Assessment of Quantitative Land Evaluation Methods and Suitability Mapping for Cotton Growing Soils of Nagpur District

The cotton growing soils of Nagpur district have been mapped according to their suitability classes based on modified Riquier's criteria developed from farmers' yield and Requier's productivity index correlations, derived from the attributes of soil survey information at 1:50,000 scale. While correlating between index and cotton lint yield, it was found that Riquier's parametric index shows the high correlation (r=0.85), whereas Sys method yields poor correlation (r=0.42), indicating that Riquier's method is more meaningful when reconnaissance soil survey data are utilized for land evaluation study for cotton, although, the Sys's land evaluation method utilizes many crop specific parameters. The modified criteria-based land suitability map depicts that 57.5% of the area is high suitable, 28.5% of area is moderately suitable and 5% of area is marginally suitable and 9% of area is unsuitable. Therefore, the cotton technology should be implemented in highly suitable and moderately suitable areas and the rest of the area may be diverted to other arable crops. The Riquier's index and yield has also been modeled and found that the cotton yield is related to the Riquier's index by geometric function, y=ax^bx where y=lint cotton yield (kg ha⁻¹), x = index, a = 126.75, b=0.0020, r=0.99.