องค์ประกอบของคาร์บอนอินทรีย์และสมบัติของดินภายใต้พืชร่วมยางพาราที่แตกต่างกัน

Abstract

Due to low rubber price problem, various agencies are implementing to find a way to solve the problem. Rubber based intercropping is a way to raise farmer incomes and also increases plant residues to the soil. Addition of the plant residues increased soil organic matter as an indicator of soil fertility. Therefore, physico-chemical properties and the organic carbon composition of soils under different rubber-based intercrops were studied. In addition, the amount of rubber- based intercrop residues return to the soil, biochemical composition, plant nutrient content in plant residues and changes in soil nitrogen (N), phosphorus (P) and organic carbon (C) composition resulting from different rubber-based intercrop residues were also studied. Rubber growing soils were sampled from rubber monoculture, rubber- bamboo, rubber-Hopea odorata (Ta-khian) and rubber-Gnetum gnemon (Phak-liang) to evaluate soil properties and organic carbon composition. The result showed that soil saturated hydraulic conductivity in the rubber-based intercrop growing soils tended to be higher than in the rubber monoculture growing soil. The rubber- Phak-liang growing soils tended to gave the highest primary and secondary macronutrient contents and aliphatic group but tended to be the lowest carboxyl and polysaccharide group. In addition. the amount of plant residue returning to the soil was the highest in the rubber-bamboo plot while the lowest values was recorded in the rubber-Ta-khian plots. However, Phak-liang residue had the highest amount of primary macronutient and C:N, C:P and L:N ratios were the narrowest range. For soil incubation with 3 types of plant residue, the result showed that soil incubation with Phak-liang leaves had the highest amount of N and P release from plant residue affecting to the highest amount of available N and P in soil. In addition, there were relatively high amount of remaining C and decreasing rate of aliphatic group was the lowest. The results from the field and in the laboratory indicates that Phak-liang is an interesting plant to intercrop with rubber for improving soil fertility.