Down to Earth with Bob Freebairn: Strengths and weaknesses of tropical grass varieties

Some are tough and long lasting, others short lived.

There are literally dozens of tropical grass species and varieties.

Hence why it is important to carefully assess which ones to choose.

Setaria, with several varieties, for example Splenda, is more suited to high rainfall areas, especially coastal ones.

Some varieties have useful cold, and even useful frost, as well as water logging tolerance.

Like all tropical grasses, quality depends greatly on soil fertility and growth stage, and can be as high as 20 per cent protein.

There are several Rhodes grass varieties with a range of maturities from early to late.

While initially mainly a coastal high rainfall perennial species, especially the earlier maturing ones, they were gradually tried and adopted in some lower rainfall inland areas.

However, NSW Department of Primary Industries trials showed the species was not as drought-hardy as species and varieties like Premier digit grass.

Rhodes grass does suit some other soils. For example Rhodes grass has more salt tolerance than some other types.

Gatton and Green panic were around well before Premier digit but, in lower and medium rainfall environments, have often not been near as long term persistent.

Note assessing tropical perennial grasses for most areas need to be long term trials, including a drought or two, to adequately assess long term persistence.

Suited more to medium textured soils with Gatton commonly more persistent than Green.

Curley Mitchell grass, a native perennial, with periodic good seed harvests, is an excellent drought-hardy species suited to hotter environments and neutral to high pH clay and loam soils.

It is sometimes quoted as moderate quality, but like most grass species, quality is a reflection of soil fertility.

Mitchell grass is susceptible to waterlogging and if re-establishment is contemplated, for example after a flood event or after cropping, inclusion with a species like bambatsi panic is worth considering.

Buffel grass is another species more suited to hotter environment of the state and have not performed well in research conducted in central west and slopes type areas.

There is a range of varieties with some more suited to well-drained lighter soils and some more for well drained loamy, even moderate clay soils. Buffel is extremely drought tolerant when well established and, again, feed quality is good if soil fertility is good.

Kikuyu is an interesting species. Although mainly advocated for high rainfall coastal type environments, and for irrigation, some kikuyu varieties, in detailed research, have shown good long term persistence in moderate rainfall environments.

However, production has not matched varieties like Premier digit in these areas.

Kikuyu has other advantages such as waterlog tolerance, cold tolerance and it's great for soil binding.

Bambatsi panic is especially suited to heavy clay, high pH soils and has good tolerance to waterlogging.

It also has useful frost tolerance, moderate salt tolerance and has persisted well in drier western environments.

Floren bluegrass is another drought-hardy species suited to heavy alkaline cracking soils and tolerates waterlogging.

There are other tropical grasses with good features like paspalum is waterlogged tolerant, good cold and drought tolerance and productive.

I have not detailed Premier digit, my favourite for much of NSW, at least as part of the pasture mix, with wide soil type adaptation.

Consol lovegrass is the toughest most acid soil tolerant species.

There are many very good native grass species but seed of most of them is generally scarce, very expensive, and commonly in mixtures with all sorts of good and not so good species.

Always check variety details for aspects like toxicity, common in many pastures including lucerne (bloat).

While normally not an issue oxalates can be found in rapidly growing species of Setaria, Buffel grass, Kikuyu and panics.

These can be problems for horses and sometimes sheep and cattle. A good understanding of risk factors can help avoid problems.

Next week: Research confirms grain sorghum has a bigger sowing window.