I-A01: Soil and water quality in agricultural systems along the rural-urban interface

Project Summary

Bangalore is a rapidly expanding metropolis which heavily depends on the surrounding rural areas for supply of food, vegetables, and other services. As in other Asian cities this has led to the widespread replacement of diverse dryland farming systems by intensive irrigated vegetable production on open lands at the city fringe and even within the city. The consequences of such changes in traditional Indian farming systems on the organic matter status, nutrient dynamics, and ultimately soil productivity are largely unknown. In recent years studies across India have indicated a decline in the organic matter status as a result of reduced application of organic manures. Negative organic carbon balances may affect the soils’ ability to timely supply N, P, K, and S at critical crop stages and to buffer macro- and micro-nutrient imbalances / deficiencies. On the other side increased use of urban compost and sewage sludge in urban areas may contribute to addition of micronutrients while at the same time contributing to surface water contamination. While there is evidence that S, Zn, and B have become yield-limiting in many Indian soils (Sudhir et al., 2002; Ramakrishna Parama and Munawery, 2012), very little is known about the effects of changes in land use intensity on micro-nutrient availability in the State of Karnataka.

This project therefore addresses transformation-related changes in the intensity of agricultural production systems by analysing their effects on (i) the organic matter status, (ii) plant macro- and micro-nutrient availability, and (iii) surface water quality of soils along the rural-urban interface of Bangalore. To achieve its objectives, soil and water samples will be taken in close cooperation with the DFG-funded FOR2432 on rainfed and irrigated on-station fields at UAS, on 36 selected farmer fields, and in relevant surfaces water sources along two rural-urban transects. The obtained data will complement the investigations of carbon and nutrient dynamics and of soil physical and chemical properties collected in projects A01, C01, and C02 of FOR2432 along the rural-urban transect. This will give new insights into regulating mechanisms of nutrient dynamics in rapidly changing agro-ecosystems of the target environment.