Current issue: 53(4)
Willows (Salix phylicifolia) were grown for four months in organic rich soil at four nutrient levels (fertilization with a micronutrient-macronutrient mixture of 0, 100, 500 and 1,000 kg ha-1 per month) and four CO2 concentrations (300, 500, 700 and 1,000 ppm). Nitrogen and phosphorus concentration of the willows were reduced at CO2 enhancement, the decrease being larger in the leave and roots than in the stems. Nitrogen content of the willows plus extractable nitrate-N in the soil coincided well with the doses of nitrogen supplied, but the corresponding sum of phosphorus in the plants and soil were smaller. The total nitrogen content of willows grown in unfertilized soil was nearly two times higher than the sum of the extractable nitrate-N in soil and N content of the cutting at the beginning of the experiment. The contents of nitrogen and phosphorus of the unfertilized willows were independent of CO2 concentration, suggesting that CO2 concentration did not affect through increased mineralization the availability of those nutrients to the willows.