Modern interpretation systems for soil and plant analyses in the United States of America

Abstract

Although over 3 million soil samples and over a half a million plant tissue samples are assayed in the some 450 soil-testing and plant analysis laboratories in the United States of America, both techniques are considerably under utilised by farmers. It has been estimated that <15% of the cropland is soil-tested each year and about 30-40% of farmers seldom soil test. Plant analysis is primarily used as a diagnostic tool, except for fruit and nut growers, many of whom test yearly in order to formulate fertiliser recommendations for next year's crop. Considerable standardisation of assay procedures and methods of reporting soil and plant analysis results have occurred in the last decade, although much has yet to be done. Laboratory accreditation and proficiency testing are current issues that will begin to impact the laboratories, while environmental issues will probably demand increasing testing by farmers to insure that fertiliser practices are not contributing to soil and water degradation. This paper reviews past, current, and future roles of soil testing and plant analysis in the U.S.A.