Agronomy II -Grains

Course CodeBAG309
Fee CodeS2
Duration (approx)100 hours
QualificationStatement of Attainment

Learn to grow cereals, pulses and pseudo grains

  • Grow grain crops on a small or large scale.
  • Learn production methods, from soil preparation and planting to harvest and post harvest treatment of the grain.

This course is an ideal foundation for farmers, farm workers and anyone supporting agricultural grain production or marketing.

Lesson Structure

There are 9 lessons in this course:

  1. Introduction to grains
  2. Cereal/grain infrastructure and machinery requirements
  3. Wheat, triticale, spelt, barley, oats, rye.
  4. Maize, Sorghum, millet
  5. Rice
  6. Pulse crops
  7. Pseudo cereals
  8. Processing grains for human consumption
  9. Grains for livestock consumption

Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.

Aims

  • Classify important existing and emerging grains or cereals grown around the world and explain the production systems both large and small scale, used for growing, harvesting and storing grains in different countries.
  • Describe important farm structures, equipment, vehicles, supplies and natural resources required for successful production of cereal/grain crops
  • Describe and compare the properties and production systems of the major ‘cool season’ cereals, namely: wheat, triticale, spelt, barley, oats and rye.
  • Describe and compare the properties and production systems of the major ‘warm season’ cereals, namely: maize, sorghum and millet
  • Describe the four main broad habitats where rice is grown and explain the variety of production systems used within these different habitats.
  • Explain and compare the production systems and uses of important cool and warm season pulse crops grown around the world.
  • Describe production of ‘non-grasses’ that are existing or emerging as important‘cereals’, such as chia, quinoa, amaranth and buckwheat.
  • Explain post harvest storage and processing methods used for cereals for human consumption and examine the various sales procedures used.
  • Describe the production of important warm and cool season grasses used for forage and stock feed
  • Describe the storage, processing and sale of cereals used for livestock and demonstrate the calculation of some sample stock rations

Grain and Pulse Production Involves More Than Just Growing

Successful production of a grain crop starts with an ability to select an appropriate cultivar and know how to grow it and ends with knowing how to harvest, treat and store the grain once the crop has matured.

After Harvest the Next Step is Usually Drying

The crops discussed in this course are grown to produce either forage or grain. Forage is food for livestock, where the vegetative part of the plant itself is an important component of the crop. Grain, on the other hand, is the seeds from these crops used for human consumption. In this case, the grain is removed from the rest of the plant, then readied for eating. The type of consumption and amount of processing required varies according to the grain type and use.

A combine harvester is a machine that harvests grain crops and it usually combines three separate operations: reaping, threshing, and winnowing into a single process.

Reaping is the physical cutting of the crop. In harvesters, usually the crop is gathered in by the header at the front of the harvester and a slowly rotating wheel (pickup-reel) pushes the crops down towards the cutter bar. This often has teeth which open/close repeatedly to cut the crop off at the base. The cut crops are fed to the centre by spinning augers and travel up a conveyor. A thresher (drum) beats the crops to break them and the grain is shaken off; the grain then falls through sieves into a collecting tank (winnowing) and the chaff is released through the back of the machine by a spreader or it can be baled up.   

These processes can also be done by separate machines or by hand in smallholder farming systems. A thresher can also be a standalone piece of equipment on smaller farms without harvesters. It works by beating the plant to make the seeds fall out. Winnowing separates the loosened chaff from the grain, often by a process of lifting the grains up and allowing them to fall with a current of fair which carries away the lighter chaff allowing the heavier grain to fall downwards. Once winnowed, the grain can be dried and stored. It can then be processed when required.  When the grain reaches primary processing, the steps may vary some – rice, for instance, is often hulled then sold without milling.

Although crop regulations vary from country to country, drying is a government requirement in most places. This is because some level of drying is usually necessary for safe storage. Determining how much drying is required means the moisture content of the grain must first be assessed. This can be done by several methods ranging in their accuracy and cost:

  • Morphologically
  • With a moisture meter
  • With a simple drying test
  • Laboratory tests (NIR, Microwave)

Types of Drying

Once the moisture content of the grain has been determined, a drying process can be decided upon. There are two major methods of drying:

  • Natural drying, also known as no-heat or low-heat drying
  • Heat drying

Time from harvest to storage, sale, or storage and sale usually determines which method is chosen. Natural or low-heat drying can take much longer, but kernels are generally more robust. Seeds also remain viable. Heat drying can be very quick, but if grain is overheated, it is more likely to crack or shatter, and the germination rate of seeds is significantly reduced.

Most grain must be dried to between 12 and 14% moisture content depending on the grain type. Check your local legislation or industry organisation for exact percentages in your area. 

Natural Drying
Natural drying is a form of aeration and cooling. Here, grain is stored in a large bin with fans which regularly aerate the grain (see picture below). Although top-down fans are available, these are usually undesirable as they push the grain downward. Fans positioned at the bottom of the bin push air upward through the grain, allowing it to move and settle naturally. It is possible, however, for the grain that is highest within the bin to re-wet, or remain wet, due to condensation. Natural drying has limitations though – if grain is too wet at harvest, it can be hard to remove enough moisture this way before spoilage occurs.

Natural drying usually begins around 10oC. If the air is colder, moisture movement is significantly reduced. Relative humidity is also a factor; most companies manufacturing drying systems include tables listing temperature and relative humidity standards along with recommended fan strength and run times.

Aeration also prevents mould and reduces the likelihood of insect development. Without aeration, the small pockets of air within the stored grain and the air in the bin outside of the grain will come to equilibrium. This is bad because it means moisture will move into the grain and encourage insects and mould. If you choose to use an aeration system to dry your grain, the system will run the fans appropriately throughout the day. Note that there must be sufficient space at the top of the bin or silo for drying to occur evenly. If space is too small, the risk of uneven drying and wet pockets is increased. Aim for around half the bin's diameter. For instance, if your storage bin is 1 m across, there should be at least 0.5 m of space between the grain and the top of the bin. In many cases, the air is pushed through a perforated floor for even dispersal.

Heat-drying (hot air drying)
This is when grain is dried through the application of heat, to reduce moisture content. Sometimes heat-drying is used when the environment prohibits natural drying, or to dry grain quickly, or even if natural drying has failed to adequately remove moisture. Heat drying removes moisture much faster than natural drying.  Heating can be achieved with LP gas or by solar driers (e.g. using desiccants) and drying can be achieved using many techniques such as batch drying, continuous flow drying etc.

A major risk in heat-drying is over-drying. This affects sell weight – if the grain is over dried, then the quantity sold per weight (kilogram) is more grain and less water. This is important because it can affect profit, loss, and inventory calculations. It is important to note that fuel costs must also be accounted for, as heating costs more than natural drying with cooling fans.

 

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