Grass has long been recognised by farmers as the cheapest feed-source available for grazing animals. Through the improvement of grassland management practices, the quality and availability of grazed grass can be increased and feed costs lowered. Getting horses to eat more grass throughout the year can cut costs by reducing the need for hay, haylage and concentrate feeds. Improvements in grassland management are not just for larger stud farms or livery yards to consider, they can also be implemented on smaller blocks of land.

Low levels of growth occur up until early April, after which grass growth continues to increase, until it peaks in mid-May with upwards of 80kg dry matter (DM)/ha growing per day. Grass growth then slows down, but there is a second, lower peak of about 60kg DM/day in early August, followed by a rapid decline until growth almost ceases in mid-November. There is little grass growth over the winter months.

Soil Fertility

Standard soil analysis includes a test for the levels of the major nutrients phosphorus (P) and potassium (K), and soil pH and lime requirement. The results can be converted into a soil index level to simplify fertilizer planning. Low fertility soils are classified as index I (very low) or index II (low). The optimum index level is index III (medium), while index IV soils are high and will be productive without additional P or K fertilizer. It is recommended to have soils sampled at least every five years. There is no soil test for nitrogen (N).

Soil pH

Irish soils tend to be acidic and can produce poor quality grass as a result. Liming is the principal way of neutralising this acidity. The optimum pH for grassland soil is 6.3. Lime should be applied to manage the soil pH and the rate of lime application can be determined by soil analysis.

Lime will also provide a source of calcium (Ca) for the grass. Be careful not to over-lime as it can cause trace element imbalances in the soil. Where lime requirements are greater than 7.5t/ha (3t/ac), apply 7.5t/ha initially and then apply the remainder after two years. Lime can be spread all year round. Apply to bare swards if possible.

Only 34% of soil samples coming through Teagasc, from horse enterprises, between 2007 and 2013 had a soil pH > 6.2, indicating that a substantial proportion of soils would respond to an application of lime.

P & K

The optimum soil index for P and K is index III (Medium). Approximately half the soils coming through Teagasc from horse farms show soil P and K levels that are very low (index I) or low (index II). These soils would respond to fertiliser P and K. The fertiliser P and K advice for index III soils is normally based on replacing offtakes. However, since offtakes in horse systems are usually very low, very little P and K is required. Higher rates are advised for index I and index II soils as these low fertility soils would benefit from higher rates of fertilisers. Advice for hay is higher than for grazing.

Nitrogen

Nitrogen is the main driver of grass production on the farm. High rates of nitrogen application used on the more intensive dairy and beef farms is not appropriate for horses, as grass rich in nitrogen can cause digestive problems.

If significant amounts of grass are required in March, April and May, apply 20kg/ha to 30kg/ha of N early in spring. In normal summers, when temperatures are high, there should be enough N in the soil to allow sufficient growth. If growth is poor, 20kg/ha to 30kg/ha can be applied during the summer to increase grass growth.

Getting the balance right

It is important to consider if the composition of the grass in a given paddock will maximise the productivity and quality available for the grazing horse. Botanical composition tends to reflect soil fertility and site conditions. Permanent perennial ryegrass dominant paddocks are invariably in fertile situations and on most farms newly reseeded paddocks tend to receive relatively high inputs of fertilisers, or other manures, to sustain their productivity.

Perennial ryegrass is by far the most productive grass, if paddocks appear to be unproductive or have a high proportion of non-perennial ryegrass species consideration should be given to reseeding these paddocks. To ensure that paddocks are productive and remain perennial ryegrass dominant, a nitrogen fertilisation programmeshould be put in place. The first application of nitrogen should be applied in early spring to ensure that grass growth is kick-started. Regular top-ups should be applied during the year to ensure that sufficient grass is grown.