Healthy soil is the foundation for successful crop growth

Soil is often overlooked even though it is the foundation of any successful farming enterprise - grassland or arable. There are over 1000 tonnes in the top six inches of soil on every acre – and it is estimated that it takes over 500 years to produce just one inch of topsoil.

Despite the fact that soil is at the bottom of the food chain, it must be treated as a valuable commodity and cared for just as much as any animal or crop on the farm.

So where do we start with soil? Key to the success of a crop is creating the right conditions that will enable the soil to thrive, break down plant and animal residues, and free up the nutrients needed for healthy plant growth.

Conditioning soil by applying lime is perhaps the single most important action that can be carried out on any farm. This is because it has an impact on a wide range of properties which affect production. Grassland pH in Northern Ireland is well below the target of 6.3 - 6.5, and this has a significant impact on soil structure, grass growth and fertiliser efficiency. Soils are constantly being subject to forces which lower pH, including leaching of calcium by rainfall, effects of nitrogen release from fertilisers, crop demand and decomposition of organic material. The top layers of the soil present the highest level of leaching and the acidification mechanisms are more active in the surface (mineralisation of organic matter, biological activity, acidifying fertiliser etc.) Consequently, the soil acidity is concentrated at the soil surface (0-5cms) where the pH can be as much as one point lower than the soil at the bottom layer (15-20cms). This means the surface pH could be 5.8, and 6.8 at 8 inches.

As an approximate guide 1 kg of CACO3 is required to counteract each kg of nitrogen applied (this varies with the type of nitrogen) or 12kgs of CACO3 for every 1000 gallons of slurry. The best approach is to bring your pH up to the correct level and then apply a high quality liming product like Granucal each year to maintain pH at the optimum level.  Experience on local farms has demonstrated that annual applications of Granucal improve fertiliser efficiency and reduce costs. At a pH of 5.5 - 23% of N, 52% of P and 23% of K is lost; increasing this to 6.0 reduces the losses to 11% of N, 48% of P and 0% of K.

As John White advised in The Farmer’s Handbook, 1952: “To use fertilisers on strongly acid soils without using lime to correct acidity is futile. Liming the soil is like lathering the face before shaving. The face is only being prepared for better shaving in the lathering process. Liming the soil only prepares it for better crop production.” Whilst the handbook is more than a few years old, the message is ever more relevant today! Start by soil sampling now to find out what corrective action must be taken.

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