Irrigation checklist to reduce run-off this summer
It’s that time again when some crops and pastures start to need irrigation. Environment Canterbury Land Management Advisor, Ian Lyttle, shares a handy checklist for irrigating well.
Good irrigation management is essential to reduce on-farm costs and loss of contaminants to waterways through run-off and leaching. Most annual irrigation maintenance will have been completed by now and the irrigators ready to do their job.
Opportunity abounds in Canterbury to improve on-farm irrigation practices to Good Management Practice (GMP) levels and to make a real difference to nutrient losses off the farm.
Here is a checklist that will help bring practice to GMP if it is not already there!
Before you start
- Check soil temperatures. Do not irrigate where the temperature is below 10ºc. Grass growth is slow below this point and water will cool soil temperatures more.
- Check soil moisture status as well
- Check your weather forecast – no point irrigating if good rain is on the way.
Make good in-season decisions
- Make good irrigation decisions based on good information. You need this information from soil moisture monitoring, rainfall and PET (potential evapotranspiration) forecasts and pasture/crop water needs.
- Start irrigating before crops get to stress points and never put on so much that you exceed field capacity – aim for 90% of field capacity.
- Apply water when the plant needs it to maximise plant growth (remember no matter how much water, plants do not grow in cold soils)
- Check if you are on water restrictions to avoid compliance issues
- Make sure your rate of application does not result in ponding or run-off, especially where effluent is applied. If it does, you are putting too much on
- Graze in advance of the irrigator to reduce soil compaction- stock hoofs compact wet soils. It is a good idea to take a spade with you during the season to check on soil compaction
- Adjust application rate or turn off irrigator where rain is forecast
- Are you recording your irrigation data and decisions for when your auditor arrives?
Check how well the equipment is operating
- How uniform is your water application? Use a bucket test to check rate of application and distribution uniformity
- Does your water meter, pivot control and bucket test all agree on application rate?
- How effective is your rate of application – is it infiltrating into the soil, ponding or running off?
- Are you able to control your system so that you do not put on more water than the soil can hold? This is more challenging for k-line and guns.
If you need more help managing your irrigation, you can get in touch with a Land Management Advisor at Environment Canterbury by calling 0800 324 636 or contact industry body Irrigation NZ.