Agriculture Reference
In-Depth Information
last 17 years (1994-2011). Similar trends have been observed for sugar beet (
Beta
vulgaris
) and corn for grain (
Zea mays
).
The introduction of new, more intensive varieties of winter wheat have increased
yields with crop rotation by 12.3%-12.6% relative to older, less productive varieties,
in both fertilized and unfertilized plots. It means that new varieties of winter wheat
have higher requirements of soil fertility but not of higher rates of mineral fertilizers.
Mineral fertilizers have decreased the positive impact of crop rotation relative
to permanent cropping for winter wheat, sugar beet, and corn for grain by 60.7%,
127.7%, and 136.6%, respectively. Nonetheless, the impact of crop rotation on yield
remains to be substantial. Excessive use of mineral fertilizers and pesticides cannot
compensate for the lack of crop rotation.
Use of mineral and organo-mineral fertilizers and irrigation increases the yields
of winter wheat and sugar beet by 19.6%-24.8% and 38.7%-43.9%, respectively.
However, these inputs are reducing the stocks of SOM both in the 0-20 cm and
especially in the 0-100 cm soil depth.
Thus, uncompensated losses of SOM in crop rotation on plots fertilized with min-
eral and organo-mineral fertilizers are estimated at 0.26 and 0.09-0.13 Mg/ha/year
in the 0-20 cm soil layer, but 0.45-0.58 Mg/ha/year with irrigation on both fertilized
and unfertilized plots.
There is a strong need for a paradigm shift from traditional toward sustainable
intensification on the basis of more intensive recycling of nutrients and energy
through use of site-specific renewable sources of energy. It is only through inte-
gration of crop rotations with perennial legumes and grasses, in conjunction with
minimum tillage and organic fertilizers (farmyard manure [FYM]), that crop pro-
ductivity and soil fertility can be enhanced and sustained.
Indiscriminate agricultural intensification, primarily focused on maximum yields
and profitability without taking into account adverse impacts on soil quality, envi-
ronment, and people's health (Boincean 2013a; Cassman 1999; Gliessman 2000;
International Assessment of Agricultural Science and Technology for Development
2009), is not sustainable. These negative consequences are externalized; however,
the consequences to soil and biodiversity can be irreversible (Weil and Magdoff
2000). The weakness of the technological reductionist approach, still dominating
agriculture in Moldova, is that the main factor of intensification (e.g., lack of crop
rotations or long periods of continuous monoculture; mechanization; intensive till-
age; mineral fertilizers) have been applied separately and not integrated within the
farming system. The new paradigm for agricultural intensification is based on the
premise of decreasing the dependence on nonrenewable sources of energy with
simultaneous reduction in the risks of pollution and degradation of the environment
(Gliessman 2000; Kassam 2011).
The Republic of Moldova is a unique country. Almost 80% of the territory is cov-
ered by Chernozems. A typical Chernozem from Balti steppe (the northern part of the
Republic of Moldova) was the foundation of soil science in the 19th century. The father
of soil science, the Russian scientist V.V. Docuceaev, described “Russian Chernozem”
in his book published in 1877. A typical Chernozem is deep, fertile, and rich in SOM
on humus and has a good structure. Soil monoliths from Balti have been displayed by
V.V. Docuceaev in Chicago and Paris as the best soil in the world. Chernozems are
