To do or not to do? Conservation farming in marginal areas
The rainfall in central NSW is often unreliable, and unseasonal. Long-term averages for Trundle and Condobolin show there is no 'summer dominant' or 'winter dominant' pattern, and frequently January can be as wet as any other month and can be when we get the heaviest rains, as storms. The driest months are frequently March, April and May.
From long fallow to chemical fallow
The 'good old long fallow' stores moisture from the previous spring (or winter), by keeping the paddock free of any growth from this period until autumn sowing.
There are also benefits from mineralisation of nitrogen, a disease break from keeping the paddock grass-free and weed benefits from prevention of seeding from the previous season. It is likely that all these added up to making cropping over the years more reliable when crops were grown on fallows, compared to those on stubbles.
Concerns about soil effects of repeated tillages (erosion, plough pans, structure damage, compaction from machines and sheep), coupled with decreases in prices of herbicides relative to the costs of cultivation (i.e. fuel and machinery have risen while glyphosate has fallen), have led many to look at spraying instead of cultivating.
Innovations — including point design, row spacings, and stubble-handling ability — have led to many looking at ways of getting a crop in without the time and costs of the long fallow, or any cultivations at all.
Some first-hand experience
At one property, west ot Condobolin, a system using no-till into stubbles, and no-till pasture establishment into previous cereal paddocks was tried in the late 1990s. This seemed to be working, with yields in 1997 around or above the district average, but with considerable reduction in costs, machinery and labour.
When coming into a cropping phase from several years of pasture, a cultivation or two is still needed. These are often the only cultivations a paddock will have in several years of cropping (two paddocks have now grown five crops in a row, and continue to improve). These initial cultivations are needed to break old hard pans, and surface compaction from sheep. After the first crop almost all crops have been sown no-till into the stubble of the preceding crop.
The general plan for cropping
|Old pasture||Spray-top 1-2 years prior to cropping to reduce grass content.|
|First crop preparation||Cultivation for compaction and hard pans. Once soil in condition suitable for sowing herbicides used for weed control.|
|Crops following this||Summer rains and subsequent weeds controlled with herbicides. Crops no-till, pre-plant herbicide if needed.|
|Crop rotation||Includes canola on more fertile paddocks, either at start of rotation, or after cereals. Something like: fallow-canola-wheat x 2-barley, then assess paddock for more crops or out to pasture. Will try legumes, e.g. lupins, chickpeas, but some doubts about profitability.|
|Weed control strategy||Pre-plant knockdown when needed. First cereal also gets Glean or Logran. Subsequent crops as needed post-emergent. Will look at Trifluralin in no-till in 1998. Work on weeds in pastures prior to cropping phase.|
|Fertiliser||All wheat at least 16 kg/ha of P. Barley 12-14kg of P. Canola 18 kg P + 10 kg S +(depending on soil test) 50 kg N.|
|Key management points||Summer weed control, plus in-crop and pasture weed control. Sow on time. Dry sowing of canola has been successful, allowing better timeliness of the sowing of wheat and barley. Solid fertiliser rates, e.g. 60-80 kg/ha DAP on all cereals. Improved pastures to follow a period of cropping. Aim to establish quality legume-dominant pastures into the final crop stubble(no till) in winter after the last crop. Use of contractors for timeliness, reduction on capital and labour costs.|
|Seeding machinery||Primary Sales Superseeder points, 22.5 cm spacings, presswheels. This rig used for sowing cereals, canola, pastures (lucerne + medic + clover|
|Use of contractors||Approx. 50 per cent of seeding done by contractors (same machinery set up), almost all spraying, and 80 per cent of harvest and cartage.|
Paddocks ranked by $$ nett return/ha
|Paddock no.||Crop 97||t/ha||Gross 97||Costs 97||Nett 97||System||Crop no.|
|B1||Wheat||3.25||$601.25||$195.00||$406.25||Cult L Fallow||1st|
|G1||Barley||2.62||$432.30||$155.00||$277.30||Cult S Fallow||2nd|
|B2||Wheat||2.39||$442.15||$165.00||$277.15||Cult L Fallow||1st|
|G3||Wheat||1.45||$268.25||$150.00||$118.25||Cult S Fallow||2nd|
|GL1||Barley||1.37||$226.05||$135.00||$91.05||Cult S Fallow||4th|
The points to make from the above results are:
- A good long fallow following some years of lucerne remains one way of producing high-yielding and profitable crops (Bl paddock). However, fallow by itself, where the fertility of the paddock may not be good, was not any better than another paddock where the crop was sown into the previous year's canola stubble.
- The no-till paddocks were the lowest in terms of gross costs. This reflects the savings that can be made by reducing or eliminating cultivations in stubbles. Yields are similar to those from the other systems. However, when ranked in terms of nett $$ returns, they have came back to the top of the table. This shows the importance of no-till in reducing input costs, and providing profitable returns.
- Apart from Bl, the no-till paddocks in 1997 were the most profitable. This in my view was due to savings in costs, while maintaining weed control and moisture preservation from harvest onwards, plus sowing at the right time (if rain permits), and using higher-than-average rates of fertiliser. The presswheels seem to assist with getting better germination, especially when moisture is getting marginal.
Other cost savings
Other cost savings occur from adopting a program of reduced tillage in western NSW. By not spending as much time on tractors, savings are seen in lengthened tractor life, less labour requirements, and lessened need for cultivation equipment. The capital tied up in machinery is an important cost that can be reduced by going to a no-till or reduced-tillage program.
A long fallow will still be useful when coming from pasture to cropping. This is best when the pasture has carried a dominance of legumes, and is best commenced with herbicides, with a cultivation or two inserted later.
Take home message:
Economically attractive results can be obtained in a 'marginal' environment with no-till or minimum-tillage techniques, but only if the basics are followed.
This means weed control (especially in the couple of years prior to entering a crop phase, and following summer rains for moisture storage), sowing on time, good rates of fertiliser (e.g. 80 kg/ha DAP), and well-set-up seeding so that placement is correct. Presswheels here seem to have a benefit in assisting placement, and when moisture is marginal.
Region North, South, West