Exploration of Soil Particle Size Diversity and Primary Nutrient Status Across the Rice Productivity Regions of Mahabubnagar, Telangana, India

The current study involved a thorough field survey to assess particle size distribution and the availability of primary nutrients in rabi - grown rice soils (2022 - 2023) across three productivity regions: high (5923 - 6052 kg ha-1), medium (5793 - 5923 kg ha-1), and low (<5793 kg ha-1) in Mahabubnagar district, Telangana. A total of 225 surface soil samples (0 - 15 cm depth), with 75 samples from each productivity region, were collected before the transplanting of rabi rice crop using a stratified random sampling method and are further processed and analysed for soil texture, available nitrogen (Avl. N) available phosphorus (Avl. P) and available potassium (Avl. K). The sand, silt and clay content in high, medium and low productivity regions averaged 52.37%, 55.75%, 57.41%; 17.77%, 15.47%, 16.96% and 29.86%, 28.79%, 25.63% respectively. Low productivity areas had the highest mean sand content, negatively impacting soil particle aggregation thus affecting their rice productivity. Silt and clay content varied in three productivity regions, with the highest variation of clay content in high productivity regions. The respective Avl. N, Avl. P and Avl. K showed mean values of 257.88 kg ha-1, 253.61 kg ha-1 and 240.13 kg ha-1; 59.13 kg ha-1, 55.40 kg ha-1, 54.49 kg ha-1 and 304.96 kg ha-1, 301.25 kg ha-1, 300.19 kg ha-1 in high, medium and low productivity regions. Available N declined from high to medium and medium to low productivity regions. Fluctuations in available P and K showed wide distribution within each category, particularly in case of potassium emphasizing the inclusion of diverse soil conditions and factors influencing potassium availability. This variability study helped in identifying the fertility levels of three regions across the productivity regions.