Description of practice
Alkalinity management is needed in agricultural soils with pH >8.4. This occurs in poorly drained soils where evaporation concentrates sodium bicarbonate (alkali) at or near the soil surface. Management consists of improving drainage and/or acidification (either by applying calcium as gypsum or by applying an acid to dissolve calcium already in the soil). This is followed by leaching of the salts.
| Examples of how to use alkalinity management | Further information (see Note below) |
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Calcareous soils managementWater-logged fields with high pH are reclaimed for cultivation by a combination of drainage channel construction and injecting ammonia as an acidifying agent to dissolve calcium carbonates. |
»WOCAT technology 716
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Applying gypsumGypsum (calcium sulphate) is applied to alkaline soils to provide soluble Ca2+ to displace Na+ and maintain infiltration rates. Mixing gypsum to a depth of 15 cm is more effective than surface application. Flushing of salts is also needed. |
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Applying elemental sulphur, aluminum sulphate or pyriteSulphur is applied to alkaline soils to lower the pH by biological oxidation, producing sulphuric acid. Cost-effectiveness may be an issue, but sulphur and sulphates may reduce pH faster than gypsum. |
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Note: Most of the Further information links are to a full description of the example in the WOCAT database. However sometimes the link may be to similar practices or a research paper. Occasionally the link is to a commercial product in which case it should be understood that this does not imply any endorsement of the product by iSQAPER.