traditional tillage led to a better early growth and N
uptake of sunflower (the non-fertilized crop of the
wheat±sunflower rotation established). Thirty-®ve
days after sowing, in the third sun¯ower crop the
±N concentration and total NO3
NO3
roots were signi®cantly greater in traditional tillage
than in reduced tillage (more than 50% and 100%,
respectively). However, this early enhancing effect of
traditional tillage on the crop, which did not seem to
be due to just one factor, did not affect the yield.
Reduced tillage may be a more suitable strategy for
rainfed agriculture in areas with frequent periods of
scarce rainfall (southern Spain). However, it is still
necessary to verify whether the reduced seedling
growth and nutrition observed in conservation tillage
could affect yield under these conditions.
±N uptake by