ACS Distance Education UK
The main source of income for a farm is often the crop that is about to be harvested, so it is understandable that a fair amount of stress occurs during this period. One of the first issues is to harvest the crop while it is at its best. That is while the moisture content is at the maximum acceptable level but not too wet to cause storage or quality issues.
Another issue that approaches at harvest is weather damage. Crops are quite susceptible to loss of quality if rain falls on a ripe crop, wind, hail or heavy rain can cause crops to shed grain, or shatter pods.
As a general rule of thumb pulse crops such as chickpeas weather quite well for a short period of time as the grain is protected inside a pod, however with canola the pods become very brittle when ripe and can shatter very easily which is why a windrower is often used to lay the crop on the ground to reduce the chance of pods shatter from adverse weather.
Some cereal crops weather better than others, some wheat varieties can weather quite well where as barley has a fairly soft straw and can lodge (fall over) if too much rain falls onto a ripening crop. For this reason farmers often have some form of grain storage. Grain storage can open up a range of marketing options as well. If crop prices are not particularly attractive during harvest (which often happens) farmers can then store their crops and sell them at a time when markets are priced more favourably. So with this in mind, we will look at some basic storage options for a grain farmer.
Silos are the most permanent form of grain storage. They are usually large steel cylinder structures with a cone base; however some silos have flat bottoms. The cone base helps the grain to flow down to the bottom of the silo into a hopper where an auger can pump the grain into a truck. Most large grain farms have a silo complex (a number of silos for seed storage as well as grain storage during harvest). Silos complexes usually are attached to power so that grain dryers can be used.
Grain dryers are used to bring the moisture content down to a level that is acceptable to the grain receiver and this is particularly useful if a farmer has to harvest grain at a higher moisture content just to get the crop out of the field, whether that is because adverse weather conditions are forecast, or large areas of crop need to be harvested so the farmer just has to get on with it.
Most modern silos are fitted with aerators. These are small fans fitted into the base of the silo that forces air up through the silo. They help keep the grain at a constant temperature which maintains the quality of the grain. It is a good idea to think of grain as a living thing, as adverse temperatures or moisture in storage will ruin the viability of any grain kept for seed. Grain dryers are also particularly good at keeping grain insect free, so are a good investment if planning on constructing new silos.
Silo bags are large heavy plastic sausage-like bags that can hold up to 220 tonnes of wheat. They have a life of up to 18months out in the open. They are very useful for storing grain on the sides of fields during harvest, however, the grain must be of the right moisture content otherwise the grain will sweat in the bag and go mouldy. They are quick to use and quite good for temporary storage however you may have issues with access when the time comes to unload them if they are out on the edge of a field (as opposed to permanent silos that usually have a heavy gravel pad around them allowing for all weather access). They also require a specialise bag unloader and if you are planning on leaving them in the field for a period of time they will require an electric fence constructed around them as pigs and kangaroos etc can puncture them and they have been known to tear open like a ladder in a stocking which is can cause quite a bit of grain loss.
Bunkers describe where grain is dumped in a large pile on the ground, or a cement slab, sometimes bunkers are covered with a plastic tarp (which is most desirable to reduce weather damage). These are a very temporary form of storage and grain is usually moved as quickly as possible out of a bunker. An ideal bunker site should be raised to allow water to drain away from the grain. Most farmers would have this area known as the pad, to be built up by a grader and have the floor packed hard.
Insect Pest Control in Grain Storage
Grain insects develop quickly in stored grain if the right conditions are prevalent. Most grain pests reproduce rapidly at temperatures of around 30oC, so cool storage conditions are best if possible at around 20oC or less, this could be quite difficult to achieve in some countries but aeration of silos will help. Grain insects in some countries have already developed resistance to some grain protectant chemicals, so often a combination of protectants is necessary.