Abstract:
The long-term experiments
carried out at the Agricultural Research
Station of Podu-Iloaiei, Iaşi County,
Romania, tried to establish some
fertilization systems for getting efficient
yield increases, which maintain or increase
the content of organic carbon from soil.
These trials were set up on a 16% slope
field, with a cambic Chernozem soil, which
has a clayey-loam texture, a neuter to
weakly acid response and a mean supply in
nutrients. Analyzes performed on soil
profiles after 44 years, on land with a slope
of 16% and slope length of 310 m, shows
that the entire length of slope soil fertility
were very different, being influenced by
processes of erosion and silting. Soil
organic carbon, the depth of 0-20 cm, was
between 45.94 t / ha, the foot slope and
27.45 t / ha in the mid-slope area with
strong erosion. From the results obtained on
erosion in different crop rotations, we have
found out that in 16% slope fields from the
Moldavian Plateau, soil losses by erosion
were diminished below the allowable limit
of 3-4 t/ha/year only in case of 4 year-crop
rotations with two reserve fields, cultivated
with legumes and perennial grasses, which
protect soil. Annual soil losses by erosion,
registered during the last 30 years, in the
Moldavian Plateau, were between 0.246 t/ha
in perennial grasses, on the second year of
vegetation, and 8.976 t/ha in sunflower. The
fertilization of wheat and maize crops at the
rate of N80P80 + 60 t/ha manure has
determined the increase with 5.5 t/ha (7.8%)
in the content of organic carbon from soil,
as compared to the rate of N140P100.
