Grazing management and systems.

In this chapter, it was emphasized that some form of nutrient return is essential to maintain land fertility because nutrients are removed by the grazing animal. The grazing animal returns many of the nutrients that are consumed, but some may be leached from the soil as they are returned at high concentrations. This is particularly true for urine, rather than faeces. If the sward is conserved rather than grazed, more fertilizer, particularly potassium, will have to be applied. This may be as artificial fertilizer or as livestock manures. Particular care is required in the return of livestock manures to the land, to avoid high nutrient applications at times when the rainfall is likely to be high and the soil moisture deficit low. Smearing of the grass can occur, reducing grass growth and the intake by cattle. Some grassland is irrigated to maintain high levels of production. This will increase the predictability of grass growth, but the feasibility will depend on the cost of the water and applying it to the land. Irrigation methods have been improved to be less wasteful of water, but the shortage of water for agricultural and human use has meant that this expensive technique is often reserved for more valuable crops.