A new scientific article on the management of soil phosphorus makes fascinating reading, writes Dr Bert Quin, managing director of Quin Environmentals.
Stock wintering systems play a major role in water quality and soil health, because stock are then grazing during a time of much hydrological activity that moves contaminants off land and into nearby waterbodies.
General practice during winter is to graze stock intensively on winter forage crops supplying large quantities of feed in a relatively small area.
Now is the right time for farmers to consider the impact of stock wintering practices. These can impact surface and ground water quality and soil quality due to heavy concentrations of dung and urine, the creation of bare ground and the risk of run-off in wet weather. Many studies have shown that water quality guidelines and standards have been exceeded as a result of intensive agricultural activities.
Here are some stock wintering options that can achieve good environmental results, are animal-friendly and make economic sense.
Feed and stand-off pads protect soil physical structure in wet weather. The feed pad is a dedicated concrete platform where supplementary feeds are brought to the stock. It has higher feed efficiency, reducing wastage to about 5% versus 20% or more when silage is fed in paddocks.
Stand-off pads are a dedicated loafing area for stock. These have a softer, free-draining surface of, say, wood chips. As stock can be withheld from pasture for longer times, the area required per cow has to be bigger, say, about 8m2. Capture of effluent is an important aspect of stand-off pads. It requires the base to be sealed underneath, either with compacted clay or an artificial liner or concrete, and the captured effluent directed to a treatment system.
Animal shelters are gaining popularity. Herd homes are a combination of a feeding platform, stand-off facility and animal shelter. Sheltered feeding areas have concrete floor slats through which cow effluent drops into a concrete-lined bunker.
Composting barns are another stock wintering option, with the composting occurring in situ. The cows roam freely in the barn and lie on a mix of wood chips and straw. The beds must be kept dry by adequate ventilation and aeration.
In the past, sacrifice paddocks have been used when other options were not available to stand animals off or feed supplements when it is very wet. However, there is a risk of soil structure damage and animal health problems such as lameness and mastitis.
If soil potassium levels rise too high (potassium is excreted in urine) it may predispose the calving cow to metabolic problems. These paddocks come with a very high risk of discharges of contaminants to water, so they must be sited well away from waterways, with an area of rank growth to trap any sediment or dung that washes off.
Build your wintering structure well away from waterways and allow for solid and liquid waste disposal into your effluent disposal system. Don’t use supplementary feeds in areas where run-off may reach any waterbody.
By planning now and implementing proper stock wintering management practices, you can play an important part in improving water quality and soil health.
• Bala Tikkisetty is a sustainable agriculture advisor at Waikato Regional Council. Contact him on 0800 800 401.