Effect of POME and other organic wastes on starfruit grown on sand-tailings

Carambola has been traditionally grown on mineral soils as well as mixed-slime found on tin-tailing areas. The use of Palm Oil Mill Effluent (POME) and other organic by-products from both plant and animal origin have enabled carambola to be successfully grown on previously neglected sand tailings. Two sources of organic matter (POME and chicken manures) and 4 levels of NPK compound fertilizer with trace elements were compared in a replicated factorial experiment at MARDI research station, Kundang. Initial results after two years indicated that trees with organic matter (POME) at 60 t/ha yearly + 0.7 kg NPK/plant yearly, were significantly larger in girth than the control (no organic fertilizer added) with only 2.8 kg NPK/plant yearly. This showed that organic matter is important for plant growth on sand tailings. Similarly for yield, trees treated with organic matter gave significantly higher fruit number (at 5 percent) and fruit weight (at 1 percent) as compared to the control. However, there was no significant difference among the NPK treatments (of 0.7, 1.4, 2.1 and 2.8 kg/plant/year) and the two sources of organic matter at this early stage. This indicated that POME can be substituted for chicken manure, an organic source traditionally used by carambola farmers. In the second experiment, four different treatments of organic matter, including oil palm by-products, were tested in the planting hole, together with a control, where no organic matter was added. Plant growth at six months again showed that trees receiving organic matter at planting had significantly larger girth than those untreated. Six of the 12 control trees were randomly selected and rehabilitated at six months by adding organic by-product of empty fruit bunches (EFB) followed by POME every three months. Rehabilitated trees improved in growth and all six trees flowered and set fruit in the second year after planting. Unrehabilitated trees remained poor in growth, and only two of the six trees produced fruits. A comparison between the rehabilitated and unrehabilitated trees showed that the average yield (number of fruits and total fruit weight per tree) was significantly different at the 1 percen