Give native and introduced perennial grasses a boost

The keys to productive pastures include soil deficiency correction, where possible perennial grass-based pastures, preferably with a persistent legume component, and well managed grazing wise.

Well managed includes reasonable dry matter retention through the growth as well as dormant phases (mainly periods when it doesn't rain).

Annual legumes with good to high levels of hard seed, suitable to given soil conditions, with appropriate maturity for a given environment, are an important part of any perennial pasture; native species based or introduced tropical or temperate perennial grass.

For example, current ongoing research on the NSW Southern Tablelands, undertaken by Dr Richard Simpson (CSIRO) and Jim Virgona (ex NSW DPI research agronomist and now Graminus Consulting), is showing mid-season hard seeded yellow serradella variety, Avila, is proving a useful addition to mid-season sub clover varieties like Goulburn.

Avila serradella has a number of attributes that, if successfully grown, can add substantially to Tableland pastures. Serradella has high acid soil tolerance, performs better than other species at lower soil phosphorus levels, is non bloating, has good aphid tolerance, can hang on longer in a protracted dry period, can be very productive and is also of high feed quality.

NSW DPI studies (Dr Belinda Hackney and others) have noted that many annual legume components of pastures suffer badly because of poor nodulation, with associated poor production and persistence. The reasons include possible poor initial establishment of suitable rhizobia with the legumes sowing, acidic soils (even where lime was used, but acid soil layers remain), and poor soil fertility (including molybdenum).

These surveys commonly found serradella stands have healthier levels of suitable rhizobia. Serradella's extra tolerance to soil acidity (including its strain of rhizobia) could be the main reason for this finding. A relatively new rhizobia application technique is via Alosca pellets (bentonite clay-based), impregnated with commercial strains of root nodule bacteria. Alosca pellets retain live rhizobia for months and can be added with seed via sowing, or topdressing, with a long life, unlike most other forms of rhizobia application.

A WA seed Industry leader, Neil Ballard (Ballard Seeds) reports they have responded to the NSW Tableland research and advise they will have increased (but not enormous) supplies of dehulled Avila seed for supply to growers. Good linkages between research and industry is an often neglected part of the pasture upgrading business, hence the value of this development. Also, if anyone requires Alosca rhizobia impregnated clay-based granules it would also be advisable to order promptly. At this stage, all manufacturing comes from WA.

As so much research has shown good soil fertility is an essential part of productive pastures, including legume component. Research has assessed a large number of so-called alternative fertilisers, some often with claims of better production and soil quality. Scientifically documented studies all note that unless a fertiliser product contains sufficient qualities of deficient nutrients like phosphorus and sulphur, and in available forms, it is unlikely to lift production or improve soil quality.

As the long-running drought has shown, not only species choice is important, but also grazing management. For both perennials (including native) and introduced, as well as for legume parts of the pasture, maintaining reasonable ground cover is critical.

Ability to trap rainfall is commonly the number one reason. Allowing pastures time to establish and develop leaf area after rain is also important. Perennials not grazed into the ground commonly recover far faster. And for many perennial species, if not all, some periodic recovery to allow them to replenish and rebuild root reserves helps build their ability to survive the next difficult season.

Next week: Zero/no till best for the environment as well as for crop yield.