The evaluation of data from arable land in the southern part of upper Rhine valley that
has been cultivated in organic agriculture without livestock since 1972 showed
decreasing soil-contents of plant available P and K despite of positive fertilizer
balances as well as decreasing yields of cereals on sites of lower quality. Only on a
profound soil with a high level of organic substance this trend was not as marked; with
autumn rye and soybeans there the yield trend was even positive (see figure 1)
