Relationship of Yield and Total Nitrogen Uptake of Brussels Sprouts Plants Grown in the Greenhouse to Available Soil Nitrogen

Initial nitrate-nitrogen content of the soil gave a correlation coefficient (r) of 0.93 with yields and with total nitrogen uptake of Brussels sprouts plants (Brassica oleracea var. gemmifera DC., Jade Cross). Soil nitrogen extracted with 0.01 M NaHCO3 gave r values of 0.76 with yields and 0.75 with nitrogen uptake. Nitrate incubation results from leached, moist soil samples gave r values of 0.59 with yields and 0.56 with nitrogen uptake. However, air-drying of soil samples prior to leaching and incubation resulted in r values of only 0.15 and 0.11 with yields and nitrogen uptake, respectively. Available nitrogen determined by incubation without previous leaching of the soil samples gave high r values because of the influence of the initial nitrate nitrogen in the soil.