The learning cycles approach using facilitated participative action-learning processes and simple tools in a co-learning environment proved highly successful. The approach, plus the treatments tested, made farmers more aware of threats to sustainability and indicated the factors they saw as important in sustainability. Perhaps more important, by showing farmers that innovations can increase returns and reduce risk it appears to have made them more amenable to changing their practices.
In India, some of the promising treatments (e.g. applying farmyard manure (FYM), crop residues and mulches, the use of soil cover crops and intercrops) have potential for multifaceted actions - to protect soil and improve infiltration, to reduce runoff and erosion, and to slow the decline of soil organic matter and to improve crop nutrition. While it is unlikely that the needed quantities of FYM would ever be available in view of the declining cattle population, there is a need for farmers to be more aware of how to optimise returns from limited FYM, as well as how to use other sources of organic matter. On-farm composting of farm wastes could be an option to generate FYM; however composting processes need to be designed to optimise nutrient levels. Similarly, alternative strategies to produce green leaf for soil cover in a way that is economical and does not compete with crops are in need of development to replicate this technology.
Yet another useful outcome of the soil management experiments was the demonstration of the effectiveness of conservation furrows - an intervention quite feasible for farmers, needing no external inputs and economically beneficial while conserving soil and water. Large plot experiments on a watershed scale are needed to further assess this technology.
Although generally known, the advantages of intercropping systems like castor plus green gram with favourable canopy characteristics at Hyderabad, mixed pulses with groundnut at Anantapur and sunhemp incorporation at Bijapur came out into sharp focus through the current experiments. Their effectiveness was strengthened by the cost-benefit analysis. Such interventions involve moderate additional costs but give worthwhile returns and have tremendous scope for relatively quick large-scale adoption.
The rates of soil erosion were relatively low and sediment analysis showed that the erosion processes on the Alfisols differed from those on Vertisols. However, on both soil types erosion processes preferentially strip the finer, more nutrient-rich fraction, as well as organic matter and related nutrients, from surface soil. This finding shows that erosion may be considerably more harmful than the bulk soil loss rates indicate and highlight the need for further research, not just on erosion processes but also on nutrient management. The data collected also allowed an assessment of rainfall use efficiency as an index of how well soil and crop management provided the inputs needed to turn water into crop yield. This was affected by the type of season and rainfall distribution but some of the differences between sites and years showed scope for further research to increase yield potential.
The Ferrosols in North Queensland had high erosion rates under the bare conditions, which may occur in some cropping cycles. However grass pastures substantially reduced runoff, soil and nutrient loss and the timing of cultivation for crops such as early-season potatoes should be carefully considered by farmers. There was a little difference between reduced tillage and conventional tillage in terms of production and measured soil and nutrient losses, which was surprising but may reflect some of the climatic conditions during the course of the project. Calibration of the systems model PERFECT and the subsequent long-term predictions based on historical weather data showed that some cropping systems are more sustainable. The offsite impacts of these systems are of particular interest in north Queensland, because water quality issues in the Great Barrier Reef lagoon are a major public concern.
The Conservation Cropping Group in North Queensland evaluated a number of learning tools as part of its ongoing learning. These included runoff water sampling, decision support packages and soil water workshops. The group recognised that these tools were a valuable aid to their understanding, but still needed to establish clear linkages to farm profitability. Members gathered valuable ideas for the development of participative on-farm experiments.