About four weeks ago our local farmer, Duncan Ellis, planted out a cover crop on the fields we will be planting with vines in 2012.
I spent many weeks in the Plumpton College library reading books about cover crops and got very confused.
Essentially you plant a cover crop to protect the soil from erosion, to prevent weed growth and as a green crop to improve soil fertility, adding nutrients and improving soil structure by raising the humus level in the soil. This last point is very important to us as the soil samples we have taken indicate that, although the soil is fine for arable crops, the potassium, phosphate and magnesium levels are below the levels ideal for vines. So prior to planting our vines in spring 2012 we are trying to raise the levels of essential nutrients in the soil by direct addition of fertiliser, green waste (the council recycled stuff) and cover cropping.
I had initially planned to plant out red clover as our cover crop, however, as the soil at Rathfinny is so well draining I was advised that clover doesn’t take very well. So I then looked common vetch, Austrian peas, rye and mustard. All cover crops that have been used in organic vineyards in California.
We have settled on mustard, principally because it will take well on the soil at Rathfinny, and despite the lack of rain since planting, it has already come up well in most areas. I was advised that peas could be susceptible to some forms of nematodes and also sclerotinia crown rot. Sclerotinia is a fungal infection, which can also affect grapevine roots. In order to lessen the risk of this infection in the peas, the advice was to plant two pea crops in succession. Which is a shame because from my research peas look to be the best returner of nitrogen, and the best biomass provider. Some of the vineyards in California have had problems with common vetch, which is also a good nitrogen and biomass producer, but it became too invasive and difficult to control. So in the end, after consulting experts from Plumpton College and Ohio State University, thank you Patti, we decided on mustard. Which, when mowed and turned into the soil in early 2012, will provide a good deal of biomass, some nitrogen and will probably reseed itself after the vines are planted out.
We may plant out some crimson clover and rye grass latter this year to add further biomass. This can be turned in prior to planting in spring 2012.
Mustard, as well as being pretty good for the soil it also looks good in a vineyard.
A great blog about the use of mustard.
Our mustard is taking well… so are the nettles!
Our lecturers at Plumpton College drone on about site selection as being the most important element to consider for any vineyard site. That was highlighted last week when on the night of the 3rd/4th May, we experienced a late frost in many parts of southern England.
Late frosts are really bad news for vineyards and vines. It is like putting salad leaves into the freezer. The cold freezes the water in the plant cells killing them and leaving then shrivelled and brown. To mitigate this risk you need to choose a site on a slope, which will encourage the frost to drain away down the slope, avoid low lying areas where frost will settle, and try and get close to a river, or even a road, which helps move the frost away. Being close to the sea can help, as the sea raises the temperature of the surroundings. If you don’t have any of those then you will need to deploy “counter measures”. In New Zealand they use helicopters to force warmer air down onto the vines to disperse the frost. This sounds expensive, dangerous and could cause more damage to the vines with the down draft. Many people use small heaters which help raise the temperature, whilst other blast hot air into the vineyard from large gas fired fan heaters, or they use wind turbines to more the air around. In Martinborough in New Zealand they use water sprays to prevent frost damage. However, the cheapest way to avoid frost damage is to select your site very carefully. Like any property purchase it’s location, location, location.
We were working at Rock Lodge vineyard last week and there was some damage to younger vines on the lower slopes but most of the vineyard was okay. I hear that some vineyards in Kent and Sussex experienced some damage but hopefully they will recover.
In Germany temperatures dipped to -5oC on the same night and according to the German Wine Institute some vineyards experienced the worst frost damage for 30 years, since back in 1981 when 90% of vines in Germany experienced frost damage.
Late frost in May is not that unusual. I remember we had a very hard frost in May 2009. Luckily Rathfinny didn’t seem to suffer from the late frost this year. The minimum temperature recorded on our weather station on the night of the 3rd / 4th was 6oC.
All we need now is a bit more rain, because the wheat is really struggling, along with the mustard we planted a few weeks ago as a cover crop, more on that later.
Frost damaged vine