We often see the word bio-diversity in the media, especially used in debates about genetic engineering and in defence of endangered species. Bio-diversity has a very wide scope including grave matters surrounding the future of the planet, but also in the practical matters of farming. Let us define bio-diversity and see how it fits into your organic farm plan.
Bio-diversity simply means genetic variety in terms of different unique species in an ecosystem and different strains within a given species. The contrary would imply inbreeding within a species and the elimination of species from nature's complex mosaic. We know what that means. Among humans, we do not mate among immediate family and cousins. To do so would greatly increase the risk of congenital diseases.
We see pure bred races of pets developing blindness, deafness and other problems because of inbreeding. For this reason, farmers usually change the male in a herd every two years. On a broader scale, variety within a species increases its strength and ability to adapt to and survive changes in its environment, including pressure from predators, competitors, parasites, diseases, etc.
Diversity between species ensures a balance of nature. We remember our high school biology class! Nature will balance itself through the food change as long as there is diversity. Diversity in an ecosystem ensures that predators and prey manage their population levels and all species compete for limited space and food. If we remove a link in the food chain, then there will be starvation and over-population on either side of the missing link. This applies to both the large mammal predators and to the microscopic soil life.
I observed through a microscope the reproduction of a fusarium fungus. In an empty space, the fungus grew until the whole space was occupied. In another case, two different fungus species were growing in the same space, When they touched, they stopped progressing in that region. Hence, bio-diversity ensures a balance between good critters and bad critters. They all compete for space and nutrients and often live a predator-prey relationship. No one pest can normally become dominant and emerge as a disease. The risk of a disease is minimal but not zero as a human or an environmental impact can disrupt this balance and give an opportunity for a pest to dominate.
I understand what a scientist must do to cultivate and study a pest. He/she must sanitise the designated space to eliminate competition and predators. Then we need a steady, reliable and attractive food supply for the pest. What do we do in agriculture? We clean the field to eliminate competition for the crop. Then we mono-crop corn. And we wonder why we have corn borer problems! The same companies who sold us the pesticide in the first place then come back to sell us more pesticides and now genetically engineered crops at a higher price.
Organic farmers manage and promote diversity within their ecosystem. They avoid mono-cropping and intensive livestock production as this attracts abundant pests and diseases. Multiple livestock and crop species with sufficient space and good conditions will spread out the workload, reduce pest populations and promote good health. This will reduce the impact in the unlikely event of a problem knowing that the farmer cannot fall back on pesticides and antibiotics, and thus spread out the risk and the cost in case of a crop failure or a market failure of any one product.
Organic farmers maintain fence and tree lines to provide a habitat for birds and beneficial insects in order to prey upon nuisance insects. In the soil, diversity ensures an optimum nutrient cycle with the decomposition of crop and animal residues. It also favours the productive symbiosis between soil life and plant life. Cover crops provide nutrients to the soil organisms while competing with and smothering weeds.
Therefore, an organic farmer will maintain pest and disease populations below dangerous thresholds by promoting life and diversity with crop rotations, compost, cover crops, green manure, appropriate PH levels, natural habitats, mixed farms and especially by avoiding toxic inputs. The challenge is to get out of a vicious cycle of dependency on inputs and develop a beneficial cycle of bio-diversity.
A contribution by Tom Manley
President of Homestead Organics