Impact of urbanization on agricultural land in Rajanukunte micro watershed, Karnataka

The rapid expansion of urbanization around Bangalore city promotes complex relationships between rural areas and the urban fringe of Rajanukunte (508 ha), with emerging new socio-environmental functions for peri-urban agriculture (PUA). Given the current limitation of methodologies to analyse PUA dynamics, a quantitative approach profiling farm types over 22 years and the related agricultural landscape structure of granitic terrain in an expanding urban region of the Rajanukunte micro watershed in Eastern dry zone of Karnataka, Bangalore city is proposed. The results showed that the land use change over 22 years in the watershed indicates that the area under finger millet reduced annually by 1.48% and agroforestry with 0.42%. Interestingly, the area under grapes and guava increased annually by 0.55 and 0.26%, respectively. Results further indicate that there is increase in application fertilizers use by 67% of nitrogen and 32% of phosphatic fertilizers with one per cent decline in potash from 1980 to 2002. Because of PUA promoting fruit crops of economic value and landscape prominence, the soil acidity was built up in 287.56 ha of 124.91 ha over a period of 22 years with decline in base saturation and soil organic carbon (SOC) in the plough layer. The cost of correcting soil acidity is estimated Rs 218, 802 for the entire watershed at an average cost of Rs 761/ha. Based on economic analysis of peri-urban agriculture, a conservation strategy of preserving agricultural landscape is proposed through the promotion of peri urban farming with high-value fruit crops.