Mapping Soil-crop Nutrient Dynamics in Continuous Cotton Cultivation Areas of Sangareddy District, Telangana

A soil-crop nutrient survey was conducted in Sangareddy district, Telangana during Rabi, 2023 to study the fertility status of cotton growing soils at 0-15 cm and 15-30 cm depth. Georeferenced soil and leaf samples were collected from 112 sites covering 23 mandals during flowering stage. Soil physical and physico-chemical properties and cotton leaf nutrient content were analysed. In the study area, bulk density, sand, silt and clay content ranged from 1.36-1.66 Mg m-3, 41.84-78.02 %, 6.74-29.60 % and 10.76-42.76 %, respectively. The soils were strongly acidic to slightly alkaline in reaction (4.25-7.98; 4.44-7.97), non-saline (0.026-0.254 dS m-1; 0.020-0.241 dS m-1) and low to high in organic carbon (2.03 to 11.52 g kg-1; 1.13 to 8.24 g kg-1) at 0-15 cm and 15-30 cm depths, respectively.

Soil Nutrient Status: Available nitrogen, phosphorus, potassium and exchangeable magnesium contents ranged from 101 to 448 kg ha-1, 7 to 41 kg ha-1, and 154 to 763 kg ha-1 at 0-15 cm depth, respectively while 91 to 319 kg ha-1, 4 to 39 kg ha-1, and 142 to 730 kg ha-1 at 15-30 cm depth, respectively.

Crop Nutrient Status: Total nitrogen, phosphorus, potassium and magnesium contents in the collected cotton leaves ranged from 0.53 to 3.64 %, 0.12 to 0.68 %, 0.80 to 1.84 % and 0.27 to 0.92 %, respectively.

Soil Fertility Mapping: Soil fertility maps were prepared considering the low/deficient, medium and high/sufficient range of soil macronutrients (N, P, K and Mg) at the depth of 0-15 cm under QGIS 3.36.1. Soil fertility maps showed that soils of the study area were mostly low in available nitrogen, medium in available phosphorus, high in available potassium and sufficient in exchangeable magnesium.

Regular soil testing is crucial to monitor the variations in nutrient levels and formulation of appropriate management strategies to address it.