01. What is a certified Arborist?
02. Why hire an Arborist?
03. Do my trees need pruning?
04. What trees should I plant?
05. Why is topping a tree bad?
06. How will drought affect my trees?
07. Do I need to water my tree in the winter?
08. Do my trees need fertilizing?
09. What are humic acids?
10. What are Mychorizae?
Do my trees need fertilizing?
The soil environment is a complex of systems working independently as well as in tandem. Urban soils are typically devoid of organic material. This leads to a loss of microbial activity and nutrients essential for productive plant growth. Through the use of humic acids and mychorrizal fungi, the soil biological profile can be restored. Unlike chemical fertilizers, humic acids do not leach away thus continuing to build organic matter with each application. Secondly, there is no risk of burning roots. In fact, the more reduced organic matter the better.
Function of organic matter in the soil:
Organic matter contributes to plant growth through its effect on the physical, chemical, and biological properties of the soil. It has a:
• Nutritional function in that it serves as a source of N, P for plant growth
• Biological function in that it profoundly affects the activities of microflora and microfaunal organisms
• Physical and physico-chemical function in that it promotes good soil structure, improving tilth, aeration and retention of moisture.
• Humus also plays an indirect role in soil through its effect on the uptake of micronutrients by plants. It should be emphasized that the importance of any given factor will vary from one soil to another and will depend upon such environmental conditions as temperature and soil moisture.
Availability of nutrients for plant growth:
Organic matter has both a direct and indirect effect on the availability of nutrients for plant growth. In addition to serving as a source of N, P, S, organic matter influences the supply of nutrients from other sources (for example, organic matter is required as an energy source for N-fixing bacteria).
Effect on soil physical condition, soil buffering and exchange capacity:
Humus has a profound effect on the structure of many soils. The deterioration of structure that accompanies intensive tillage is usually less severe in soils adequately supplied with humus. When humus is lost, soils tend to become hard, compact and cloddy. Aeration, water-holding capacity and permeability are all favorably affected by humus.
The frequent addition of easily decomposable organic residues leads to the synthesis of complex organic compounds that bind soil particles into structural units called aggregates. These aggregates help to maintain a loose, open, granular condition. Water is then better able to infiltrate and percolate downward through the soil. The roots of plants need a continual supply of O2 in order to respire and grow. Large pores permit better exchange of gases between soil and atmosphere.
In terms of ion movement across the root, humic substances are responsible for up to 70% of the exchange capacity in many soils.
Effect on soil biological condition:
Organic matter serves as a source of energy for both macro and microfaunal organisms. Numbers of bacteria, actinomycetes and fungi in the soil are related in a general way to humus content. Earthworms and other faunal organisms are strongly affected by the quantity/quality of plant residue material returned to the soil.
It is widely known that many of the factors influencing the incidence of pathogenic organisms in soil are directly or indirectly influenced by organic matter. For example, biologically active compounds in soil, such as certain phenolic acids, may enhance the ability of plants to resist attack from pathogens and insects.