Drilling methods

There are four main ways to renew pasture, cultivation, spray-drilling, undersowing and oversowing.

Cultivation

Involves breaking up the soil prior to sowing with the likes of a plough, power harrow, discs or rotocrumbler. It is necessary where there is a need to eliminate compaction or levelling, or lime incorporation is required.

Advantages

• Most consistent results
• Eliminates compaction
• Best pest & weed control
• Can level paddock
• Can incorporate lime
• Allows good soil coverage by seed

 Disadvantages

• Most expensive method
• Slower to first grazing (6-10 weeks)
• Softer and more prone to pugging during establishment

Spray and drill

A direct-drill is used to sow treated seed into an uncultivated paddock after existing pasture killed by herbicide.

Advantages

• Herbicide controls competition
• Less expensive and less time consuming than cultivation
• Quicker to first grazing (6 weeks)
• White clover establishment is possible (see below)
• Long term solution

Disadvantages

• Less opportunity to correct pH
• Won’t fix soil compaction or level paddock
• May revert to old pasture more quickly than cultivated paddocks
• Two drill passes at half the seeding rate are desirable to achieve dense pasture
• Loss of pasture production after spraying

White clover establishment

White clover establishment (after killing existing pasture)

Drill ryegrass using the main-seed box. Drop white clover seed onto the soil surface from the small-seeds box in front of coulters sowing the ryegrass. Cover seed with a brush or bar harrow.

Note: Sowing ryegrass and white clover seed through the same coulter results in poor white clover establishment because the clover is drilled too deep, (1-2cm is suitable for ryegrass but not clover) and clover seedlings are forced to compete with more vigorous ryegrass seedlings growing in the same drill row.

Undersowing

Use a direct-drill to sow treated seed into existing pasture.

Works very well in the narrow window of time when a pasture has thinned out but has not yet been overtaken by weed ingression.

Use after extended dry conditions where large areas need to be sown, or after winter pugging damage.

Results are variable where it’s used in pastures too dense for the new seedlings to establish well.

Advantages

• Cheap and simple
• Allows large areas to be done
• Italian or hybrid can boost winter-early spring growth

Disadvantages

• Doesn’t work in dense pastures
• Doesn’t control problem weeds
• Not suitable for white clover establishment
• Usually only a temporary fix

Oversowing

Treated seed is broadcasted on to the surface of the soil.

Generally used

• to repair smaller areas, for example after pugging damage, or
• to establish white clover in spring into pastures
• where the land is too steep or stony for cultivation.

Not recommended for improvement of lowland pastures due to high seeding mortality.

Sowing rates are generally higher, as establishment rates of seed placed on the ground surface are lower.

Advantages

• Can introduce legumes & N fixation
• Can apply with fertiliser

Disadvantages

• Variable results
• Hard to control competition