UK agriculture has lost over 70% of the active substances at its disposal since the early 1990s, this combined with the increasing technical challenge posed by resistance, drives the need to protect the remaining modes of action we have at our disposal.
Industry-led approaches have made significant progress in highlighting the threats that exist to the long term availability of active substances, as well as the promotion of appropriate measures to mitigate any non-target impacts.
However, the threat posed by water-based legislation – notably the EU Water Framework Directive – remains, with the UK Government and associated Agencies tasked with ensuring compliance by 2027 at the latest.
Water Aware (WA) is an initiative committed to protecting sustainable products and solutions. Reducing the frequency and magnitude of pesticide exceedances in raw water is currently a key focus area in order to avoid the potential need for additional regulatory measures to deliver compliance.
Understand your soil type and drainage
Sand, silt and clay are terms relating to the particle size, the largest being sand, and clay being the smallest.
The structure of your soil will affect how quickly water moves through; many of the air spaces in sandy soils are too large to hold water against the force of gravity and this can result in a soil with a reduced water-holding capacity that is prone to drought.
Heavy clay soils on the other hand, have familiar characteristics and can be difficult to work with. They dry out slowly and can leave a hard crust that does not allow the rain to penetrate.
A sudden or prolonged downpour of rain on an impermeable soil may lead to recently applied chemicals running directly to the nearest water source.
Understanding soil moisture deficit
Field capacity can be defined as the water content held in the soil after excess water has drained away. The soil moisture deficit is the amount of water required to bring the existing soil moisture content back to field capacity.
Understand the chemistry you are about to apply and how it affects drainage water
Many crop protection solutions rely on inherent residual properties (remaining in the soil a few weeks after application) to provide long-term sustained security.
Herbicides applied when soils are at field capacity, drains are flowing or following prolonged precipitation, are at greater risk of making their way into the watercourses.
These risks are compounded during the latter months of the year when average rainfall amounts are increased and farmers are protecting emerging crops.
Predicting a suitable weather window in which to use chemistry
Assessing the suitability to apply solutions during a particular window of opportunity to suit the physical application; i.e. dry, minimal prevailing winds, no imminent precipitation, is no longer a sustainable approach if we are to protect the future of existing chemistry.
Consideration must be given to the field capacity at the time of application and future weather forecasting.
Applying crop protection solutions when the soils are drier and earlier in the season has two real benefits; it has been proven to give better herbicide control as smaller shallower rooted weeds are targeted and we take the application window out of the risk period, applying at a less vulnerable time of year.
Calculating the risks
A field-based risk assessment is considered to be one approach that could complement other measures being explored.
Understanding soil type, chemistry, and weather and soil moisture deficit information enables advisors, farmers and wider industry stakeholders to identify for themselves the “risk envelope” in relation to the timing of spray and pellet applications and the potential impact on receiving surface water bodies.
WA App – the solution
A useful risk assessment tool has been developed by Crop Protection product manufacturer, Adama – a smartphone application that forecasts risk of movement of selected pesticides from soil to water courses based on prevailing and predicted weather conditions, soil moisture deficit and soil texture.
It is designed to act as a decision support tool for those applying pesticides associated with water pollution.
The application runs a series of algorithms to alert the user to potential risk of pollution due to the current and forecast weather and soil conditions. It also combines a user-friendly checklist of operational conditions designed to reduce the risk of pollution at the time of application, making it simpler for you to be more Water Aware.
For further information on sustainability and being Water Aware see the Adama A-View digital magazine