Making better decisions on the best type of erosion control and how to lower sediment losses is going to become a lot easier for vegetable growers in February when an app is released as the outcome of a Sustainable Food and Fibre project between NIWA and Agrilink.
Agrilink managing director Andrew Barber said the sediment app concept came out of an industry best practice erosion and sediment control process vegetable growers formulated to help reduce red tape and administrative headaches around regional council rules and regulations.
“That was all fine but there was a need to be able to show the numbers that sat behind the policies. We knew the measures worked for controlling sediment loads and soil losses.”
With support from the Sustainable Food and Fibre Fund the four-year project ran trials of different good management practices, testing how best to keep soil in the paddock.
They included use of covering crops, vegetated buffer strips and sediment retention ponds.
The project found almost all larger soil articles can be stopped from entering waterways by almost any sized sediment pond.
Overall, a minimum pond size of 50 cubic metres was standard to capture over 80% of soil in suspension.
The discovery was ultimately a key part of the app programme and vegetated buffer strips were also added to its calculation capacity.
Initially, Barber thought he could lay out a spread sheet to model how different mitigation processes work in particular catchments for reducing sediment and phosphate losses.
But he was told in no uncertain terms by his daughter Victoria he needed to develop an app capable of doing the job and be easily loaded into growers’ phones.
“We can see that as farm environment plans become required for growers this is a way for them to readily do a risk assessment on their property.
“The app enables them to calculate what the highest priority mitigation should be on their particular property for their farm environment plan and provides robust evidence to support consents and prove to regional councils their control measures are effective.”
The app has can adjust for a region’s characteristics.
For example, Waikato and Pukekohe growers tend to be on steeper ground where retention ponds tend to perform best. They are similar to those now typically found alongside roads and subdivision projects for sediment capture.
It has also drawn attention to the inadequacies of some regional plans and how a one-size approach to environmental controls does not necessarily work.
Under Plan Change 1 in Waikato, for example, growers are required to have a 5m buffer between vegetable crops and waterways.
“But that is pretty hopeless when you have channeled water flow that streams right through that buffer.
“In contrast, places like Levin and Canterbury that buffer may be very effective for many growers. It is a case of being able to adjust the mitigation to the region you are in for genuine benefits to the environment.”
So far the app’s development has been targeted solely at vegetable growers with a pastoral option based as a benchmark figure only.
“Our hands are pretty full with this one and pastoral mitigation tends to have quite different demands.”
Barber said the practical and hands-on nature of the app is helping address a concern NZ’s tech development is not extending out to farmer users as quickly as it needs to.
“There has always been quite a lag between research and use, sometimes the research is used almost as an excuse for inaction.”
He views the app as a means for growers to set a downward trajectory on sediment and nutrient losses rather than be hung up on hitting exact numbers at the end of that trajectory.
“This can show them how they are tracking on that pathway and what combination of controls will help them achieve that.”
Grower interest in the app has been strong with one telling Barber to just get on with it at a recent road show on the app’s release.
Ministry for Primary Industries investment programmes director Steve Penno said the app is a practical, accessible means of mitigation for growers.
The app will be publicly available from February.
