Using precision agriculture technologies for drainage solutions

Take home messages

• Waterlogging can be managed effectively with a well-designed surface water drainage plan which should focus on a combination of increasing water infiltration rates with strategic gypsum application and a network of drains (predominantly farm-through drains).
• Interception of water destined for low lying country can deliver the benefit of directing water into dams.
• Many growers have elevation data from their 2cm autosteer systems which can be used to develop whole-farm digital elevation models.
• EM38 data is valuable for defining soil management zones and associated variable rate gypsum programs.

Background

Waterlogging is an issue which can have a significant effect on crop and pasture production, as seen in 2016. Many farms in high to medium rainfall zones lack a well-considered drainage program which can act as an insurance program against the effects of localised waterlogging.

Method

All plans start with an accurate elevation map of the farm. This data may be extracted from a grower’s or contractor’s airseeder tractor or header or the country can be mapped with a 2cm accurate global positioning system (GPS) mounted to a utility or utility task vehicle (UTV). It often makes sense to collect soil electromagnetic induction (EM38) data at the same time as collecting elevation data as this information will help define soil management zones for the application of variable rate gypsum. Strategic soil samples must be collected from each soil management zone to understand key soil properties and functions such as soil texture, organic carbon, exchangeable cations and phosphorus buffering capacity. These datasets can also be integrated into a variable rate seeding and nitrogen management program.

These spatial datasets then need to be interpreted by an experienced adviser who can advise direction of operations (paddock layout), location of drains and dams and the development of a variable rate gypsum program. Paddock layout is the first step in this process as a grower using a tine system for seeding essentially creates the effect of a corrugated iron roof which plays a major role in the movement of water across a paddock. For some paddocks, a change in direction will solve a waterlogging issue.

The final step is to work closely with the grower and their earth moving contractor to confirm the design and associated budget. The construction of drains is obviously paramount to the success of any surface water management program. It is advisable to seek out earth moving contractors who have a proven record and ideally have the technology to load drainage designs into their GPS equipment. GPS levelling technology is relatively rare among the contracting community, but those who are willing to invest in this equipment will deliver superior results for their customers.

Conclusion

Utilise a combination of data layers to generate a comprehensive strategy for improving water infiltration and managing concentration of surface water. Maintain a flexible approach to water management which integrates the options of adjusting paddock layout, installation of drains and the application of gypsum to improve soil structure in areas of the paddock which have had a history of waterlogging.

Useful resources

Surface Water Management - Precision Agriculture

Contact details

Andrew Whitlock, Ballarat Technology Park, Mt Helen VIC 3353
0458 312 589
andrew@precisionagriculture.com.au
@AgPrecision