Legumes reduce reliance on fertiliser

Dec. 9, 2023 | 5 Min read
Legumes such as lucerne, clovers and tropical/subtropical legumes play a crucial role in pasture performance and productivity. These plants can be highly responsive to nitrogen, as it is an essential nutrient to maintain high production and pasture quality.

Legumes such as lucerne, clovers and tropical/subtropical legumes play a crucial role in pasture performance and productivity. These plants can be highly responsive to nitrogen, as it is an essential nutrient to maintain high production and pasture quality.

DLF Seeds product development manager Melissa Gooseman said nitrogen fixation reduces the need for synthetic nitrogen fertilisers.

“It also conserves energy, improves soil fertility and minimises the environmental impact associated with the production and use of synthetic fertiliser,” Ms Gooseman said.

In addition, when farmers sow a legume seed that fixes atmospheric nitrogen into the soil, it promotes sustainable agricultural practices, reduces the reliance on and cost associated with synthetic fertilisers and improves pasture and 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 which 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 to 400 kilograms of atmospheric nitrogen per hectare per year.

Not all the nitrogen fixed by legumes is directly available to the plants themselves some 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 these 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, Ms Gooseman 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,” she said.

“Additionally, as a dual-purpose variety, it offers versatility for hay stands that may be occasionally grazed, providing flexibility in management practices.”

All lucerne 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 (over 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,” Mr Jordan said.

If a 7-10 year stand isn’t needed but nitrogen fixation is, Ms Gooseman suggests sowing a perennial chicory clover blend such as Rocket Fuel.

On average, a proprietary white clover may grow around 4000kgDM per ha per year, which is equivalent to 80kg N per ha per 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 per kg, 80kgN per ha fixed by a white clover is worth approximately $113 per ha per 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.

“Ultimately, legumes are an attractive option for grazing systems as they are a cost-effective and sustainable source of nitrogen.”

Categories Market insight

Read also

View all

Serenade sings to soil

Dec. 11, 2023 | 2 min read

Attention to soil pays dividends

Dec. 11, 2023 | 5 min read

Classy facility drives business in Griffith

Nov. 22, 2023 | 3 min read