Organic Farming, Soil Health, and Food Crop Quality: Considering Possible Linkages.

That the health of soils, plants, animals and people are linked is an ancient idea that still resonates. It is known that specific nutrient deficiencies and toxicities can adversely impact plant and animal health. But it is less clear to what extent healthy soils promote plant and animal health. Much of the research in this area has focused on comparing organic with other farming systems. Organic farming systems utilize carbon based amendments, diverse crop rotations, and cover crops to build soil fertility. These practices increase biologically available forms of soil organic matter and increase beneficial soil microbe and invertebrate activities, thereby improving soil physical properties and plant health. Soil organic matter also increases soil cation exchange capacity and acts as a slow release nutrient source, reducing the risk of excess nutrient loss to the environment. To date, comparisons between organic and conventional food crops have been inconclusive. Recent evidence suggests that organically grown fruits and vegetables contain higher levels of health promoting phytochemicals, possibly linked to greater plant stress and lower available N in many organic farming systems. The influence of the environment, training system, crop cultivar, and fertilization in determining produce quality is well known. But the overlap in management practices between farming systems makes broad generalizations difficult, and these issues need consideration when designing studies to determine how soil health impacts food. We offer a concise summary of the known factors influencing soil and plant health and the possible linkages with produce quality and human health, and suggest a way forward for future research.  Examples are drawn primarily from research on organic farming systems but  determining key management practices associated with enhanced soil, plant and human health remains an important goal for all sustainable food production systems.