Soil testing key to better yields and less weeds

4 July 2006

South Australian farmers and agricultural advisers are reporting improved yields, fewer weed problems, and better returns for fertiliser input as a result of testing and balancing their soils.

Balaklava farmer and agricultural adviser Greg Barr (pictured right) uses the Albrecht soil testing method because it includes all essential chemical elements and delivers a complete picture of soil condition.

Through South Australian owned and operated Australian Perry Agricultural Laboratory (APAL) at Magill, he receives a detailed analysis and an easy to read report.

“I test good and poor performing land so we can understand why the good paddocks are doing well while others aren’t,” says Greg.

“When we study the soil we can often pick up potential problems like weeds, particularly in soils with low calcium and high magnesium. But once the soil’s elements are balanced, which fixes the structural issues, some of the weeds, such as ryegrass and wireweed, go away because they suit unbalanced soils.

“The same applies with compaction problems. When we get a report back, we find some soils are high in some elements and low in others. When the elements are all properly balanced, the soils are freer.”

Greg says Balaklava has a lot of highly alkaline soils with high calcium levels that tend to “lock up” any fertiliser applied to them.

Timing of fertiliser is critical

“What we have learned is that the soil traps the fertiliser and plants find it hard to access the required nutrients. We now know that the timing of fertiliser application is critical with these soils. If you apply it at sowing, you reduce the amount of time it’s in the ground and susceptible to lock up, thereby making it more effective,” he says.

“We’ve also found applying smaller amounts of fertiliser, more often, is an effective strategy as is using foliar sprays to bypass the soil.

“Some farmers say their yields have increased by 50 per cent in some years. Some have doubled their yield in three years, but it depends on the responsiveness of the soil.”

Getting better yields for the input of fertiliser is a common comment Greg hears from local farmers after they have an APAL soil test and implement the recommendations.

Soil test is an easy read for farmers

Garry Allison, an agronomist from Elders Gambier Farm Supplies, has to have a good understanding of soils to service his clients as he deals with a vast array of different soil types and farming enterprises.

“The Albrecht test is more complex and gives you the detailed information you need to make good recommendations. The format of the soil test is excellent and is a really easy read for farmers,” he says.

Garry is impressed with the fact the APAL Albrecht test is calibrated and is of substance.

“Many labs give you a lot of numbers that don’t mean much,” he says.

Garry interprets the tests himself and makes recommendations so it is important for him to have reliable and detailed information on which to base his advice.

Some of Garry’s clients use the test religiously and have achieved excellent results.

A potato grower in the South East, once considered middle-of-the-road, won the Safries Potato Grower of the Year award last year.

Garry also works with about 50 dairy farmers, with the top five undertaking regular soil tests with APAL.

“Pasture composition and growth rates have been exceptional without putting on high rates of nitrogen,” he says.

“With the soil being balanced, we’re not having to apply a lot of nitrogen to produce dry matter which leads to a more sustainable system.”

After 40 years as a farmer and now as an agricultural adviser, Grantley Dodd of Stansbury knows the importance of soil health.

“Soil is the most misunderstood thing in farming systems today and yet it’s our most valuable asset. If you haven’t got your soil right, what do grow your crops in?” he says.

Grantley has been testing the soil on this 550ha property on the Yorke Peninsula every year for the past 17. He says farmers who do take the time to have their soil tested often make the mistake of not using the recommendations in full or applying them to the whole farm, instead of the area that has been tested.

“If you’ve been given recommendations for a 20ha area then you should concentrate on that and in the initial stages put all requirements into that area and see what happens,” he says.

“People are trying to get instant results rather than concentrating on a given area to increase its production.”

Fixing sodic soil imbalance

For New South Wales business owner and agricultural researcher Graham Falconer, understanding soils is a passion and pastime.

Graham runs a rural merchandising enterprise called Pro-Ag Forbes and is involved in government research projects.

A client of his with a property between Forbes and Condoblin has sodic soils with low calcium levels. The farmer has rectified the soil imbalance by following recommendations Graham generated from an APAL soil test.

“With applications of lime and gypsum he has had a 2.3 tonne increase (from 7 to 9.3 t/ha) in his wheat and similar with his maize yields in one year,” says Graham.

Sodic soils are the most common in the district with most soils west of Forbes recording calcium/magnesium ratios of less than 2 and sometimes less than 1.

“Gypsum has been a common management option for many years but lime has only been widely used in the last 3-4 years,” says Graham.

He has learnt that gypsum stops dispersion in the first two years but after that an application of lime achieves desirable long-term benefits.