Land suitability, water balance and agricultural technology as a Geographic-Technological Index to support regional planning and economic studies

Land suitability, water balance and agricultural technological inputs are important characteristics of the soil as a natural resource and can play a significant role in the agricultural production and productivity. Based on these characteristics, a Geographic and Technological Index, the GeoTec Index, is proposed in order to help detecting regional agricultural income inequalities and also to be used as a geographic variable in economic studies. The GeoTec Index is built as a weighted average of three sub indices, namely, Land Suitability, Hydrological and Technological Indices. The Land Suitability Index is based on the agricultural suitability or the aptitude of a given land to support a defined agricultural use. The Hydrological Index (HyI) is based on a water balance which determines the potential and actual amounts of evapotranspiration and water surplus, or excess of precipitation over evapotranspiration, and corresponds to a number that represents either the annual soil water excesses or deficits. And the Technological Index is the sum of several sub indices, based on technological inputs used in the agriculture, such as soil conservation practices, farmer’s technical assistance, use of soil fertilizers and correctives, presence of electric power, use of pest and disease control and use of irrigation. The Geographic and Technological Index (GeoTec) is a combination of the Land Suitability, Hydrological and Technological Indices and it is calculated with data from Minas Gerais State, Brazil, for the period of 1990–2001. The criterion for the regional subdivision of Minas Gerais State was the one proposed by the Brazilian Institute of Geography and Statistics (IBGE), which divides the state into 66 micro regions. The highest values of GeoTec Index are obtained at micro regions of the most developed part of the state, whereas the lowest values of the GeoTec Index are found in micro regions located in the poorest part of Minas Gerais State. There was a strong and positive relationship between the GeoTec Index and the productivity of grains and, at the same time, there is a strong negative relationship between the GeoTec Index and the percentage of poor people in Minas Gerais State micro regions. The GeoTec Index can be a powerful instrument for detecting regional inequalities and to implement public policies as an attempt to decrease the agricultural income disparities among regions.