Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: June 29, 1999
Publication Date: October 1, 1999
Technical Abstract: Increases in N fertilizer costs have caused some farmers to consider the use of a legume during the fallow phase of a wheat-fallow system as an alternative N source for dryland wheat. Our objective is to quantify measured changes in N availability as affected by legume species, legume termination date and time after termination. Four legumes, Austrian winter rpea, spring field pea, lentils, and hairy vetch, grown during the summer fallow phase of a winter wheat summer fallow rotation are terminated at four different times during the summer fallow phase. Soil and plant samples are analyzed for total and inorganic N to assess changes in inorganic N from growing the legume. In most years at wheat planting time soil inorganic N levels are higher in unfertilized traditional summer fallow than in legume green fallow plots. But the following March the reverse is true. Wheat grain N is also assessed.