If you’re considering whether to convert to drip irrigation a number of factors need to be considered. A frequent and flexible water supply is critical. This is particularly important in hot regions. Ensure you know your property’s water supply situation before making the decision to convert.
If your current water supply situation is poor keep in mind that future supply rehabilitation (pipelines, channel re-lining etc) may improve this supply situation and therefore drip irrigation may be a long term option.
This fact sheet provides tips on the key areas that need to be managed for a successful conversion to drip irrigation.
-
Drip irrigation suitability
Drip irrigation may not always be suitable as it requires a frequent and flexible water supply. For communal irrigation districts a ‘water on order’ type supply is required. In districts where this water supply is not possible other options must be considered such as the construction of an on-farm water storage, or installation of a full cover irrigation system.
-
Economics of drip irrigation
Research shows that all pressurised systems are an economical option when compared to furrow irrigation. Growers are usually surprised how economical conversion can be when all costs and savings associated with a drip system are accounted for - water use, water charges, power charges, interest rates, labour costs, tractor running costs, etc. Drip is usually the most economical due to labour and water savings.
-
Design requirements
Crop water requirements
The irrigation system must be designed to meet your crop water requirements in the peak of the season providing the ability to cover extreme water requirements during heatwave periods and also allow for maintenance during breakdowns.
Soil survey
A soil survey prior to installation is highly recommended as it will allow the irrigation system to be designed to achieve the greatest efficiency possible. Local guidelines may vary, however, they usually consist of a series of soil pits in a 75 x 75m grid pattern.
Varieties
All winegrape varieties have their own individual water requirements and therefore should be isolated in their own individual valve.
Variable speed drives are becoming more popular, allowing individual water requirement needs to be met in patches of variable size and flow rate.
-
Timing of conversion
The best time for conversion is immediately following harvest as this allows the vines to re-adjust during a root growth flush period, without a crop to support. However this is not generally the ideal time for the owner/manager, and most conversions occur later during the winter period. In recent years upgrades have occurred mid summer (in hot climates) due to the urgency created by low allocation announcements. These have been successful but do carry a greater risk of failure. During summer conversions, poor crop response has generally occurred only when no water has been available for a number of weeks during installation.
Management in the first year
Management leading up to conversion
Use practices which assist the vine to re-develop a root system immediately under the vine row in the lead up to conversion. For example, use small narrow furrows close to the vine row to reduce water applications and apply side banded fertilizers, manures and other soil additives to the vine bank.
Irrigation scheduling
The adoption of irrigation scheduling at the same time as the upgrade is highly encouraged. As drip irrigation has less room for error, irrigation scheduling should be adopted immediately to reduce this risk.
Nutrition
It is usually recommended that ample N and P is applied to vines in the first year of conversion to encourage the root system to concentrate under the vine row. This should be applied through the fertigation system, but may be banded.
RdI
It is not generally recommended to adopt RDI practices in the first year after conversion. The conversion to drip irrigation may tend to result in reduced vegetative growth anyway, and the vine will be under enough stress through the conversion itself.
Author
Mark Krstic
