Facing the Perfect Storm in the Mediterranean region: Can Organic Agriculture Play a Role by Enhancing Soil Fertility and Adaptation to Energy and Water crises? Results From a 30-years Long-Term Experiment in Tuscany (Italy)

The phrase “Perfect Storm” has been used to describe the future coincidence of food, water and energy insecurity. The current global energy crisis no longer allows the massive use of high energy inputs, such as chemical fertilizers, pesticides and irrigation. Several modelling studies have promoted the idea of organic farming being a viable option to face future adverse scenarios, mostly because of its capacity to achieve satisfying levels of food production while improving soil quality and consuming less resources. In the Mediterranean region, farmers have few technical and agronomical options due to arid conditions, prolonged droughts, scarce levels of water retention, most probably due to low levels of organic matter in soils. Against this background, more insights are needed to enhance soil fertility by exploring alternative methods to high-input conventional agriculture. In this context, there is a compelling need to delve into agronomic practices that can reconnect crop and animal production, thereby enhancing soil chemical, physical, and biological fertility, with cascade effects on agroecosystems productivity and energy use efficiency. The main objective of this Ph.D thesis was to carry out a systemic soil fertility assessment to asses organic and biodynamic agriculture as alternative methods to high-input agriculture in the Montepaldi Long Term Experiment (Italy), the most durable long-term experiment in the Mediterranean region where two arable farming systems — organic and conventional — have been running since 1992. The results of the present thesis showed that yields significantly decreased with time in both organic and conventional systems (about -79% and -37% for spring and winter crops, respectively). This decrease could be attributed to a substantial drop (about -40%) in cumulative rainfall during the vegetative crop cycle and an increase in temperature (+1°C). Organic winter crops constantly yielded about 21% less than the conventional ones while spring crops did not show significant differences. Despite the higher productivity in conventional winter crops, the organic system showed a considerably higher energy use efficiency. For each unit of energy input, the energy output was found to be 33% higher in the organic system for winter crops. Even greater energy use efficiency was observed for spring crops, with a 44% higher efficiency in the organic. Therefore, the organic system undoubtedly exhibited better performance in terms of energy balance. In a country such as Italy, we can reasonably conclude that organic farming is an option to face the “Perfect Storm” in the Mediterranean, since it imports 2/3 of energy demand and cultivates only 12.5 million hectares of UAA as compared to 21.9 millions in the ’60. Moreover, it was found that organically managed soils are more biologically active and less resistant to penetration, which might help farmers in storing more water and plants in reaching deeper layers in the soil profile. Such aspects of organic farming are promising but apparently they are not sufficient in coping with water scarcity. These problems require more advanced research on crop species and varieties more productive under water stress. The very same approach is required for heterogeneous seed material having very diverse characteristics that allow it to evolve and adapt to growing conditions where water supply is restricted.