Got waterlogged grassland?  To function as a growing environment, the soil needs to contain 25 per cent air and 25 per cent water. The air is essential for microbial respiration and the water is essential to allow the dissolved nutrients to move from the soil into the plant root hairs.

Paddocks this year certainly contain too much water! And, also consider that 25mm of rain per acre exerts 110 tons of pressure on the soil, squeezing the air and life out.

Soil borne microorganisms are crucial for the fabrication of healthy productive grass, and they will struggle to breathe underwater. These bacteria and fungi have a symbiotic relationship with the plant that benefits both species. Allowing air back in will stimulate their productivity and speed up the repair of the sward.

The bacteria stimulate the production of plant growth promoting hormones which rapidly boost the plants natural defence mechanisms. The boosted natural defence mechanisms will also generate a plant with a stronger constitution better able to withstand the vagaries of the British weather and recover faster.

What to do about waterlogged soils

1 Knife aerate the soil
As soon as the soil is firm enough to allow a quadbike or small tractor to travel on it, knife aerate the soil (see below). This speeds up the rate of water evaporation from the soil and the air that enters the soil significantly speeds up sward recovery. Virtually all soil will benefit from this activity this year.

Knife aerator

2 Aerate with a chain harrow
Once the grassland is firm and dry enough to travel on without damaging the sward, aerate with a chain harrow or modern equivalent. This activity will always be the most cost-effective sward management strategy that could be implemented, as the benefit of scratching the soil surface is that a chemical reaction occurs resulting in a small quantity of nitrogen being extracted from the atmosphere and placed directly into the root zone stimulating growth.

3 Introduce grass species
When the soil starts to warm up and recover in the spring, but still remains damp, incorporate appropriate grass species into the sward, and especially:

Sheep’s Fescue Festuca ovina.
This fescue has the unique ability to generate its own mycorrhizal activity in the soil and therefore flourish in nutritionally poor soil conditions. Not only does it thrive, but the other grass species in the sward become healthier and more prolific because of this innovation.

Timothy Phleum pratense
Provides ‘early bite’ in the spring and a ‘late bite’ in the autumn as it is a cool weather grass and grows before other species in the spring, and after them in the autumn. Timothy also grows a deep root that penetrates to over a metre, which significantly helps with sward viability.

Cocksfoot Dactylis Glomerata
This is an extremely hardy native British species, which has developed the extraordinary ability to withstand challenging environments. Very deep rooting, and therefore tolerant of the adverse British weather conditions and maintains sward viability. It also provides energy throughout the peak demand from the horses.

4 Sample soil
Ensure that soil is sampled, and appropriate fertiliser is applied.

Phosphate (P) – Phosphate stimulates root growth and protein production.

Magnesium (Mg) – Magnesium regulates the uptake of Phosphorous; structural component of ribosomes; major constituent of chlorophyll production; and plays a crucial part in transforming sugar and starch within the plant to utilisable energy. Magnesium is also a crucial component of nerve and muscle function in all creatures. Hence animals that are short of this nutrient tend to be hyperactive and unpredictable.

Calcium (Ca) – Calcium is an integral part of all cells, and the major constituent of the middle lamella which is formed during cell division. Obviously also required for bone development, Calcium plays a significant role in muscle contractions, and a shortage will lead to cramp. In extreme cases the autonomous peristaltic function within the gut can stall, with dire consequences.

Potash (K) – Potash drives Transpiration The movement of dissolved nutrients in water (sap) up the plant to sites of utilisation

Boron (B) – Also ensure that your horses have access to an appropriate supply of Boron to maintain hoof health while paddocks dry out. Not only does Boron help maintain hoof health, but promoting a healthy foot will help reduce laminitis incidents too.

Got waterlogged grassland? Get in touch with Lordington Park Agronomy
for help renovating your soil.