Perubahan penggunaan lahan dan karakteristik tanah daerah pasang surut batang berbak - pamusiran laut, Jambi

Abstract

Reclamation of tidal swamp land carried out by the Government of Indonesia for the purpose of transmigration and food security program in the Province of Jambi in 1973 faced with some problems, namely: (1) peat and mineral soils that have a low capability for agricultural development, (2) decomposition of the peat at fibric stage with low nutrient availability, (3) limited accessibility, (4) land cover domination by forest vegetation, and (5) very poor drainage. To improve this condition, construction of drainage canals is necessary to get rid of the excessive water and land preparation for rice cultivation. It has led to changes in land use and soil characteristics after reclamation. The purposes of this research were to: (1) study land use changes and their affecting factors, (2) analyze the changes of soil characteristics and their affecting factors, and (3) study the relationships between land use changes and soil characteristics and land productivity of tidal swamp of Batang Berbak - Pamusiran Laut, Jambi after reclaimed. The research was conducted at Batang Berbak - Pamusiran Laut, Jambi that was reclaimed by the early 1973 until 2008. Data of land use type of the early reclamation period of the study area were obtained from the 1973 survey report, while those of 1989, 1998 and 2008 were analyzed from the Landsat imagery and farmer information. Image processing was done by supervised classification and used Tasseled cap transformation. Data were analyzed with Geographical Information System (GIS) ArcView 3.2 / ArcGIS Software. Soil and water characteristic were analyzed in the Department of Soil Science and Land Resource, Faculty of Agriculture, Bogor Agricultural University. The research results showed that the land use of tidal swamp of the Batang Berbak - Pamusiran Laut, Jambi changed from three types at the early period of reclamation into six types after 20 years of reclamation and developed into eight types after 35 years of reclamation. Land use changes in the Batang Berbak - Pamusiran Laut, Jambi were due to changes in land and hydrological characteristics and farmer attractiveness to the higheconomic value commodities such as rubber and oil palm. Paddy fields were predominantly on the relatively lower land position with enough water availability. Coconut plantation, mixed farms, rubber and oil palm were predominantly on the relatively higher land. After 35 years, the land reclamation improved soil ripeness and drainage condition, caused a decrease in soil pH and CEC, and increase in soil exchangeable-Al and sulfate as well as a decrease in exchangeables -K, -Na, -Ca and - Mg. Thickness of the organic material at the site of observation decreased between 22 cm to 40 cm. Loss of thickness of the organic material is strongly influenced by the condition of drainage and land preparation for rice planting by burning. Land productivity increased in the first ten-years of the reclamation and decreased in the second ten-years period otherwise increased again after 35 years of reclamation and this phenomenon was in line with changes in soil characteristics and water quality and availability. For the purpose of tidal land management which contain potential acid sulfate, it is necessary to carry out land use zonation and water regulation. It is urgently needed to further research on the hydrological aspect especially on the river, canals, and land water level, water circulation, and tidal range which is a basic data for water management.

Reklamasi lahan rawa pasang surut yang dilakukan oleh Pemerintah Indonesia untuk program transmigrasi dan ketahanan pangan di Provinsi Jambi tahun 1973 dihadapkan pada beberapa masalah, yaitu: (1) tanah gambut dan tanah mineral yang memiliki daya sangga rendah untuk pertanian, (2) dekomposisi gambut pada tingkat fibrik dan hemik dengan ketersediaan hara rendah, (3) aksesibilitas yang terbatas, (4) ditutupi oleh vegetasi hutan dan (5) drainase sangat buruk. Untuk memperbaiki kondisi ini diperlukan saluran drainase untuk membuang air berlebih dan persiapan lahan untuk tanaman padi. Hal ini menyebabkan terjadinya perubahan penggunaan lahan dan karakteristik tanah setelah reklamasi. Tujuan penelitian ini adalah: (1) mempelajari perubahan penggunaan lahan dan faktor-faktor yang mempengaruhi perubahan tersebut, (2) menganalisis perubahan karakteristik tanah dan faktor-faktor yang mempengaruhi perubahan tersebut, (3) mempelajari keterkaitan antara perubahan penggunaan lahan dan karakteristik tanah serta produktivitas lahan pasang surut setelah direklamasi.