11:00 〜 13:00
[AGE30-P05] Improving red-soil in Thailand by mixing natural latex
キーワード：タイ、赤土、ラテックス、団粒化、土壌流亡
In Thailand, red soils are widely distributed, but they are not suitable for agriculture because they are poor in nutrients and hard. The conversion of forest land to agricultural land started in the 1960s, which made soil runoff more likely. It would be beneficial if the physical properties of the soil could be improved to increase its suitability for agriculture and its durability against soil erosion. In this study, the effects of latex on soil permeability and water holding capacity were examined by mixing latex produced from Para rubber tree, which is widely cultivated in Thailand.
The test samples were prepared by mixing 0.01, 0.05, and 0.10 w/w% of latex in red soil from Thailand that passed through a 2-mm sieve. Each sample was packed into a PVC pipe (I.D. 5.6 cm, H 30 cm) to 20 cm-depth. The artificial rainfall of 2 and 20 mm/h was applied to the soil, 40 and 4 hours, respectively, and the infiltration process was monitored by soil moisture sensor at 3 and 15 cm-depth. After the rainfall, soil moisture was measured continuously in an incubator at 35°C to observe the evaporation process.
The results showed that volumetric water content at 15 cm-depth increased faster in the latex-mixed soil than in the soil alone, and also increased faster in the soil if with a higher percentage of latex. All the artificial rainfall was retained in the soil in the soil-only case, but some of it drained from the latex-mixed soil. In response to evaporation, the latex-mixed soil decreased in volumetric water content faster than the soil-only soil, and the volumetric water content at the end of the evaporation was higher in the soil-only case than in the latex-mixed soil. Observation of the soil with a stereomicroscope showed that the formation of aggregates was enhanced, and the increase in coarse pores led to an increase in water permeability, but not in water holding capacity. It showed that the latex was effective in preventing soil erosion, but it is also desirable to improve the water holding capacity.
The test samples were prepared by mixing 0.01, 0.05, and 0.10 w/w% of latex in red soil from Thailand that passed through a 2-mm sieve. Each sample was packed into a PVC pipe (I.D. 5.6 cm, H 30 cm) to 20 cm-depth. The artificial rainfall of 2 and 20 mm/h was applied to the soil, 40 and 4 hours, respectively, and the infiltration process was monitored by soil moisture sensor at 3 and 15 cm-depth. After the rainfall, soil moisture was measured continuously in an incubator at 35°C to observe the evaporation process.
The results showed that volumetric water content at 15 cm-depth increased faster in the latex-mixed soil than in the soil alone, and also increased faster in the soil if with a higher percentage of latex. All the artificial rainfall was retained in the soil in the soil-only case, but some of it drained from the latex-mixed soil. In response to evaporation, the latex-mixed soil decreased in volumetric water content faster than the soil-only soil, and the volumetric water content at the end of the evaporation was higher in the soil-only case than in the latex-mixed soil. Observation of the soil with a stereomicroscope showed that the formation of aggregates was enhanced, and the increase in coarse pores led to an increase in water permeability, but not in water holding capacity. It showed that the latex was effective in preventing soil erosion, but it is also desirable to improve the water holding capacity.