Nitrogen Relations in Bermudagrass During Growth and Dormancy Cycles

Abstract

Use of recycled water for turfgrass irrigation is increasing in the southeastern U.S. because of population growth and interest in protecting water quality. Turfgrass systems are perceived to be well suited for effluent dispersal due to their proximity to waste treatment facilities, in-ground irrigation systems, and ability to efficiently absorb (i.e. filter) nutrient contaminants when actively growing. However, effluent generation is continuous and bermudagrass growth is seasonal in the southeastern U.S. Clearly, there is a need to more thoroughly understand the capacity of bermudagrass, the turfgrass most often involved with effluent dispersal, for receiving effluent irrigation. This series of experiments was designed with the overall intent of examining the capacity of a bermudagrass turf⁄soil system for handling effluent applications. Experiments involved 1) characterizing seasonal changes in nitrate assimilation efficiency of the system, 2) determining the effects of prolonged soil saturation on nitrate uptake efficiency, and 3) characterizing internal nitrogen relations during the spring emergence period. While it is difficult to extend the results of these experiments, quantitatively, to situations where effluent is being applied in the field, the evidence does support a few basic observations. Bermudagrass appears to be capable of assimilating large amounts of N when growing, an ability that may well extend into transition months when little vertical shoot growth is occurring. Furthermore, although reduction in quality occurred, shoot growth and nitrate uptake efficiency of bermudagrass and centipedgrass was relatively unaffected by prolonged saturated soil conditions, a condition that may be likely with effluent irrigated sites.