Impact of Livestock on Soil

Impacts of livestock on soil fall into two main categories, the physical impact and a chemical and biological impact. The physical impact results from the pressure on and disturbance to the soil as the animals move around. The chemical and biological impact are the result of the faeces and urine that the animals deposit on the soil. Physically damaged soil can be even more susceptible to the chemical and biological impact of faeces and urine.

Physical Impact Chemical / Biological Impact

Physical Impact

Heavy livestock such as cattle compact soil structure and destroy vegetation on parts of a field that they move over most often. This is easily seen around drinking water troughs, entrances to fields and other parts of any area of land where the animals tend to congregate. Destruction of soil structure in this way is known as 'poaching'. Lighter livestock such as sheep and goats have less of an impact on the soil structure. Compacted soil becomes more dense making it more difficult for new shoots to penetrate the soil and emerge. Soil in such areas is unlikely to drain well and will pond after only light to moderate rainfall. Soil particles from these zones will then be be susceptible to erosion with soil particles and organic matter being carried away to drainage lines and rivers.

Pigs in particular, can have a significant impact on the soil due to their natural feeding habits. The destruction of plant roots results in a loss of soil structure and a greater impact from other activities such as repeated trampling. High stocking rates on pig farms make the problem significantly worse.

 

Soil is the main focus of the impacts of animal wastes on the environment. (See the page on Pollution). Again, the major causes of pollution of the soil originate from cattle, whilst smallstock are generally seen as having a lesser impact. The main impacts result from the amount of urine delivered to the soil. Large volumes of urine may be toxic to plant roots which cannot immediately recover to take up the Nitrogen - but again, these impacts are greater from cattle than from sheep and goats.

The impact of manure and urine on soil from livestock also includes the presence of additives such as copper, zinc, anthelmintics and antibiotics or other veterinary treatments that are given to livestock. The presence of copper and zinc in particular can make manure unsuitable for use as a fertilizer on other farms and pose a long-term risk to soils because they tend to accumulate and are only slowly removed by leaching or offtake in vegetation.