Add value to perennial pastures with nitrogen fixed from legumes
Legumes have always been a valuable addition to perennial pastures.
Considering nitrogen prices have skyrocketed over the past 12 months, this is now true more than ever.
The current high nitrogen (N) costs serve as an important reminder of why proprietary legumes are beneficial to an operation by fixing free slow-release nitrogen for perennial grasses.
Legumes fix atmospheric nitrogen into usable nitrogen through a symbiotic relationship with rhizobia and root nodules. For every 1,000kgDM/ha above ground legume growth approximately 20-30kg/ha of free atmospheric nitrogen can be fixed. In other words, legumes can potentially reduce the synthetic N fertiliser requirements of pastures, while increasing overall quality as legumes are naturally high in crude protein (CP) and metabolisable energy (ME).
On average a proprietary white clover within a perennial ryegrass pasture will grow around 4,000kgDM/ha/year. That’s 80kg N/ha/year of free nitrogen fixed from the atmosphere. With the current cost of urea at around $1,100/t (or more), a unit of N costing approximately $2.39/kg; 80kgN/ha fixed by a white clover is worth approximately $191/ha/year to the farmer, excluding the extra pasture growth and increased animal performance from increased pasture quality when including legumes.
To optimise performance of perennial legumes and maximise persistence within a perennial pasture sward:
- use the PGG Wrightson Seeds Programmed Approach® to pasture renewal for an easy to follow, 10 step process on pasture renewal and maximising the persistence of a perennial pasture with legumes (Step 8 and 9 of the Programmed Approach™).
- use high sowing rates at establishment (4 – 6kg/ha white clover) or 20% of the pasture mix.
- use legume friendly herbicides during establishment.
- maintain high soil fertility especially phosphorous, potassium, sulphur and molybdenum and be mindful of soil pH.
- use proven proprietary clovers bred within a pasture sward.
- use the appropriate legume species for rainfall and soil type.
So, who needs free nitrogen? Pair high performing perennial ryegrass varieties such as Base AR37, Reward Endo5, Platform AR37/AR1 or summer active tall fescues such as Quantum II MaxP® or the new Quantica MaxP with proprietary white and red clovers and maximise pasture mixes fixing up to 80kgN/ha/year plus.
Proprietary clovers such as Legacy large leaf white clover, Quartz medium leaf white clover, Hilltop small-medium leaf white clover and the new generation red clover, Amigain, have been bred in a pasture sward offering the following benefits and more.
Legacy large leaf white clover: A high performing large leaf clover offering greater persistence, high yields and improved year-round production, resulting in more nitrogen being generated to drive pasture performance.
Quartz medium leaf white clover: A high yielding, persistent medium leaf white clover with high stolon density and broad adaptability across various environments and farm systems.
Hilltop small-medium leaf white clover: Bred to cope with more challenging environments from variable soil fertility to variable moisture availability, Hilltop is a very robust and persistent small-medium leaf white clover.
New Amigain red clover: As the latest generation red clover bred for increased persistence and growth in permanent or short term, high performance pastures, Amigain will perform in both pasture mixes and pure swards. As a specialist multi-year crop, Amigain provides high quality feed and produces lower formononetin (oestrogen) levels compared to older varieties.
Red and white clovers available from DLF Seeds are bred and selected from within a high performing perennial ryegrass sward whereas, traditional clover selection was completed under cut and carry trials for two years. Amigain, Legacy, Quartz and Hilltop clovers were evaluated for growth and persistence under cattle grazing over multiple years. Through these trials it was evident that the increased stolon density fibrous root systems and their ability to compete and persist in the modern pasture sward make them the ideal companion to a perennial pasture.
Ultimately, if established and managed well, sowing legumes as part of a pasture mix may increase the overall pasture quality, reduce fertilizer (N) requirements, improve stock performance and provide a higher return on investment.
Article written by PGG Wrightson for Seasons magazine.
PGG Wrightson Seeds recently combined with Stephen Pasture Seeds and AusWest Seeds and are now called DLF Seeds. The PGG Wrightson Seeds proprietary product portfolio is available through DLF Seeds.
Ask about the PGG Wrightson seed range at your local Elders store.