Abstract:
The investigations
conducted in stationary experiments, at the
Podu-Iloaiei Agricultural Research Station,
which were set up in 1967, under nonirrigated,
have followed the influence of
mineral fertilization on wheat and sunflower
yield and on the evolution of soil physical,
chemical and biological characteristics. In
bean-wheat-sunflower-wheat-maize crop
rotation, applying mineral fertilizers during
2005-2008 has resulted in getting mean
yield increases, which varied, according to
rates, between 41 and 94% (767-178 kg/ha)
in sunflower (N40P40-N120P80) and between
89 and 146% (1658-2718 kg/ha) in wheat
(N80P80-N160P80). The mean yield increases,
obtained for each kg of a.i. of applied
fertilizer, were comprised between 8.4 and
8.9 kg in sunflower (N80P80-N120P80) and
between 11.3 and 16.2 kg in wheat (N60P40-
N160P80). On the Cambic Chernozem from
the Moldavian Plain, a good supply in
mobile phosphorus in bean-wheatsunflower-
wheat-maize crop rotation (47
mg/kg) was done at the annual application
of a rate of N80P40, while a very good supply
(93 mg/kg) was achieved at the rate of
N160P100. After 41 years of experiences, in
bean-wheat-sunflower-wheat-maize crop
rotation, the content of organic carbon from
soil has decreased by 22.5% (4.5 g/kg soil)
at the unfertilized control, by 17.0% (3.4
g/kg soil) at the rate of N80P80 and by 13.5%
(2.7 g/kg soil) at the rate of N120P80. After 41
years of experiences, in bean-wheatsunflower-
wheat-maize crop rotation, with
high fertilizer rates (N160P80), the content of
organic carbon from soil had close values to
the initial ones, with a slight diminution of
approximate 0.31 g / kg soil/ year.
