Tall Wheatgrass and Russian Wildrye Growth on Natrustoll Horizons Treated with Phosphate and Calcium Amendments 1

The central Great Plains of Colorado and Wyoming contain over 500,000 ha of saltgrass [ Distichlis stricta (Torr.) Rydb.] meadows. In many places these meadows are subirrigated by a shallow, nonsaline water table. Rehabilitation of these meadows with palatable, salt‐tolerant species would greatly increase the grazing capacity. We conducted a greenhouse study to evaluate the effects of three levels of phosphate (P) and two levels of Ca on herbage growth and on the root development of tall wheatgrass [ Agropyron elongatum (Host) Beauv.] and Russian wildrye ( Elymus junceus Fisch.) when grown in a mixed horizon and in a simulated profile of Typic Natrustoll soils. Both species showed significant increases in herbage production with P and substantial increases in P uptake. Calcium treatments and P ✕ Ca interactions were significant only in the second and third herbage harvests and in roots of tall wheatgrass. Tall wheatgrass absorbed considerable quantities of Na* (>1%), while Russian wildrye absorbed appreciably less, which suggests an exclusion mechanism for Na* by Russian wildrye. No direct enhancement effect was noted in plant vigor due to fertility‐salinity interactions. In the mixed horizon treatment, which simulates plowing to a depth that would mix saline C horizon material with the A and B horizons, tall wheatgrass responded to both P and Ca, and Russian wildrye responded to P. One should avoid plowing into the saline C horizon, but if this cannot be avoided, applications of P and Ca fertilizer may help ameliorate the effects of the salinity. In the simulated horizon treatment, which simulates cultural practices that do not mix the C horizon with the A and B horizons, the addition of P and Ca was neither necessary nor beneficial.