Impovement of Latex Quality Using Locally-Produced Organic Fertilizer From Sewage Sludges in a Rubber Processing

Abstract

Most rubber plants in Indonesia are cultivated in highly-weathered soils; therefore, their annual productions have been relatively low with low quality latex as well. Therefore, some measures must be taken. The aim of this reseach was to increase latex quality from a rubber plantation in low fertility soils using a locally-produced organic fertilizer (LOF). This research consisted of two steps: LOF production and a field fertilization experiment. The LOF was made mainly from wastes materials from a latex processing industry. The field study was to assess the effects of LOF additions enriched with two micronutrients, using a randomized complete block design with 6 LOF levels, 4 soil fertility levels, and 5 rubber trees in each block, resulting in 120 rubber trees. The LOF level were 0, 10, 20, 30, 40, and 50 kgtree-1. The LOF contained 17.35% organic-C, 1.14% total N, 0.53 ppm available P, 1.21 cmol (+)kg-1 echangeable K, and was slightly alkaline (pH 8.0). The soil had low fertility i.e low total N and exchangeable bases (K, Na, and Mg), and very acid (pH 4,5). Variables of quality of latex comprising blockage index, ash-, impurity-, and dry latex-content were observed. Although there were no significant differences in most observed latex variables due to LOF addition, their values tended to be higher when the rubber trees were fertilized