The majority of farmers at a recent pasture field day rated improving legume content and productivity as a major priority.
High pasture legume content has several important advantages including building soil nitrogen - essential for the grass component - greater winter feed and improved feed quality.
As part of better pastures, legumes can also contribute to improved soil organic matter.
Several key factors are important for improving pasture legume content.
Choosing the best species and varieties within a species for a given environment is essential.
Some newer species are commonly worth a try and have the capacity to increase legume content and productivity.
Their careful introduction to an existing pasture, native, tropical or temperate, is important.
Establishing them successfully with their correct root nodule bacteria (rhizobia) is critical.
And no legumes succeed in a pasture if significant soil deficiencies are not addressed. Grazing management is also important.
Previous articles in this column have discussed choosing appropriate legumes for specific environments, including soil type.
Most paddocks have a range of soils, so a range of species is often best.
Soil pH is important as some species suit very acidic soils, some moderately acidic, some neutral, some alkaline. Some suit soils occasionally subject to water logging, some don't.
For most areas, varieties with high levels of hard seed are important for long term survival. Variety maturity is also critical.
Additions to mainstream pasture legumes, like biserrula, serradella, gland and rose clover, are commonly worth adding to the pasture mix.
For example, in the field day I attended at Sam and Megan Clifton's property east of Coonabarabran, biserrula and rose clover had successfully been added to tropical grass pastures.
They were autumn direct drilled via a double disc seeder with press wheels.
While more care with grazing management is needed for species like biserrula, it's added features include suiting a range of soils, very low bloat risk, deeper rooted, tough and productive.
A rhizobia application method is a key area to ensure success.
As a general rule, rhizobia perform best when soils are a little less acidic than that favoured by a given species.
For example, sub clover can generally tolerate soil pH (calcium chloride) down to 4.7 but their appropriate rhizobia perform best at 5.5 to 7.0. Liming can be a good option.
It is important to choose the most appropriate rhizobia strain for each species - there are 39 different inoculant groups - to ensure best for each species.
Legumes will not thrive in any pasture if significant soil deficiencies exist.
Extensive NSW DPI research over many years has identified sulphur and phosphorus as by far the most common and critical soil deficiency.
Their correction via appropriate fertilisers that supply these elements in available forms has commonly improved legume productivity by 100 to 500 per cent.
Not only is production increased but equally important is soil nitrogen build-up for companion grasses.
Lots of research has looked at many alternative fertilisers.
Unless they contain sufficient levels of deficient elements, such as phosphorus and sulphur, and are applied at rates needed, they are not going to help.
If stored well and handled, animal manures - as well as some waste products - provided they are applied at appropriate rates, can be used as a substitute for conventional fertilisers.
Grazing management is important. Coming out of summer as well as spring are especially important periods.
Good summers with heaps of grass drying off going into autumn can adversely impact on winter legumes germinating.
Options to help include: cutting some tropical grass paddocks for hay or silage, concentrating on grazing some paddocks down to 2000 kilograms per hectare drymatter and maybe put up with paddocks with too much dry feed, knowing they will be poor the coming season for legumes.
Dry springs can be challenging, especially for newly sown pastures.
Giving new legumes every opportunity to seed down before grazing is a high priority, especially for aerial seeders until a good soil seedbank has been achieved.
Once that occurs good seeding each year in not critical for hard seeded varieties.
Next week: Wheats that germinate better in tough conditions.
- Bob Freebairn is an agricultural consultant based at Coonabarabran. Email robert.freebairn@bigpond.com or contact 0428 752 149.
