[If you are interested in getting any seed, a few of us are looking to buy some seed together. Please contact Michelle so she can include you on the list. Prices will be around $15-$20kg plus freight. Sowing rates can be very light (2kg-10kg /ha) depending on what you already have in your mid-row. Biserrula is very difficult to source, and may have to come from WA. Alosca inoculant on a 1:1 ratio with the seeding rate will be around $2/kg plus freight, also from WA]
Why legumes for Nitrogen?
Organic fertilizers, in the form of compost, manures or pellets such as Organic Booster (QLD organics) are typically low in Nitrogen (N), and supplementary N is often needed. But supplementing with high N fertilizers such as Urea, Ammonium nitrate, sulfate of ammonium DAP, cal- nitrate, nitofoska, eco88 etc, have many negatives. These include:
- losses through leaching or volatilization to the air,
- acidify the soil
- killing soil microbes and harming the biology of the soil
- high environmental costs in production and application
Legumes as a source of N for the vineyard
Rhizobia form nodules on the roots of legumes and take N from the air and convert it into Nitrogen that plants can use.
It is a free source of N, and does not have the disadvantages of other high N fertilizers.
Using legumes could be a good way to balance up the low Nitrogen level in manures and compost, while also building soil organic matter, water holding capacity and soil biology.
Twisted Gum provide nutrition to the vineyard primarily through fertilizer and nutrient cycling of Organinc matter in the mid-row. (plus foliar sprays for trace elements, and Magnesium). We estimate that a pasture mix of about 30% legumes in the mid-row should provide sufficient N for yields of around 10T/Ha. when combined with 250/500 kg/ha of organic booster or similar.
[We also monitor soil nutrition through soil tests every 3-5 years, and test pH annually with a kit].
file:///C:/Users/miche/Downloads/Bulletin4805Biserrula.pdf see pages 19-22 for details of Nitrogen generated from biserrula.
In some years however, due to lack of winter rain, we do not have enough clovers/medics or vetches to provide N to the vineyard. So drought hardy legumes may be an option.
Our goal is to find a large number of different legumes, grasses and plants, all with different seasonal and nutrient requirements, that can grow in the midrow, self -seed and regenerate, so that no matter what seasonal conditions exist, there will always be at least some plants that will be able to grow.
Other benefits include:
- having a permanent “cover-crop” which you do not have to plough or plant.
- a mid-row with greater bio-diversity which will attract beneficials and natural predators year-round.
2 varieties: SERRADELLA AND BISERRULA,
|Sprawling prostrate growth|
|Prefer sandy soil|
|Hard-seeded drought hardy-self sowing avoid false starts|
|tap root -drought tolerant -non invasive|
|Tolerant to temperatures up to 35 degrees|
|Low bloat in sheep and cattle|
|Grows in annual rainfall of 300-400mm|
|Can set seed in extreme drought conditions of less than 200mm|
- Supply of N
In the sandy soils of WA, Serradella and Biserrula have been planted as a single variety rotation crop, and they have successfully provided 100% of N to the cereal crop the following year.
But… all these areas in WA have winter dominant rainfall, eg Narrogin an average of around 350mm falling in the 5 months from May to Sep.
However, these varieties have also been used in much lower rainfall conditions. We want to see how they perform in the GB. We are impressed with the few plants we have seen on our place already.
- Summer growth-beneficial or competition?
There is a good chance that serradella and biserrula may grow through our summer, as they are able to withstand higher temperatures than white clover, and we usually have summer rains. We see this as an advantage, because they will continue to grow and build healthy soil all year, and help in building soil organic matter, and hence storage of soil moisture. Some may see this as a form of competition during the growing season.
- Inoculating seed with rhizobia-VERY Important
To be sure that the correct rhizobia stain are available to the plant, the seed should be inoculated.
Biserrula is a new variety which uses a unique rhizobia strain (Strain S, or BS) which does not occur naturally in the soil. Hence the seed must be inoculated with this strain.
Serradella needs a different strain to biserrula, but can make use of the same rhizobia strain as Lupins, so soil with recent lupin crop may not need inoculating.
Pre-inoculated seed has been proven to be of very limited benefit. Inoculating with peat and rhizobia is more effective if cone properly, but messy and time consuming. Alosca clay granules impregnated with rhizobia offer a new alternative. Alosca is used in WA with great success. Twisted Gum are trialling this product.
We used Alosca on a 1:1 ratio with the seeding rate.
Interesting read here on cover-cropping and legumes in vineyards: https://kiwiseed.co.nz/images/Shop_News_Letters/art_and_science_of_covercropping.pdf
Thanks Dawn (cellar/vineyard hand at Ridgemill) for sharing this article.
Article in the land about biserrula and seradella in summer dominant rainfall regions, and their performance during drought
For summary of sowing rates and methods etc:
1-5kg/Ha mixed sowing rate.
7kg/ha if straight
Serradella margarita-French serradella –
Serradella santorini- Yellow serradella–
already used in the GB with promising results
sow at 1-2kg /ha when mixed pasture sowing rate. Suggest autumn planting.
Drought testing Biserrula and Serradella (Charles Sturt Uni)
This article talks about setting up a seedbank for self- regeneration with hard-seeded varieties. It also demonstrates drought hardiness.
For those who could not make it to the walk, and would like to see biserrula and serradella growing, please contact Tim or Michelle to organize a time firstname.lastname@example.org.
For those who were at the vineyard walk and would like to see other areas of our vineyard where yellow serradella and arrow leaf clover are growing, also contact us.
Tim and Michelle Coelli
Twisted Gum Wines
2253 Eukey Rd, Ballandean QLD 4382, Ph: 0746841282