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Fertiliser resistance

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Farmers regularly fertilise their fields. This may involve adding phosphate or nitrogen-based mineral fertiliser or organic fertilisers such as slurry or dung. However, some substances in fertilisers can increase corrosion of vehicles, machinery and components. These include ammonia (HN3), ammonium nitrate (NH4NO3), urea ((NH2)2CO), potassium chloride (KCl) or calcium carbonate (lime, CaCO3). The result: rust on harrows, gates or tractors is commonplace. And in a short time bolts or chassis begin to rust even in new vehicles.

Corrosion protection in agriculture is therefore faced with a particular challenge: not only is it necessary to protect against aggressive agents such as oxygen, but also against substances in fertilisers. In addition, protective coatings also need to withstand high mechanical stresses and be temperature resistant in the vicinity of engines. Premium manufacturers in particular are also placing increasing emphasis on the long-term high-grade appearance of their products. There is no standard or other generally-recognised regulation for the testing of fertiliser resistance of coatings.

Today, a large number of coatings with multi-layer structure exist for components of vehicles and machinery used in agriculture. Phosphate and varnish are applied, electroplating and hot-dip galvanisation are employed and powder coatings added. In vehicles, the protective coating usually consists of two coats: an electrolytically-applied coating (keyword: cathodic dip coating, KTL) and a powder coating. This combination provides passive protection against corrosion. If these coats are damaged, components can rapidly begin to rust.

There is also another approach: studies show that multi-coat systems containing zinc flakes provide better protection against corrosive agents such as fertilisers than the combination of KTL coating and powder coating. This multi-layer system with good fertiliser resistance usually comprises two layers: the base coat contains zinc and aluminium flakes. These flakes provide active protection to the component against corrosive agents such as oxygen and moisture thanks to active cathodic corrosion protection. Their scale-like arrangement also results in a barrier effect that slows attacks by corrosive media.

The top coat consists of an organic or inorganic material, depending on application. This top coat protects against chemicals such as acids and lyes, as well as aggressive substances such as fertiliser.


Corrosion protection
Curing in process
Conveyor belt oven (continuous oven)
Tray oven (continuos oven)
Chain conveyor oven
Chamber oven
Drying process
Cooling (after annealing)
Exhaust air treatment
KTL breakdown voltage
Condensed water test according to DIN EN ISO 6270-2
Sacrificial anode
Local element
Surface protection
Hot-dip galvanising
Flame spraying
Galvanic coating
Conversion layer
Dry-film coat thickness
Fastening properties
Gloss level
Artificial weathering test
Test procedures
Surface properties
Chemical resistance
Mechanical resistance
Natural weathering test
Physical properties
Passiveness, passive state
Protection, galvanic
Protection, temporary
Chromate Coating
Passivation coating
Rack coating
Bulk process
Partial production lot
Drum coating
Erichsen ball recess
Coating thickness, total
Coating thickness, local
Coating thickness, reference
Coating weight
Dry to the touch
Reference surface
Spray coating
Electroplated coating
Specific surface
Passive corrosion protection
Inorganic protective coatings
Organic protective coatings
Active corrosion protection
Forms of corrosion
Types of corrosion
Surface corrosion
Shallow pitting corrosion
Pitting corrosion
Contact corrosion
Bimetallic corrosion
Stress corrosion cracking
Hydrogen induced cracking
ISO 9001
Electro-dip painting (ETL)
Electrostatic powder spraying (EPS)
ISO 14001
Trueness of gauge
Coefficient of friction
Setting behaviour
Fastening and assembly
Kesternich test
Material effectiveness
Environmental management
Quality management
Magnetic induction measurement
Scaling protection
Powder coating
Coil coating
X-ray fluorescence analysis
Beta backscatter method
Mandrel bend test
Eddy current method (phase sensitive)
Eddy current method (amplitude sensitive)
Corrosion College
Powder sintering process
Zinc flake coatings
Dip coating process
Stone impact test
Process stages of KTL-seperation
Corrosion testing atmospheres conducive corrosion
Coat thickness and coat thickness measurement
Adhesion test according to DIN EN ISO 10683
Cross-cut test for adhesion
Thread tolerance
Pressure water jetting test
Fertiliser resistance
Anodic dip coating (ADC)
Cathodic dip coating (CDC)

Technical terms can not always be avoided. As corrosion experts, we not only want to give you comprehensive advice, we are also interested in making you a corrosion expert yourself.

The variety around the topic of corrosion and corrosion protection is also in our glossary at home: explanations from A as in Adhesion to T as in Thread tolerance. Have fun clicking through!