Research in WA ( www.agric.wa.gov.au/cropupdates/1998/cereals/deeprip.htm ) has demonstrated increases in yields of wheat by as much as 40% and Field Peas by about 30% using a combination of appropriate nutrition, deep ripping and Gypsum. But what is it that makes Gypsum so beneficial?

Gypsum is an excellent source of both Calcium and Sulphur - essential for both yield and grain quality (especially useful in combination with high analysis fertiliser) - but its benefits go much further. It also helps improve soil structure and balance the soil by both adding Calcium and displacing harmful Sodium.

When Gypsum is applied, the Calcium seeks out clay particles - sticking to them in much the same way that dust will stick to an old vinyl record (remember - before CDs). The value of calcium is that it can stick to two clay particles at once, causing them to clump together - improving soil structure.

One of the enemies of soil structure is Sodium and in soils with lots of this element (termed 'Sodic'), there may be little room left for Calcium on the clay particles. But Gypsum has another weapon - Sulphur. Gypsum is made up Of Calcium Sulphate, so when Calcium moves in to exchange places with Sodium, the Sulphate captures this Sodium and carries it away in the soil water.

Another problem with soil structure in Australian Soils is that many are high in Magnesium. This is a useful and important element, but with lots of Magnesium and little Calcium, soils set hard when dry, limiting root access and inhibiting crop establishment. Again, Gypsum can correct this situation - helping to restore the proper Calcium:Magnesium ratio.

Conditions that indicate the use of Gypsum include:

• Low calcium or sulphur on a soil test (especially if Sodium or Magnesium levels are also high)
• High soil pH
• Signs of poor moisture infiltration or waterlogging
• Soils that are very soft and sloppy when wet or very hard when dry (or both) . Crusting of the soil surface after rain that can cause poor germination
• Burning of shoot and root tips caused by calcium deficiency.

If you have any concerns about your crop yields and would like more information concerning the use of Gypsum, contact SWEP Analytical Laboratories (03) 9701 6007 or Gypsum Australia Pty Ltd on (03) 9546 9400

and some other interesting links relating to the use of gypsum in agriculture:

Residual effect of soil amelioration on field peas yield in a very dry season
www.agric.wa.gov.au/cropupdates/2001/farm_systems/hamza.htm

Calcium:magnesium ratios; are they important?
www.agric.wa.gov.au/cropupdates/2001/cereals/Bowden_Strahan_Gilkes.htm

Improving wheat yield, soil physical and chemical fertility by a package of deep ripping, gypsum and complete nutrients
http://www.agric.wa.gov.au/cropupdates/2000/cereals/Hamza.htm

Identifying gypsum-responsive soils
http://www.agric.wa.gov.au/agency/Pubns/farmnote/1990/F05790.htm

Recommendations for gypsum in agriculture
http://www.dktgypsum.com/recommend.html

Gypsum application and deep ripping for vineyard development
http://www.groguard.com.au/gypsum.html