Soil Fertility and Nutrient Cycling

Abstract

Plant production and nutrient cycling are two of the key functions that intensively farmed soils must perform. Nutrient cycling is the capacity of the soil to provide nutrition for food, fuel and fibre crops that are grown across the landscape. This chapter explores the availability of macronutrients and micronutrients in Irish soils. Overall, the nutrient status of the 11 Great Soil Groups identified in Ireland will have been influenced by agricultural production to some degree. The more intensively farmed and productive soils such as Brown Earths, Brown Podzolics, Luvisols, Alluvial soils, Surface water and Groundwater Gleys are more likely to receive active management by farmers to influence their soil fertility status. Weathering and soil formation processes that place soils in each Great Soil Group category have a major influence on their response to fertiliser and manure additions and also how they maintain their long-term soil fertility status. Of the 16 essential plant nutrients, the primary nutrients—N, P, K and secondary nutrients, sulphur (S), Magnesium (Mg) and calcium (Ca) are required in largest quantities by forages and crops. Total fertiliser use on Irish farms has declined in recent years mainly due to increasing fertiliser costs and regulation of nitrogen and phosphorus use. Crucially, a balance between maintaining soil fertility at optimum levels while minimising nutrient losses to the water and the atmosphere must be achieved.