A seven step process is proposed for the assessment, management and conservation of soil biodiversity (Figure 1) in which all the different stakeholders, especially farmers, are involved in each step (adapted from Chambers, 1991; Swift, 1997).

In the past soil quality assessments focused on chemical and physical properties and complex classifications and soil survey/testing procedures were developed requiring high level soil science expertise. Reflecting increased attention to ecological principles and to human management considerations, several minimum data sets for assessing soil and environmental quality have been proposed (see e.g., Doran and Jones, 1996). These generally include a characterization of the current farming system and practices of different farmer groups, including human resources (labour, time, socio-cultural habits), available organic resources (manures, household wastes, leaves, wood and other residues, composts) and biological indicators of soil quality and function. The most useful bioindicators associated with soil function, and the ones that are easiest to measure, are those consisting of plants, soil organisms and their processes (Pankhurst et al., 1997). Data on indicative values of different soil organisms and processes for various agroecosystems and sites and in both temperate and tropical regions would be very valuable to allow effective assessments of the current ‘health status’ and trends within an agroecosystem.

It is essential that the stakeholders involved determine how the different limitations to agricultural production and sustainability can be overcome using local or imported resources, knowledge and capacity. The limitations or constraints may include social, cultural, economic, political, agronomic, biological, environmental, edaphic and/or genetic factors. They will vary from one group of farmers to another. In addition, in determining best soil biological management options, and other solutions to overcome constraints, adequate knowledge is required of how agricultural practices (e.g., tillage, pesticides, fertilizers, liming, rotation, residue disposal, irrigation, drainage) affect soil biota and their activity.

A hierarchical organization of the limitations or constraints to soil biological management and the potential options to overcome these constraints (adapted to the local human, climate, soil and agro-ecosystem conditions) can be developed. This would guide farmers and land use decision makers to the potential practices that can be adopted or changed.

Swift (1999) proposed a series of potential entry points at which management practices could be improved (Figure 2). These include both direct interventions such as: inoculation for disease and pest control and soil fertility improvement (such as. rhizobia, actinomycetes, mycorrhizae, diazotrophs) and indirect interventions through, for example, cropping system design and management, organic matter management, genetic control of soil function (manipulating resistance to disease, organic matter and root exudates).

After choosing a number of different possible solutions, these must be tested on-farm, using an iterative and participatory screening process through adaptive experimentation. In this adaptive process, different treatments and techniques are tested simultaneously, and repeated over several cropping cycles to identify the most resistant, economic, practical and socially acceptable practices. The Tropical Soil Biology and Fertility Programme (TSBF, 2000) offers an interesting approach to the adaptive management of soil biological processes, emphasizing an iterative, cooperative interaction between farmers, extension agents, local community facilitators, and scientists. Their approach consists in:

• Extensive farm site characterizations to identify various ecological, social, economic and cultural constraints, as well as to define opportunities for intervention (Steps 3 and 4 above);
• Participatory design and implementation of on-farm and off-farm experiments;
• Evaluation of results and sharing of experiences by participants;
• Feedback of results and experiences in order to design further experiments, to refine databases, models and predictions, and to develop new technologies;
• Introduction of new technologies into on-farm testing after a satisfactory number of iterations of the above process.

Once the long-term productivity and sustainability trends of the potential biological management interventions have been assessed through participatory research, and the non-compatible options have been revealed (and discarded), the stakeholders in the decision-making process must select the appropriate technologies for implementation at various levels. The feasibility of each management option should be evaluated and adapted according to local agricultural, edaphic, climatic, socioeconomic and cultural conditions. The success of this process depends on the ability of the farmers and other stakeholders to discern the best management strategies and to eliminate any potential loop-holes that may lead to future failure in the adopted practices. These include assuring the appropriate incentives for, and compensation of, any opportunity costs or other losses associated with the practices to be adopted.

A major point to recognize is that the final decision of the stakeholder groups as to which practices are to be implemented will be substantially different for small-scale versus large-scale farmers, and for resource-poor versus resource-rich farmers. This is because of the inherent differences in the problems and priorities of each group. Once the best solutions have been identified by each group of stakeholders, these should be taken to the final step of implementation and further long-term testing.

The final adoption of the best practices for integrated soil biological management is a long-term process, resulting from the assessment, learning, identification, prioritization, choice, testing, adaptation, participation, discussion, agreement and decision of the best management options (following the six steps outlined above). A final selection process occurs, as the farmers evaluate the best choices in the field, and decide whether to implement these practices on larger and long-term scales, or to revert to their traditional management strategies. This is a critical step, where the hard work of carefully following the previous steps is often at risk of being permanently lost. To ensure wider adoption of the best adapted soil biological and associated management techniques, appropriate incentive measures and long-term monitoring are required, so that the improvements in agricultural production and human wellbeing can be efectively demonstrated and sustained.

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