Soil Type
Oats are suited to a wide range of soil types in Western Australia and have the reputation of being considered a low-input crop, requiring less nutrients and therefore suited to marginal soils. As a result, soil management and maintenance are often overlooked but research has shown that healthy soils with good fertility and physical conditions always give better yields particularly when growing dwarf varieties.
- Oat crops are generally less sensitive to soil acidity and waterlogging, but good quality soils are required for profitable yields. Acidity, waterlogging and salt problems can adversely affect yield and quality.
- Deep well-drained soils are ideal as they maximise the opportunity to store sub-soil moisture and allow the crop to explore the maximum available range of moisture and nutrients. Ideally, select soils with at least 50cm of suitable root zone (freely drained, without hardpans or surface crusting). On poorly drained soils, yield may be unprofitable.
- Medium textured soils are preferred to sandy soils because of their greater water holding capacity but research has shown that oats can be successfully grown on sandy soils provided they are supplied with adequate nutrients and moisture.
Soil acidity
Soils with low pH often have high levels of aluminium in the soil solution. Oats can tolerate soil pH as low as 4.3 and although they are considered more tolerant of acidity and aluminium toxicity than other cereals, significant yield losses can occur under extremely acidic conditions with high levels of exchangeable aluminium. Paddocks with low soil pH should still be subject to a liming program even if being sown to oat grain and oat hay crops.
Waterlogging
Under waterlogged conditions, soil and crop environment is affected by the depletion of oxygen, leading to reduced root respiration and other vital plant physiological processes. This results in impaired plant growth and yield loss, as well as increasing susceptibility to disease, reducing plant vigour and potentially causing plant death.
Oats are seen as more tolerant of waterlogging than other cereals, particularly prior to germination. When growing in waterlogged conditions they tend to maintain green leaves while wheat and barley often become chlorotic.
Agronomic management strategies for growing oats in waterlogged areas include:
- Sowing as early as possible in waterlogged conditions. Delayed sowing results in a greater yield reduction and loss of quality.
- Use long season varieties so crops are established before waterlogging occurs and still flower at their optimum time.
- Ensure adequate nitrogen is available to the crop before and after waterlogging. Supplementing nitrogen fertiliser can offset a portion of the yield loss because nitrate can act as a secondary source of oxygen for the plant.
- Minimise weed competition.
Salinity
Excessive soil salts can reduce the performance of oats. Although they are considered a moderately salt tolerant crop, oats are more sensitive than other cereals.
In saline environments oats show decreased seed germination and stunted plant growth, turning dull, bluish yellow green and many tillers die, ultimately affecting yield.
Caution should be taken when combining waterlogging and salinity. Under these conditions, low oxygen concentrations around the roots limit energy available to the plants and they are not able to exclude salts from their tissues.
Acknowledgements
This has been based on information produced by Kelly Winfield, Blakely Paynter and Raj Malik.