Macronutrients include nitrogen, phosphorus, potassium, calcium, magnesium and sulphur, while the micronutrients are minerals such as boron, chlorine, copper, iron, manganese, molybdenum, zinc, nickel, cobalt, iodine and selenium.
Each nutrient has an effect on grass production and the health and development of the horses that graze on the pasture.
A laboratory analysis of your soil can identify which nutrients are deficient -- information that can be used to make fertiliser and liming recommendations.
In general, soil pH can range between 3.0 and 8.0 but the optimum pH is between 6.0 and 7.0. Outside this optimum level nutrient availability and microbial activity in the soil are affected.
Where nutrients are deficient, the land can be fertilised with organic manure from the farmyard or bagged chemical manures.
Organic manures are generally preferred for horse pasture because they release nutrients over a longer period, and at a slower rate, than chemical fertiliser, which tends to produce a rapid burst of grass growth. Organic manure also helps to improve the soil texture over time.
Laboratory analysis of the forage from the paddock can also be used to give an accurate profile of the nutrients available and deficiencies in the grass.
Not only will this analysis help you to balance your horse's feed correctly but it could also help you to cut the cost of your feed budget. Grass is the most economic feed available, so efficient use of your grass can help to reduce the overall feed bill.
"There are several essential grassland management tools for horse owners," explains Fiona.
"Topping is essential during the growing season and should start from mid-May to maintain quality.
"Harrowing helps to spread manure, levels the ground and lifts dead grass.
"Rolling is effective for poached ground but should only be used when required."
Mixed grazing of cattle and sheep with horses helps to manage the roughs and plains that are typical of horse paddocks because cattle and sheep will eat grass that horses leave behind.
Spiking can be used to prevent shallow compaction of the soil, and direct drilling or broadcasting of new seed around poached or over-grazed areas can renew the pasture.
Ploughing is a last resort for horse-sick pastures and fields with excessive ragwort.
Weed management is the bane of a horse owner's life but Fiona insists that good grass cover suppresses weed growth.
Docks are a sign of soils with high nitrogen contents, while buttercups are indicative of poor drainage. Topping pastures before weeds shed their seeds is essential to prevent further infestation.
Ragwort, of course, is in a category of its own, being both persistent and poisonous. The entire plant must be pulled before going to seed, and burned away from the field.
So what species of grass are ideal for horses?
The answer is a range of grasses quite different to those preferred by cattle. Grasses such as red fescue, cocksfoot, meadow grasses, rested dogs tail, timothy, ryegrass and white clover can be used.
Herbs should also be used in the mixture, ideally a mixture of dandelion, yarrow, reword plantain, chicory and burnet.
Maintaining good grass covers requires rotation and closed periods, according to Fiona.
"Close certain paddocks in October to November for spring grazing," she advises.
"Poor grass cover will lead to poaching and a slower recovery period, and an open cover is an opportunity for weeds.
"Owners should identify winter/summer paddocks. Paddocks require a three to five-week recovery period after tight grazing during the growing season. Winter rotations can be less frequent. A good idea is to increase the size of winter paddocks to help maintain a good grass cover."
She also advocates the use of an all-weather paddock or feeding area where horses can be turned out or fed, without affecting the grazing paddocks.
"To summarise, the key points for quality pasture are to maintain a good grass cover, regular topping, mixed grazing, rotation of paddocks and soil fertility and pH," the grassland expert concludes.