Direct Seeding Systems in Australia

Allen Postlethwaite

Zero till grain grower, Member of Wimmera Conservation Farming Assoc.

Victoria, Australia

 

Direct seeding and intensive cropping is a farming system requiring intensive management. It has the potential to greatly increase production and profitability with less cost to the environment. Direct seeding and intensive cropping provide solutions to economic and environmental problems. The benefits reach far beyond the farm gate. Most farmers lack the management skills to fully implement such a system with out advice. Quality advice is difficult to find.

Farm profile

Our farm of 1834 ha, is in the Wimmera region of Victoria at 36.5o latitude and 143o longitude. The area is slightly undulating. Soils range from self mulching grey clays with a pH of 8.5 to hard setting red duplex soils with a pH 6. Both soil types are sodic. Our farm is rainfed with an annual precipitation of 400 mm falling as rain. 275 mm falls during the growing season between April and October. The whole farm is cropped every year to a range of winter crops including cereals (wheat and barley), oilseeds (canola, linola, and safflower), and grain legumes (chickpeas, lentils, lupins and faba beans). As a result of meeting with Dwayne Beck at Minot in 1994 we are now experimenting with summer crops and last year successfully grew our first 40 ha crop of grain sorghum.

Farm history

Prior to 1982 our farm was a typical Wimmera farm growing wheat in rotation with long fallow, and pasture. Long fallow meaning 12 months of bare cultivated soil with up to 8 or 10 cultivations. Long fallow is still widely practiced in our area. Most farmers burn their crop residues prior to cultivation. A practice that is very costly to the environment. We have not burnt any residues since 1982 and no cultivation has taken place since 1984. All crop is direct seeded into the undisturbed residues from the previous season's crop.

In Australia the belief that pasture must be included in a crop rotation is deeply entrenched in the minds of not only traditional farmers but agricultural research and extension people as well. It is a practice that has come from the early settlers from England and still persists today. However, this desire to run livestock, mainly sheep, in a cropping rotation is the greatest impediment to the successful adoption of intensive cropping systems. It is my belief that cropping and grazing do not mix.

Why change from traditional systems?

Yvonne, my wife, who is trained in business management, analysed our financial performance in 1981 and found 90% of our income came from crop production, which occupied 50% of our area, the other 10% came from our livestock production also from 50% of the area.

We then started asking questions.

1 Should we have erosion during wind storms? Should the whole community suffer our top-soil and nutrients polluting the environment?

2 Why do we have water erosion during heavy rainfall events? Should our topsoil and nutrients be allowed to contaminate and silt up our rivers and streams?

3 With dryland cropping, are we making the best possible use of available moisture? Is water running off and being wasted? Is water leaking below the root-zone into the water table and contributing to salinity? Is our water use efficiency reaching the potential?

4 Should we accept the soil surface sealing making crop emergence difficult?

5 Is fertility adequate to produce potential yields?

6 Are we satisfied with the lifestyle our income is enabling us to enjoy?

7 Could our farm support two sons keen to take on farming?

 

The answer was NO to all these questions.

Financially the solution was simple - sell the livestock, crop the whole area. That is exactly what we did but the cropping program had to change entirely.

Zero till or bust

The drought of 1982 brought opportunities of good deals on machinery so we traded all our cultivation and seeding equipment and bought an International air seeder coupled to a chisel plow. Selling all our cultivation equipment meant there was no turning back. We had to make the new cropping program work or we were out of farming!

1983 saw the first crop sown on 12@ rows - prior equipment seeded on 7@ rows. We used 14@ points (shovels) and towed harrows behind to level the soil. We sowed through the straw and found the harrows very ineffective at levelling soil containing straw. Paddocks looked anything but professional. The next year we used 8@ points and added mounted finger tyne harrows but still had problems. 1985 we used 2@ points and direct seeded the entire farm in a single pass operation for the first time. Harrows still caused problems. 1986 we made our own ultra narrow points 1/2@ wide to disturb less soil and threw the harrows away altogether! This change made an enormous difference to the appearance of the finished job and for the first time ever we had even seed depth. Even with all these problems during the early years of zero till our yields never dropped.

Since then we have added press wheels and moved to 14@ row spacings for cereals and oilseeds, and to 28@ for grain legumes where there is adequate residue to minimise evaporation. Occasionally, we grow cereals on 28@ rows when we have difficulty handling the residues at 14@ spacings. It is of interest that the highest wheat yield grown was with 28@ drill rows - in spite of all the research that points to narrower rows giving higher yields. It is management of the overall system that is important not single factor issues such as row spacing.

Disc equipment is unsuitable on our sticky grey clays so tyned equipment is used. Our chisel plow is purpose built to our own design with 30 A under frame clearance. It has two tynes with 500 lbw break out pressure in each drill row. The tynes are set one behind the other, each independently adjustable both vertically and horizontally. The front tyne places fertiliser at a pre-determined depth the second tyne sows seed above or to the side depending on the crop and fertiliser. Each row has an independent press wheel with adjustable pressure springs. Points are 10 mm wide for minimum soil disturbance.

Stubble management

Seeding operation commences at harvest with straw cut at a maximum height of 15@ to pass through the tynes with minimum plugging. The residue is spread evenly across the width of the header. This not only facilitates seeding but re-distributes nutrients evenly for future crops.

Rotation

Rotation is the most important tool in the control of weeds and diseases. There is no set rotation. However, grain legumes alternate with oilseeds and cereals. Canola is grown only once in four years, always on a legume stubble. Alternate years of legumes has allowed wild vetch a native legume to increase. Therefore we must watch for changes in weeds and diseases and use rotations that allow us to control these problems. Before planting a non-selective herbicide gives a complete weed kill. After planting weed control is identical to conventional cropping systems.

Changes to the weed burden means changes to our weed control methods. This necessitates adequate records of chemicals used, their families, their plant back periods. The major change is the emergence of herbicide resistant plants, such as ryegrass. This has meant rethinking our system to include summer grasses in rotation with our winter crops.

Heaven or hell

Crops have two distinct areas - the drill row and the inter row space. We make the crop row as hospitable to plant growth as possible leaving the inter row space hostile to weeds. We treat each area differently. Conventional cropping with cultivation treats both areas equally. Weeds and crop have equal access to the seed bed, moisture, fertiliser, etc.

Crop row requirements

1. Seed bed - narrow cultivated row provides a miniature seed bed.

2. Fertiliser - placed in an advantageous position for seed. Nutrients exported are replaced.

3. Moisture - seed placed accurately in moist firm soil.

4. Temperature - tyne clears residue from drill row to allow unhindered entry of sunlight.

5. Herbicide - apply residual herbicides pre seeding. Sowing action moves most chemicals clear of drill row reducing retardation of the crop.

6. Disease - rhizoctonia is controlled by cultivation below the seed. (fertiliser placement achieves this.)

Inter row space

1. No soil disturbance to stimulate further weed germination.

2. No fertiliser for weeds.

3. Weed seeds remain on surface where herbicide has strongest effect.

4. No oxidation of organic matter from cultivation.

5. Extra herbicide swept from drill row.

6. Residue swept from drill row blankets weeds.

Advantages of no till system

1. Yields and water use efficiency equal to or better than cultivated cropping systems

2. Rapid water infiltration, no water run off, no erosion, no sediment washed into rivers and streams.

3. No dust or smoke to pollute the atmosphere.

4. Reduced evaporation.

5. More earthworms and bird life.

6. Organic matter is maintained or increased.

7. Elimination of surface sealing.

8. Easier root penetration.

9. Seedling protection.

10. Reduced tractor hours.

Plans for the future.

# Increase use of summer crops in rotation.

# Research a summer legume to include in rotation.

# Green manure crops.

# Possible inter row herbicide control. 28@ drill rows facilitate this.

Intensive cropping and direct seeding will provide solutions to environmental and economic problems for those who make the effort to Aget it right@. Good luck!

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