Patcharee Saenjan

Response of methane emissions, redox potential, and pH to eucalyptus biocharand rice straw addition in a paddy soil

This study aims to comprehend the links between soil Eh and pH changes in eucalyptus biochar (BC) and rice straw (RS) amended soils and CH4 emissions. Increased CH4 emission rates and high total CH4 emissions (TCH4) were found in RS soils. In contrast, higher concentrations of refractory lignin, fixed C and volatile matter in BC suppressed C mineralization and terminal methanogenesis, resulting in low TCH4. Eh in RS soils decreased more rapidly than in BC soils during the first phase as a single exponential function. This indicated that RS is a fast electron donor for an instant electron acceptor reduction and methanogenesis. During the second phase, Eh in BC soils decreased to very low values, probably because of the higher concentrations of electron donating phenolic compounds coupled with terminal methanogenesis. Meanwhile, hydrogen is consumed via electron acceptor reduction and methanogenesis simultaneously produce OH corresponded with a rise of pH, a characteristic of reverse single exponential function.

Effect of Rice Straw on Rice Yields, pH, Electrical Conductivity and Bulk Density of Paddy Soil

The objective of this experiment is to study the effect of incorporated rice straw combined with chemical fertilizer (CF, basal with fertilizer 16-16-8, 40 kg/rai and top dressing with urea (46%N), 60 kg/rai) on rice yield, soil bulk density, pH and electrical conductivity. Six treatments with 4 replications in RCBD were laid out. Rice seeds cv. Phatumtani1 were sown. The results showed that plots with incorporated rice straw, 1-4 t/rai, gave rice yield ranged from 660 to 757 kg/rai, which higher than that of the control (283.55 kg/rai). Bulk density of the soil with combination of incorporated rice straw and CF were 1.27-1.17 g/cm, significantly different compared to the control, 1.45 g/cm. Rice straw at all rates with 1 Corresponding author: patsael@kku.ac.th * นกศกษา หลกสตรวทยาศาสตรมหาบณฑต สาขาวชาปฐพศาสตร คณะเกษตรศาสตร มหาวทยาลยขอนแกน ** อาจารย ภาควชาพชศาสตรและทรพยากรการเกษตร คณะเกษตรศาสตร มหาวทยาลยขอนแกน *** รองศาสตราจารย ภาควชาพชศาสตรและทรพยากรการเกษตร คณะเกษตรศาสตร มหาวทยาลยขอนแกน วารสารวจย มข. (บศ.) 13 (2) : เม.ย. ม.ย. 2556 2 chemical fertilizer did not affect soil pH during the growing season, but they increased the soil electrical conductivity (EC) with high significant differences through the growing season. Correlation coefficient (r) between rice straw rates and soil bulk density after growing season was negative significantly, while those between rice straw rates and electrical conductivity and rice yield were positive with very high significance. This experiment concluded that some physical and chemical properties of paddy soil as well as rice yield could be improved by rice straw incorporation. ค�าส�าคญ : ฟางขาว ผลผลตขาว คณสมบตของดน