The Right Placement is all about keeping nitrogen where crops can access it. This is simultaneously the most intuitive of the Four R’s and the most often forgotten when problem-solving nutrient management issues.
What does the “wrong” placement of nitrogen (N) look like?
N application outside of the rootzone:
- N inputs may be added to the soil in ways that are laterally or vertically beyond the reach of the growing roots and inaccessible to the crop.
- Excess N that is left for long periods of time outside of a potential crop rootzone is at greater risk of leaching, particularly during high rainfall or irrigation events and especially in coarse-textured soils. Leaching can push water-mobile N (nitrate) outside of the rootzone and eventually out of the soil and into waterways. This creates waterway contamination and results in applying less N to your crops than intended.
N application left too long on the soil surface:
- Solid N inputs (ammonium) can be converted to gas (ammonia) and lost to the atmosphere through a process called volatilization. This generates air pollutants and results in applying less N to your crops than intended.
- Methods to reduce the loss of N to volatilization (compared to surface broadcast alone) include post-broadcast incorporation of N inputs or placement of N inputs directly into the soil (e.g. manure injection).
- If using the method of surface broadcasting plus subsequent incorporation into the soil, incorporation should ideally occur within three days of initial broadcast to have a meaningful impact on reducing N volatilization.
N application too close to waterways or drinking sources:
- Runoff from agricultural fields can carry dissolved nitrogen (and other nutrient contaminants) over land and eventually contribute to contamination of surface water.
- Respecting recommended setback distances for nutrient application helps protect waterways. These setbacks generally range from 1.5 m to 30 m, depending on the risk factors.
- More information on minimum setbacks for the application of nutrient sources can be found in the Code of Practice for Agricultural Environmental Management or by talking to a local nutrient management planner/specialist.
Wondering if you are using the right N placement method for your fields?
Ask yourself:
- Am I applying N to areas of the soil where crop roots are actively growing?
- Am I leaving N inputs that contain ammonium or ammonia on the soil surface? If yes, how can I incorporate them into the soil as soon as possible (ideally within three days after application)?
- Are there any drinking water sources or watercourses on/bordering my fields that might require a nutrient application setback?
This resource is provided by E.S. Cropconsult.
