Soil Aeration Importance & Implementation Tips

What Is Soil Aeration?

The process of soil aeration provides air supply underground by moving O2 and CO2 between the earth pores and the atmosphere. It helps avoid oxygen starvation in crops and reduce harmful carbon dioxide levels in the subsurface air if they rise too high.

Causes Of Poor Soil Aeration

To ensure proper aeration of soil, it is critical to outline what affects it. Thus, farmers understand how to implement it and mitigate negative consequences. The factors affecting soil aeration include:

• soil moisture;
• soil texture;
• infiltration properties;
• machinery traffic;
• organic matter application;
• use for grazing, etc.

These factors may lead to soil compaction, excessive carbon dioxide content, and poor oxygen saturation.

Soil Compaction

In most cases, poor soil aeration is caused by compaction. The finer the earth, the more prone it is to compaction. The smaller its particles, the more densely they attach to each other, leaving less space for oxygen. Denied oxygen, neither plants nor aerobic earth biota can survive. Compaction may be an adverse consequence of irrational irrigation and other field operations.

Waterlogging

Irrespective of whether it is induced by natural forces or anthropogenic factors, waterlogging tampers with soil aeration. After downpours, floods, or excessive irrigation, water fills up the earth’s pore space, displacing the air and reducing the oxygen level nearly to zero. Roughly speaking, the air can’t penetrate the earth when the room is occupied with water. However, when it dries up again, the balance is restored. Water evaporates, and the air gets back to earth.

Soil Organic Matter

Organic matter boosts soil fertility. Nonetheless, the decomposition of organic matter involves a strong carbon dioxide release. Correspondingly, when organic matter content is too high, the production of CO2 may be too fast. Consequently, its removal slows down and may reach toxic levels. Another point is that carbon dioxide retention also interferes with oxygen supply, which the plant roots rely on and are supposed to get in the process of the earth and atmospheric air exchange. This is why it is necessary to add organic matter moderately or in an already decomposed state.

Grazing With Livestock

Grazing practices contribute to soil fertility with organic manure. However, trotting around the pasture, animals also cause soil compaction with their hoofs if they stay too long in the same area. In this regard, rotational pastures prove to be an efficient problem solution.

Regular Vehicular Traffic

Heavy machinery compresses farmlands, thus also leading to compaction. For this reason, the movement of massive field equipment like forage harvesters, manure spreaders, etc., should be limited, and treatment frequency wisely reduced. The situation gets even worse when the earth is wet ^{Stephen Davies, Derk Bakker, Jeremy Lemon. The science of soil compaction. Department of Primary Industries and Regional Development's Agriculture and Food division.}.

Soil Aeration Methods

The aim of soil aeration is to supply oxygen to the topsoil to make it available for crop roots and earth microorganisms. Aeration also makes the topsoil softer and improves its infiltration properties. It is carried out with a number of methods, each of which depends on the area scope and land specifics.

Actually, the radical approach suggests removing the land cover and restarting it. However, it is not always feasible, to say nothing of the costs and efforts applied. Aeration of soil is a far better solution. In this case, its standard techniques include spike, plug (core), and liquid aeration.

Spike Aeration

The spike aeration method produces the least land disturbance by making holes for the air to penetrate. However, it embraces a relatively small area due to limited coverage of applicable tools, which include soil aeration shoes, prongs, rollers, and mower attachments. They all contain spikes for earth piercing. The first three options imply walking or manual operations, by pushing or rolling. On the one hand, they are the least sophisticated. On the other hand, they require considerable physical strength. Mower attachments demand less human efforts since they are adjusted to machinery.

Core Aeration

The core soil aeration method addresses “cores” or “plugs”, which is especially relevant for compacted clay soils. Cores consist of clay, roots, thatch, etc., in the topsoil layer. Unlike the previous method, it suggests not piercing the earth but pulling its parts out, leaving them on the surface.

Core aeration makes the field somewhat messy yet has certain advantages. The benefits of soil core aeration comprise:

• enhanced gaseous exchange;
• intensified oxygen saturation to the root zone;
• raised water infiltration;
• improved earth structure;
• incorporated organic matter.

Core-removing soil aeration equipment includes manual aerators and mower attachments.

Liquid Aeration

The previous methods work with the soil directly, but liquid applications contribute to aeration differently. Liquid aerators consist of a wetting agent and nourishment for earth-dwelling biota.

Wetting agents improve infiltration, and water reaches deeper levels of the soil profile. It enables microorganisms to dig deeper, too. By digging, they improve soil aeration and allow water to seep even lower as well, which boosts root development.

Furthermore, liquid aerators contain food for bacteria (mainly seaweed extract) to boost their activity. In its turn, this is beneficial for worms that move underground adding to earth porosity. It helps air and water penetrate farther through the prepared “ways”. Besides, worms and insects process organic matter, boosting soil fertility.

Why Tillage Is Not The Best Option For Aeration

Tilling is the most intensive earth disturbance that implies digging, turning it upside down, and breaking huge parts into smaller pieces. Obviously, tilling operations reduce compaction and enhance oxygen supply, but they are helpful in the short run only. The adverse effects of heavy earth disturbance make its repeated implementation a dubious and unjustified practice:

• disrupted soil health due to risks of wind and water erosion;
  
• destroyed beneficial microorganisms (however, tillage also impacts pests and their larvae as part of integrated pest control);
  
• uncovered weed seeds from the subsurface layers (yet, at the same time, tillage places the seeds from the surface underground and destroys weeds, being a mechanical method of integrated weed management);
  
• polluted atmosphere with fossil fuel emissions from tilling machinery (which contributes to climate change).

Assistance Of EOSDA Crop Monitoring

Although one cannot observe poor soil aeration directly, it will definitely impact field productivity. The EOSDA Crop Monitoring zoning feature allows farmers to track it by generating productivity maps. Growers can also compare them in the long run to understand if the crops are still healthy. If they are not, it may be due to a lack of required nutrients and favorable soil structure. Then, they can assign scouting tasks through the crop health monitoring system to inspect the situation properly. It is ultimately beneficial for farmers who practice no-till. It is crucial for clay farmland owners, as this soil type is highly prone to compaction. They can monitor the crop state and outline different field zones depending on vegetation levels. This way they will be able to estimate their field’s productivity.

Also, as decreased soil aeration depends on the moisture level in the ground, it is necessary to maintain the optimal moisture content. EOSDA Crop Monitoring enables farmers to track moisture in the root zone and surface zone (5-cm topsoil). The product displays the analytics of the selected period with several consequent curves and other data:

• vegetation index of your interest (NDVI, NDRE, MSAVI, ReCl) or moisture index NDMI;
• root-zone and surface moisture;
• stages of plant growth;
• precipitation.

Why Is Soil Aeration Important?

The availability of nutrients for crops immediately relates to the degree of soil aeration. Well-aerated soils provide more favorable growth conditions, while nutrient imbalance and poor aeration impede plant development.

The impact of soil aeration on nutrient supply is as follows:

• Nitrogen. Organic nitrogen fixation and mineralization are carried out with nitrogen-fixing plants (especially legumes), organic matter, and livestock wastes. Organic nitrogen is reduced to plant-digestible forms by aerobic bacteria that can function properly only under sufficient soil aeration. Poor aeration induces a split of nitrates to nitrous oxide (N2O), which is among the potent gases contributing to the greenhouse effect. Besides, denitrifying bacteria are more likely to deprive crops of nitrates in poor earths. This happens because most denitrifying bacteria are facultative aerobic. It means that when O2 is available, they will use it (aerobic respiration). When the O2 level is poor, they will switch to NO3 or NO2 (anaerobic respiration).
  
• Manganese and iron have high valence in well-aerated soils and low valence in poorly-aerated ones. Although plants can consume only low-valency forms, their excessive absorption is harmful to crops. For this reason, excessive access to low-valency forms must be limited, and toxicity risks are mitigated with aeration.
  
• Sulfur is represented by sulfate in aerated soils, which is suitable for plants. Sulfate turns into sulfide under poor aeration (waterlogging), and hydrogen sulfide is harmful to crops, too.

Nutrient imbalance results in the deviance of root formation, which will inevitably affect the whole plant and cause yield losses. Signs of poor aeration include thick, short, dark roots of abnormal shapes, poorly developed hairs, etc.

Another important disadvantage of insufficient aeration is higher crop susceptibility to pathogens and root-rotting fungi, in particular. Correspondingly, aeration becomes an effective prevention technique, decreasing crop and tree disease risks.

The aforementioned factors reveal different perspectives of soil aeration importance. Understanding its necessity and proper implementation time is easier with online farming tools. Request a demo and see what you can do with EOSDA Crop Monitoring in your fields.