Cool Season Production of Tropical Grasses

Arthur Cameron, Principal Pastures Agronomist, Darwin

There is interest in growing fodder under irrigation during the Top End dry season to supply hay to live cattle export yards and cubing/pelleting plants.

Tropical grasses generally do not grow well under irrigation during the cooler months of the year in the Top End.  Sugargraze forage sorghum (Sorghum sp) and Finecut Rhodes grass (Chloris gayana) have been shown to produce commercial yields of 25 to 35 tonnes per hectare per year at Douglas Daly Research Farm.  Both of these options for fodder production under irrigation have limitations. The Forage sorghum generally needs to be re-sown every year to maintain a productive stand. In the Top End, the Finecut Rhodes grass is not liked by cattle as a fodder, and it has a high tensile strength, which makes it difficult to grind and make into fodder cubes and pellets.

There are a number of other tropical grasses which have cold tolerance and may be suitable as alternatives to Forage sorghum and Finecut Rhodes. The cool season growth of seven other tropical grasses is being compared with that of Finecut Rhodes at Coastal Plains Research Station to select one or more cultivars, which have equivalent or better cool season growth, better acceptance by cattle and better grinding characteristics.

Seven of the grasses were sown by seed in December 2014. The eighth grass, Strickland finger grass, was planted by runners in February 2015. The first year’s yield results are presented in Table 1 (below).  The establishment was good except for the Premier digit grass, which was attacked by Crab grass leaf beetle larvae.  While Strickland finger grass and Premier digit yields were lower overall, the yields were similar for all of the grasses at the final harvest.

The trial will continue this year to get a full dry season’s results. Samples from each harvest will be submitted for nutrient and quality analysis.

Table 1. Dry Matter yields of cool season grasses

Grass

DM kg/ha (2015)

Total DM Kg/ha

6 May

25 Jun

11 Aug

29 Sep

17 Nov

Finecut Rhodes

5980

5500

3000

6900

7080

28450

Gulfcut Rhodes

6980

4720

2690

7350

6990

28720

Reclaimer Rhodes

7730

4990

2850

6570

7500

29640

Premier digit

940

1540

2110

4940

7120

16640

Strickland finger Grass

4690

4360

2450*

6030

6770

24370

Gatton panic

7340

6510

2230

4930

6340

27350

Nucal panic

8980

4630

3590

6538

7880

31320

Splenda setaria

9280

5870

2290

6210

6320

29980

Mean

6490

4760

2660

6180

7000

27100

*Strickland finger grass yield was decreased by selective grazing by wallabies prior to the 11 August harvest

Daly Basin Gravity Survey June-July 2016

Last updated: 21 April 2016