Fertilizer quality is a major concern for farmers when making purchases. Identifying the true quality of fertilizers has always been a topic of interest and challenge for many. Currently, fertilizers available on the market can be categorized into four main types: single-element fertilizers, compound fertilizers, mixed fertilizers, and foliar fertilizers.
Starting with single-element fertilizers, one of the most commonly counterfeited products is nitrogen-based fertilizer, such as fake urea. There are two typical situations in which this occurs. First, the contents of the bag may not be consistent—while the top layer flows smoothly, the bottom may clump or not flow at all, emitting a strong ammonia smell. This usually indicates that the top is real urea, while the bottom is fake ammonium bicarbonate. If the entire bag has good flow but varying particle size and color, it might be adulterated ammonium nitrate. Another case involves bags with the same composition, where counterfeit products like Jilin ammonium nitrate or Russian particulate ammonium nitrate are found, often mixed with organic materials like polyols.
To distinguish these, you can use the following methods:
1. **Appearance**: Urea appears as white, translucent granules without any reflection, whereas ammonium nitrate granules have a more reflective surface. Polyol, on the other hand, is opaque and milky white.
2. **Touch**: Urea feels smooth and dry, while ammonium nitrate has a slightly damp feel. Polyol is loose but not overly smooth.
3. **Burning test**: When placed on red-hot charcoal or an iron plate, urea melts and emits white smoke with an ammonia odor. Ammonium nitrate burns violently, producing bright light and white smoke. Polyol does not melt as easily and may remain solid.
For single-element phosphorus fertilizers, calcium sulfate is the most common product, but counterfeits include phosphogypsum, calcium magnesium phosphate, waste cement slag, and brick dust. Identification methods include:
1. **Appearance**: Calcium sulfate is a gray, powdery substance with a sour taste, while phosphogypsum is a hexagonal crystal or powder with no sour smell. Calcium magnesium phosphate is gray-green, and waste cement slag is hard and non-glossy.
2. **Touch**: Calcium sulfate feels greasy, while phosphogypsum feels soft and cotton-like. Waste cement slag is heavy and hard.
3. **Water solubility**: Calcium sulfate is partially soluble, phosphogypsum fully soluble, and calcium magnesium phosphate insoluble. Waste cement and brick dust tend to settle in water.
4. **Impurities**: The presence of stones, coal gangue, or excessive moisture indicates poor quality or incomplete processing.
Moving on to compound fertilizers, diammonium phosphate is often counterfeited with substances like nitrophosphate, heavy superphosphate, and particulate superphosphate. Key differences include:
1. **Appearance**: Diammonium phosphate has irregular, dark brown particles with some translucency. Nitrophosphate is dark brown and smooth, while heavy superphosphate is dark gray.
2. **Solubility**: Diammonium phosphate, nitrophosphate, and heavy superphosphate are all water-soluble, but particulate superphosphate is only partially soluble.
3. **Burning**: Diammonium phosphate and nitrophosphate melt quickly and release ammonia, while heavy superphosphate does not emit an ammonia smell.
Mixed fertilizers, also known as compound fertilizers, are often falsely labeled. Counterfeit versions may contain sludge, soil, or coal ash and lack nitrogen. To identify them:
1. **Appearance**: True compound fertilizers have smooth, glossy particles, while mixed ones are rough and dull.
2. **Burning test**: When burned, real compound fertilizers melt and emit ammonia, while fake ones may not react or leave residue.
Finally, foliar fertilizers are often poorly packaged, lacking proper licensing and clear ingredient lists. Some have low concentrations or significant sedimentation. To identify them:
1. **Packaging**: Check for proper registration numbers, trademarks, and accurate labeling.
2. **Appearance**: Liquid foliar fertilizers should match their described ingredients in color. Solid ones can be tested using similar methods as single-element or compound fertilizers.
3. **Field effect**: After application, crops should show visible changes within 3–5 days. If no change is seen after a week, the product is likely fake.
By understanding these methods, farmers can better assess the quality of the fertilizers they purchase and avoid counterfeit products.
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