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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!

How and when to lime

· Lime should be broadcast (spread) uniformly over the soil surface and then thoroughly mixed into the top 15-20 cm of soil (normal depth of topsoil) by plowing or hoeing. Harrowing (disking) alone will only move the material down about 5-8 cm and is inadequate.

· When broadcasting lime by hand, divide the amount in half and apply the second portion at right angles to the first. Wear a mask or bandana, and be careful if using burned or slaked lime; these are caustic materials won't burn as long as your skin is dry, but watch your eyes.

· When applying lime over established pastures, it can be spread directly over the pasture without working it in.

· Apply liming materials at least 2-6 months ahead of planting since the reaction time is slow. The caustic forms of lime are unlikely to injure the crop. Note that lime won't react during the dry season (unless the soil is irrigated), because moist soil is required.

· Where lime is expensive or difficult to apply, you can try "spot-liming" the immediate row or plant zone of the crop. Adjust the rates accordingly.

· Don't mix lime and fertilizer together since it will tie up P or release ammonia gas from N fertilizers.

· Thoroughly wash all lime from any metal application equipment to prevent corrosion.

· How often to lime Where high rates of manure and other acid-forming fertilizers are used, liming may be needed as often as once every 2-5 years. Sandy soils and others of low buffering capacity will need reliming the most often, but they'll also require lower rates per application. Refer to Table 9-1 in Chapter 9 for more information on acid-forming fertilizers.