Reme Soilmaster Copyright 1996 -Reme Soilmaster(TM)
POKING ABOUT IN THE DIRT with ROB CUMMING. (Soils Consultant)
The subject of acid soils is becoming one of the more important ones, to farmers, agriculuralists and those concerned for soils. It was even mentioned in the Prime Ministers recent Statement on the Environment.
But, why is it important?
A recent survey in N.S.W. points out that 2.9 million hectares of land is severely acidified, with a further 5.6 million hectares likely to become acid. All this land is in the highly productive and agriculturally important higher rainfall areas, generally east of Griffith, Dubbo and Gunnedah.
And what of our area ?
The tablelands and slopes have been long recognised as having acid soils.
This is due to the type of farming activities and the soil types which abound in the area. The lighter soils often show the affects of acidity first, although the problem is not isolated to these soils and can also occur in the heavier soils, such as the basalts.
The problem is associated with the time since initial pasture improvement, the introduction of sub clover and the use of superphosphate to improve our pastures and increase productivity.
And, what causes the acidity build-up ?
Clovers are used in pasture to build up fertility and they do this by producing nitrogen in the form of nitrate - the same nitrate that comes in the bag. If the plants growing do not use all the nitrogen, what is left over then goes into the soil and acidifies the soil.
It is this very gradual acidification that we refer to, when talking about acid soils; so gradual in fact, that we cannot see it occurring and must rely on soil measurements to determine what is the actual acidification.
Some soils have taken 30 to 50 years to become acid enough to become a real problem. However, others take only a few years.
So it is important to look at your soil type and see if you are likely to have a problem, or if there is one there now. A look at your length of time since a paddock was first improved, is a very good guide and if the soil has been improved for more than 20 years, there is likely to be some acid build up.
Next time we will look at some of the symptoms which help us to recognise acid soils.
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