Nilai pH dan ZPC dalam hubungannya dengan erapan Fe dan efisiensi P

Abstract

Peatkjlnds in Indonesian cover a significant part of the W lands of the country which a w n t for lhe Iargest trow pats amounting to about 16 mitliion hectares, The most of w a n d s in this country that suitable fur ag&utturai crop have k n cuttinrated by fanner fur paddy. Be- nutrient ddldencbs, the dewlopm63nt of peatfands for agriculture fac;ss a M of cwiirtrains which are assosiated with the inherent propribs and behawbur of peatlands. One of the important chmiml aspect in soil management which has nat begn yet much attended in m n d is soil P C in its ref- with ~ e r * sorptian and P Mdency. Peatsoils contain the high organic acids and Rave #e varfabd charges (pH depsndmt) wMcR are domi&& the negative charges. Therefore, pcsatswls have the low capacity of anion sorp$on, The aims of the resemh are as fotlow (1) to know jlPC value of coastal, trsntional, and inland peals respectively in the degree of dmpositian of saw, hmic, and fibric. (2) ta study kvd uf ~ e *so rption at pHzpcs under pHpC and a - pHz* on the various physiography and decumposition degm of past sdis (3) to study relationship between the actual pH and P C with fhe increase of Fe3+ surpfion and &Wency of P. This research consists of severat experimental steps as fdlow: (1) debmining of ZPC value, (2) measufing uf ~ e *so rption, (3) measuring of Mciency of P. Sail samples were taken from Jam& and Central Kalimantan that representative for coastal , trantional, and inland peat$ rspe&v&y in the degree of dewrnpasition of sapfic, hemic, and fibk. Based an the result exprimnb were concluded: (1) on the same decomposition dwm, 2% value uf coastat peat was higher than that in tiantianal and inland peats . (2) in the same /&on and the same decomposition degree, the sorption of ~e*abuve pHtK was higher than under pHzpc; Few sorption in the cuasfaf geaf higher than that in trantional and inland pats; and ~ e s*ow n in ihe sapric peat was higher than that in irenic and fib& pats. (3) Mciency d P in the cuastal pat was higher than that In trantEanal and inland pests, but the increase of efficiency of P with Fe* addition in the inland peat was higher than that in tranfionaf and coastal peats.

Di Indonesia terdapat lahan gambut yang cukup luas yaitu sekitar 16 juta hektar. Areal gambut ini paling luas bila dibandingkan dengan total luas gambut tropika yang tersebar di Asia Tenggara. Sebahagian besar lahan gambut di Indonesia yang cocok untuk tanaman pangan telah dimanfaatkan petani untuk lahan padi sawah. Selain kekurangan unsur hara, pengembangan lahan gambut memiliki kendala-kendala yang berkaitan dengan sifat inherent gambut itu sendiri. Salah satu aspek kimia yang penting dan belum banyak menjadi perhatian adalah nilai ZPC tanah dalam hubungannya dengan erapan Fe³+ dan efisiensi P. Tanah gambut mempunyai muatan variabel (bergantung pH) yang tinggi dan didominasi oleh muatan negatif, karena mengadung asam-asam organik yang tinggi. Oleh karena itu, tanah gambut mempunyai kemampuan yang rendah terhadap pengikatan anion seperti P.