Tuesday, May 22, 2012

Bahia Grass - Best Turf for Water Efficiency

In the rush to use new turf species and new varieties sometimes this old stalwart is overlooked.

Bahia grass - Paspalum notatum is one of the very best grasses for water efficiency in the monsoonal tropics.  In areas with an extended dry period, it will stay green for the longest, and quickly rebound after extended dry weather - even as long as 7 or 8 months - to continue to thrive.

In the NT, it is best to avoid using the more readily available variety - Pensacola - as it is not as tough as others, tends to be more clumping, often appearing to have bare areas betwen plants and most importantly, it produces abundant seed heads year round so you are always needing to mow.

The older areas of Darwin often have a locally adapted ecotype, of unknown origin.  It produces seeds, but is usually sown by runners [ the other varieties can be too].  It was the predominant lawn in Darwin from the 1950s to about the 1980s, but less used today.  This line is ok as a turf species, and is very tough, and water efficient, but does tend to have a lot of spicules on the leaves - silica spurs that can irritate skin, especially where kids are rolling around on the lawn.  Argentine has less of these spicules, and so does Pensacola.  Its disadvantage is planting by runners, a time consumimg job.

The preferred seed sown line is Argentine.  We originally organised testing of this variety in the early 1970s in the Top End, importing seed from the USA, and first seeds were sown at Berrimah Farm.  It is still there, looking great. 

From the original evaluation, Argentine was selected and used in a lot of the early development around Palmerston in grassed waterways, and in park and landscape development after Cyclone Tracy in the reconstruction of Darwin.  Seed sowing is relatively low cost and a lawn can be developed in 10 -12 weeks.  No Australian production of seed has occurred and all Bahia grass seed is imported from the USA [ so is all couch, zoysia seed etc too].

The advantages of the Argentine variety of Bahia grass include:
  • almost no seed head production, except a small amount around January in the north of Australia
  • excellent spread and forming a dense surface cover
  • very tough, reasonably resistant to wear
  • low water needs
  • excellent drought resistance and quick recovery when water is applied
  • easily mown at around 30 - 45mm high, although it does grow moderately quickly in warm, wet weather - weekly mowing needed in the wet season for domestic lawns; maybe every three weeks in the dry season
  • very little thatch development
  • mostly free of pests and diseases
All of the Bahia grass types tend to become invaded by the awful weed grass "red seedy grass" or "Mackey's pest", which is botanically Chrysopogon acicularis.  This spreads by very insidious runners and produces huge numbers of seed heads.  There are herbicide solutions available for the control of this weed in Bahia grass, but products are not easily available for domestic use because of commercial packaging sizes - we can do this work if needed.  Efforts to eradicate it will pay big dividends.  Often seed is carried on legs, clothes, equipment and similar items so a biosecurity approach is needed to keep it out in the first place.

For a large lawn or open space area and especially where there is a need to be prudent with water use in the dry season.......Argentine Bahia grass is a good option.  It is also widely used as a water efficient turf in Florida [which is where the photo was taken].  Do not over water, as this induces ingress by other water loving species, including broad leaved carpet grass in our environment.

1 comment:

SJ said...

Thanks a lot.
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