Department of Primary Industry, Fisheries and Mines GPO Box 3000 Darwin NT 0801 Phone: (08) 8999 2133

ISSN 1320-727X

Editor: Phil Hausler

Editorial – Issue 37 Hello and welcome to the 37th issue of Top Paddock, which is also the second in the new digital format. It’s nice to experience some cool weather in June with even some rain earlier in the month.

In this edition we have included an article from a 1993 edition of Top Paddock titled “When do you want to turn off your steers?” This article outlines DPIFM trials on various options for turning off steers on improved pasture in the dry season utilising crop stubbles and supplementation. The authors were Robyn Rann and Colin Tidswell, former Top End Animal Production officers with DPIFM.

We also have a summary of the commercial farm walk at Douglas Daly in May, an update on the Best Practice for Sustainable Land Use Management in the NT project; annual production figures for NT crocodiles, agriculture and horticulture; and an article on seed harvesting techniques.

Darwin Show Cattle section

This flyer advertises the highlights at the Cattle section of the Royal Darwin Show. I encourage producers to enter cattle in the commercial cattle classes. You can contact the editor for entry forms.

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Plant Industry Profile The Plant Industry Profile outlines annual production statistics for the plant industries in the NT. Included is annual yield and estimated value of production for; field and fodder crops, fruit and vegetables, ornamentals and forestry. Figures are divided into regions; Darwin, Douglas Daly, Katherine, and Central Australia.

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TABLE OF CONTENTS

Editorial------------------------------------------------- 1

Darwin Show Cattle section----------------------- 1

Plant Industry Profile-------------------------------- 1

From the Archives - When to turn off your steers ---------------------- 2

Invasive grasses, Gamba grass and friends-------------------------- 2

New Publications on Water Resource Management ------------------- 2

Crocodile Industry General Overview ---------- 3

Seed Harvesting in the Northern Territory----- 3

New National Pest Animal Strategy------------- 5

Best Practice for Sustainable Land Use in the NT Project ------------------------------------- 6

Topics from Turf to Timber ------------------------ 7

Seminar on Best Practice Management of Sugarcane--------------------------------------------- 8

The Editor---------------------------------------------- 8

Attachment A Northern Territory Crocodile Industry Production 1996-2006 --------------------------------------------- 9

I S S U E 3 7 1

From the Archives - When to turn off your steers From the Archives - When to turn off your steers - options for improving weight gains in the wet and dry seasons of the Top End.

This article is sourced from the first issue of Top Paddock, published in September 1993.

Download article

Invasive grasses, Gamba grass and friends A summary of the KRS Seminar presented by Arthur Cameron, Principal Pastures Agronomist, DPIFM. The definition of an invasive grass depends on your situation. Different grasses are considered invasive in lawn, pasture or cropping situations. The most commonly accepted definition of invasive grasses is those which can colonise undisturbed native vegetation. A list of over 20 potentially invasive grasses was presented. Most of these grasses are found only in disturbed situations, such as roadsides, overgrazed areas, cropping areas and improved pastures, not in areas of native vegetation. The six grasses which have shown the ability to invade native vegetation are listed below:

• Gamba grass (Andropogon gayanus)

• Mission grass (Pennisetum polystachion)

• Buffel grass (Cenchrus ciliaris)

• Grader grass (Themeda quadrivalis)

• Olive hymenachne (Hymenachne amplexicaulis)

• Para grass (Urochloa mutica)

Of those listed, buffel grass is not invasive in the Top End of the NT, and Olive and para grass are floodplain grasses. The problems which these invasive grasses cause are altered fire regimes (generally hotter), reduced biodiversity, effects on wildlife through changed habitats and in some cases reduced production. The origin of these six grasses is pasture trials for four, as a seed contaminant for the Grader grass, and unknown for the Mission grass.

Almost 900 accessions of grasses in 200 species of 59 genera were tested in introduction trials in the Top End of the NT. Only about one half of the plots sown established, and most did not persist.

Of the persistent genera only 2, Andropogon and Hyparrhenia demonstrated spread by seed in 3 years. The rate of spread at Mount Bundey Station was 15 metres in 11 years for Andropogon, and 30 metres in 11 years for Hyparrhenia. There is a body of knowledge available on Gamba grass, both from overseas and locally. We have carried out research which shows that it can be easily killed with glyphosate at standard rates. Pastures Section has carried out a project on major roads which demonstrated that gamba grass can be controlled. The knowledge and experience has been extended to the public through the development of a Gamba grass information sheet, and a series of seminars and workshops. To control or manage any of the invasive grasses, all landholders must work together to develop and implement a management plan.

New Publications on Water Resource Management The Bureau of Rural Sciences has just published the following three reports:

Connected Water brochure The brochure provides information on an adaptive management framework for connected groundwater and surface water resources, tools to assess connectivity, management options and the Connecter Water website designed for policy makers, water managers and catchment groups. Mapping potential stream-aquifer connectivity This report describes a new method for mapping the potential stream-aquifer connectivity in a catchments. An index model approach combines the available catchment-scale data sets such as watertable depth, geology, geomorphology and soil type to identify the level of connectivity along river reaches. The method allows a first-cut prioritisation of stream reaches enabling targeting of sites for further investigations and priority management. Q-Lag: a new hydrographic approach to understanding stream-aquifer connectivity This report describes a new method of analysing available streamflow and rainfall monitoring to

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gain insights into the groundwater contribution to streams. This takes advantage of the fact that such monitoring is the most commonly available hydrological datasets in Australian catchments. There is great potential to use the parameters derived from this analysis, in combination with conventional indices, to derive a useful classification scheme for Australian streams.

You can download a pdf copy of the reports from: http://www.connectedwater.gov.au/resources/Downloads.html For further information please contact: Dr Baskaran Sundaram Tel: 02 6272 5767 Fax: 6272 5827 email: baskaran.sundaram@brs.gov.au

Crocodile Industry General Overview. There are seven crocodile farms in the Northern Territory (NT). Of these, three are classed as hatcheries and sell live young animals to other farms within the NT and four farms produce skins and meat. Three of the seven farms have a tourism side as well.

The crocodile industry relies on captive breeding and wild harvest of eggs to increase stock numbers on farms. Eggs are incubated on farm and young animals or “hatchlings” are introduced into pens soon after hatching.

Young animals are classed as hatchlings until 9 months of age, at which they are classed as “raisings”. Raising animals are grown to approximately two years of age before they are slaughtered.

The size of slaughter animals are determined by market forces but generally it is when they measure around 35 centimetres across the chest of the animal.

Older animals are usually captured from the wild as they become problem animals or occupy areas frequented by people. These animals usually become farm “breeders” particularly females and are part of the captive breeding program on farm.

Annual data is reported as part of the Northern Territory approved management program which is governed by Environment Australia to meet the requirements of the Convention in the Endangered Species of Flora and Fauna (CITES). The issue of annual farming licences requires the submission of production data on a monthly basis.

The table (attachment A) shows production figures for the whole of the NT crocodile industry for the last ten years (1996-2006). The table shows end of year numbers of hatchlings, raisings and breeders; meat production; live sales and annual skin exports.

Seed Harvesting in the Northern Territory The cost of seed can be significant when establishing native or improved pastures. This cost can be reduced by collecting your own seed, which can be done several ways.

The first option is to hand pick the seed, but it is certainly not an option if you have a large area to cover.

The second option is to use a catching implement on the front of a vehicle (Figure 1). This vehicle could be a tractor, quad bike, 4 x 4 Ute / car etc. This catching implement is simply an L shaped frame usually made with angle iron with an arc-mesh bottom and rear wall, and hessian / shade cloth covering it. The Hessian / shade cloth will allow the wind to pass through but catch any seed heads and/or seed. The catching bin should be adjustable on the vehicle so it can be placed at the correct height to harvest the seed without catching too much foliage. The forward momentum should be fast enough to dislodge any ripe seed/seed heads and deposit them into the bin.

Manufacturing this implement is straightforward and simple, just remember a few hints:

1) Don’t make it too wide; keep it close to the operating vehicle width as this will lessen the possibility of an accident.

2) Keep it light but sturdy enough to withstand driving through standing grass.

3) Ensure it is height adjustable.

Continued page 4

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Bin frame with Hessian covering harvesting a Jarra seed crop

Bin frame made for use on quad bikes

Another option is to use a beater-harvester (Figure 2). These were quite popular years ago for harvesting buffel and gamba grass seed. The beater-harvester is simple in design like the L shaped seed bin but has rotating beater paddles. The paddles are wooden slats that are bolted to arms attached to a central axle. The whole beater assembly is like a skeletal drum. The rotating beater assembly is situated directly above the seed bin so that a paddle at its lowest arc is just above the leading edge of the seed bin. The paddle drum is rotated via pulleys and a small petrol motor and they rotate in a downward direction towards the seed heads and bin. The paddle hits the seed stalks onto the leading edge of the bin thus dislodging ripe seed or simply breaking the entire seed stalk off and depositing it into the bin. The base, sides and rear wall of the seed bin are of solid material, usually tin sheeting. The height of the beater drum should be adjustable on the seed bin and the height of the whole harvester needs to be adjustable. This is easily achievable by attaching the harvester to the arms of a front-end loader.

The advantage of a beater-harvester over the catching bin on a vehicle is that you do not have to rely on fast forward motion to dislodge the seeds and this is very useful when traversing rough terrain.

Figure 2 Beater-harvester

This is a deluxe model of a beater-harvester. Notice the brushes attached to the beaters and the air-blower transporting the seed from the bin to a container at rear of tractor.

A fourth option, the brush harvester is slightly more complex in design. The brush harvester was designed for harvesting grass seeds. Grasses tend not to ripen seed heads at the same time and therefore there might only be 30% ripe seed ready for harvesting at any given time. This is where the brush harvester has an advantage over the other harvesters.

The brush harvester, as the name implies, brushes the seed stalks in an upward motion removing any ripe seed and leaving unripe seed on the stalk to ripen for harvesting another day. The brush harvester has rows of brushes attached to a drum situated between two metal shrouds. The bottom shroud is a short one and has the same concave shape as made by the outer ends of the brushes in rotation. The top shroud is longer and the concave shape larger (see Figure 3). The brushes can be straight across the drum or arranged in a spiral.

This design allows the brush drum to create its own wind flow, which assists in transporting and depositing brushed seed into the seed bin. The seed bin has a short front wall that the bottom shroud butts on to. The tips of the brushes just touch the top lip of this wall and this is enough to break the wind cycle. The seed bin has an opening on the top to allow the brush created wind to exit after depositing any seed in the bin. As stated previously the drum rotates so the brushes stroke the seed stalks in an upward direction. The drum can be driven by a direct-coupled hydraulic motor or a small petrol motor and pulleys. Ideally, brush harvesters should be attached to the arms of a front-end loader for ease of operation.

Continued page 5

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There are three important things to get right when manufacturing a brush harvester:

1) Don’t make the circumference of the drum too small. This is important as the size of the drum dictates the mouth opening (see Figure 3). Seed stalks vary in height in the one crop so the mouth opening has to be wide enough to accommodate this variance.

2) Don’t use soft brushes.

3) Get the drum speed right (700 rpm to 900 rpm).

Figure 3. This cross sectional drawing is based on the Woodward Flail-Vac Seed Stripper manufactured in the USA.

This brush harvester was manufactured utilising the design illustrated above.

A fifth option would be to use a combine harvester. These can be very complex in design, are very efficient and expensive. If you are not into harvesting professionally then you won’t be rushing out to purchase one. The sixth and last option is a suction harvester (see Figure 4). These are also complex in design and are primarily used for big, hard seeds (such as legume seeds) that have ripened and fallen from the plant onto the ground. Suction harvesting is a very slow and dusty operation. Suction harvesters can give very dirty samples as they suck up weed seeds, small pebbles and other trash lying on the ground as well as the targeted

seed. The majority of hard-seed harvesting now days is by combine harvesters. Figure 4. Suction harvester

Ben Beumer Extension Officer Pastoral Production DPIFM Darwin

New National Pest Animal Strategy (Press Release from Senator the Hon Eric Abetz Minister for Fisheries forestry and Conservation)

The first national strategy to tackle existing populations of wild pigs, foxes, dogs and other pests has been agreed. Minister for Conservation, Senator Eric Abetz, said the plan, agreed to at the recent Primary Industries Ministers’ Council meeting in Brisbane, was a major step forward in the fight against feral pests.

“Pest animals are one of the major threats to the biodiversity of Australia’s environment and primary production,” the Minister said.

“They compete with livestock and native animals for food and water and can also cause severe

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land degradation through soil erosion, stream turbidity and the spread of weeds.

“It is estimated that just 11 of Australia’s major pest animals – wild populations of foxes, pigs, rabbits, mice, goats, carp, dogs, cane toads, camels, cats and horses – cost Australia over $720 million every year.

“Of these pests, foxes and rabbits have the biggest impact on biodiversity. However, pest animals like feral pigs and wild dogs have a dramatic and adverse impact on agricultural land in Australia.

“The plan, known as the Australian Pest Animal Strategy, has been developed by the Australian, State and Territory governments through public consultations with people affected by pest animals.”

Key steps in the plan include:

1) establishing a national monitoring system to better determine the locations and numbers of various species;

2) identifying on-ground management gaps;

3) adopting uniform control methods for highly mobile pests such as wild dogs and feral pigs;

4) improving border security to prevent new pests entering Australia.

An expert group as determined by the intergovernmental Vertebrate Pest Committee will be formed in the near future to implement the plan.

For further information contact: Media enquiries: Brad Stansfield, 0419 884 666

By Tim West

Best Practice for Sustainable Land Use in the NT Project During 2004 representatives from the Northern Territory Horticultural (NTHA) and Northern Territory Agricultural (NTAgA) Associations along with NT Department of Primary Industry Fisheries & Mines (DPIFM), NT Department of Natural Resources, Environment and the Arts (NRETA) and the Federal Department of Agriculture Forestry & Fisheries (DAFF) delegates developed a project aimed at assisting Northern Territory primary producers with sustainable use of their natural resources. The impetus for this project was the fact that there was very little NT relevant sustainable agricultural information available and no ‘best practice’ guidelines to assist producers

with the sustainable land management of their enterprises.

The Associations recognise that – “identifying, understanding and addressing the diverse range of natural resource management and environmental issues are fundamental to the development of sustainable production systems”. Also that, “Industry responsibility for sustainable production is integral to community acceptance and ultimately the successful development of horticultural and agricultural industries”. As such, this project was developed and a submission for funding lodged during 2004.

The ‘Best Practice for Sustainable Land Use in the NT’ project was funded in early 2005 under the National Landcare Program (NLP) as a joint project between the NTHA and the NTAgA. The project has been designed to develop a program that can be adopted by all land users regardless of their developmental / production stage, financial capacity or culture. The aim of the project is to ensure that everyone has access to current ‘best practice’ tools in a format that can be adopted at whatever level of environmental management the producer is currently at. The guidelines will be developed in a format that will allow producers to undertake self-assessment at their pace and provide them with a pathway to accredited Environmental Management Systems (EMS) if required. It is envisaged that growers will be able to work through a three tiered process that will involve self-assessment, peer assessment and finally independent accreditation. It is also planned that participation will be acknowledged by produce brand-marking (NT sustainable produce) and enterprise gate signage

It is important to note that this project will develop Sustainable Land Use (SLU) guidelines that are holistic (big picture) and will underpin other sector specific (i.e. Nursery - EcoHort) guidelines that have been, or will be developed in the future. The guidelines will be a generic, evolving document that will need to be updated regularly as research and technological advances relating to sustainable agriculture in the wet / dry tropics come to light. The project was initiated in May 2005 with the employment of a project officer based with the NTHA. A baseline survey was developed and undertaken during late 2005 which assessed grower attitude, concerns and stage of environmental management. A framework of thirteen (13) ‘key areas’ were identified from this initial survey, which, under the title of ‘Sustainable Agriculture’ have been used to develop the body of the SLU guidelines.

These key areas are;

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• Water • Soils • Nutrients • Chemicals • Carbon • Climate

• Energy • Waste • Air • Weeds • Fire • Biosecurity • Ecosystem Services

The first consultative phase involved stakeholder comment on an outline of contents for each of the above key areas. These comments were then collated and formed the framework for sourcing ‘best practice’ information from relevant local, interstate and international institutions and developing the draft SLU guidelines during 2006.

The second consultative phase, which was initiated in November 2006, involved circulating a raw draft of the SLU guidelines (150) to stakeholders for comment. Stakeholders were given the option of commenting via CD or attending workshops held in regional centres during Jan – Mar 2007, to comment on the draft. These comments are currently before the projects’ steering committee who will make an assessment on the final content of the guidelines.

Phase three of the consultative process will involve ‘ground-truthing’ of the guidelines with interested growers during 2007. Participants will undertake a self-assessment process utilising the action checklists and plans contained within the guidelines. A comprehensive assessment of the practicality and useability of the guidelines will be made at this stage, prior to printing and launching of the guidelines in early 2008.

Any queries regarding the project should be directed to Tim West at tim.west@ntha.com.au, or the NTHA office on 8983 3233.

Topics from Turf to Timber

Farmers had the opportunity to exchange ideas and knowledge about a range of enterprises at a Farm Walk of commercial properties on the

24th May. The day involved a tour around the Douglas Daly district, where farmers and cattlemen paused from their hectic schedules of cattle work, mowing, baling, harvesting and planting, to talk about their respective activities.

After cakes and coffee for Australia’s Biggest Morning Tea, the group of approximately 20

individuals headed to the first stop at Ceres Downs, where Dan Thomson talked about his turf growing enterprise. “We are gradually increasing the market into Darwin, both with home-owners, and landscapers”. The wide expanse of lush green ‘Sir Walter’ grass excited the golfers and polocrosse players in the group.

Malcolm Bishop at Kumbyechants discussed production of his 200ha maize cropcurrently being harvested. Although sown late – at the end oJanuary, he was happy with the yields, and alsthe demand for the grain. “The phone has been ringing non-stop with queries……the whole lot has been sold already”.

,

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Although not traditionally thought of as a horticultural area, Bill Mitchell currently grows seedless watermelons. Bill paused in the middle of planting his next crop of seedlings, to demonstrate the planting operation, and to discuss the ups and downs of the melon markets. “Freight costs are a bit of a killer, and cold winters down south lower the demand for melons, but overall, we do all right”.

Brett Gill from Northern Australia Fodder Exports was mowing a crop of irrigated Sudan grass at Early Storms, but took a break to describe the operation. “We are currently doing the 3rd cut on this circle, and hope to get about 6 cuts this year. A lot of our hay at the moment is heading to dairies down south….there is obviously big demand with the impact of the drought”.

The group then travelled to Midway Station, where Chris and Marie Muldoon outlined their cell-grazing system. “For most Top End grazing properties, cattle are set-stocked. We aim to better utilize our pastures using smaller paddocks and changing stocking rates over the wet and dry seasons, depending on grass growth. It is a very intensive system, but we enjoy working with cattle, so generally, it’s good fun, as well as providing advantages in sustainable pasture and cattle productivity!”

The final stop for the day was at WhyNot station, operated by Northern Tropical Timbers. The group compared the mahogany trees planted last June – 72,000 trees, to those planted this wet season, while Gordon Atkinson discussed markets, production issues, and the long-term objectives of the company.

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The day finished up at the new Fleming townsite, where farmers, agents and government staff did some informal networking, and further expanded their exchange of ideas.

Seminar on Best Practice Management of Sugarcane I recently attended a very interesting seminar hosted by the Department of Natural Resources, Environment and the Arts (NRETA), Palmerston. The seminar was presented by Mr Rob Quirk, a sugarcane farmer in the Tweed valley of Northern NSW. I have included a press release from the Commonwealth Department of Agriculture Forestry and Fisheries which outlines the presentation by Mr Quirk.

Some major points from the presentation were:

Acid sulphate soils – too much disturbance (ie cultivation) can result in the release of acidity and in his case runoff water flows into the river estuary can result in fish kills.

There is enough acid in 1 cubic m of soil to turn an Olympic size swimming pool from pH 7.0 to pH 3.0.

Mr Quirk doesn’t burn the cane before or after harvest.

He practices no-till establishment and uses legumes in rotation.

By implementing Best Practice Management, Mr Quirk has doubled the per hectare yield of cane produced on his farm as well as preventing any flow of acid into the river system.

All farmers in the local district have undertaken self regulation to implement these best practices on their farms.

The entire farm has been laser levelled to prevent water pooling and releasing the acidity.

The Editor Tweed Valley sugar cane grower Robert Quirk has won the 16th McKell Medal for excellence in natural resource management. The McKell Medal is presented by the Natural Resource Ministerial Council to commemorate the work of Sir William McKell, a former NSW Premier (1941-47) and Governor General (1947-53), who made a significant contribution to soil and land conservation in Australia.

For nearly 45 years, Robert has run a 200ha farm devoted to the intensive cultivation of sugarcane in northern NSW’s Tweed Valley.

During that time, he has worked hard to get the best out of the region’s volcanic and tidal soils with their high acid sulfate content.

The results have been impressive to say the least — a 25 per cent reduction in chemical use; an 80 per cent decrease in heavy metal and acidity discharges; and a 38 per cent increase in productivity.

“It’s possible to reconcile environmental and economic aims on farm,” he said

“Through my environmental stewardship, I’ve had an increase in productivity, reduced my inputs, fertiliser and chemicals by 25 percent, which has given me a unit cost decrease of about 50 per cent.”

Robert has put in place a system that enables a single harvester and seven workers to harvest 150,000 tonnes of sugarcane a year. He is also involved in a milling venture that includes its own sugar refinery and can co-generate electricity by burning bagasse.

Many of the practices Robert has developed are now considered world's best practice for farming acid sulfate soils. Not surprisingly, the Quirk family farm at Duranbah has become a popular stop-over for politicians, growers, engineers, tourists and students to study his management practices first-hand.

“I think it’s terribly important that farmers start to realise that you can link environmental stewardship to productivity increases,” Robert said. “I’m looking forward over the next 12 months to push this message forward on behalf of the McKell Medal.”

Robert is a regular contributor to local newspapers and journals, and a frequent participant in local, national and international conferences.

He was one of five farmers asked to help prepare a self-assessment workbook ‘COMPASS’, which enables growers to compare their performances against those of their peers.

Not content to sit on his laurels, Robert is now developing a 2ha wetland to reduce discharges from his farm and recover harmful monosulfides and heavy metals.

Attachment A Northern Territory Crocodile Industry production 1996 - 2006

Year End of year hatchlings (number)

End of year raisings (number)

End of year breeders (number)

Hatchlings gained (number)

Raisings processed (number)

Exported skins (number)

Flesh produced (kg)

Animals

sold live

(number) 1996 10,816 23,869 897 27,930 6,675 6,565 35,410.7 221997 12,489 23,446 867 17,866 8,098 5,513 38,380.7 01998 7,108 23,339 845 11,003 12,481 6,881 42,931.3 01999 6,213 20,582 854 13,769 8,469 5,424 45,651.6 4,3322000 6,549 12,117 901 10,875 7,643 6,972 41,502.0 1,3692001 7,516 12,961 862 15,757 6,439 4,728 28,634.3 3,2262002 8,261 17,760 892 18,383 3,938 3,468 14,794.9 5,4982003 8,494 20,136 892 19,192 4,114 3,127 18,744.3 7,6712004 4,636 36,295 924 25,104 5,104 4,526 19,017.5 9,6472005 8,617 46,091 937 32,273 5,346 5,726 24,260.6 6,4702006 (data not complete)

3,085 39,028 23 29,609 3,028

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