The Real Wealth of the Land
Conventional agricultural practice is tailored toward the production of monocultures of various plants and to the concentration of large numbers of animals in small areas in search of efficiency of production. This reliance on monocultures plus common production practices such as pesticide use and tillage greatly reduces the number of kinds of plants, animals and microorganisms present onthe land and in the soil. This lack of biological diversity in the production units sets the scene for a large number of the problems encountered in modern agriculture since simple communities of plants and animals are inherently unstable. The constant onslaught of weeds, diseases and pest animals that plague the modern farm or ranch are nothing more than nature’s efforts to put in place those organisms needed to reestablish a functioning community of plants and animals that uses and reuses all of the available resources of water, energy, minerals and space while wasting none of them. Encouraging biodiversity is the only way to promote production that is sustainable and both financially and ecologically stable.
There are no monocultures in nature for the reason that no single species of plant can utilize all of the resources of water, sunlight and mineral nutrients that are available in an area over the course of a year. Nature abhors wasted resources and left alone will fill all empty ecological niches with life that is adapted to that particular set of environmental conditions. These special adaptations include the obvious such as: the ability of legumes and rhizobia bacteria to symbiotically fix nitrogen in low nitrogen soils or that some plants are adapted to warm season growth and some adapted to the cool season so that sunlight is converted to biological energy over long periods of time. There is also a multitude of less apparent traits such as the ability of some forbs to concentrate certain minerals that are in short supply, the ability of tap rooted plants to break hard pans and bring unused deep soil profiles into the system and the ability of mycorrizial fungi to multiply the effective root system of plants. There are organisms capable of surviving under any set of environmental circumstances found on Earth and, simply by existing, each of these organisms improves conditions for the whole soil-plant-animal complex.
There are no junk organisms; there are just organisms able to function in a particular set of circumstances. Large numbers of the plants we label weeds, the microorganisms we label diseases and the animals we label pests are not of themselves problems but rather they are, in high concentration, symptoms of deeper problems in the health of our local environment. In many, perhaps most, cases, these problems arise from a lack of complexity in the local system. In highly complex systems, one species of organisms seldom reaches populations high enough to be considered a pest species due to competition from other species. Plants and animals that are noxious in high concentrations are valuable to the system when present in lower concentrations. In a pasture sward that is seventy percent ragweed, the ragweed is properly named but if the sward contains only .5 percent, the ragweed becomes a valuable member of the community providing soil improvement, forage and feed for birds and other small animals. Grasshoppers are excellent sources of protein for a wide range of animals and increase the rate of nutrients cycling in the system by digesting fibrous plant material; they become pests only when conditions allow their population to explode. Weeds become plentiful not because weed seed is present but because the conditions of the vegetative sward and the conditions of the soil fit the special abilities of the weeds and thus favor the growth of weeds over the growth of more desirable plants. Examples of such conditions include bare ground, low soil organic matter content, mineral nutrients lacking or tied up, compacted soil layers, lack of plant diversity and continuous exposure to defoliation. The conditions that favor the explosion of pest species are, with some rare exceptions, brought about by how the land is managed; the hallmark of the good manager is the ability to understand the total and long term effects of management practices. In most cases, understanding is gained by applying a practice and then monitoring the results over time but with thought, it is possible to predict the effects of practices without having to actually apply them.
If the goal is a productive and stable landscape, then any practice that reduces the effectiveness of the water cycle, reduces the quantity or cycling rate of nutrients being cycled or reduces the amount of energy flowing through the system is likely not a good choice. Simplifying the system by reducing the number of species present brings about all of these deleterious effects in the long-term. Conventional agriculture stresses increasing production near term and short-term financial effects (cash flow) as decision-making criteria. While these are important considerations, they do not rate over riding importance when dealing with a complex enterprise such as agriculture, which has financial, ecological and sociological components. For a decision to be valid, it must be beneficial to all three of these components. Many common agricultural practices offer short-term benefits that must be paid for with long-term costs; this is particularly true of practices aimed at killing pest organisms such as weeds, insects and predators. If the practice is effective in reducing the numbers of the targeted species, it is certain to reduce the complexity of the system by reducing the number of species present and thus set the scene for even worse outbreaks of pest organisms. Insecticides can be used to kill insect pests on plants but they will at the same time kill the insect predators that control pests. Since predators always reproduce at a slower rate than do their prey species, the population of the pest prey species is free to explode and over time the problem has been made worse not better. Herbicides to control weeds have much the same effect for different reasons. In plant communities there is strong competition among plants for moisture, sunlight, mineral nutrients and favorable germination sites plus pressure from diseases and plant eating animals. In a plant community simplified by herbicides many of the plants present are competing for resources using a very similar set of abilities so that some resources are over taxed while others go unused. The unused resources are wasted as far as the conversion of solar energy to biological energy is concerned so that the amount of energy available to the entire system is reduced as complexity decreases. As the number of species is reduced, the number of individuals within a species population increases. The concentration of large numbers of the same species allows disease, parasite and predator organisms of the species to flourish, which creates a very unstable situation with the species prone to wide swings in population with periodic catastrophic population die offs.
Biological capital is biodiversity plus the long-term effects of having biodiversity; it is soil with high organic content that has excellent tilth and structure and holds a lot of its’ mineral content in organic form, it is diverse and healthy populations of plants and animals both in and on the soil made up of healthy individuals. Biological capital is what allows the ecological processes; water cycle, nutrient cycle and energy flow to function properly and it provides a system of natural checks and balances that limits the populations of pest organisms. It is wealth in the truest form and is vital not only to agriculture but to society as a whole. When biodiversity is high through out the entire soil-plant-animal complex, both productivity and stability will be high. Weeds, disease, parasites and pest organisms of all types will still be present but not in concentrations high enough to interfere with the functions of the local environment or those of the humans living in the environment.
2005 ã Walt Davis