Detecting Depth and Lateral Spread of Roots of Native Range Plants Using Radioactive Phosphorus

Abstract

Radioactive phosphorus (P32) was used to measure root depth and lateral spread of four native plant species which had been subjected to heavy grazing for many years. Compared with root excavation measurements from an earlier study on the same area, rooting depths of all species tested were found to be quite similar by the two methods. Lateral spread differed substantially, however. Roots were found to have a greater lateral spread by the P32 estimate. The isotope method using autoradiography was found to be a sensitive method of determining depth and lateral spread of in situ plant roots in a mixed plant community.