August 31, 2015 Bill Crabtree
Is Soil Tillage Ever Justifiable? No-Till Bill Checks In!
Hi, I’m Bill Crabtree, consultant, farmer and no-till champion!
“I hear that Western Australia (WA) has gone back to the plough” is the headline! This media spin title is perennial since no-till use exploded in WA in the late 1990’s. The same one-liner is now being used in other states, who 10 years later also adopted no-till.
Ploughing has been an important tool in Australian agriculture and likely will remain so forever! The no-till movement in WA has always promoted tillage – I say this as the first 10-year newsletter editor. This may seem strange to other no-till enthusiasts in other parts of the world. So let me explain!
More than 95% of WA, and perhaps now 90% of most other regions, is no-till cropped every year. Farmers observe that the longer they no-till the better their soils become, even after 30 years the soil continues to improve and become more productive. So why would no-till farmers want to do some tillage?
There are six main reasons why no-till farmers do some tillage, including where;
- Trees and bushes aggressively regenerate on cropped paddocks
- Wodgil soils naturally exist and the subsoil pH levels are 3.5-4.5 (in CaCl2)
- Wheel ruts need filling in after driving in very wet conditions
- Water repellent sandy soils need ameliorating with clay
- Sheep grazing on heavy-bare soil has compacted it and
- Poor herbicide use that has led to herbicide resistance
In most cases the area of tillage in any one year is less than 2% of a farm. The use of tillage is just restricted to where it is needed, depending on the issue and in some years tillage is not used at all. I don’t think any no-till farmer is enthusiastic about using tillage and usually it is a tool of last resort. But if you are going to do tillage then you should do it properly and thoughtfully, right?
No-till farmers do tillage so that they can return to efficient no-tillage! Ploughing the soil is an expensive activity and is not done from peer group pressure. Our farmers are very pragmatic about the value of no-tillage and tillage tools, and of this, we are proud. WA farmers love no-till and they know the efficiencies it provides and the confidence it gives them for weed control, timing, trafficability and safe crop establishment, indeed, it remains their foundational seeding methodology.
On my 2,800 ha farm, at NE Morawa, the first two issues (trees and acidity) are a significant challenge. Each year I have had to conduct tillage on about 1% of my farm. My farm has perhaps 150 ha of Wodgil soils occurring in small patches over my farm. These acid loamy sands naturally have a pH of 3.8-4.8 down to 60 cm depth (perhaps) and surface applied lime in my low annual rainfall of 305 mm is not adequate to enable the lime to dissolve and move to depth.
I have applied 6-9 t/ha of lime on small areas over 3 different years and have still observed minimal crop growth for 8 years on these areas. The rainfall has done nothing to wash the lime through the soil profile. Physical mixing of limesand through the soil profile makes a lot of sense. Without tillage this soil will remain unproductive, biologically inactive and degraded and can encourage acidic and salty groundwater recharge and wind erosion.
The third example of the need for tillage is to fill in wheel ruts that are created when the soil is excessively wet. The use of controlled traffic, which is a good fit for Australian no-till practice, can result in deep wheel ruts and these ruts need to be filled in or renovated. The large size of Australian farms and the duplex and heterogeneous nature of many soils can result in wheel ruts being unavoidable and need filling in with tillage.
The forth issue is ameliorating water repellent soils. These are the very sandy soils that contain almost no clay and have very little surface area. These sands, in our hot summers, can bake to 45C and the surface organic material which contains some wax can then be melted through the top 10 cm of the soil. This melted wax coats the surface of sand particles and makes it waxy such that water cannot penetrate it. This wax coating can only be effectively and permanently cured by applying clay and aggressively mixing it through the topsoil profile. The clay increases capillarity suction that overcomes the problem. The no-till movement (www.wantfa.com.au) has promoted tillage as a cure for this problem since its birth 1992.
The fifth issue is where sheep grazing compacts clay based soils, especially if the soils are low in organic surface cover and wet while the sheep are grazing on them. This scenario is common in WA and it is a highly misunderstood romantic view of Australian ley-farming systems. This grazing system might be sustainable if the soils could produce more green cover for more than 4-5 months a year, but the Australian wheat-belt is rightly known as a sunburnt region. Some no-till farmers who do run sheep do narrow (12 mm) opener cultivation to 10 cm deep in the autumn. This cuts slots in the soil and cracks the hard set clay and allows subsequent rain water to penetrate the soil and not run-off. This issue was a main driver for many no-till farmers to abandon sheep farming completely.
The last main reason for ploughing is for herbicide resistant weed control and it is a drastic practice. Before farmers learned about how to slow herbicide resistance, we regularly used low rates of herbicides which induced rapid herbicide resistance. In particular, the weed “wild radish” proliferates in the water repellent soils in the northern agricultural region of WA, near Geraldton. Farmers in this region have learned to use mould-board ploughing to ‘kill two birds with one stone”. However they are mindful not to do tillage again and bring these viable weed seeds back to the surface for a very long time.
In summary, yes no-till farmers in Australia do conduct some tillage in some small areas. But those Australian farmers who quickly grasped no-till and have maintained it well will continue to reap more rewards each year. There are small pockets where tillage needs to be done and it always makes for a great journalistic read to onlookers.
I hope this clarifies the tillage issue to international agriculturalists who are often puzzled by the idea that Australia, who is a world leader in no-till, does some strategic and small areas of tillage each year.
The pictures in this blog are of my no-till operation.
I welcome your comments. Find me @NoTillBill or @NOTILLville