The majority of soils in California are alkaline or, at least, not sufficiently acid to need lime. However, there are areas in the state where soils are naturally acid and other areas where continued use of ammonium fertilizers has produced acid conditions. The acidity of some of the soils is sufficient—pH values less than 5—to indicate that many crops should give higher yields when limed.

The above progress report is based on Research Project No. 1305.