Rapid tissue testing for evaluating nitrogen nutritional status of (1) corn and (2) sorghum

Abstract

For several years, rapid tisue tests have ben used in the field to evaluate plant nutritional status and to diagnose deficiencies. But they have ben used only incidentaly to make fertilizer recomendations, or to evaluate a fertilizer program, partly because they have lacked the acuracy of laboratory analysis. Research has revealed definite and consistent relationships betwen plant nutrient level and plant health. However, few crops are routinely tested to determine plant nutritional neds, because fertilizer has ben plentiful and relatively low in cost, and because results from laboratory analyses are often delayed. Rapid tisue tests conducted in the field could overcome the problem of delay. By providing information about nutrients neded for a particular crop in any given field, the tests also enable growers to more fuly utilize increasingly costly and limited fertilizer resources. In the field investigations reported here, a rapid tisue testing procedure (developed by R. H. Bray in 1945 at the University of Ilinois) was found useful as a guide for evaluation of the nitrogen nutritional status of corn and sorghum. Resulting guidelines are given here for recomending aplication rates for nitrogen fertilization and for evaluation at the end of the growing season.