Tillage advice: Minimum buffer zones to protect water
As we enter the New Year, attention will soon shift to ploughing and cultivation. With this in mind, Crops Specialist at Teagasc, Ciaran Collins reminds us why it is essential to adhere to buffer zones near water sources.
Buffer zones along watercourses help prevent sediment, nutrient loss and pesticides entering watercourses. A 3m uncultivated buffer zone is mandatory next to watercourses for all non-grass crops.
While a 3m uncultivated buffer zone is mandatory next to all watercourses for non-grass crops, the buffer increases to 6m for late harvested crops. A ‘late harvested crop’ includes vegetable crops harvested after 15th September, as well as fodder beet, sugar beet, main crop potatoes and maize, excluding cereal crops and beans. The minimum uncultivated buffer of 6m applies to the ‘intersecting’ proportion of the watercourse, i.e. where the natural slope of the field directs water runoff into the river.
Figure 1: Minimum buffer zones to protect water
Nitrate leaching is one of the major issues on light, free-draining soils typically used in crop production. Nitrogen does not bind tightly to the soil and is susceptible to leaching when excess nitrogen is applied, especially after heavy rainfall.
Phosphorous is most prone to loss from low permeability clay soils or soils which are peaty in nature. This loss occurs through overland flow of water which carries sediment and P into drains and surface waters. When we see ‘brown water’ flowing into a watercourse following heavy rain, this normally contains high levels of phosphorous.
Buffer strips are a way of breaking the pathway of nutrients by slowing water runoff, trapping sediment and enhancing infiltration of the soil.
Organic manure
As the end of the prohibited period for the spreading of organic manure approaches, it is important to remember that low emission slurry spreading (LESS) equipment must be used to apply livestock manure to arable land or else the livestock manure or it must be incorporated within 24 hours. Pig slurry is low emissions only.
The mandatory buffer zone for organic manure spread near watercourses is 5m, but this increases to 10m for the first two weeks after the prohibited period. E.g., Zone A slurry application buffer is 10m between 13th January and 26th January and 5m thereafter.