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winter 2013 PArtnerS
URUGUAY 655,000 ha
SOUTH AFRICA 368,000 ha
VENEZUELA 300.000 ha
NEW ZEALAND 162,000 ha
COLOMBIA 102,000 ha
Data compiled from Derpsch et al. (2010),
mainly based on estimates made
by farmer organisations and agro-industry.
Retain stubble from previous crop as ground cover.
Replace the plough with specialised zero-till seeders.
Sow crop into undisturbed stubble.
What is conservation agriculture?
Conser vation agriculture (CA) is characterised by three principles that enhance natural biological processes,
allowing farmers to better conser ve soil and water resources while reducing labour and fuel costs.
1. Minimise mechanical soil disturbance from ploughing or harrowing to maintain soil fertility, prevent soil
erosion and the loss of soil-stored moisture.
2. Retain an adequate amount of stubble and straw, and sow seed directly through the permanent ground
cover using specialised zero-till or direct seeding machines to open a narrow slot or trench in other wise
3. Diversify annual crop rotations (or intercropping) to improve soil fertility and control pests and diseases.
ACIAR conservation agriculture projects
CA adoption by smallholder farmers in developing countries has often lagged or been trialled
as part of well-intentioned aid projects only to be abandoned due to poor outcomes.
The problem is that CA is a suite of tools—including specialised farm machinery—that needs to be adapted
to local growing conditions, farming systems and evolving constraints. Adapting CA to local needs, in turn,
requires relatively sophisticated RD&E capacity.
As an early adopter with advanced research capacity, Australia possesses both expertise and experience
with dryland CA that is especially suited to help developing-world farmers avoid some of the looming yield
and environmental crunches, including catastrophic soil erosion and creeping desertification.
ACIAR has tapped this expertise in its well-received series of CA projects located throughout the
world’s diverse farming systems. In this issue of Partners we look at CA projects underway in:
* the Middle East—Iraq and Syria
* the Maghreb region of Northern Africa—Morocco, Tunisia, Algeria, Libya, Sudan and Eritrea
* the Indo-Gangetic Plain—India, Pakistan and Bangladesh
* eastern and southern Africa—Ethiopia, Kenya, Tanzania and Zimbabwe.
Why adopt conservation agriculture?
CA was developed to help farmers, especially in dryland farming systems, to make better use of their natural
resources while striving to achieve acceptable profits through high and sustainable production levels.
Historically, the development of CA is a response to disastrous environmental consequences of
unsustainable farming practices that involve excessive soil cultivation. This includes the devastating dust
storms in the Great Plains of the US in the 1930s.
Over time, CA has been found to build up soil organic levels, which act as fertiliser and promote the growth
of beneficial microorganisms that preser ve soil fertility. They also allow soil to be productive for longer periods
of time. CA can also reduce time, production and labour costs for farmers, especially where it replaces the need
to plough soils several times before sowing.
There is some controversy in the scientific literature regarding CA benefits to farmers. ACIAR takes the view
that CA technology is geographically and environment specific, requiring research and appropriate machine
seeders to properly adapt the technology to different farming systems and sites. Due consideration is also
needed when there are competing uses for the retained straw, particularly as feed for livestock.
Who uses conservation agriculture?
CA is practised on an estimated 111 million hectares of farmland, primarily in the agricultural
export powerhouses of Australia and the Americas.
The pattern is significant to agricultural engineer Professor John Blackwell of the International Centre
of Water for Food Security at Charles Sturt University in Australia. He explains that machinery favoured by
Americans and Australians did not require much adaptation for CA given relatively low stubble situations.
This was due to the wide spacing between tines or discs that allowed the stubble through.
“In Australia, in our rainfed wheatbelts, the yields are relatively low and so the machinery has little
difficulty getting through the stubble without ploughing,” Professor Blackwell says. “The engineering
challenges mount with the stubble load, which is huge in the case of rice farmers.”
The world over, rice straw continued to be burnt as engineers tried and failed to solve the problem. This
changed with an ACIAR project that recruited Professor Blackwell, who literally dreamt the solution and
went on to build, patent and test the Happy Seeder in India in 2001. The technology is currently in its sixth-
The engineer’s inventiveness has brought CA to part of the crop rotation in five million hectares of the
Indo-Gangetic Plain in India, Pakistan, Bangladesh and Nepal. There, CA has made it possible to cultivate a
second crop during the dry season, which is sown directly into rice stubble using residual soil moisture
trapped in the soil by the retained stubble.
World total: 110,655,000 ha
In 2011, CA was practised on about 110 million hectares of farmland worldwide, although
the accuracy of this data is limited by patchy surveying of farming practices across the globe.
This figure represents about 8% of global cropland. This total includes a wide mix of farming systems –
farms of all sizes, in temperate, subtropical and tropical climates, and using everything from advanced
satellite-driven mechanised power to animal and manual methods for seeding.
Extent of no-tillage adoption worldwide for the year 2008–09
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