Soil test standardization in west Asia‐North Africa Region

Abstract

In dryland fanning of the Mediterranean zone, which has rain in the winter with long dry summers, inadequate soil moisture is generally the dominant factor limiting crop growth. Nitrogen (N) and phosphorus (P) can significantly and economically increase yields in most circumstances when both elements are deficient. However, soil testing for fertilizer recommendation is in its infancy in the vast area of West Asia‐North Africa (WANA) with a winter rainfall climate. Fundamental to such endeavors is the use of appropriate tests and consistency of test results. Thus, a standard soil sample (Vertic Xerochrept), along with a questionnaire, was sent to 50 laboratories in the region which are involved with soil analysis. Of the 22 respondents, most tested for available nutrients, pH, and electrical conductivity (EC), but few did tests for total P, boron (B), or sulfur (S). Most laboratories made recommendations for clients. Few laboratories were involved with 15N or 32P analysis, while a small number performed clay mineral analysis. Units of measurement varied among laboratories. While most laboratories were close to the normal values for the test sample, others showed wide variation, especially for Olsen‐P and organic matter. We hope that the sources of such variation can be identified and communicated to the survey participants. The survey can help broaden and improve communication among soil scientists in ICARDA's Soil Fertility Network and improve the effectiveness of soil and fertilizer use research