Peningkatan produktivitas tanah gambut yang disawahkan dengan pemberian bahan amelioran tanah mineral berkadar besi tinggi

Abstract

Dari beberapa hasil penelitian yang dilakukan terakhir ini menunjukkan bahwa rendahnya produktivitas tanah gambut terutama disebabkan oleh kandungan asam-asam organik yang tinggi, sehingga bersifat racun bagi tanaman, terutama asam-asam fenolat. Asam-asam fenolat tersebut merupakan hasil biodegradasi dari senyawa lignin yang dominan dalam bahan asal kayu-kayuan. Pengaruh buruk dari asam-asam fenolat dapat dikurangi dengan penambahan kation polivalen Fe. Dalam penelitian ini dicobakan penggunaan tanah mineral yang mengandung Fe tinggi sebagai bahan amelioran untuk menurunkan kandungan beberapa derivat asam fenolat dalam tanah gambut dalam kaitannya dengan produksi tanaman.

Fi·om the results of the research carried out in the last few years, which indicate that the low productivity of peat soil is mainly caused by the high organic acid contents especially the phenolic acids, which have phytotoxic effect for the plants. These acids are resulted from biodegradation of lignin compound in that are ve,y dominant in wooden materials. Adding cation of Fe can reduce the harmful effect of these phenolic acids. This research used mineral soil with high content of Fe as an amehorant to reduce the content of several phenolic acid derivations in peat soil in relation to the plant production. The research locations were chosen, which are considered to be representatives: coastal peat in San111da, transitional peat in Sampit. and inland peat in Berengbengkel, Central Kalimantan. This research consists of three experimental steps as follow: (a) laboratory research co,•ering of the determination of Fe sorption curve, the solubihty of Fe .fi·om amelioranl. the effect of amefiorant application on availability of se1·eral 1111rricnrs, and phosphor binding in peat aier the a11plication (b) green house experin1ent to slltlijl the growth and n111rient uptake by plants; and (c) jield experimem covering of the plant production. and measurement of several phenolic acid derimtion in soil sample from the field. The ameliorant are applied with the rate as n1uch as 0, 2.5. 5. 7.5. and 10 % of Fe maximum sorption. The initial analysis result of chemical propenies of peat soil and a,ne/iorant sho111ed that as a whole peat soil reaction were vety acid to acid (pH 3.80 - 4 40). 1\1eamrhde. the ash content of peat soil in Sanwda. Sampit. and Berengbengkel is 4. 62. 4.53. and 0. 63 % respectively, or it is equivalent to the lost of ignition of peat as much as 95.38. 95 . .J7. and 99.37 %. These indicate that this peat soil is classified as tnie peat soil. The hgnin content of peat so;/ used in this research is high (78 - 93 %). Also the quanhty of'iron content in ameliorant is high i.e. 22.06 %.