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Add value to perennial pastures with Nitrogen fixed from legumes

Legumes have always been a valuable addition to perennial pastures and considering Nitrogen prices have skyrocketed over the past 12 months, this is true now more than ever. These high Nitrogen (N) costs serve as a reminder of the importance and value proprietary legumes can contribute to an operation by fixing free slow-release nitrogen for perennial grasses.

Research has shown that for every 1000kgDM/ha above ground legume growth approximately, 20-30kg/ha of free atmospheric nitrogen can be fixed. Legumes fix atmospheric nitrogen into usable nitrogen through a symbiotic relationship with rhizobia and root nodules. When foliage is removed from a legume, for example grazing a white clover, this induces the root nodules to break down and release nitrogen available for plant uptake.

In other words, legumes can potentially reduce the synthetic N fertiliser requirements of pastures while increasing the 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 4000kgDM/ha/year, that’s 80kg N/ha/year of free Nitrogen fixed from the atmosphere. With the current cost of Urea at around $1100/t 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.

Article by PGG Wrightson Seeds