Abstract:
Because many of the soils have low organic matter content they are
exposed to degradation, erosion and desertification through intensive
cultivation, excessive ploughing, allied to years of unsuitable agricultural
practices. These practices reduce the quantity of vegetal remains returned to
the soil and accelerate the mineralization of whatever humus is in the soil.
The inevitable result is a progressive decrease of the organic matter content
and the negative consequences that this entails [10].Investigations were
carried out in order to determine the effects of sewage sludge application on
soil and plants. In the course, plots with an area of 100 m2 were treated with
different fertilization systems (mineral fertilization, organic fertilization, and
mineral and organic fertilization). The effect of the tillage systems on the
contents of these heavy metals, shows different results. A higher content of
Cd in crops occurred in the no-tillage system and a higher content in Zn was
found in crops of the minimal tillage system, excepting the content in Zn in
rape seeds, where this higher Zn content occurs in crops of the conventional
tillage system. A lesser content of Cd and Zn occurred generally in crops of
the conventional tillage system.
