Field investigation of soil organic carbon and soil respiration rate from paddy cultivation area of Alor Senibong Kedah, Malaysia

This study investigated soil organic carbon content and soil respiration rate under two different fertilization treatments (NPK and NPK+HTOC) from paddy plots in Alor Senibong, Langgar, Kedah. Three paddy plots were identical in soil properties, developed to cultivate rice, were adjacent to each other to follow the conventional agricultural practice. The study area was experienced with soft clay soil problem that result in soil became less fertile. Thus, increasing soil organic carbon had an important key in improving soil fertility for better crop yield. Soil organic carbon could be enhanced by organic soil amendment application like HTOC (Hasil Tani Organic Compound). Soil samples were collected in the topsoil (0-20 cm), while soil respiration rate was measured by EGM-4 system linked to a cylindrical soil respiration chamber SRC-1 (diameter 10 cm; height 15 cm) in two season sampling. The results of the both practices have been inter–compared. For the NPK+HTOC plots, the soil organic carbon was high in the range from 40.12±0.07 g kg−1 to 43.87±0.06 g kg−1 and the respiration rate was the highest with 0.57±0.13 g m−2 hr−1 as compared to the NPK plots. Soil organic carbon content was a significant positively correlated to soil respiration rate (R2=0.8002). The results indicated that the use of HTOC or organic amendment in this study gave the positive effects on increasing soil organic carbon and maintaining soil fertility in paddy soil.