Black walnut soil nitrogen

Table I. Juglone Concentration in Soil According to Depth and Treatment in a Mixed Planting of Black Walnut and Nitrogen-fixing Species...

To gain more understanding of the European alder decline and because of our concern about the future growth of black walnut planted with nitrogen-fixing species, a study was initiated to measure soil juglone concentration and to estimate the number of Nitrobacter and Nltrosomonas bacteria in a black walnut plantation containing plots of black walnut alone and in mixture with European alder and autumn-olive. 

Soil beneath European alder/black walnut plots had higher nitrate nitrogen levels than soils beneath autumn-ollve/black walnut or walnut-alone plots (Table III). Mean total nitrogen did not differ significantly between treatments. 

Table III. Mean Total and Nitrate Nitrogen, Organic Matter, and pH in Soil Beneath Black Walnut Planted in Mixture with Nitrogen-fixing Species...

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