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The following article explores how various legume seed varieties can reduce the reliance on traditional/synthetic Nitrogen fertiliser with an alternative resource that fixes FREE atmospheric Nitrogen into soil.
Legumes that are used in Australian pasture based systems such as lucerne, clovers and tropical/subtropical legumes play a crucial role in pasture performance and productivity. Pasture based systems are highly responsive to Nitrogen, as it is an essential nutrient to maintain high production and pasture quality.
Melissa Gooseman, DLF Seeds Product Development Manager, says, “Nitrogen fixation reduces the need for synthetic Nitrogen fertilisers, conserves energy, improves soil fertility and minimises the environmental impact associated with the production and use of synthetic fertiliser.”
In addition, when farmers sow a legume seed that fixes atmospheric Nitrogen into the soil, it promotes sustainable agricultural practices, reduces the reliance on/cost associated with synthetic fertilisers and improves pasture/crop diversity. Legumes also directly improve diet quality. Pasture legumes have higher protein and digestibility for a longer period of the year than grass only pastures. This helps achieve better liveweight gains and reproductive performance.
The amount of atmospheric Nitrogen that a legume can fix varies depending on several factors such as the species of legume, environmental conditions, and the presence of effective Nitrogen-fixing bacteria. On average, legumes can fix around 100-400 kilograms of atmospheric Nitrogen per hectare per year.
Not all the Nitrogen fixed by legumes is directly available to the plants themselves. Some of the fixed Nitrogen is used by the legume for its own growth and development, while a portion is released into the soil, much of which is available to other plants in the ecosystem.
If you are in tropical or subtropical regions with a high performance pasture in the ground and are looking to oversow legumes for some added Nitrogen. Consider oversowing proprietary, Envirogro® treated legumes such as Caatinga or V8™ stylo.
Moving further south, where areas have been inundated with rainfall and wetter than average seasons; Nutrients (including Nitrogen) have been removed from the soil due to higher yields and leaching (caused by the increased rainfall). Incorporating more legumes into theses systems will help improve soil conditions and increase soil Nitrogen levels for future crops in which the previous crops have mined from the soil.
In these areas, Melissa recommends incorporating Stamina® GT5 grazing tolerant lucerne this spring “Stamina® GT5 is renowned for its resilience to hard grazings and exceptional performance in dryland environments meaning the Nitrogen fixation benefits can last for longer (7 to 10 years) compared to traditional varieties that may need to be pulled out after 3 years. Additionally, as a dual-purpose variety, it offers versatility for hay stands that may be occasionally grazed, providing flexibility in management practices.”
All lucerne’s from the Stamina® range offer long-term Nitrogen fixation benefits compared to traditional varieties as the lucerne Stamina® range can stay in the ground for longer (7+ years) whilst handling some seriously tough grazings. Tamworth NSW Farmer Wade Jordon recently experimented with the new Torrens GT8 variety, the first highly winter active lucerne with grazing tolerance.
“Torrens GT8 has been ideal for our hay operation as it’s providing us with high quality, soft leafy hay. Sown under irrigation, our yield was roughly, on average, 145 bales per hectare at a bale weight of 25kg+ (per bale). Considering this was a new Lucerne stand, I’m pretty happy with the numbers, which will only improve with each cut as the stand matures,” explains Wade.
If a 7 to 10 year stand isn’t needed but Nitrogen fixation is, Melissa suggests “sowing a perennial chicory clover blend such as Rocket Fuel™ for the Nitrogen fixation benefits clover offer.”
On average, a proprietary white clover may grow around 4000kgDM/ha/year which is equivalent to 80kg N/ha/year of free Nitrogen fixed from the atmosphere. Assuming the cost of Urea at around $650/t, a unit of N costing approximately $1.41/kg, 80kgN/ha fixed by a white clover is worth approximately $113/ha/year to the farmer.
“Rocket Fuel™ is carefully designed to fit various environmental conditions, making it suitable for multiple geographical locations. It has an impressive animal performance package, ensuring optimal results for livestock. The proprietary white and red clover combination contributes Nitrogen to the chicory over time and improves soil health,” says Melissa.
DLF Seeds proprietary seed legume varieties, such as the Stamina® lucerne range, V8™ stylo, Caatinga stylo and more along with clovers in Rocket Fuel™, are an excellent option for farmers looking to fix free atmospheric N into their soil and reduce their reliance on fertilisers.
“Ultimately, legumes are an attractive option for grazing systems as they are a cost-effective and sustainable source of Nitrogen,” Melissa concludes.
For more information on DLF Seeds varieties, including our range of legumes, get in touch with your local DLF Seeds Sales Agronomist.
