Vol. 12, Special Issue 8 (2023)

Author(s):
Sowjanya TV, Yadav OS, Sujaina M, Bidari BI, Indhumathi P and Pushpalatha M

Abstract:
This study investigates the soil fertility status of Bt cotton cultivated fields in Dharwad district of north Karnataka. The cultivation of Bt cotton in Dharwad districts involves diverse soil types. This field survey conducted during the kharif season of 2021-22 aimed to examine the chemical attributes, nutrient levels of Bt cotton cultivated fields in these region. A total of 97 sites were chosen across Dharwad districts. Soil properties such as pH, electrical conductivity (EC), free lime and organic carbon contents ranged from 6.67 to 8.80, 0.16 to 0.67 dS m^-1, 5.56 to 18.49% and 1.50 to 11.56 g kg^-1 with a mean value of 7.90, 0.38 dS m^-1, 11.57% and 6.30 g kg^-1, respectively. Among the essential nutrients, available nitrogen, phosphorus (P₂O₅), potassium (K₂O), and sulphur content in cotton fields' soils spanned from 120.56 - 562.82, 12.54 - 85.88, 110.76 - 497.28 kg ha^-1 and 5.67 - 23.53 mg kg^-1, with a mean value of 290.03, 41.41, 291.46 kg ha^-1 and 15.20 mg kg^-1, respectively. Likewise, exchangeable calcium ranged from 10.10 to 35.24 cmol (p+) kg^-1 and magnesium ranged from 3.36 to 16.44 cmol (p+) kg^-1. The average iron and zinc (DTPA extractable) content, as well as available boron contents in soil was 5.05, 0.60 and 0.43 mg kg^-1, respectively. The wide range of values observed underscores the need for tailored soil management practices to optimize Bt cotton productivity in this region.