Oats: seeding and establishment

Page last updated: Tuesday, 1 May 2018 - 1:41pm

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Cultural practices from paddock preparation to seeding rate and sowing date help promote plant establishment and survival. In Western Australia, with our unpredictable and erratic rainfall combined with poor soils, this start is essential to help maximise oat production.

Keys to good establishment

  • Use plump good quality seed from paddocks with a good fertiliser history, uniform in size, not cracked or broken, stored in dark cool dry conditions (not more than one year old) and free from pests and disease.
  • Seed should have a high percentage germination, free from weed seeds and inert rubbish.
  • Good soil-seed contact and 'sufficient' soil moisture for quick germination.
  • No weeds should be present at sowing.

Paddock preparation

Legume based pasture and crops provide more nitrogen, which increases grain yield and protein. Lower levels of applied nitrogen are needed following a good legume rotation.

Control grasses prior to the oat crop through pasture manipulation or spraytopping in the previous pasture. Control in the preceding grain legume is essential to reduce root disease and allow early sowing.

There is a requirement by customers of the export hay market that hay be free of any contamination. Paddock preparation is a major part of management for export hay and requires:

  • removal of old crop residues (burning)
  • removal of sticks, tree branches, stones , carcasses, wire etcetera
  • in some cases, rolling of paddocks

For no-till systems before seeding, follow standard paddock preparation protocols such as knocking down the weeds. See Oats: weeds and integrated weed management for more information.

Plant population

Establishment of an optimum plant population is essential to achieve the maximum possible yield. The desired number of plants per square metre is mainly dependent on yield potential but also can improve crop competitiveness against herbicide resistance ryegrass.

  • The recommended plant density for oat grain production in the higher rainfall regions is 240 plants per square metre (m2), while in the lower rainfall region it is 160 plants/m2.
  • The recommended plant density for oat hay production is between 240-320 plants/m2, with higher density helping to compete better with weeds and to reduce stem thickness, which is desirable in quality export hay.

Reasons to increase plant density include:

  • Hay production - to help plants compete against weeds and to produce finer stems as required for the export market. Target 320 plants/m2.
  • Dwarf varieties - plump-grained varieties can be sown at higher density.
  • Seedling emergence and establishment are likely to be reduced.
  • Plant tillering is expected to be low because of variety or soil fertility effects.
  • Delays to sowing.
  • Good rains expected during the season.
  • Soil fertility and moisture levels are high.
  • A dry finish is expected.
  • Likely infestation of insects which may cause seedling mortality.
  • A high risk of waterlogging (mid season) - to compensate for a lack of tillering.
  • Moderate to high grass weed densities are likely - increase competitiveness.

Avoid higher plant densities where:

  • Plump grain is required for milling quality.
  • Lodging could be a problem - slightly lower densities can encourage thicker stem growth.
  • Crops are growing on stored soil moisture and may risk deplete most of the moisture before the crop matures.

Seeding rate

Calculate seeding based on seed size, target plant population and calculated germination percent. Work in terms of plants per square metre rather than kilograms per hectare (kg/ha) because grain size and weight varies between crops, varieties and seasons.

To determine the average grain weight, count and weigh 1000 seeds of the graded sample. The seed rate calculation is:

Seed rate (kg/ha) = [Target plant density (plants/m2) * Average grain weight (mg)] / Expected establishment per cent (%)

For example, if the desired plant population is 240 plants/m2, the average grain weight is 40 milligrams (mg) and expected establishment is 80% the calculation is: 240 * 40 / 80 = 120 kg/ha

Table 1 shows examples of seed rates calculated on the basis of target plant population, seed weight and establishment percentage of 80%.
Average seed weight (mg) 160 plants/m2 240 plants/m2 320 plants/m2
33 66 99 132
35 70 105 140
37 74 111 148
39 78 117 156

Sowing depth

Sowing plump seed at the right depth is an important first step towards achieving vigorous, healthy seedlings. Planting should be deep enough to provide uniform coverage of the seed and to help maintain moist conditions for germination.

  • The recommended depth for most oat varieties is 3-6cm.

Oat seedlings emerge by elongation of the mesocotyl and coleoptile (in wheat and barley it is only through elongation of the coleoptile) so oats can safely be sown deeper than wheat and barley.

Sowing too shallow may:

  • Place the seed in dry soil and it may fail to emerge.
  • Cause shallow crown depth that may cause the plants to lodge when soil is very wet and in high winds.

Consequences of deep sowing can include:

  • Delayed seedling emergence.
  • Emerging seedlings that are weaker, limp and easily damaged by wind and insects.
  • Reduced root development making plants more susceptible to root diseases.
  • Delayed plant development and tillering.
  • Reduced competitiveness with emerging weeds.

Use press-wheels to compress the soil directly above the seed for even distribution during seeding. When using standard tyned seeders without press-wheels, the seed is often spread through a depth of 2-3cm with the occasional seed left on the soil surface.

Sowing into water repellent sands early in the season where the wet soil may be at 5cm or more necessitates the use of press-wheels to ensure even establishment.

Coleoptile and mesocotyl length are temperature dependant so early sowing into warmer soils will result in them being longer compared to later sowings in winter.

Row spacing

In cereal crops that receive adequate moisture, narrow row spacing generally results in higher grain yields than wider rows by promoting ground cover, optimising light interception and by suppressing weed growth.

For crops expected to yield greater than four tonnes per hectare (t/ha), rows should be sown no further apart than 25cm and preferably less than 20cm. For hay this will give good ground coverage by plants so that the windrow can be held off the ground to improve air circulation and reduce staining.

Sowing date

Seed at the optimum sowing date for growing season length and variety maturity to maximise yield and reduce the risk of downgrading the quality of both grain and hay.

In most regions of Western Australia, the ideal time to flower (flowering window) is in September. For areas around and north of the Great Eastern Highway (Beverley, Wongan Hills and Chapman Valley), the flowering window is the whole of September. For the Great Southern (Katanning, Mt Barker and Newdegate), the flowering window ranges from mid September to early October.

Flowering too early will mean maximum growth and yield will not be achieved and risk of frost damage and weather staining is increased. Flower too late increases the risk of running out of soil moisture and filling grain at higher than optimum temperatures leading to lower yields and higher screenings.

Early sowing

Sowing as early as possible with a later maturing variety will:

  • Give the crop the opportunity to give the highest possible yield.
  • Reduce grain protein content - one month delay in sowing date can increase protein by about 1%.
  • Increase the severity of foliar diseases - choose varieties with good disease resistance ratings.
  • Produce taller crops in good growing condition which may lodge.

Early sowing (May) results in higher hay yields compared to late (June) sowing, however if early maturing varieties are sown there is a greater risk of rainfall on the cut hay.

Late sowing

Sowing late in the program with an early maturing variety:

  • Will give lower yields with higher protein because flower and grain fill will be later into spring when miosture is likely to be limiting and temperatures high.
  • Foliar diseases, lodging and shedding will be less severe.
  • Hay quality will be reduced.

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