Soil Element Assessment in Organic Paddy Fields in the Thung Kula Ronghai Zone, Thailand

Abstract

Organic rice production (ORP) has been promoted as a means of sustaining both farmers and the ecology of paddy fields, so this research aims to evaluate soil properties and soil elements in the ORP and general rice production (GRP) systems in the Thung Kula Ronghai (TKR) zone in Thailand. Soil samples were collected in Roi-et province from fields classified as ORP (5 fields) or GRP (4 fields), and interviews were also conducted with the field owner about rice yield and rice production. Data from the ORP and GRP groups were compared by t-test, and soil enhancement practices were measured by one-way analysis of variance (ANOVA) for variances. Results indicate there were 14 indicators of soil element control in the TKR. All indicators in the ORP and GRP systems were lower than the rate in soil that is suitable for rice production. The macroelement content in the TKR zone was total nitrogen > total potassium > phosphorus available at a ratio of 338: 3: 1, and the soil organic matter (SOM)/soil organic carbon (SOC) ratio is about 3.45. The soil improvement techniques used in the ORP systems—manure only and manure combined with green manure—have a higher pH value (p < 0.05) than the fertilizer only input but a lower TK value (p < 0.05) than the fertilizer only input. As a result, the ORP yield was higher than that of the GRP systems (p < 0.05), greatly affecting farmers’ practices.