Diagnosing calcium deficiency in wheat
Calcium deficiency rarely occurs due to the application of single superphosphate fertilisers (containing 20% calcium), lime and gypsum. These factors would increase and/or maintain the calcium status of the soils. However, greatly reduced superphosphate use and long-term use of compound fertilisers may increase the likelihood of deficiency.
What to look for
- Sandier more acidic parts of the paddock will be most affected.
- Symptoms appear first on the youngest leaf and gradually spread to older growth.
- Tips of new leaves go pale, then roll inwards, die and may twist back and tear off.
- Base of affected leaves remains green and healthy.
- Plants are stunted with short stout stems and erect dark green leaves.
What else could it be
|Diagnosing copper deficiency in wheat||Youngest leaf twisting and death from the tip||Copper deficient plants are light green rather than dark green and have shrivelled and rat-tail heads.|
|Diagnosing boron deficiency in wheat||Youngest leaf death||Boron deficient plants have water-soaked leaves with notched edges and that kink in the middle.|
Where does it occur?
- Calcium deficiency of crops typically occurs on sandy acidic soils with low exchangeable calcium. These soils are common in the cropping regions of South-Western Australia but cereal grain yield responses to applied fertiliser calcium have not been obtained in field experiments.
- Calcium deficiency is exacerbated in acidic, sandy soils with high soluble aluminium.
- Lime or gypsum are the cheapest sources of calcium.
How can it be monitored?
- Use whole-top plant test to diagnose suspected calcium deficiency and compare paired good/poor plant samples where possible. Levels below 0.2% in whole shoots at the boot stage are adequate. In the youngest leaf a concentration of <0.12% is likely to reflect a deficiency.
- There is no locally calibrated soil test for calcium.