emphasis in agricultural production has shifted from mere quantity to quality products. practical experience and scientific investigations have shown that, of the various culture measures, balanced fertilization above all exerts a considerable influence on the quality of agricultural products. simply adding more of what the crop has already absorbed to capacity is unproductive, expensive, wasteful and damaging to the environment. therefore, balanced crop nutrition increases crop quality, safeguards natural resources and brings benefit to the farmer. otherwise rapid population growth and severe urbanization will exhaust our natural resources.