Nitrogen and Phosphorus Fertilization for Production of Crested Wheatgrass and Native Grass in Northeastern Montana
1968
Black, A. L.
Nitrogen and N-P fertilization consistently increased forage yields of native grass and crested wheatgrass (Agropyron desertorum [Fisch.] Schult., ‘Standard’). Plant responses were greatest the year of fertilization, but residual effects were significant 1 to 2 years later. Aplications of N at rates of 45 kg/ha or greater, regardless of P treatment, increased water-use efficiencies of both grasses 1.5- to 2.5-fold for 2 to 3 years. Increased wateruse efficiency was at least partly due to more efficient extraction of subsoil water. Plant P content was increased substantially by applied P the year of application and 3 years later, regardless of N treatment. Plant recovery of N applied alone at rates of 45 or 90 kg/ha for the 4-year period averaged 65.8% for crested wheatgrass and 60.0% for native grass. Recovery of N applied in combination with P averaged 73.1% for crested wheatgrass but only 38.2% for native grass. Phosphorus fertilizer stimulated uptake of soil N by both grasses about 20%. Nitrogen increased the 4-year production of crude protein 1.5- to 2.6-fold for both grasses. High N fertilizer rates were more economical than low N rates, regardless of P treatment.
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