Participatory research in dryland cropping systems - Monitoring and simulation of soil water and nitrogen in farmers' paddocks in Central Queensland

Abstract

Collaboration of researchers and service-providers with farmers in addressing crop and soil management, using on-farm experiments and cropping system simulation, was negotiated in 2 districts in Central Queensland, Australia. The 2 most influential variables affecting crop productivity in this region (soil water and mineral nitrogen contents) and the growth of sown crops, were monitored and simulated for 3 years beginning in December 1992. Periodic soil sampling of large experimental strips on 3 farms, from paddocks that differed in cropping history and soil properties, provided robust datasets of change, over time, of soil water and mineral nitrogen status. Farmers participated in twice-yearly discussions with researchers, informed by the accumulating data, which influenced thinking about soil behaviour and possible new management strategies. As the study period coincided with a prolonged drought, so that cropping opportunities were few, the objectives of the work were modified to concentrate almost exclusively on the soil variables.
The contribution of the Agricultural Production Systems Simulator, which was used to simulate the measured changes in soil water and mineral nitrogen, was found by all participants to be useful. The APSIM output generally demonstrated close correspondence with field observations, which raised confidence in its applicability to local cropping systems. Exploration of hypothetical situations of interest to farmer participants, in the form of what-if scenarios, provided insights into the behaviour of the production system for a range of soil and seasonal conditions. The informed speculation of the simulator became a substitute for the farmers' own, more tentative, efforts.

The regular participative review sessions proved to be highly effective in stimulating the learning of both farmers and researchers. The farmers were able to feel comfortable as owners of the collaborative experiments and custodians of the learning environment. Clear evidence for the ongoing learning of these farmers appeared in post-collaboration practices and experiences.