|
Fertilizer losses during transportation and storage can be related to their ability to segregate (for mixed fertilizers), vapor elasticity and viscosity (for liquid forms), bulk density and the angle of natural slope (for powder forms). Organization of transportation and storage of fertilizers is also associated with fire and explosive properties, residual acidity, rate and conditions of decomposition, and toxicity. For example, potassium nitrate when mixed with sawdust is capable of forming fire- and explosive mixtures, and liquid ammonia or its aqueous solutions have a strong asphyxiant stock.
Properties of fertilizers can vary widely depending on the technical features of production, raw materials and their composition, are regulated by technical specifications (regulatory documents). For example, for urea allowable moisture is not more than 0.2-0.3%, calcium nitrate – not more than 14%, powdered superphosphate – not more than 12%, potassium fertilizers – from 1 to 6%. Failure to meet the requirements entails changes in the physical and mechanical properties of fertilizers, which makes them of little use.
One of the properties of fertilisers that greatly affects their use is hygroscopic properties, i.e. their ability to absorb moisture from the air. Among the highly hygroscopic fertilizers are calcium nitrate (9.5 points out of 10 possible) and ammonium nitrate (9.3 points), potassium chloride 3.2-4.4 points, potassium sulfate 0.2 points. Conditions for storage, transportation and packaging of fertilizers are determined by this property. Strongly hygroscopic fertilizers are stored and transported in sealed containers, often in polyethylene bags.
Friability – the suitability of fertilizers for mechanical spreading with fertilizer spreaders, depends on the moisture capacity. The maximum moisture content of mineral fertilizers corresponds to the maximum moisture content, at which the ability to disperse with fertilizer sowing machines is retained.
Fertilisers may cake if stored or transported for an extended period of time. Fertilisers that are caked on the ground require more grinding before spreading. The amount of caking depends on hygroscopicity, moisture, particle size distribution, storage conditions and duration. Traceability is estimated on a 7-point scale and is determined by the resistance to breakdown of caked fertilizer. Simple powder-like superphosphate (7 points), fine-crystal potassium chloride (6 points) are prone to strong caking, ammonium sulfate is weak (2-3 points), resistant to caking potassium sulfate, potassium magnesia (1 point).
Physical and mechanical properties of mineral fertilizers associated with granulometric composition, i.e. particle size. It is determined by the method of sieves. Granulometric composition affects the uniformity of application over the area of the field. Homogeneous granulometric composition when spreading with centrifugal spreaders provides uniform distribution across the width of the machine. When the grain size distribution is not uniform, separation, i.e. scattering of fertilizer particles of different sizes and weights at different distances from the fertilizer spreading unit is observed: larger and heavier particles are thrown at a greater distance, which creates an uneven distribution.
Preservation of granulometric composition during storage, transportation and application in the soil depends on the strength of granules, which is characterized by the mechanical crushing strength (in kgf/cm3) and abrasion (in %). The strength of granules is related to humidity, size and shape of the particles, the presence of hydrophobic additives, the density of fertilizer packaging, and the duration of storage.
Fertilizer spreadability, or flowability, is the mobility of fertilizer particles at their application with fertilizer seeders. Fertilizer spreadability is evaluated with a 12-point system.
When transporting fertilizers and calculating the size of storage space, we take into account the density of fertilizers, that is, the volume per unit mass (1 t/m3) and weight per unit volume. The least dense are ammonium chloride and urea (0.58-0.65 t/m3), heavy – tomaslak, limestone and phosphate rock (2.01-1.62 t/m3).
Some fertilizers with good physical and mechanical properties, such as ammonium sulfate, potassium sulfate, allowed to transport and store bulk – in bulk. When storing them take into account the angle of natural slope (rest), which is formed by the horizontal plane (surface) and the slope line of the fertilizer heap.
Do'stlaringiz bilan baham: |
