Does Fertilizer Expire After Being Left for a Long Time

At present, the country does not have clear regulations on the shelf life of fertilizers for the time being, but some specific fertilizers have marked shelf life on the outer packaging, after the expiration date is no longer available. From the analysis of the characteristics of fertilizers, fertilizers can generally be stored for a long time as long as the bag is not broken, not rained on, not damp, not mixed with alkaline substances. For example, urea, potassium sulfate and other fertilizers in a cool, dry warehouse can be stacked for 20 years, except for fertilizer will be slightly caked, nutrient content and other indicators have not changed. Several major common varieties are introduced as follows.
Sodium bicarbonate will only lose amount and not fail
 
In winter, when the temperature is around 0 ℃, ammonium bicarbonate fertilizer effect almost does not change, farmers can use the opportunity of seasonal price reduction of ammonium bicarbonate in winter to buy early and spare for spring planting. In summer, when the temperature is above 30℃, ammonium bicarbonate will volatilize a lot, and the originally dry fertilizer becomes wet due to ammonia volatilization, and the net weight of fertilizer is reduced. At this time, the bag should be tightened to strictly prevent moisture and reduce losses.

Urea will only lose amount not fail
In a dry state, urea can be placed for a long time. When the temperature is as high as 122 ℃, urea decomposition to produce ammonia and carbon dioxide, volatile loss of weight, but the chemical properties will not change. It should be noted that: urea is most afraid of moisture, easy to meet the water wet leaching loss of weight.

Calcium superphosphate is prone to failure after a long time
Calcium superphosphate is prone to failure, one is the calcium superphosphate in the rain, the fertilizer effect will be gradually lost; second is the calcium superphosphate stored for about 170 days, the contained calcium carbonate will slowly transform into iron phosphate, aluminum phosphate and other insoluble substances, the overall fertilizer effect becomes worse. Therefore, when calcium superphosphate is often produced in contact with phosphate ore powder containing high iron and aluminum, it should not be stored for more than one year.
 

Potassium chloride and potassium sulfate are very stable compounds
They are very stable compounds. When they are caked with water, they are broken and applied with the same effect. However, the dosage should be calculated by dry weight at the time of application.
 
Diammonium phosphate is afraid of high temperature
When diammonium phosphate encounters high temperature, such as above 30 ℃, it will be slowly converted into monoammonium phosphate, with a small amount of ammonia volatilization. Therefore, the storage of diammonium phosphate to tighten the mouth of the fertilizer bag to avoid ammonia volatilization.
 
Ferrous sulfate absorbs moisture will deteriorate
Ferrous sulfate is a strong oxidizing agent, such as moisture in water is easily converted into iron sulfate, crops can not absorb. Therefore, ferrous sulfate moisture deterioration of fertilizer efficiency is poor, the most vulnerable to failure.
 
Fertilizer containing bacteria can not be used after the expiration date
Biological fertilizer in the strain of bacteria activity is a certain time limit. The standard of bacterial fertilizer will be marked on the bag with the expiration date of the strain, which is generally valid for two years at most under normal storage conditions, and the microbial fertilizer cannot be used after the expiration date.
Bacterial fertilizer must be kept at low temperature (optimum temperature 4℃-10℃), cool, ventilated and protected from light to avoid failure. Some strains need a specific temperature range, such as harz wood mold stored in 2 ℃ -8 ℃ thermostat, valid for one year; and some bacterium to determine the validity of the production of high quality, budding level and other conditions, budding high can be stored for a year and a half or even longer, bad budding can not reach half a year to expire.