Protein-rich legumes are recognised as being drivers of animal production, but increasing their content in uncultivated hill country pastures can be a challenge.
Banks Peninsula farmers Hamish and Annabel Craw are 18 months into a three-year project “Plus 3 Tonne with Legumes” that aims to determine the optimal spray out method and legume pasture mix to improve the quality and quantity of their hill country pastures.
The couple are part of Beef + Lamb New Zealand's Innovation Farm programme (formerly known as 'Demonstration Farms'). The programme supports farmers in projects that improve farm profitability.
Upscaling to field trials
Hamish and Annabel farm 422ha on the northern side of Banks Peninsula. The couple have already developed 80ha of cultivatable land using legume-based forage mixes and have seen the value of these mixes in driving stock performance – particularly lambing percentages and kilograms of lamb weaned. They are now keen to find a pasture management strategy that allows legumes to flourish – and drives stock performance – on their hill country.
As with most Innovation Farm projects, the couple have started out with plot trials and based on their findings, are now upscaling to field trials.
Much of the focus has been on the chemical control of poorer pasture species, to allow existing clover to thrive. The treatments have been a light chemical top, a heavy chemical top and grass eradication. These involved using different rates of both glysophate and Valiant in November 2014. Some glysophate treatments received a second spray in autumn 2015.
Three different seed mixes (predominately legumes) were broadcast onto each of the treatments in autumn 2015.
Early results indicate that the Craws can achieve their objectives of increased legume content with just one application of Valiant, although they did find that to build a bank of legume-rich pasture for weaned lambs, the spray treatments needed to happen in October rather than November. The couple have now upscaled the trial to a single spray Valiant treatment of 500ml/ha on a 5ha block of hill country.
They have based this decision on finding that, between November 2015 and February 2016, legume content (existing clover species) increased to become 32% of the total herbage in the plots sprayed with Valiant. This is compared to 4% legume content in the control plot – and this was over a particularly hot, dry summer.
Hamish says early results suggest that the one-spray Valiant treatment is a cost-effective way of improving pasture quality, even in challenging conditions such as they experienced last summer.
The metabolisable energy (ME) of the pastures sprayed with Valiant remained between 11.6 and 11.8 over summer, while the energy content of the control plot pastures dropped from 11.6 in spring to nine.
While it is recommended that oil is added to Valiant to improve plant uptake, the Craws did not do this. They suspect this may have been an advantage, as it is has allowed better quality grasses to be retained while killing poor quality grasses.
To quantify this, the Craws have extended the plot trial to incorporate various rates of Valiant with and without oil. This will give them an understanding of the optimal application rate, taking into account pasture production, legume content and application costs. They will be using Valiant without oil in their 5ha field trial.
Yarrow was the main weed in the Valiant treatments and there is no treatment available that controls yarrow without killing the clover.
Hamish and Annabel have had limited success introducing new pasture species through broadcasting seed. This, they say, could be a combination of competition and climatic conditions.
While only halfway through the project, the Craws have calculated that, based on the extra quality and quantity of drymatter produced with the one-spray Valiant treatment, they can expect a payback within 16 months.
Going into year two, the couple will continue to monitor and measure the production of the trial plots. They will also adjust the rate of Valiant, to minimise costs while maximising production gains.