Poor Management of Animal Wastes in
Grazing Systems and Mixed Farming Systems
Environmental Assessment: Pressure State Response Indicators

The impact of animal wastes from grazing systems on water quality is less one of poor management interventions, than one of few attempts at management. If water quality is a consideration, then simple pollution avoidance strategies and basic treatment can resolve the issue. The inherent absorptive capacity of the environment can usually deal with the overall low pressure of livestock managed in extensive grazing systems and mixed farming systems. | Pressure State Response Further reading

In higher intensity mixed farming systems, the treatment of domestic water supply is generally adequate to deal with the incremental problems of pollution from livestock wastes. It is only at the industrial scale that animal wastes again become a major water quality concern.

The impact on surface systems can vary considerably throughout the year, and this variation is likely to be highest in arid and semi-arid grazing systems.

The pressure will vary according to the seasonal movement of stock. The impact is likely to be least during the rainy season when stock are dispersed and highest during the dry season, when low surface water flow/recharge regimes limit the dilution of pollutants, and livestock populations are concentrated around few water points.

"Acceptable" levels of pollutants will depend on the specific environmental quality objectives for the water body. But this will vary according to the downstream requirements of the system; water quality for industry may have fairly low requirements, while discharge for ecosystem functioning may be higher than for industry but less critical than supplies used for drinking water.

Pressure

The pressure on the system is characterised by livestock numbers and management. In this case management includes both avoidance strategies to limit pollution by faecal matter and other animal waste contaminants, and treatment strategies to minimise environmental health risks.

- The type of enterprise - communal grazing systems, ranching or mixed farming;
- The number of livestock involved, and the number of similar or comparable enterprises discharging waste - including those from other sectors;
- The management and technology used to limit pollution - restricted water access points, pumped water supplies to watering troughs, covered wells and boreholes;
- The methods used to treat water for human consumption.

While the impact of animal wastes in grazing systems and low intensity mixed farming systems tends to be low, the problem arises with intensification of production to industrial levels. One of the key factors in monitoring pressure is to identify trends in production systems that lead to the introduction of industrial production in areas previously under extensive grazing or mixed farming.

State

Faecal contamination is still the primary water quality issue in surface water systems, particularly in areas where human and animal wastes are disposed with little or no pre-treatment. The problem of defining the extent of the water quality degradation related to livestock management, is the difficulty of differentiating between the impacts of livestock contamination of water sources and human contamination. Both livestock and human populations depend on the water sources, both livestock and human populations discharge waste that can pollute these same water sources.

From a State Impact perspective, it is difficult to distinguish between the different sources.

The State of the environment is characterised by the concentrations of pollutants in surface and groundwater. The key pollutants are excessive levels of N and P and bacterial and viral contamination, as well as in specific instances the presence of parasites than affect both livestock and human health.

The health issue is the contamination of water with pathogenic (disease-causing) organisms. Given that these pathogens pose a hazard at relatively low levels in the water supply, and that there are many strains each requiring unique microbiological routines to identify them, the analysis for pathogens is rarely practical.

As a result the approach that has been adopted is to assess the level of overall contamination of the water with gut flora that is present in the faecal matter, rather than look for specific pathogenic organisms.

The presence of high counts of faecal coliform bacteria is an indication of high levels of pollution, and hence a high risk of pathogenic contamination.

State indicators are characterised directly by:

- Change in bacterial contamination, and specifically faecal coliform, this will need to be monitored for seasonal changes related to seasonal livestock pressure change and to seasonal changes in river flow and groundwater systems;
- Change in levels of Nitrates, Nitrites and Phosphates in the water body;
- Presence or loss of indicator species - vegetation and microfauna;;
- Human and livestock disease incidence;

Response

The control of pollution from animal wastes in grazing and mixed farming systems is not a technical issue, although there may be financial constraints to implementing waste treatment or water treatment interventions.

The implementation of basic management strategies to avoid or minimise negative impacts is often a question of public health awareness.

The classic approach to regulation is to specify acceptable levels of discharge, or acceptable levels of pollutants within water bodies. However, in this case pollution is concomitant with livestock watering, the management intervention relates to watering practices not waste discharge.

The two approaches to regulation can be characterised as follows:

- Specification of appropriate livestock watering practices for surface systems and groundwater systems; and
- Specification of appropriate practices for extraction and treatment of water for human and livestock consumption.

However, given that much can be done through simple hygiene practices, an appropriate response mechanism may well be health education.

In this case Response is characterised by:

- Levels of health education in schools;
- Introduction of appropriate health messages;
- Presence of "grass roots" health workers;

Further Reading:

UNESCO/WHO/UNEP 1996. Water Quality Assessments E&FN Spon 2-6 Boundary Row, London SE1 8HN UK.

Cairncross S and Feacham R., 1978. Small Water Supplies. Ross Institute Ross Bulletin 10, London School of Tropical Hygiene, London WC1E 7HT, UK.

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