Abstract:
Rice (Oryza sativa L.) is one of the main crops in Sri Lanka. Currently,
rice farming in Sri Lanka is highly dependent on external inputs such as fertilizers
and pesticides. However, many studies have revealed that long-term use of chemical
inputs negatively impacts soil health. Organic farming is considered a feasible alter-
native to overcome these negative consequences. Hence, this field experiment was
conducted to investigate and compare the soil characteristics in continuously grown
paddy in an organic input system over the last three years (2019, 2020, and 2022 Yala
seasons) at the research field, Faculty of Agriculture, Rajarata University of Sri
Lanka. Soil samples were collected from the surface (0-15 cm) and subsurface (15-
30 cm) soil just before land preparation in an organic input system with three repli-
cates. Soil nutrient levels were studied using standard analytical procedures. Data
analysis was done using mixed procedure of SAS 9.0 version. Soil pH and cation
exchange capacity (CEC) were not significantly different (P>0.05) among two depths
while significantly different (P<0.05) across three rice growing seasons. Soil organic
matter content and microbial biomass carbon were significantly greater (P<0.05) in
the 2020 and 2022 Yala seasons. Also aforementioned parameters were significantly
greater (P<0.05) at surface soil compared to the subsurface soil. Soil organic matter
content, organic carbon and CEC have increased with time. Therefore, it can be con-
cluded that continuous application of organic fertilizers has improved soil health and
sustained soil fertility in the rice-grown Alfisols in Sri Lanka. Hence the findings
could be applied into rice grown in Tank Cascade Syetems in the dry zone of Sri
Lanka
