- 3.8.1 Lack of Information
- 3.8.2 Effluent Ponds Under Scrutiny
- 3.8.3 Farms Don't Meet Resource Management Act Standards
- 3.8.4 International and Local Pressure
3.8 FARM WASTE MANAGEMENT
3.8.1 Lack of Information
Very little is known about the GHG implications of farm waste. International attention on GHGs has so far been centred around C02, but research indicates methane and nitrous oxides are the major concern for livestock farming. It appears that C02 from livestock systems is GHG neutral with the gas being cycled within the system. On the other hand, little is known about the nitrification process involving methane and nitrous oxide, although current estimates may understate by 50 % the GHG impact (Campbell, pers. corn., 1993).
3.8.2 Effluent Ponds Under Scrutiny
The obvious areas of concern are around areas of heavy stock concentration including piggeries, dairy sheds and feed lots. For example, it is estimated that 10-15% of dairy cow effluent is dropped in the yard prior to milking. Under the standard two pond system of effluent disposal, for the average 170 cow herd, the treated effluent discharge represents the equivalent of the raw sewerage from 700 people. Current interest centres around control of wastes entering water systems (Dairy Exporter, 1993). The GHG impact of farm waste has yet to be considered.
Operating effluent ponds under current practice of anaerobic fermentation is about eight times more GHG inducing than necessary. By covering the ponds and flaring the resulting methane around 75% of the GHG impact can be eliminated. Of the remaining 85-90% of manure in the paddock between 10-90% ends up in rivers and other water ways. Lassey, et al, consider the GHG impact of the waste in the paddock is likely to be minor in New Zealand.
The fate of ammonia which is oxidised to nitrate and subsequently to nitrous oxide is largely unquantified.
3.8.3 Farms Don't Meet Resource Management Act Standards
Even under the old Soil and Water Act traditional effluent disposal on farms was no where near up to standard. It is expected that very few, if any, livestock farms in New Zealand would meet the standards that are being suggested under the Resource Management Act (RMA).
It is estimated that less than 5% of industry met the requirements of the 1967 Soil and Water Act, only a hand full would meet the requirements of the RMA. Wool scourers in particular, but also tanneries, fertiliser works, meat works and dairy factories are very exposed to the enforcement of the standards in the RMA. The size of the solids waste management problem is, as yet, indeterminate.
3.8.4 International and Local Pressure
International pressure, because of the global implications of GHGs, is mounting for the cleaning up of pollution. In Western Europe, Britain appears to be most vulnerable. The expectation is that New Zealand as an exporter of farm products to Europe is likely to be required to conform to European standards to retain access. This has major implications for New Zealand farmers and exporters.
The ultimate objectives, in terms of farm waste management, will be the collection and burning of methane from intensive livestock systems and the further treatment of liquid effluent so that it can be safely irrigated back onto pasture as a beneficial fertiliser and soil conditioner. In theory it is possible to collect the methane from effluent ponds and flare it, thus removing 75% of the GHG problem. The final step is to use the gas to heat water, keep pigs warm and possibly for central heating and glasshouse heating.
Research programmes in New Zealand on the farm waste management problem have received little support from science funders. Given funding, it is expected that the technical manuals required for the fundamental design criteria could be ready within 18-24 months. The production of GHGs, pollution control, nutrient management, electricity consumption for pollution control, the generation of thermal electricity (from GHGs) for solid, liquid and air pollution control are inextricably linked and are very complex. For example:
- what should happen to the solid sludge that has filled farm ponds over the last 10-20 years?
- Where should it go and does the disposal need a Resource Consent under the RMA?
| © MAF 1993 |  |
|
| MAFnet Help | Important Disclaimer |
Contact for Enquiries
MAF Information Services
Pastoral House
25 The Terrace
PO Box 2526
Wellington, NEW ZEALAND
Fax: +64 4 894 0721
Contact this person
