THE RHIZOSPHERE (MICROBES NEAR ROOTS)
The zone of soil next to plant roots supports a much higher population of microbes than the soil even a short distance away. The number of microbes near the roots (rhizosphere) is 10 to 100 times greater than 1/4" away. The high population of microbes near plant roots is varied in composition and activity. This is the area of greatest digestion of nutrients by microbes. A number of microbes live in a symbiotic relationship with the roots, using as a source of food energy the varied organic substances that the roots exude. These exudates stimulate a variety of microbes to obtain nutrients the plant needs for balanced nutrition.
One of the important factors that influence changes in the microbial populations is the nature of the organic residues on which the microbes feed. Variations in the microbe populations surrounded the roots of different plants are related to the nature of the root exudates and sloughed off root tissues on which the microbes feed. Certain kinds of plants appear to have specific types of microorganisms congregating near their roots. Mutually beneficial nutrient environments, produced by exudates from the plant roots and by-products from the microbes, promote specific associations of root and microbe.
Improvement in crop growth obtained from crop and soil management practices is the result of increased activity of microbes in the vicinity of the plant roots. There is still much unknown in the relationship of roots and microbes because of the complexity of this symbiotic relationship. Vesicular-arbuscular mycorrhizal (VAM) fungi are critically important for virtually all crop plants. Research has shown that the lack of VAM can result in poor plant growth. Most crop fields have adequate VAM spores present if crop residue is placed back into the fields. Intensive pesticide use, fumigation, or intense fertilizer use will reduce VAM so low that plant growth will be in jeopardy. The presence of at least 1 to 5 spores per gram of soil is adequate for most crop fields.
Maintenance of an environment around plant roots which is favorable for the good growth of most microbes will result in increased fertilizer efficiency and higher crop yields.
The zone of soil next to plant roots supports a much higher population of microbes than the soil even a short distance away. The number of microbes near the roots (rhizosphere) is 10 to 100 times greater than 1/4" away. The high population of microbes near plant roots is varied in composition and activity. This is the area of greatest digestion of nutrients by microbes. A number of microbes live in a symbiotic relationship with the roots, using as a source of food energy the varied organic substances that the roots exude. These exudates stimulate a variety of microbes to obtain nutrients the plant needs for balanced nutrition.
One of the important factors that influence changes in the microbial populations is the nature of the organic residues on which the microbes feed. Variations in the microbe populations surrounded the roots of different plants are related to the nature of the root exudates and sloughed off root tissues on which the microbes feed. Certain kinds of plants appear to have specific types of microorganisms congregating near their roots. Mutually beneficial nutrient environments, produced by exudates from the plant roots and by-products from the microbes, promote specific associations of root and microbe.
Improvement in crop growth obtained from crop and soil management practices is the result of increased activity of microbes in the vicinity of the plant roots. There is still much unknown in the relationship of roots and microbes because of the complexity of this symbiotic relationship. Vesicular-arbuscular mycorrhizal (VAM) fungi are critically important for virtually all crop plants. Research has shown that the lack of VAM can result in poor plant growth. Most crop fields have adequate VAM spores present if crop residue is placed back into the fields. Intensive pesticide use, fumigation, or intense fertilizer use will reduce VAM so low that plant growth will be in jeopardy. The presence of at least 1 to 5 spores per gram of soil is adequate for most crop fields.
Maintenance of an environment around plant roots which is favorable for the good growth of most microbes will result in increased fertilizer efficiency and higher crop yields.