Abstract:
Since 1965, at the
Agricultural Research Station of Podu-
Iloaiei, Iaşi County, Romania (47°12´ N
latitude, 27°16´ E longitude), investigations
were conducted on the influence of different
fertilizer systems on production and soil
fertility. For wheat and maize crops, placed
in a three-year rotation (pea - wheat -
maize), three fertilization systems were
experienced: (1) mineral fertilization with
nitrogen and phosphorus rates until N140P100;
(2) manure fertilization (20, 40, and 60
t/ha), with and without mineral fertilization
and (3) mineral fertilizers + hashed residue
applied in autumn under the base ploughing.
The paper presented the results of
investigations concerning the influence of
long-term fertilization (46 years) on some
chemical characteristics of Cambic
Chernozem from the Moldavian Plateau.
The climatic conditions in the Moldavian
Plain were characterized by annual mean
temperature of 9.6oC and a mean rainfall
amount, on 50 years, of 553.5 mm, of which
141.5 mm during September-December and
412.0 mm during January-August. After 46
years of experiences, in pea-wheat-maize
crop rotation, the content of organic carbon
from soil has decreased by 22.3% (4.2 g/kg
soil) at the unfertilized control and by
14.4% (2.7 g/kg soil) at the rate of N120P80.
In wheat and maize, nitrogen uptake by
weeds was between 7 and 9.5 kg/ha from all
the plots. Applying moderate rates of
mineral fertilizers (N80P60), together with 6
t/ha wheat straw or 40 t/ha manure, has
determined the increase in organic carbon
content from soil by 0.5 and, respectively,
2.8 g/kg.
