Direct seeding vs planting. In most situations direct seeding is far more cost effective than planting seedlings for broadscale vegetation establishment. Various practitioners report that costs per plant for direct seeding of between 5% and 50% of those associated with planting seedlings. There are some situations where the extra costs of planting seedlings are justified, primarily small scale projects and high value plantings requiring even spacing such as timber plantings. However in general direct seeding is the only viable way of establishing very large scale plantings. Some broad direct seeding principles - use seed with high genetic and physical quality - treat seed to break dormancy where necessary - the single most important factor in site preparation is weed control. Methods vary according to soil type, climate, weeds species present (both standing and in the soil seed bank) , the scale of the project , equipment available and propensities of those undertaking the project. A very good method is to remove or "scalp" the topsoil layer (100-200mm depending on soil type and weed seeds presnet) complete with standing weeds and the weed seed bank. This is achieved using earthmoving equipment, usually a grader or bulldozer. (The topsoil is not removed from the site, it is simply left in windrows adjacent to the planting strips). This method works very well on soils with a reasonably consistent profile for at least the first 300-400 mm of soil depth, providing extremely good weed control for at least twelve months. The other options are to use knockdown herbicides such as glyphosate, residual herbicides such as simazine or a combination of both. If knock-down only is used the more than one application is usually necessary to kill of successive flushes of germinating weeds from the weed seed bank. Residuals provide better control but more expertise is required in order to apply them at correct rates, and the seed must be sown using equipment capable of inverting the soil close to the seed to provide a chemical free zone. -in general weeds respond better to high soil fertility than native species. Therefore the less fertile the soil (particularly levels of N and P) and the lower the soil's cation exchange capacity, the more easy it is to direct seed native plants. Similarly, the greater the suite of weed species seed present in the seed bank (usually associated with cropping and grazing histories) the more difficult it is to establish native plants via direct seeding without excellent weed control. -as a general rule, weedy forbs and annual grasses pose quite different threats to direct seeded natives. Firstly, it is extremely difficult for any native seedlings to germinate from among a dense sward of perennial grasses (whether native or otherwise). Thus physical or chemical removal of the existing perennial grass sward is absolutely critical. This removal is often followed by a flush of weedy forbs (broadleaved plants such a Pattersons Curse, Bathurst Burr etc) and annual grasses. At this stage the broadleaved forbs are a particular threat because they can simply smother the emerging native plants very rapidly. However once established (say 100-200mm high) many native seedlings are able to survive quite intense forb competition. However if perennial grasses again begin to dominate at this stage then they are capable of killing even well established seedlings. - control of grazing animals particularly rabbits and hares may be necessary. kangaroos and wallablies can also exert pressure on seedlings although unlike planted stock, direct seeded plants rarely die as a reult of marsupial grazing. - soil ripping is important in some situations. Ripping helps seedling roots penetrate deeper into the profile which means higher success rates with less rainfall. This can be important where non-local species are being used (which may not be so well adapted to the soil type or rainfall regime) or where the soil profile has been compacted or modified in some other way. Even some locally indigenous species on pristine soils may only naturally regenerate in exceptionally wet years, so ripping may allow such species to be established every year rather than, say, one in ten. - timing is less critical than in the case of seedling planting because if temperature and moisture are insufficient then the seed can remain in the soil until conditions are right. In other words direct seeding can be done at any time of year. It is however preferable to time works to allow germination as soon as possible soon after sowing (i.e to coincide with warm temperatures and high soil moisture levels). This minimises predation by insects and lessens the chance that weeds will become established in the meantime. In areas of heavy frosts (below -5 degrees) it is not advisable to sow in autumn or winter as newly germinated seedlings can be destroyed by frosts. -if weed control is sufficient then the next most important factor is providing a niche for seeds to achieve good soil contact that allows imbibition (absorbtion of water). Seed can be broadcast or drilled using a variety of techniques. Good results can be obtained by both broadcasting over the soil surface or drilling below the surface. Surface broadcasting is usually only successful if the soil surface has been disturbed sufficiently to allow good soil-seed contact after rain. This involves some kind of drilling, ploughing or ripping equipment. Surface sowing also leaves seed more vulnerable to predators. Sowing using agricultural or native seed machinery tends to be more reliable although very good results can still be achived simply by broadcasting seed. -post germination weed control is far more difficult than weed control before sowing. Some knock-down and pre-emergent herbicdes can be applied post germination but great care must be taken with rates and calibration. Further information For more information try the links below or simply contact us. http://asgap.org.au/APOL20/dec00-5.html http://brg.cma.nsw.gov.au/index.php?page=direct-seeding http://www.gbcma.vic.gov.au/revegetation/chapters/pdf/ch8.PDF http://www.woadyyaloak.com.au/pdf/Direct%20Seeding%20Shelter%20Belts.pdf http://www.florabank.org.au/default.asp?V_DOC_ID=976 http://www.agric.wa.gov.au/content/lwe/vegt/trees/f03498.pdf | 
