Agriculture Reference
In-Depth Information
associations, such as rice, sugar cane and cereals is much more diffi cult to
estimate (see [30,33,34] for reviews).
To feed the world population in 2050, which will probably reach 9 bil-
lion people, it will be necessary to increase agricultural production by 1.7
fold [6]. It is clear that even if this increase in production must be realized
in developing countries that need it most, other countries that use intensive
agriculture do not consider reducing their production of N fertilizers. As
such, they will continue to produce as much or more mineral fertilizers,
while at the same time protecting the environment will be essential to pre-
serve the equilibrium of most earth ecosystems. The detrimental impact
of the overuse of N fertilizers on the environment can be minimized if it
is accompanied by sustainable agricultural practices, such as fertilizer use
rationalization, crop rotation, establishment of ground cover and burial of
crop residues. Rational fertilization means that the application of fertil-
izers both organic and inorganic is performed under the proper conditions
required to prevent runoff at the appropriate growth stages of the plant
and in the correct doses [6]. For example, fractionating N fertilization is
currently being performed to grow wheat and other crops such as rice and
oilseed rape. Such fertilization strategies have in 15-20 years decreased
by 15-20%, the amount of N fertilizer applied to crops in the fi eld [35].
Alternatively, cropping systems using carefully designed species mixtures
may be a way to lower N fertilization input, while maintaining economic
profi tability [36].
Other strategies to improve NUE are to use genetic modifi cation or to
breed for new varieties that take up more organic or inorganic N from the
soil N and utilize the absorbed N more effi ciently [6,37].
Additionally, breeding for more effi cient symbioses with
Rhizobia
and
arbuscular micorrhizal (AM) fungi can be an interesting alternative for
increasing plant productivity using the same amount of synthetic N fertil-
izer [38,39]. Conservation tillage using no till and continuous cover crop-
ping cultures are also known to increase signifi cantly the potentiality and
diversity of plant colonization by AM fungi in comparison to conventional
tillage [40-43]. Thus, these new alternative farming techniques could also
be an attractive way to increase NUE for a number of crops through the
benefi cial action of AM.
