The study of soil and crop responses to N fertilization under
different soil tillage systems is useful to understand the interaction
between these two factors, and to define best practices for
improved N fertilization. Conservation tillage systems may
improve water capture and retention, thus increasing crop growth
and N uptake. This may reduce the availability of soil mineral N and
may require increased N fertilization (Malhi et al., 2001; McConkey
et al., 2002). In our Mediterranean dryland systems, a previous
study in the area found that the interaction between these two
practices in the short-term (1–3 years) was not significant and no
additional fertilizer was needed when MT and NT were adopted.
However long-term adoption (>10 years) may lead to a different
response.
We hypothesized that long-term adoption of conservation
tillage systems and reduced N fertilization would be a sustainable
strategy in the region 10 years after their adoption, and that WUE
and response to N fertilization would be increased under
conservation tillage systems due to improved soil water conservation.
Consequently, the objective of this study was to evaluate
long-term effects of tillage and N fertilization on crop response and
WUE in a rainfed Mediterranean agroecosystem.