The effects of long-term fertilization on soil properties and nutrient availability are not well documented for cassava cultivation in Vietnam. In 1990, a field research plots were established with 12 treatments to test the effect of different rates of nitrogen (N), phosphorus (P) and potassium (K) on soil properties in Acrisols at Thai Nguyen University in Northern Vietnam. In 1999, composite soil samples (0 to 20cm depth) were collected from eight selected plots for measurements of nutrient supply rates by ion exchange membrane probes and for growing corn and canola in a growth chamber with and without added lime. Generally, long-term nitrogen (N) fertilization increased available N supply rates but decreased available potassium (K) and magnesium (Mg). Long-term phosphorus(P) applications increased canola N, calcium (Ca) and Mg uptake. Canola P uptake increased with increased P rates only when lime was added. Long-term K applications increased canola N, K, Ca, Mg uptake but only significantly increased corn N uptake. Liming significantly increased uptake of N, P, K, Ca, Mg and S for both corn and canola. However, N H4- N, K and Mg soil supply rates were reduced when lime was added, due to competition between Ca from the added lime and other nutrients.

wx 126조합으로부터 분리된 농녹색업과 담녹색엽 near-isogenic계통의 광합성 정도와 생장특성 및 수량관련형질들을 비교 검토한 결과를 요약하면 다음과 같다. 1. 농녹색엽계통이 담녹색영계통보다 엽록소 a, b 및 총엽록소 함량은 현저히 높았으나 엽록소 a, b의 비율은 큰 차이가 없었다. 2. 출수기 지엽에 있어서 단위엽면적당 광합성율은 농녹색엽계통이며 높았으나 단위엽녹소당 광합성량은 담녹색엽계통이 더 높았다. 3. 이앙부터 출수기까지의 CGR은 농녹색엽계통이 더 높았으며 이는 NAR이 높은 데서 기인된 것으로 해석되었다. 4. 농녹색엽게통의 주당수수, 주당영화수 및 주당수량은 담녹색엽계통에 비해 각각 높았으나 1,000입중과 등숙율은 두 계통간에 차이가 없었다.