Soil organic matter (SOM) plays an important role in determining the land productivity. The effect of rice plant and inorganic fertilizer on the SOM content with time and soil depth in a lowland paddy field was investigated in this study. Two factors (fertilizer: with urea, without urea, and plant: with rice plant, without rice plant) with four treatment combinations were arranged in a randomized complete block design in a low land paddy field at a minor irrigation tank in Kurunagala district in Sri Lanka during the 2013/2014 Maha season. The soil samples were collected at 0 - 8, 8 - 16, 16 - 24 and 24 - 32 cm depths at 27, 43, 65 and 98 days after sowing (DAS) and SOM was measured using a standard method. Data were analyzed as a factorial design. The interaction between fertilizer and soil depth found to be significant (p=0.030). At the depth of 24 - 32 cm, the SOM content was significantly higher without urea than with urea. Fertilizer also showed a significant (p=0.024) interaction with DAS. The SOM content at 43 DAS was higher with urea than without urea while it is reverse at 65 DAS. Therefore, urea application has an influence on SOM content at different depths and time.
Tropical Agricultural Research Vol. 26 (2): 415 – 421 (2015)