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

1. Introduction

The previous research results indicated that humic substabces extracted from some compost materials were effectively and more rapidly improved soil chemical properties of marginal or acid soils. It could decrease exchangeable Al and increased soil P availability through chelating process Winarso, et al, 2009a; 2010, therefore it could be an alternative to cope with problems of marginally acid soils in Indonesia, which covered almost 102.8 million ha Puslitbangtanak, 2006. On the other hand, intensive agricultural lands were under harmful condition, due to high content of high heavy metals. Wang 2006, stated that more than 10 of cultivated lands were contaminated with Cd, As, Cr, and Pb, which caused production lost more than 10 million tons, and more than 12 million tons agriculture product per year became hazardous, which also caused economical lost at least 3 billion US dollars per year. Heavy metals accumulation varied along with plant species, and generally higher on dicotyedoneael compared to monocotyledoneae plants Taub and Goldberg, 1996. While, on the other hand, the potential agriculturalorganical waste, especially from palm oil was very abundant, approximately 6 million tons empty bunches in 2004 23 of total, excluding of wet decanter solid 4, stem 6.5, fiber 13.0, and liquid waste 50. Based on the data released by Ditjenbun 2006, within the last 20 years, the addition of Palm Oil Estate areas reached 5 million hectares, or increased by 837. Up to nowadays, the utilization of organic waste for soil was just as composting, without any added values, therefore its commercial value was low. Increasing commercial value of compost by extracting it to produce humic substabces was a very promising practice. The humic substances extracted from compost could utilized as the raw material of biofertilizer and environmentally friendly bioremediation for heavy metals. In addition, humic substances have superior characteristics compared to that derived from mining Leonardit which has been marketed commercially, especially abroad Winarso, et al., 2009b. Humic substances originated from mining contained very high Na, approximately 5., while Na is generally needed by plants in very small amount. In fact, if Na is continuously added to soil, would cause soil compacted and dispersed when wet, and became easily eroded. The mass and cheap production of humic substances usually would harvest low concentration, and its characteristic was determined by the quality of its raw materials. Therefore, some efforts should be applied to activate its functional groups, such as through pH manipulation and adding synthetic organic substances rich in functional groups. In addition, enriching humic substances with nutrients is very useful and beneficial to improve its functions and purposes as soil conditioner, fertilizers, and as heavy metals bioremediation. The chelating capability of humic substances could improve their main function as bioremediation for heavy metal or other soil- environment pollutants The aim of this research was to evaluate the effectiveness and the capability of humic substance extracted from Palm Oil bunches waste in improving cucumber or other plants production and in reducing soil Cu heavy metals content.

2. Materials and methods

This research was performed at the Faculty of Agriculture, the University of Jember, during year 2013 to 2014. The main material utilized in this research was humic substance extracted from paln oil waste, which then enriched by macro nutrients, N, P, and K. The amount of N, P, and K applied were based on the fertilizer recommendation for Cucumber and the treatments applied. The N, P, and K amount were: 4,38:8, 24:9,24 or 4,38 N; 8,24 P 2 O 5 ; and 9,24 K 2 O Wichmann, 1992. The humic substance was harvested from the solution originated from composting process of Palm Oil empty bunches. The composting process was undergoing naturally without any additional enhancing materials, but only water and plastic cover to maintain the moisture content. Palm oil waste ustilized in the research was collected directly from the production process. The humic substances accumulated from the process contained: 4000 ppm C or approximately 2000 ppm humic substance Stevenson, 1982. The other humic substance characteristics were presented in Table 1. Table 1., showed that humic substance derived from Palm Oil waste contained N, P, and K low to very low, therefore it needed to be enriched to improved their functions to be used as liquid fertilizer. The enrichment of humic substance as to be in line with the research treatments was conducted by adding 4000 ppm C; 2.71 kg Urea 46 N; 6.54 kg SP 36 P 2 O 5; and 4.8 kg KCl 60 K 2 O. The planting medium utilized was 8 kg of soil in each polybag. The plant indicator used was the Cucumber, which then planted at the field. Some plant and soil variables were then measured within and during 6 weeks. The experimental design used for this research was Randomized Complete Block Design RCBD having two factors. The first factor was the rates of NPK enrichment materials per plant. Those were as follows: Control No NPK enrichment, 13 of recommended rate 13 NPK: 3.3 gr Urea, 7.7 gr SP-36, and 5.7 gr KCl per plant; 23 of recommended rate 23 NPK: 6.7 gr Urea, 15.3 gr SP-36, and 11.3 gr KCl per plant; 33 of recommended rate 33 NPK: 10 gr Urea, 23 gr SP-36, and 17 gr KCl per plant; and 43 of recommended rate 43 NPK: 13.3 gr Urea, 30.7 gr SP-36, and 22.7 gr KCl per plant. The second factor was the rates of Cu heavy metal CuOH 2 , as follows: 0 Control: 0 mg CuOH 2 .kg -1 soil medium; and 1: 300 mg CuOH 2 .kg -1 soil. The treatment combination of this experiment were replicated 3 times. Table 1. Chemical Characteristics of humic substance extracted form Palm Oil Bunches Compost and Other Humic Substabces Variable Unit Palm Oil 1 Palm OIl 2 Cassava Rice Straw Soybean Humic K-Plus 26 3 Humic Substances 2,01 1,09 - 1,13 - 63,6 Humic Acid 1,57 0,9 - 1,10 - 29,1 Fulvic Acid 0,51 0,2 - 0,30 - 34,5 Organic Acids:: Acetate ppm 56 - 46 94 39 - Citrate ppm 18 - 10 12 16 - Oxsalate ppm 20 - 16 17 22 - Propionate ppm 2 - 4 6 9 - Butirate ppm 1 - Tt 1 Tt - Succinate ppm 21 - 11 16 18 - Fumarate ppm 9 - 21 11 8 - Ketoglutamate ppm 2 - tt tt 1 - pH 8,60 5,50 4,60 7,60 8,70 10,00 Organic-C 0,32 0,12 1,69 0,17 0,17 5,53 CN 23,2 8,1 30,2 15,0 6,8 3,0 CP 37 14 194 39 39 - N 0,01 0,01 0,06 0,01 0,03 1,86 P 2 O 5 0,02 0,02 0,02 0,01 0,01 0,00 Basic Cations: K 2 O 0,11 0,10 0,06 0,06 0,10 29,19 NaO 0,01 0,02 0,02 0,01 0,02 4,66 CaO 0,62 0,62 0,68 0,49 0,92 1,23 MgO 0,13 0,09 0,31 0,13 0,13 0,13 Micro Nutrients and Heavy Metals Variable Unit Palm Oil 1 Palm OIl 2 Cassava Rice Straw Soybean Humic K-Plus 26 3 Fe Ppm 11,0 3,8 68,3 1,3 6,0 9,8 Cu Ppm t u t u t u t u t u t u Zn Ppm 0,75 1,83 9,00 2,38 3,50 6,75 Mn Ppm 298 1012 295 679 834 1272 Mo Ppm 163 87 101 71 121 81 Pb Ppm 0,43 t u t u t u 1,00 9,00 B Ppm 305 203 148 250 314 259 Al Ppm 1,58 1,58 3,15 4,70 t u 3,53 - Not Analyzed; tt Not detected, 1 Source of empty bunches; 2 Source of waste process; 3 Traded Products of Australian Industries Winarso et al., 2009.

3. Results and discussion