Agronomy III (Root Crops)

Course CodeBAG310
Fee CodeS2
Duration (approx)100 hours
QualificationStatement of Attainment

Root crops provide food security for people all over the world, and especially in developing nations. The carbohydrates provided by root vegetables such as potatoes, cassava, and yams are an essential part of the human diet. Many root crops can also be used for livestock feed.

With this course, you'll learn important differences and growing practices for many root crops, including:

  • potatoes
  • sweet potatoes
  • yams
  • salsify
  • turnips
  • carrots
  • daikon

You'll also learn the difference between culinary root vegetables and true root vegetables, how to distinguish between different pest and diseases, and more.

Lesson Structure

There are 10 lessons in this course:

  1. Scope and Nature of Root Cropping and the Botany of Roots
    • What are root vegetables?
    • Human nutrition and root vegetables
    • Botany of roots
  2. Cultural Practices A: Soil Management, Crop Scheduling and Soil Water
    • General guide to growing root vegetables
    • Improving soils
    • Sampling soils
    • Cover crops
    • Cultivation techniques
    • Soil fertility and plant growth
    • Plant nutrition
    • Fertiliser
    • Soil and water
  3. Cultural Practices B: Weed control, Pest Management
    • Weed and weed management
    • Methods of weed control
    • Pest and disease management
    • Toxicity
    • Diseases
    • Common environmental problems
  4. Potatoes
    • Growing conditions
    • Nutrient requirements
    • Planting
    • Care
    • Watering
    • Problems
    • Harvest and post-harvest
  5. Carrots and their Relatives
    • Carrots
    • Parsnips
    • Bulb fennel
    • Turnip rooted chervil
    • Skirret
    • Celeriac
  6. Turnips and their Relatives
    • Turnips
    • Rutabaga (swede)
    • Radish
    • Horseradish
    • Daikon
    • Kohlrabi
  7. Beets
    • Growing conditions
    • Nutrient requirements
    • Planting
    • Care
    • Watering
    • Problems
    • Harvest and post-harvest
  8. Taro, Yams and Sweet Potato
    • Growing conditions
    • Nutrient requirements
    • Planting
    • Care
    • Watering
    • Problems
    • Harvest and post-harvest
  9. Other Root Crops
    • Salsify
    • Scoronera
    • Scolymus
    • Mashua
    • Jerusalem artichoke
    • Potato bean
    • Arrowroot
    • Oca (New Zealand Yam)
    • Dandelion
    • Chinese artichoke
    • Water chestnuts
    • Yacon or jicama
    • Root chicory
    • Ullico
    • American groundnut
  10. Harvest and Post-Harvest Management
    • Harvesting root vegetables
    • Cooling methods
    • Storage


  • Describe root vegetables, their variations and nutritional value and the morphological internal and external structures of roots.
  • Outline the cultural practices needed to produce vegetable crops.
  • Outline methods of weed and pest management and the use and range of specialised machinery used in root crop production.
  • Outline the cultural requirements and growing techniques for potatoes.
  • Outline the cultural requirements and growing techniques for carrots and their relatives.
  • Outline the cultural requirements and growing techniques for turnips and their relatives.
  • Outline the cultural requirements and growing techniques for beets and their relatives.
  • Outline the cultural requirements and growing techniques for Yams, Taro and Sweet Potato
  • Outline the cultural requirements and growing techniques for a range of other root crops not studied earlier this course.
  • Describe the harvest and post-harvest requirements of root vegetable crops.

What You Will Do

  • Cultivate a root vegetable bed
  • Create and update a log book recording your bed's details
  • Conduct experiments to determine moisture range
  • Discuss ways to improve soil for a set of root crops
  • Discuss crop rotation systems
  • Discuss seed treatments and planting techniques
  • Prepare a weed collection
  • Develop pest and disease control programs from planting through to harvest
  • Write a crop production schedule
  • Discuss timing of varieties and harvest

Learn How to Grow Red Beet (Beetroot)

Beetroot prefer temperate climates, but are adaptable. In warm climates beetroot is best grown during the cooler months. If the weather gets too cold, the root may stop expanding and the plant can produce a seed head. In hot dry conditions, and dry soils the root may become stringy and tough. The leaves as well as the root can be eaten, either raw or cooked.

Grow them in a free-draining light soil enriched with well-decomposed organic matter and a top dressing of general purpose fertiliser before planting for best results. Alternatively, for clay soils grow them in no-dig garden beds, or in well-cultivated raised beds. The ideal soil pH is around 6-6.5, so avoid over-liming. Weeds should be well controlled. 

Planting/ Propagation

  • Seeds should be sown from late winter to late summer once day temperatures are around 20 degrees Celsius. Seedlings should then be thinned to a spacing of 15 cm x 30 cm between rows. You can also dust the seeds with a fungicide prior to planting.
  • The seeds can be very slow to germinate and are actually a solid cluster of several seeds so soak seeds for 24 hours before sowing.
  • Plant the seeds to a depth of 1-1.5cm in rows. Plant rows of globe types about 30cm apart. For long-rooted types allow about 45cm between rows. Seedlings should emerge after 10-14 days. When seeds emerge thin them out to one every 5-8cm. You can also try transplanting greenhouse grown seedlings into rows but the success rate of transplants is not always high.
  • Germination rates can often be poor. They can be started in sand and transplanted when 6 8cm high, though transplants might not grow as well as plants direct sown.
  • The seeds need to be kept moist until they have germinated. A sprinkling of vermiculite may help to stop them from drying out. Seedlings require sufficient water so as to prevent them from becoming woody. Adequate watering will also help to stop the early cropping types from bolting. 
  • Extend the harvest by sowing new rows of seeds every four to six weeks.   

Note: Rotate beetroot annually with other crops such as leaf vegetables like lettuce, celery or cabbage. 

Nutrient Requirements

Overfeeding with nitrogenous fertilisers will cause the development of excessive foliage and root growth will be poor. Boron, manganese and potash are particularly important nutrients for beetroot. Boron deficiency may be caused by excessive nitrogen or lime. Boron deficiency may be corrected by adding 1 teaspoon of borax to 5 litres of water and applying this quantity to each square metre. The ideal pH is around 6-6.5, avoid over-liming. 


Beetroots have few serious problems and aside from the mineral deficiencies already mentioned, the main diseases are leaf spot which is caused by fungi. Areas of the leaf become discoloured and fall out. Damping off can kill off seedlings before they get established and if this happens the seedling withers and falls over. Crown gall may cause lumpy growths on the roots. Root rots can cause decay on the inside of the root like in heart rot, or on the outside as in violet root rot which is seen as a velvety purple layer. 

Pests can include leaf miners which leave behind squiggly tunnels in the leaves. The caterpillars of some moths can also be problematic, particularly on older plants. 

Harvest and Post-Harvest

The time to harvest can vary considerably depending on variety and time of year. As a general rule of thumb, you can expect to be lifting beetroots from 10-16 weeks after sowing.

  • Pick when size of small cricket balls.
  • Harvesting of large, tender roots can be done nine to ten weeks after initial sowing.
  • Be careful not to damage the roots when lifting them because they will bleed profusely. Leave a centimetre or two of stalk on your beetroots when harvesting otherwise they may bleed. If picking some early and leaving others it's a good idea to lift alternate plants so that those remaining in the rows have more room to grow.   
  • If you plan to have plants continue into the colder months in cold temperate regions then put a layer of pea straw down to protect the roots from frost and cold weather damage.    
    Beetroot lasts for several months if stored in the fridge. In cold storage it will last for several weeks. 



  • Farmers and farm workers
  • Farm equipment and service suppliers
  • Agriculture students and professionals
  • Small farm or hobby farm owners considering new 'niche' crops
  • Livestock owners/managers, wanting to produce animal feeds

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