion focuses on the aspect of knowing how the lebak typology and compare between the condition of lebak before the landfilling (1988) Source: Google Map, 2017 with existing condition (2017).Knowing the lebak typology and comparing the impact of landfilling is important to evaluate the extent of changes in occurring to the lebak swamp.

Lebak Swamp Typology
The lebak swamp can be divided into six typologies, namely lebak lebung; deep lebak; middle lebak; levee lebak; shallow lebak and dry land (Table 1).Typology of the lebak ecosystem is an important part in the formation of socio-economic and cultural local communities who live and settle in the lebak ecosystem.Functions of lebak swamp are not only as business and residential areas, but also as water resources, washing, domestic need of water as well as social and cultural interactions.
Lebak lebung is a depression in swampy areas and is always flooded, water level > 150 cm, and peaty 50-100 cm.In general, lebak lebung often accumulate freshwater fish, especially at low tide during the dry season.Lebak lebung is formed in two ways, namely naturally, especially in the depression area, and man-made with the purpose for collecting freshwater fish in the dry season.Lebak lebung is utilized as a major business area for the community and as government revenue (PAD) by lebak lebung auction.PAD varies according to the potential of each region, the circumstances of each district, for example in district of MUBA and OKI, their revenue earned from the lebak lebung auction around Rp 2.5 billion/year.Results of lebak lebung is obtained various types of fish, including fish for consumption and ornamental fish, for example belida fish (Notopterus sp.), arowana or tangkeleso fish (Scleropages formasus), sumpit fish (Taxotes sp.), botia fish (Botia sp.), serandang fish (Ophiocephalus pleurophthalmus) and any others.Types of consumption fishes, such as catfish, sepat fish, betok fish, patin fish, tembakang fish, toman fish, baung fish and others.
Deep lebak is a part of swampy area that is much lower than middle lebak.It is flooded 6-9 months/year, water level 100-150 cm, and peaty < 50 cm and cultivated only in the middle of the dry season when the ground water level has shrunk.In the wet season deep lebak is dominated by plants of natural waters, such as the lotus or teratai (the fruit is useful as a snack food), eceng gondok (usually used for handicrafts materials), water grass, keman (a type of putri malu that lives in water and is used as an ingredient side dish or vegetables at meals), and other wild plants.
Middle lebak is a part swampy area located lower than levee lebak and usually planted at the beginning of the dry season in order to make the surface of the water had receded for rice.It is flooded 3-6 months/year, and water level 50-100 cm.Levee lebak is defined as similar with shallow lebak.It is differentiated that levee lebak is flooded < 3 months/years, water level 25-50 cm and dry in the dry season.This swampy area is planted with rice in wet season and will be dry in the dry season.It is mostly located on the levee and the river valley and flat topography.
Shallow lebak is a part of swampy area planted to rice during the wet season.It is inundated only in wet season (< 3 months/years), water level < 25 cm, and dries in the dry season.Shallow lebak was being extremely dynamic meaning that regional development will directly influence the shallow lebak area.Direct impact of the regional development will increase sedimentation resulting in the total area flooded in riverbank is widespread.Because of its very dynamic, then the extent of their area can most small or very large.Compared with deep lebak and lebak lebung because of the permanent inundation of typologies, they are less dynamic than shallow lebak.
Dry land (Palembang local language is called the Tanah Nyurung) is partly swampy area that during the wet and dry season it is dry and flooded potential during at the wet season annually 5-10 years as well as serves as a place for living and to farm, especially subsistence agriculture.Dry land is generally located on the right or left side or in river center or general waters.The dry land in the river center or open waters is named as "pulau", according to local language) and functions as agricultural fields, namely rice fields or cereals.
There is a small part of Jakabaring area which is not touched by human activity, did not function as rice fields and covered with natural vegetation and it is called as lebak kumpai.Lebak kumpai can be divided into two parts, namely rawang forest and lebak rawang.Rawang forest is entirely untouched by human hands and is still a native habitat and vegetation is dominated by trees.The main functions of rawang forest as a place for fishing and looking for gum rosin (damar).Lebak rawang is a swampy area and dominated by kumpai shrubs and no trees.In general, the vegetation type was dominated by kumpai or prumpung or other types of grasses.Lebak rawang is utilized as cattle pasture and swamp buffalo and looking for raw materials of the mat making.Due to Jakabaring area is adjacent to the Palembang city, the pressure of population and economic development, then gradually Jakabaring area was experiencing land conversion and done by landfilling started in 1989.All this land conversion has changed Jakabaring into a form that is totally different from its initial condition before 1970.
Composition changes in lebak swamp typology impact directly on the economic activities of the community, private sectors and industry.If further analysis that acreages of deep lebak and lebak lebung is less than 10%, this is negatively affecting the overall area because this area is susceptible or vulnerable to surface water overflow, i.e. overflow of Musi River water and excess of rain water.As we know that main function of deep lebak and lebak lebung are acting as water catchment areas during the wet season or reservoir water especially in the dry season.Ideal conditions of Jakabaring have lebak lebung and deep lebak minimum 810 ha (30%) of the total area (2,700 ha) landfilled.

Landfilling
Generally lebak swamp in Jakabaring is dominated by four major orders, i.e. orders of
However these soil orders have changed dramatically after landfilling with dominance as follows: Entisols occupy the highest around 2,165.67 ha (80.21%),Inceptisols are almost 338.85 ha (12.55%),Gelisols cover an area of 114.75 ha (4.25%) and the most minimum position is showed by Histosols only around 80.73 ha (2.99%).Composition changes of soil orders effect generally to land suitability and land capability for supporting agricultural production.
Entisols area characterized by no differentiation horizon and means that soils are still undeveloped.Jakabaring area is dominated by this soil order around 2,165.67 ha (80.21%) as the landfilling results.Before landfilling Entisols were found only around 30.54%.This expansion is due to the process of landfilling.
Inceptisols are determined by weak horizon differentiation, but Gelisols belong to highly developed soils.Histosols are showed by accumulation of organic materials with its thickness at least 30 cm.Before landfilling fourth soil orders were relatively balanced and after landfilling Gelisols and Histosols were buried by landfilling and replaced by Entisols.Gelisols and Histosols are generally found in deep lebak and lebak lebung.If the average rice production of lebak swamp before landfilling was around 2.50 tons of milled dry rice (MDR)/ha/year, thus total rice production was approximately 3,240 tons MDR/year.In existing condition the rice production potency was only remaining 506.25 tons MDR/year.This amount continued to decrease due to intensive land conversion of agriculture to non-agriculture purposes.By 2025 it is estimated there is not found rice fields and probably farmer profession is no longer found in the research area (Table 4).
It means that Jakabaring area cannot be mentioned as lebak swamp or agricultural land as happened before landfilling (1988).In accordance with population pressure and economic development, farmers in Jakabaring are displaced to other places due to agricultural land unavailability and government support for activities agriculture is also minimal.Moreover government wanted to develop this area as international sport centers, residential, industry, recreation areas and any others.

Figure 1
Figure 1 Research Site in Jakabaring Palembang (Google web)

Table 2 Acreages of Lebak Swamp Areas before and after Landfilling
It was measured in the fields and supported by land use map (1:250,000 scale), Landsat, 2016., Google map, 2017., as well as field survey,(2017)

Table 3 Changing Soil Orders before and after Landfilling
It was measured in the fields and supported by land use map (1:250,000 scale),Landsat, 2016., Google map, 2017., as well as field survey, (2017)

Table 4 Potency of Rice Production before and after Landfilling */
Source: */ It was measured in the fields and supported by land use map (1:250,000 scale),Landsat, 2016., Google map, 2017., as well as field survey, (2017)