Effectivity of Humic Substance Extracted from Palm Oil Compost as Liquid Fertilizer and Heavy Metal Bioremediation

Abstract

Humic substances extracted from compost materials were proven able to chelate heavy metals. While the waste from Palm oil as the source material of compost is increasing, consequently the humic substances production from palm oil waste is promising. On the other hand, agricultural lands that were treated with high input which caused heavy metal accumulation (pollutant) up to hazardous level also increasing. The aim of this research was to evaluate the effectiveness of humic substance extracted from Palm Oil compost as liquid fertilizer and bioremediation of copper (Cu). The experiment was designed to discover a product which effectively improved the characteristics of acid soils, bioremediation of heavy metals, and plants production. The results of the experiment revealed that the content of pure humic substance extracted from compost of Palm Oil empty bunches waste was very low, 2.01%. It also contained very low in N, P, and K, which were 0.01%, 0.02%, and 0,11% of N, P2O5, and K2O respectively. The treatment of metal Cu as much as 300 mg Cu(OH)2.kg-1 into the media added with humic substance enriched with NPK (4.38; 8.24; and 9.24) showed non significant differences on some cucumber plant variables. NPK enrichments to humic substance showed significant differences on some agronomic variables than that of control. The length of plant treated with 3/3 NPK enrichment revealed the longest average of 564.2 cm, or increased by 38%. The highest fresh weight was obtained by 4/3 treatment followed by 2/3 rate of NPK enrichment. Whie the longest cucumber fruit was obtained by 3/3 rate. Total soil N was very low, consequently the NPK sorption by cucumber was very low. While soil P availability was high, however the NPK enrichment lowered the fresh cucumber fruit P content instead. The ratio of NPK nutrients in plant and in soil was higher if treated with Cu addition compared to that of control