If you’re considering sowing undervine cover crops, now is the time. But what cover crops should you plant?
Our 101 of Cover Crops will help you on your way.
Tim Cavagnaro is a Professor in Soil Ecology at the University of Adelaide. He says contrary to old thinking, cover crops – for the most part – will not have any adverse effects on vines.
‘In fact, our trials have shown that there are many advantages to planting cover crops, including increased nitrogen in the soil, an abundance of earth worms and higher levels of microbiome diversity’, he said.
He advised growers do their research, and select cover crops that were suitable and well adapted to their climate and environment.
‘If the cover crop is suited to the environment and is not too aggressive, it can offer a good alternative to herbicide spraying’, Professor Cavagnaro said.
University of Adelaide research agronomist Chris Penfold agrees that research is the key to success.
‘It is important to spend some time considering the options available.
‘Planting the wrong type of crop can be quite detrimental to vineyard productivity and reversing that decision may be costly. For example, planting summer active perennial grasses or legumes, such as lucerne, is assured to reduce yields due to competition for water, so would only be recommended in the most vigorous of sites where significant reduction in canopy size is the aim.’
In contrast, correctly-selected plants could provide year-long soil cover, restriction of weed growth, minimal competition for water, additional nitrogen to support the vines and improved soil quality and habitat for beneficial insects.
So what to choose?
In general, Chris said the preferred species for most Australian viticultural regions would be winter active self-regenerating annual pasture grasses and legumes that set seed in spring then naturally senesce to provide a mulch covering the surface as protection over the summer period.
‘Growing varieties that are known to perform well in the local environment from seed that is readily available will keep the costs low and increase the reliability of initial success and on-going regeneration from the seed bank, which is established in the first spring’, Chris said.
He said nitrogen is the most important soil nutrient in vineyards, and leguminous cover crops are an excellent source.
‘Even growing pasture legumes under-vine has been shown to have considerable benefits to soil quality without jeopardising yield or fruit quality – and provides an alternative to the herbicide strip.’
Quick tip
Many growers like to plant winter cereals (wheat, barley, oats, triticale, rye) and/or legumes (peas, beans, vetch), which have benefits to the soil and compete strongly with weeds.
However, as planting needs to be repeated annually it is a more expensive exercise than the regenerating pasture legumes – and is not cost effective in dry, inland regions. ‘These tall crops should either be laid down in spring with a crimping roller or side thrown under vine to make the best use of their nutrient laden biomass’, advised Chris.