1. Presentation

Characterization of the technique

Description of the technique:

Philippe Evaillard	UNIFA	peveillard(at)unifa.fr	Paris (75)
François Dumoulin	CA 60	francois.dumoulin(at)agri60.fr	Fresnoy le Luat (60)
Rémy Ballot	INRA	remy.ballot(at)grignon.inra.fr	Grignon (78)

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Choose nitrogen fertilizers with a high nitrate fraction (posing no volatilization risk). The solid granular form is less directly exposed than the liquid form which establishes a large exchange surface with the atmosphere (however, the granular form of urea causes a very localized pH increase during granule dissolution, increasing the risk of ammonia volatilization). Nitrate nitrogen fertilizers (calcium nitrate, potassium nitrate or sodium nitrate) pose no risk but are too expensive per unit of nitrogen for large crops. Solid nitrogen fertilizers such as ammonium nitrates, sulfonitrates represent a good compromise between reducing volatilization risk and unit cost.

Implementation period On established crop

Spatial scale of implementation Plot

Application of the technique to...

All crops: Easily generalizable

All soil types: Easily generalizable

Implementation of the principles of this sheet is all the more important when in conditions favorable to volatilization: basic calcareous "chalky" soils, low CEC, and with poorly developed crops.

All climatic contexts: Easily generalizable

Implementation of the principles of this sheet is all the more important when in conditions favorable to volatilization: warm, dry and windy weather (low humidity) on poorly covering crops and calcareous soils.

Regulation

POSITIVE influence

France and the EU have made international commitments to reduce transboundary atmospheric pollution, particularly concerning ammonia, an acidifying gas (Gothenburg Protocol of 1999 ratified by France in 2008).

No regulation at the plot scale but the European directive on atmospheric pollution sets emission ceilings that member states must not exceed. 97% of ammonia emissions originate from agriculture, with 76% from livestock and 21% from mineral fertilizers according to the national inventory (CITEPA).

2. Services provided by the technique

3. Effects on the sustainability of the cropping system

"Environmental" criteria

Effect on air quality: Increasing

GHG emission: DECREASE

Particulate emission: DECREASE

Effect on water quality: Variable

N.P.: VARIABLE

Effect on fossil resource consumption: Decreasing

Fossil energy consumption: DECREASE

Other: No effect (neutral)

Air: Decrease in ammonia emissions. If volatilization is reduced, fertilization must be perfectly adjusted to the potentials of the plot and crop to avoid increasing nitrogen residues in the soil and thus increasing the risk of soil emissions of nitrous oxide (N2O), a greenhouse gas.

Water: If volatilization is reduced, fertilization must be perfectly adjusted to the potentials of the plot and crop to avoid increasing nitrogen residues in the soil and thus increasing the risk of nitrogen leaching to deep or surface waters.

Fossil energy: The nitrogen saved for the crop improves the energy cost of the technical itinerary: reducing nitrogen loss by volatilization leads to decreasing nitrogen input and saves fossil energy consumed to produce it (a little more than one toe in natural gas to produce one ton of nitrogen N).

"Agronomic" criteria

Productivity: Increasing

The economic optimum yield is reached with a lower nitrogen input.

Soil fertility: Increasing

A larger share of nitrogen is recovered by plants or conserved in the soil (microbial organization).

Functional Biodiversity: Increasing

Reduction of ammonia emissions results in decreased deposition in natural or cultivated environments (uncontrolled nitrogen). In some nitrogen-poor and ecologically important areas, this nitrogen fallout tends to reduce ecosystem biodiversity (e.g., peatlands, acidic environments...).

"Economic" criteria

Operational costs: Increasing

The fertilizer forms least sensitive to volatilization are (generally) more expensive and more difficult to spread uniformly (solid forms). This extra cost is not always offset by the dose reduction allowed by the absence of volatilization (often a 10% decrease) and better fertilizer use efficiency by the plant. Only on calcareous soils (more than 30% total limestone), where volatilization losses are so high, is it economically advantageous to use, for example, ammonium nitrate instead of a nitrogen solution.

Mechanization costs: No effect (neutral)

There is very often on farms a spreading equipment by projection used for phosphate, simple potash fertilizers or compound fertilizers. This equipment is usable for solid nitrogen fertilizers. The cost of solid spreading compared to a boom applying liquid solution is not very different. Note however: spreading solid fertilizers requires sufficiently precise spreader adjustment and a physical quality of the fertilizer adapted to the working width and thus the projection of granules to be achieved. Control devices (GPS, DPA, onboard weighing...) facilitate spreading precision.

Margin: Variable

Fertilizer forms less sensitive to volatilization, "solid" forms, are more expensive, however, they are generally more efficient (better efficiency = better yield) and allow reducing quantities applied (-10 to 15%). Moreover, they also produce better results on "quality" aspects (e.g., improved protein content due to better efficiency of solid fertilizer).

"Social" criteria

Working time: Variable

Depending on farm organization.

Observation time: No effect (neutral)

4. Favored or disadvantaged organisms

Favored Pests

Organism	Impact of the technique	Type	Details

Disadvantaged pests

Organism	Impact of the technique	Type	Details

Favored Auxiliaries

Organism	Impact of the technique	Type	Details

Disadvantaged auxiliaries

Organism	Impact of the technique	Type	Details

Favored climatic and physiological accidents

Organism	Impact of the technique	Details

Disadvantaged climatic and physiological accidents

Organism	Impact of the technique	Details

5. For further information

Nitrogen fertilizers: finding the right techno-economic compromise
-Escoffier I. (France Agricole)

France Agricole n°3268, p29, Press article, 2009

Ammonia and nitrogen greenhouse gas emissions in agriculture
-CORPEN

Technical brochure, 2007

brochure

Reducing emissions into the air
-UNIFA

Website

site

azote.info
-ADA (Directly Assimilable Nitrogen)