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close this bookSoils, Crops and Fertilizer Use: A Field Manual for Development Workers (Peace Corps, 1986, 338 p.)
close this folderChapter 11: Liming soils
View the document(introduction...)
View the documentThe purpose of liming
View the documentWhen is liming needed?
View the documentHow to measure soil pH
View the documentHow to calculate the actual amount of lime needed
View the documentHow and when to lime
View the documentDon't overlime!

Don't overlime!

Avoid raising the pH by more than one full unit at a time, and don't raise it much above 6.5. It may only be necessary to raise the pH up to 5.5 to 6.0 for best yields of most crops. Overliming can be worse than not liming at all because:

· Raising the pH above 6.5 increases the likelihood of micronutrient deficiencies (except for molybdenum), especially in the case of iron and manganese.

· Phosphorus availability starts declining above a pH of 6.5, due to the formation of relatively insoluble compounds with calcium and magnesium.