The effects of fertilizer placement and soil moisture level on soil N movement, uptake, and use by tomato plants (Lycopersicon esculentum Mill) grown with drip irrigation and plastic mulch were evaluated at two locations on two types of sandy soils. Broadcast or band fertilizer placement had no effect on fruit size, fruit number, or total yield. Fruit size was increased at one location, and the incidence of blossom-end rot was decreased by increased frequency of irrigation. Nitrate-N distribution within the bed was not affected by initial N placement. In the soil with a rapid infiltration rate, NO3-N levels in the center of the bed were always low, with highest concentration observed in the areas of the bed most distant from the drip tube. In the soil with the slower infiltration rate, NO3-N concentrations were more uniform throughout the bed, with highest concentrations in the bed center: Increasing soil moisture levels (–20 kPa vs. –30 kPa) resulted in increased leaching and reduced NO3-N concentration throughout the bed. Foliage N concentration was not affected by N placement, but decreased seasonally. Total N uptake by the above-ground portion of the plants was not affected by fertilizer placement or soil moisture level.
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