Field selection for fall manure or compost application

Sep 14, 2021

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There are several factors to consider when selecting the right fields before applying manure or compost this fall.

‘There are several management considerations to make when deciding where and how to best utilize available manure and compost resources,’ says Trevor Wallace, nutrient management specialist with Alberta Agriculture and Forestry. ‘Knowing the rules and using the 4R Nutrient Stewardship principles (considering the right place, right source, right rate, and right time) helps to optimize nutrient use efficiency when applying manure or compost, while keeping nutrients in the field and reducing nuisance impacts on neighbours.’

When selecting the right fields to apply manure or compost, there are several factors one should consider including legislative setbacks, soil and field conditions, and future nutrient need.

‘Producers are required to take reasonable care to ensure runoff from manure or compost does not leave the field or create an inappropriate disturbance. Alberta’s Agricultural Operation Practices Act (AOPA) minimum setback requirements for spreading manure or compost need to be factored into both the field selection process and manure application plan.’

Setbacks help to reduce the risk of manure or compost leaving the land on which it was applied and to reduce the nuisance impacts of the application. Producers must:

apply manure or compost at least 150 m away from neighbouring residences or other unowned occupied buildings when applying on directly seeded land or forage,
keep 30 m away from any water wells,
stay 10 m away from a common body of water if subsurface injecting, or 30 m away if surface applying,
increase setback distances when the land sloping towards a water body increases with slope: 30 m for less than 4%, 60 m between 4% and 6%, and 90 m for slopes between 6% and 12%, and
not spread on slopes equal to or greater than 12%.

The right field will also be determined by considering the previous crop/forage, soil fertility, moisture conditions and current ground cover. Sandy soils, dry field conditions and limited ground cover significantly increase the risk for soil erosion.

‘Field conditions may not be suitable for manure or compost application if the AOPA requirement for incorporation is going to significantly increase the risk of soil erosion,’ explains Wallace. ‘AOPA rules state that manure and compost applied to cultivated fields must be incorporated within 48 hours from the time when it is first applied, unless operators have a permit that specifies a different incorporation requirement.’

Wallace adds in extreme cases where erosion is already an issue, operators may be able to protect the soil, at least in the short-term, by spreading manure onto fields with no incorporation. Producers should contact the Natural Resources Conservation Board (NRCB) if they are concerned about soil erosion in their fields, prior to spreading.

‘Producers should consider spreading on fields with forage or direct-seeded crops because these fields do not require incorporation of manure or compost and thus reduces the risk for soil erosion. In addition, producers can check with neighbours, who may be interested in the soil health benefits from manure and compost application, for access to fields that pose minimal risk to soil erosion and nutrient loss.’

Low moisture conditions, resulting in poor plant growth, means that there has been limited crop nitrogen (N) removal. Also little or no leaching means that unused fertilizer N remains in the soil from the past year’s fertilizer application.

‘Unless we have an unusually wet winter and spring, this nitrate-N will be mostly available for crop use next year. The only way to know the availability of soil nutrients is to soil test and adjust manure and compost application rates accordingly to get the biggest benefit from your manure resources. The amount of carry over and future crop need should be a factor in field selection.

‘Considering these rules and 4R stewardship principles when choosing the fields for application will keep your soil healthy and nutrients in the field, not to mention, help you to get the biggest bang for your buck to maximize crop/forage potential and minimize costs especially during low moisture conditions,’ says Wallace.

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