Monitoring in Soil Fertility Change in Tung Kula Rong Hai Using Geographic Information Systems

— Tung Kula Rong Hai is a major source of jasmine rice in the northeastern region and is a major source of the country, but its yields are still very low at an average of 2,187-2,500 kg/hectare, compared to rice grown in other regions. The limitations such as drought and floods, because most of the area is located in rainfed area, the soil is low fertility, resulting in lower rice yield. So, in this study, we have monitored changes in soil fertility in rice fields in Tung Kula Rong Hai area to obtain basic information on improving the productivity of jasmine rice, the area has the potential to increase rice yield in Tung Kula Rong Hai area. The soil fertility evaluation was used to assess the Soil Survey Division Method (1980). The five soil chemical properties were determined, organic matter, cation exchange capacity, base saturation, available phosphorus and available potassium. The result of soil fertility evaluation showed that in 2004, most of the area had moderate abundance of 51.23% and low abundance of 37.95%. For the year 2017, Soil fertility in most areas was low at 84.86%, and moderate abundance was 0.50%. The results indicate that fertility of the soils in Tung Kula Rong Hai area is decreasing. This may be due to inadequate soil management methods for example the use of chemical fertilizers may increase. Some chemical fertilizers contain some trace elements in the soil, causing the soil to be more acid. This will reduce the availability of nutrients in the soil or the lack of soil improvement with organic matter, such as the use of manure, compost, or fresh manure. As a result, the soil lacked abundance.