Importance of Soil Aeration in the Growth of Plants

After reading this article you will learn about the importance of soil aeration in the growth of plants.

1. Growth of Plants and the Development of Roots:

The growth of plants are adversely affected by poor aeration namely:

(i) The development of plant roots are restricted or inhibited,

(ii) The absorption of water and nutrients is decreased,

(iii) The formation of toxic substances are encouraged by poor aeration, especially under puddled waterlogged condition in case of rice cultivation.

2. Adaptations of Plant:

The ability of different plant species to grow in soils with low soil air porosity varies greatly. Certain plants such as rice that are adapted to growth without an external source of oxygen for the roots have large internal air spaces. Plants adapted to poor aeration show shallow root system in the upper part of the soil where aeration is greatest.

The roots of plants adapted to growth in aerated soils have been found to carry out some anaerobic respiration if oxygen is deficient, the effects are detrimental. The relatively low rate and energy output of anaerobic respiration and the accumulation of toxic products are perhaps the most important reasons.

In compacted soil the root penetration within the impervious layer is restricted and such restricted root systems are not able to absorb sufficient moisture and nutrients for normal plant growth.

3. Microbial Population and Activity:

Soil aeration influences the activity of soil micro-organisms and also affects the rate of decomposition of organic matter. The poor soil aeration decreases the microbial activity as well as oxidation of organic matter. This decrease may be due to lack of O₂ than with an excess of CO₂.

The different beneficial biological processes carried out by different micro-organisms such as decomposition of organic matter, biological nitrogen fixation, nitrification etc. are largely dependent upon the aeration status of the soil.

All aerobic organisms are unable to function properly in the absence of oxygen in soil. The microbial population, therefore, is drastically affected by soil aeration. Only the anaerobic and facultative organisms function properly in poorly aerated soils.

This is possible owing to their ability to utilize combined oxygen and as a result reduced forms of different elements like iron and manganese are produced as their toxic concentration to plants.

4. Production of Toxic Substances:

Heavy rainfall, excessive irrigation or puddling together with flooding brings about a reduced condition of the soil and subsequently reduction of elements like, Fe and Mn and slow rate or incomplete of decomposition of organic matter will take place in the soil.

Thus production of various organic toxic acids like, lactic, butyric and citric acids etc. and also toxic concentrations of Fe and Mn are found in the anaerobic soil condition, absence of CK Due to production of such toxic substances plant roots get injury and thereby lost their ability to absorb nutrients and water for their growth.

5. Absorption of Water and Nutrients:

Effects of aeration on the uptake of nutrients by plants may result from changes in nutrient availability that occurs in the soil in response to the aeration or they may result from changes in metabolic status of the plants.

The mineralization of nitrogen is generally not affected by the aeration status of the soil whereas the availability of other nutrient elements like phosphorus, iron and manganese are increased by poor aeration due to flooding.

The other micronutrients like Cu and Zn show deficiency under poor aeration (waterlogged) conditions. Poor aeration decreases the uptake of water, as evidenced by the wilted condition of many plants after flooding. The permeability of roots to water decreases under conditions of poor aeration.

6. Incidence of Diseases:

Plant roots and soil borne disease organisms occupy the same environment and respond in characteristic ways to prevailing conditions such as aeration. Changes in aeration may modify the susceptibility of the plant, the virulence of the organism or both, so that disease incidence may vary with conditions of soil aeration.

The effect of aeration has to do mainly with the sensitivity of the disease organism and not the plant. Cereals are moderately tolerant to poor aeration.