Stopping the scouring winds from ripping off topsoil

It's already paid dividends for one mixed farmer on the Mendooran road to Gilgandra in the central-west who ripped part of his paddocks that were "like concrete" before. Of course any ripping must be done carefully to not only avoid long-term damage to the paddock, but also machinery.

The ripping methods are based on research that showed that any soil particles that are 0.8 mm or less are highly likely to blow.

Luckily he got under a recent storm that dumped 40mm, and according to Elders Dubbo agronomist Anthony Stibbard retained at least 90 per cent of the run-off that otherwise he wouldn't caught if he hadn't ripped.

Emergency tilling can play its part in the constant wind assaults farmers are suffering under and prepare them for the day it rains.

Mr Stibbard said ripping could stop up to 80 per cent of the erosion from wind storms if done properly.

"its been a great thing to and something we've had to implement with many of our clients under the circumstances we're in. It certainly is working," he said.

"When you've got a paddock like a piece on concrete the wind will just sweep along the surface area and take up everything. But when you do some deep aggregation through the paddock it beaks up the wind cycle."

The idea is to deep rip paddocks at intervals, even if a paddock is ripped just every 3 to 4m. "Not only that but when it does rain that water will be held in the channels." Money and water were the two big issues for farmers in the drought, and this small amount of ripping was worth the effort, although some horsepower and diesel was needed for the deeper rip.

"My feeling is that this ripping is reducing loss of topsoil by up to 80 per cent," he said. "Even if you rip just 10 per cent up to 20 per cent it will reduce the erosion."

The farmer near Mendooran had ripped at 2m intervals and hardly any of the recent storm rain ran off.

Any deep-ripping tough on soils that didn't have much clay content would probably not work, he warned. One sandy paddock they had ripped had returned to normal within six weeks, he said.

Local Land Services Central-West cropping officer Tim Bartimote recently explained the best emergency till methods and warned the wrong method can damage a paddock in the long run - and also machinery going into hard red soils.

"The biggest thing to remember is that emergency tillage is a last resort and is a short-term solution," Mr Bartimote said. "By cultivating, particularly when the soil is so dry, you are breaking aggregate stability and as these clods break down over time you could be left with a more susceptible surface then when you started."

Test strips

"When introducing roughness to the paddocks put lines perpendicular to the wind direction. Begin by doing test strips in part of the paddock and observe the impact. This will enable you to see if you have produced significant clods and at an adequate depth. Be conservative when implementing emergency tillage. When satisfied with test runs, do a strip of cultivation then leave a gap before doing the next one. This enables you to increase roughness later once your initial ridges have worn down."

How deep to till?

"Some research suggests effective tillage depths lie between 4 to 8 inches (10-20cm), while others suggests to the minimum extent necessary to produce clods. The later seems more practical in terms of machinery ware, hardness of the soil and the potential to bring soil issues at depth, such as sodicity which causes soils to be dispersive, to the surface. Greater depths will be more achievable in heavier soils or soils with some moisture."

Machinery

"In terms of machinery, I would be hesitant to use a disc implement due to the degree of destruction as opposed to a narrow tyne or even tyne sweeps. A heavy breakout may be required to be able to handle the current soil conditions and achieve the desired depth. Narrow tynes can be placed roughly 24 inches (60cm) apart and those with sweeps can be pushed further, up to 48 inches (120cm). Discussing the situation with producers, some have found success with chisel ploughs and scarifiers."

Soil types

"Soil type has a large impact on success. Producing decent sized clods is more achievable in soils with less sand. Operations in sandy soils tend to struggle to produce enough roughness and the roughness produced is generally short lived. Deeper ridges need to be created in sandier soils than other soils types and hence I would normally advise against emergency tillage in these situations. Soil structure in sandy soils is quite fragile and will take a long time to recover from cultivation. So the benefit of the operation does not outweigh the consequences in my opinion."

Landscape

"The landscape of the paddock needs to also be considered. Avoid loosening soil on slopes and hilltops due to the risk of exposing country to be more readily washed by intense rainfall events.

"Emergency tillage in red country can be particularly hazardous. This soil has the ability to set very hard, and is often compared to setting like concrete. Tillage in these situations often causes extreme damage to machinery, even when hard faced. Again test strips and slow speeds are crucial, due to the high potential to turn these soils into bulldust and make the current situation far worse."

Mr Bartimote said emergency tilling should not be seen as an alternative for not having proper ground cover.