Geospatial Status of Available Potassium and Sulphur in Low Base Status Soils

Aim: This study aims to analyse the required parameters to determine the availability of potassium and sulphur in red soils representing low base status soils of Sivagangai block of Sivagangai district, Tamil Nadu.

Study Design: Survey.

Place and Duration of Study: Survey was conducted at Sivagangai block of Sivagangai district, representing the red soils of Tamil Nadu during the winter season of 2021.

Methodology: Geo-referenced surface soil samples representing one hundred red soils were collected from the plough layer (0 to 30 cm depth) at an estimated frequency of 1 km grid over the red soils of Sivaganga block in Tamil Nadu's Sivagangai district using a handheld global positioning system (GPS). The collected samples were processed and analysed for the necessary parameters and based on that data thematic maps were created by kriging the fertility status and then exhibiting the relevant legends.

Result: The physico chemical properties of soils indicated that soils were strongly acidic to acidic in soil reaction, non - saline and low in organic carbon content. The available potassium content of the Sivagangai block ranged from 101 kg ha-1 to 260.5 kg ha-1 with a mean value of 179.4 kg ha-1. When categorised 26 per cent of samples were found low in available potassium content and the remaining 74 per cent of samples were medium. Soil available sulphur status in this block ranged from 3.10 mg kg-1 to 18.20 mg kg-1 with a mean value of 10.65 mg kg-1 indicating that 59 per cent of soil samples were found low in available sulphur status, 39 per cent of soil samples were medium status and 2 per cent of soil samples were under high status.

Conclusion: Using the geocoordinates, thematic maps for all the parameters were prepared, which indicated that the major area of the block was acidic in soil reaction, non-saline, low in organic carbon, low in free calcium carbonate, low to medium in available potassium and low in available sulphur. These maps will be useful in constructing homogenous units and assist farmers in determining the quantity and kind of potassium and sulphur fertiliser to be applied in order to optimize economic returns based on site-specific nutrient management.