New Zealanders are keen composters. In fact, almost half of Kiwi households currently compost. Last year urban Auckland households diverted 9 million kilograms of food scraps from the landfill by using the council-supplied food scrap collection bins.
On-farm recycling, collection and safe disposal services are a responsible way to deal with farm waste, reducing the negative effects on the environment and the health risks for both people and animals.
Disposing of dead stock is a common problem on farms. Action needs to be taken quickly to ensure this type of organic waste is dealt with in an environmentally friendly way and cannot be seen from the roadside to avoid causing distress to the public.
Collection services are the preferable option for casualty stock, but if there is no collection service there are other disposal options:
- Burial/offal holes
- Burning
- Composting.
Each of these methods has pros and cons that should be considered carefully depending on the farm and regional council requirements.
Comparing composting of waste from urban source or wastes from on-farm is primarily a difference of scale and content (ingredients). Urban composting contains predominantly food and plant matter, whereas rural composting also includes dead animals and effluent.
To produce quality compost it takes time, knowledge, and good management practices, including control of pests, and odours and being mindful of neighbours and minimum distance requirements to dairy sheds and waterways.
What is composting?
Composting is the biological process in which microorganisms break down and feed on decomposing organic materials and convert this into a nutrient rich product – compost – which can be added to soil or mulch. The process employs heat, moisture, oxygen and microbes.
Decomposition is a natural process. Composting fast-tracks the process by providing a controlled environment for the decomposition to occur.
The quality of your compost will be determined by the feedstock – the raw ingredients for composting: manures, leaves, plant trimmings, and food waste.
What can I compost on-farm?
Common raw materials used in on-farm composting include:
- Bark
- Crop residues
- Fruit and vegetable wastes
- Grass clippings
- Leaves
- Lime
- Newspaper/cardboard
- Livestock manure
- Casualty stock
- Sawdust and shavings
- Spoiled hay and silage
- Straw
- Wood ash
- Wood chips.
On-farm composting methods
Farmers will need to use different composting methods depending on the type of organic waste being composted. This could include: passive composting (stacking materials in piles to decompose over time), creating windrows (creating narrow piles and turning), aerated piles, or compost bins and reactors (combining mechanical aeration and passive aeration).
Dead stock needs to be dealt with differently. While many farms will use a collection service to dispose of dead stock, sometimes this is not feasible and the animals will have to be dealt with on-farm. If managed well, composting dead stock can provide farms with a useful end product. Check with your regional council around the local regulations around composting dead stock.
Traditionally, farms have used offal pits to dispose of dead stock or buried them. In some locations, however, this practice is not ideal, particularly when the water tables are too high.
DairyNZ has produced advice on composting dead stock on-farm using purpose-built compost stacks/bins – created using materials found on-farm. It advises locating the compost stack at least 100 metres away from waterways, the dairy shed, and out of public view. Ease of access is critical – in all weather.
Where can I use compost on-farm?
Just as different composting methods are required on-farm, different uses of the resulting product will also be required.
Co-op Programme Lead Sue Fowler says finished compost is a great fertiliser but cannot be spread onto grazed pastures or anywhere ruminants can access it. This is because the composting process may not kill all pathogens and diseases and there are concerns for impacts on dairy cows’ health.
“This compost cannot be used on grazed pastures. It can be used on cultivated soils where the crop will be harvested before feeding to cattle e.g. maize, and grain; but not forage crops e.g. brassicas. Other uses could include domestic gardens, nurseries, under shelter belts, or planted areas,” she says.
“Some farmers are looking at composting options on-farm. It can make sense to compost on-farm but there are biosecurity considerations. Ensuring you get the approach right from the outset is essential.”
Find out more about stock collection and composting at your local Farm Source store.
Visit DairyNZ for details on dead stock disposal and composting: