INNOVATIVE ¹⁵N MICROPLOT RESEARCH TECHNIQUES TO STUDY NITROGEN USE EFFICIENCY UNDER DIFFERENT ECOSYSTEMS

Abstract

Use of labeled ¹⁵N techniques can help improve and refine knowledge required to understand the dynamics of the N cycle under agricultural systems. The examples reported in this paper illustrate that, with creativity and careful planning, use of ¹⁵N-enriched or depleted fertilizers can be used in many types of N experiments with various crops, cropping systems, and in many types of agroecosystems. The objective is to report examples of a wide range of field studies that researchers can hopefully draw upon to design and utilize N isotope techniques that accomplish the objectives for their own research. Examples of microplot studies with and without physical barriers are discussed along with some of the strengths and limitations of each approach. Even though ¹⁵N technology offers considerable opportunity to understand N cycling, it too has limitations to its use. Types of fertilizer ¹⁵N materials and methods for applying ¹⁵N materials are discussed including some discussion about the use of ammonium versus nitrate forms; literature sources are provided for additional reading about the use of ¹⁵N techniques.

ACKNOWLEDGMENTS

The author gratefully acknowledges the suggestions made by the peer reviewers of this manuscript and by Dr. Delgado as editor. The author especially acknowledges the analytical and other contributions of Mr. Edward Buenger to the studies conducted by the author and for invaluable insights and contributions to design of equipment and its fabrication.

Notes

Trade and company names are included for the benefit of the reader and do not imply endorsement or preferential treatment of the product or the manufacturer by the authors or the USDA.

Personal communication with Dr. Jorge Delgado, USDA-ARS, Fort Collins, CO.