01893naa a2200265 a 450000100080000000500110000800800410001910000170006024500550007726000090013252012110014165000160135265000120136865000130138065000150139365000130140865300210142165300180144265300250146065300200148565300260150565300180153170000170154977300610156615226652023-12-06 1979 bl uuuu u00u1 u #d1 aWIGHT, J. R. aRange fertilizationbplant response and water use. c1979 aAbstract: During the 10-year study, herbage production on an unfertilized, mixed prairie range site in eastern Montana averaged 1,047 kg/ha and ranged from 720 to 1,321 kg/ha. Elimination of nitrogen (N) and phosphorus (P) deficiencies by fertilizing increased herbage yields an average of 114% (ranging from a low of 32% in a "dry" year to a high of 218% in a "wet" year). Nitrogen was the major growth-limiting plant nutrient with measurable responses to P occurring only when N was nonlimiting. Single high-rate applications were about equal to annual N applications when compared on an annual rate equivalent basis. Species composition varied as much among years as among fertilizer treatments. At N rates of 336 kg/ha or less, cool-season grasses increased in about the same proportion as did forbs and shrubs, maintaining a relatively constant composition of the major species groups. On unfertilized plots, herbage yields and water use reached maximum values of about 1,250 kg/ha and 265 mm, respectively, regardless of further increases in available water. Unfertilized plots produced an average of 2.60 kg/ha for each 1 mm of precipitation received as compared with 5.81 kg/ha on fertilized plots. aFertilizers aGrasses aNitrogen aSoil water aPastagem aAdubacao mineral aFertilization aGrassland Management aGrowing seasons aPlant water relations aPrecipitation1 aBLACK, A. L. tJournal Range Managementgv. 32, n. 5, p. 345-349, 1979.