Ten Steps to Successful Sowing
Frank Mickan
Pasture and Fodder Conservation Specialist
DEPI, Ellinbank Centre
"Many farmers and contractors argue over which sowing technique is best", says Frank Mickan, Pasture and Fodder Conservation Specialist. Apart from cost considerations there are only small advantages/disadvantages for each sowing technique in various soil types. Some soils, such as those with a very shallow topsoil, may dictate that sowing is done by direct drilling, and not by cultivation. Generally the state of the paddock preparation, timeliness, current weather, and considering the following ten points are usually far more important than sowing technique.
1. Good soil/seed contact.
The seed should be surrounded by a moist, firm and fine seedbed to maximise the amount of soil in contact with the seed to ensure a high rate of germination. For this reason, rolling before drilling into a cultivated seedbed or, rolling after broadcasting will greatly improve germination rates. The importance of a good soil/seed contact can often be seen in the tractor wheel ruts of paddocks not rolled. To avoid the possibility of soil erosion or wash out, rolling on steep slopes should be avoided. Buffer strips such as old pastures left unploughed across the slope may help to reduce soil erosion after heavy rains.. Soils that may crust should not be rolled either, especially if in a moist state.
2. Avoid competition (weeds, existing/old pastures).
Newly sown seeds cannot handle competition from weeds, or old pastures. Whether you cultivate, direct drill or oversow, ensure that you have reduced as much competition as possible, and continue to do so until the new pasture is well established. This may involve spraying, heavy grazing, harrowing, etc. If direct drilling into existing pasture continue to graze heavily for 2-3 days after sowing to slow down the recovery of the old pasture.
3. Drilling Vs. broadcasting.
Drilling allows the seed and fertiliser to be placed close together whereas broadcasting does not. The new seed requires a supply of phosphorus, potassium, sulphur and often molybdenum, to get it up and away. If drilling, sow shallower rather than deeper. When broadcasting seed also increase the seeding rate by 30 to 50 % to ensure a satisfactory germination.
4. Fertilise well.
If possible soil test before sowing, particularly if broadcasting or direct drilling the seed. Cultivated paddocks are best soil tested in the following 12 months since the cultivation may greatly alter the current soil fertility.
Sow with super, super/lime (and molybdenum if needed) or DAP but do not sow pasture seeds with potassium, copper or large amounts of nitrogen. These may affect germination if in contact with the seed. Apply DAP or NPKS mixes before, or soon after the first grazing. Apply P and K fertilisers the following spring and next autumn.
5. Use inoculated and lime coated clover seed.
Various longer term seed coatings, incorporating an insecticide and other coatings are now available. These will allow a longer period to elapse before sowing occurs, and provide some protection against lucerne flea, red legged earth mite, etc. and a more favourable environment directly around the seed itself.
6. Apply lime (if necessary).
If your soil is very acidic and lime is needed, apply and incorporate it into the soil at cultivation, but still use lime coated seed as the lime will not have had time to alter the soil pH (acidity) at this early stage. If sod-seeding and direct drilling, apply the lime before/after but also sow lime coated seed. Apply lime in soils with a pH(water)5.6 and below if cultivating. It may be many years before there is another opportunity to incorporate further lime. If not cultivating at sowing lime can be topdressed in high rainfall areas or on light (sandy type) soils with pH(water)5.3 or less.
7. Do not bury the seed too deep.
Sow at 10 - 15mm depth. Rolling beforehand results in a more even seedbed if using a drill in cultivated soil. Avoid heavy harrowing after drill sowing. An alternative used by many farmers is to pull the hoses out of the boots and drop the seed on the surface. This is then rolled, or covered by dragging a heavy piece of carpet or light chain harrows behind.
If sowing by broadcasting, roll afterwards, or drag a heavy piece of carpet, light chain harrows, or weldmesh over the paddock. The seed may be buried too deep, and/or may be separated from the fertiliser.
8. Control insects before/during/after germination.
Regularly check the newly germinated pasture. Lucerne flea, red-legged earth mite and slugs can wipe out your new pasture very quickly. The failure of clover seed to germinate is often actually due to the work of lucerne flea which have been, eaten the seedling, and gone, without the farmer's knowledge. Either treat the seed before sowing (gives about 2-4 weeks protection) or be ready to spray soon after germination.
9. Control weeds before sowing and after emergence.
Weeds will usually out compete newly germinated pasture seedlings if follow up weed control is late or non-existent. Some sprays are available to control weeds soon after emergence but the young clovers must be at the 3 - 4 trifoliate leaf stage ie. 3 leaves each having the 3 lobes/leaf and stem.
More advanced broad leaved weeds can be cheaply and satisfactorily controlled by the Spray - Graze Technique (sub lethal rates of 2,4 D amine or MCPA amine followed 7 - 10 days later with a hard fast graze). Block/strip grazing may also be reasonably successful if well grazed and soil fertility is moderate (above an Olsen Phosphorus of about 13 - 15).
10. Use the correct grazing management.
Graze earlier rather than later for the first grazing. Direct drilling allows far earlier grazing compared to cultivated land. Graze when plants reach a height of ~8 - 10 cm. This will encourage tillering of the ryegrass and also prevents shading of the clovers. If you can break off a sprig of pasture with your fingers without pulling it out of the soil, it is ready for grazing! From then on graze when pasture height is about 10 - 15cm, and remove the cattle when at ~3 - 4 cm height.
In autumn and winter silage/hay/grain etc. may need to be fed to achieve these heights. Avoid cutting new pastures for fodder in the first year but cutting excess pastures for silage/hay in spring in following years will prevent them from becoming too long, thereby shading out clovers and young tillering ryegrass.
Below Table 1 shows what are commonly thought to be the causes of sowing failures but also the more common actual causes of sowing failures.
Table 1. Perceived and actual causes of sowing failure