Use nature for better soil and crops


The ninth annual Tri-State Conservation Tillage Conference was Jan. 24 at the Radisson Inn in West Middlesex, Pa. This conference attracts crop and livestock producers and crop consultants from New York, Ohio and Pennsylvania.
The 2006 conference featured Jill Clapperton, distinguished rhizosphere ecologist at the Agriculture and Agri-Food Canada Lethbridge Research Center in Lethbridge, Alberta, Canada.
Clapperton is an internationally respected researcher and lecturer on soil biology and ecology. Her research group addresses the activities of soil organisms and how they affect the cycling and availability of nutrients to crops, disease cycles, weed management, soil tilth and erosion potential. They also study how soil management practices influence soil biological activity.
The following are some of the principles and concepts Clapperton presented, along with her conclusions about their practical application in efficient crop production.
Real dirt. Living in the soil are plant roots, viruses, bacteria, fungi, protozoa, algae, mites, nematodes, worms, ants, maggots and other insects and insect larvae (grubs) and larger animals.
Along with climate, these organisms are responsible for the decay of organic matter and cycling of both macro- and micro-nutrients back into forms plants can use.
Microorganisms such as bacteria and fungi use carbon, nitrogen and other nutrients in organic matter. Microscopic soil animals such as protozoa, amoebae, nematodes, and mites feed on the organic matter, fungi, bacteria and each other.
Together, these activities – known as the soil food-web – stabilize soil aggregates, building a better soil habitat and improving soil structure, tilth and productivity.
Biology is better. Soil organisms affect soil fertility and the productivity of the soil/micro-flora/plant systems we use to produce crops.
Soil biological processes are responsible for approximately 75 percent of the available nitrogen and about 65 percent of the available phosphorus in the soil.
Plants can take up and use nutrients made available through biological processes more easily and efficiently than raw nutrients provided by chemical fertilizers. In fact, soil fertility is largely dependent on the processing of organic residues or soil organic matter through the soil food-web.
Clapperton showed photomicrographs of the intimate interconnections between plant roots and certain fungi that greatly enhance crop nutrient uptake from soil.
Management, environment. Some fields are far more productive than others with the same soil because farm management practices, such as crop rotations, tillage, fallow, irrigation and nutrient inputs can all affect the population and diversity of soil organisms, and in turn, soil quality.
These practices, and the effects they have on soil organisms, will also influence the health of the environment on and around farms, and on a broader scale.
Studies have shown that soil bacteria and fungi regulate the destruction of toxic environmental pollutants such as nitrous oxides and methane (greenhouse gases), and some pesticides.
Though the incorporation of nitrogen-rich crop residues or cover crops can contribute to soil erosion and the draining of nitrogen into ground or drainage water, leaving the residue on the soil surface over winter may reduce surface runoff and retain more of the residue nitrogen for future crops.
This could have positive effects on regional and global carbon and nitrogen budgets, sustained productivity and environmental quality.
Systems. Soil microorganisms, particularly fungi, form intimate relationships with plant roots, greatly affecting the ability of plants to absorb and use nutrients.
Larger soil animals such as earthworms, when present in large numbers, dramatically affect soil permeability, structure and the distribution of nutrients throughout the soil profile. They also greatly influence the speed at which residues are broken down to release nutrients back into the soil to become available again to microbes and plants.
In soils containing large numbers of earthworms, residues actually disappear from the soil surface several times faster than in soils with no earthworms.
Tillage. Management practices such as tillage, which affect the placement and incorporation of residues, can make it harder or easier for soil organisms responsible for cycling nutrients because they can affect the numbers, diversity and functioning of the living soil organisms, which in turn affects the establishment, growth and nutrient content of crops grown.
No-till soils are more biologically active and biologically diverse, have higher nutrient loading capacities, release nutrients more gradually and continuously, and have better soil structure than reduced-tilled or cultivated soils. No-tillage dramatically increases the population and diversity of soil animals, particularly soil mites that feed on fungi.
Under no-till, residue is primarily decomposed by fungi that accumulate nitrogen in their hyphae. In response, the population of fungal feeding mites increases rapidly, using some of the nitrogen from the fungi and releasing the remainder into the soil to be used by plants and other organisms.
Rotations. The benefits of diversified crop rotations together with reduced tillage and especially no-till, can dramatically increase soil productivity while reducing off-farm costs.
The residual benefits of nitrogen from legumes, for example, can persist for several years.
Soils that have grown cover crops have been shown to have larger and more diverse populations of microorganisms compared to soils with manure soils.
Scientists also speculate that a more diverse soil community results in a more flexible soil, able to successfully grow a wider variety of crops and better withstand drought, low nutrient conditions and soil disturbances such as tillage.
Conclusions. According to Clapperton, creating a soil habitat is the first step to managing soil biological properties for long-term soil quality and productivity.
This means using soil management practices that reduce soil disturbance, managing weeds and diseases with crop rotation, mixed cropping, under-seeding, and using compost and composted manure.
Keep in mind that soil is a living, breathing and ever-changing thing. The potential exists to manage and use soil properties more effectively to produce nutritious food at less environmental cost
Clapperton contact. For more information on Clapperton’s work, contact Clapperton at 403-317-2221 or Lethbridge Research Center, P.O. Box 3000, Lethbridge, Alberta, T1J 4B1, Canada.
(The author is an agricultural extension educator in Columbiana County. Questions or comments can be sent in care of Farm and Dairy, P.O. Box 38, Salem, OH 44460.)

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