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Soil is not only the substrate on which plants grow, it also plays a crucial role in nourishing and protecting plants. A distinction is made between the soil (inorganic material that forms the basis of everything) and the humus layer (organic material that is constantly replenished by dying plant parts or continuously consumed by microorganisms and soil organisms) that usually lies above it.

Some of the most common soil types found in Europe with their essential characteristics:

  1. Loamy and clay soil
    • Properties: Clay soil is fine-grained and sticky when wet. It is significantly denser than sandy soil and holds water extremely well.
    • Advantages: It retains nutrients and water well, making it very fertile unless the water is stagnant (which leads to anaerobic conditions in the soil, killing off the important microorganisms and microbes).
    • Disadvantages: It can be difficult to work, especially when wet, and it tends to get cold in winter (sensitive plants will freeze) and hard in summer when dry, which hinders root development. These are soils on which water often remains standing for a long time after rainfall, large cracks can form and stay.
    • Use: Clay soil is good for moisture-loving plants; high-sugar grasses for example which are undesirable for horses to eat. Clay soil can and should be improved by adding compost or sand to improve the structure so that it becomes looser (=better root penetration) and suffers less from waterlogging when it rains. If you want to use this type of soil as a winter turn out area, it is essential to gravel it up and ideally also reinforce it with paddock slabs.
  2. Silty soil
    • Properties: Silty soil feels soft and is finer than sand, but coarser than clay. It is more permeable than clay and at the same time holds moisture better than sand.
    • Advantages: It is fertile and easier to work than clay soil.
    • Disadvantages: Can compact when overwatered and harden in dry conditions, therefore requires constant maintenance, and suffers particularly when being trampled on by horses.
    • Utilisation: Suitable for most agricultural crops, i.e. grasses with medium nutritional values, good management practices to maintain soil health are required. Well suited for hay production, if the land is grazed, it is essential to remove the horses frequently so that the soil can air itself and recover, soil impaction will occur otherwise.
  3. Sandy soil
    • Properties: Sandy soil is coarse-grained and loose. It has a high permeability, which means that water flows through it quickly, there is always sufficient oxygen for soil life and there is hardly any waterlogging.
    • Advantages: It warms up quickly in spring and is easy to work with.
    • Disadvantages: It retains water and nutrients poorly, which can lead to frequent water or nutrient deficiencies for plants, especially during prolonged dry periods.
    • Use: Ideal for plants that prefer well-drained soils, such as many bulbous plants and root vegetables, as well as mainly lean grasses and herbs adapted to dry locations, i.e. low-nutrient forage for horses. When used as a winter turn out area, the manure should be removed frequently, as otherwise the droppings will clog the openings in the ground between the grains of sand, leading to waterlogging in the long run.
  4. Gravel soil
    • Properties: Consists mainly of gravel and has a very coarse stone structure.
    • Advantages: Excellent drainage, practically no waterlogging, as the pebbles are too coarse to be completely clogged by organic material (e.g. horse manure).
    • Disadvantages: Low in nutrients and dries out quickly. Difficult to work, as the stones quickly dull the tools. Building up humus is therefore often very difficult, especially at the beginning.
    • Use: Without humus build-up, hardly anything of value for horse usage grows on gravel soils. Once a good humus layer and appropriate vegetation have been built up, these soils are well suited for grazing, but they must be well maintained, otherwise the humus will quickly erode again.
  5. Peat soil
    • Characteristics: Peat soil is the result of wet meadows or bogs where standing water over centuries has ensured that a layer of decayed organic material, sometimes several meters thick, has formed which has not really decomposed due to a lack of oxygen and low pH values, giving it its dark colour. Even today, the pH value is generally acidic due to the high proportion of humic acids. Peat soil consists almost exclusively of organic material, which enables it to store immense amounts of water.
    • Advantages: Very high-water storage capacity and rich in nutrients, peat soil is one of the most fertile soils and is often found in the alluvial areas (floodplains) of rivers or lakes or where the groundwater table practically reaches the surface.
    • Disadvantages: Usually acidic, which is why sour grasses, sedges and similar lean plants grow, although the vegetation is lush (in contrast to sandy soil, where the plants always tend to look dried out and barren due to the lack of water). Due to its high-water content, it can only be used as a hay meadow or pasture in dry summers, as the machines sink in, or the horses’ hooves destroy the sward in damp conditions.
    • Utilisation: Peaty soil can be found wherever there are or were wet meadows or moors, as the areas have often been drained over the last two hundred years by digging drainage ditches. Very suitable for horses as pasture or hay meadows, as the vegetation is often low in sugar, but can only be used in dry weather, which means that it can often only be used as pasture for a few weeks or months of the year.

Optimising soil types

Each soil type can be optimised by specific measures such as adding compost or other organic material as well as other soil-improving measures to improve the conditions for plant growth. All too often, however, there are changing soil conditions, even within the same field. For example, areas where the water always remains standing after long periods of rainfall, areas where the plants are particularly green and lush in summer compared to the rest of the vegetation or corners where plants grow that favour particularly warm and dry or particularly moist or cool locations (‘indicator plants’).

Knowing your own soil type helps you to select suitable grass and herbal plants that suit each location to plan the best cultivation methods for the respective soil, the result will be a very equine suitable and enjoyable meadow pasture also for hay making.

Soil sample is taken for soil analysis
Before applying seed or fertiliser to the pasture, it is essential to carry out a soil analysis. This is the only way to get an overview of the soil’s nutrient supply and coordinate further measures accordingly. © Adobe Stock / AlDa.videophoto

Why a soil analysis is so important

The basis for soil improvement is always a soil analysis. The aim is to find out what the soil needs so that it is suitable for providing the plants, that have been chosen to grow for the horses, with the correct location and conditions to optimise the nutrients supply.

So before you sow expensive seed that doesn’t take off or wonder why these or those undesirable plants such as sugar-rich ryegrass or poisonous buttercups always come back on the land, you first have to understand what the soil actually offers in terms of possibilities for vegetation.

It is not dissimilar as to going to see the doctor, a prior examination will determine which type of mediation suits certain conditions? Firstly, a statues overview clarifying the type of soil you are dealing with and what the most suitable management would be is therefore advisable.

The supply situation of the soil

As the soils, as described, have different nutrient binding abilities, the measured values must be categorised for the existing soil type. The laboratory therefore assigns each individual measured value a so-called supply or content level. These levels describe the supply status for each individual nutrient:

Grade A: acute shortage

Grade B: moderate supply

Grade C: optimal supply

Grade D: slightly oversupplied

Grade E: too much

For our horse pastures, we aim for a value at the lower end of supply level C, because ‘too much’ usually ends up meaning too many nutrients that will grow in this soil and therefore end up ‘oversupplying’ the horses.

The right fertiliser

Particularly with fertilisers containing several nutrients, such as manure, compost or mineral NPK fertilisers, it is important to ensure that the individual nutrients are not over-fertilised, which can lead to imbalances in the soil and ultimately in the plants and thus in the horse.

The next challenge is that not all nutrients are needed in equal amounts. This results in a similar situation to the composition of feed rations: if I ‘overfeed’ my soil with a nutrient that it does not need, this not only creates costs that are unnecessary, but can also lead to problems in cultivation and plant development that are not wanted, having an impact on the nutritional value that is consumed by the grazing horses further down the line.

On the contrary, all expensive nutrients bought are useless if only one important nutrient is missing or deficient, which is required to fulfil the task.
For example, if it is persistently dry, all the minerals applied as fertiliser cannot be utilised until it rains again, meanwhile they just sit on the soil not doing much. In the worst case scenario if we then get an abandon amount of rain they will get washed away before the plant can absorb them.

This doesn’t just apply to water. If, for example, phosphorus is the only nutrient in my soil that is deficient, the growth of the plant will be orientated towards the amount of phosphorus present. This is known as ‘the law of the minimum’.

The cycle of nature?

As we remove nutrients from the soil every year by using it as pasture, hay meadow or arable land, we have to replace this removal so that the plants can thrive in the long term. In nature, grazing animals leave behind their faeces, with all the nutrients they contain, as they graze over an area. The faeces are decomposed, and the nutrients are washed into the soil, which are then available to the plants for renewed growth.
Nature has created a cycle in which the nutrients that are extracted, are returned to the land in a slightly different form.

Unfortunately, this cycle does not always work with modern farming methods and legal requirements, so that we have to make adjustments to ensure that the soil remains healthy and productive. If you want to optimise your soil through targeted fertilisation, you have to make sure when calculating the requirements for each individual nutrient that it is not too much and not too little.

Unfortunately, very few of the feed recommendations offered in this day in age are guided by the requirements that are suited to horses.
More often than not, the recommendations are suited to high-performance pastures that will fatten up dairy cattle to supply the milk or meat industry. Obesity, laminitis and similar diseases are sadly the consequences when harvesting the raw material for either hay making or for feed productions.

Conclusion

For that reason, it is important to have a good understanding of the soil you are dealing with: Which type is prevalent on which pasture? This give information provides a helpful guidance as to what directions is most helpful to take in regard to the nutrients. The soil analysis will provide additional information such as

  • Selecting the right seed to provide the horses with a healthy pasture
  • manage the pasture according to its need (‘not too much, not too little’)
  • keep fertiliser costs manageable as they are strictly adapted to requirements

The soil is your ‘silent co-worker ’, make sure you keep it happy.

Helmut Muß
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