On-farm research for efficient organic matter management in low-input farming systems

Summary

This thesis work has the objective to study alternative ways of managing the organic matter in diverse agro-ecosystems, focusing on both quantitative and qualitative aspects.
The effect of several organic matter-based farming practices, that are characteristic of the organic and biodynamic method, on biomass production, productivity, and soil microbial activity has been investigated through a multidisciplinary approach that embraced on-farm trials as well as reductionist greenhouse and laboratory experiments.
The open field trials have been conducted in organic commercial farms in the Marche region and in low inputs small subsistence farms in the African Kingdom of Swaziland. In both cases, the farmers were involved as "partners" in the research, which allowed to get a system perception on the efficacy and feasibility of the investigated techniques, and helped to highlight main constraints in organic matter management.
Over the three years of the PhD study, five experiments were carried out:
 Laboratory experiment to test phytoxocity effect due to diverse organic matters;
 Greenhouse experiment to assess the effect of one biodynamic preparation on the germination of a highly-diversified green manure mixture;
 On-farm research in two biodynamic and organic farm in the Marche region (Italy) to investigate the effect on arable crops productivity and olive growth of diverse combinations of organic matters (qualitative and quantitative);
 Laboratory experiment to investigate the effect of one biodynamic preparation on soil microbial metabolism;
 On-farm research in Swaziland (Africa) to assess alternative organic matter managements in a small-scale subsistence farming system, through a community-based approach.
It is concluded that when low inputs cropping systems have to be performed, the appropriate use and recycling within the farm of organic matter becomes crucial to optimize nutrients flows as well as maintain overall soil fertility at acceptable levels. Highly humified organic matter showed to be quite effective in stimulating soil microbial activity, even in low doses, whereas the practice of "massive" green manuring proved to promote plant production although its feasibility is highly bound to the site characteristics.
The on-farm methodology turned to be useful in formulating applicable research objectives, close to the farmers needs, and to test the field feasibility and adaptability of the technical solutions under the farmers' perspective in two far socio-economic and cultural contexts. However, the inevitable experimental simplification did not allow to achieve highly significant statistical results.