Agriculture Reference
In-Depth Information
mentioned intercropped crops is separate, depending on suitable periods for seed emergence
and growth.
Weed control
High weed pressure is one of the main problems of organic cereal and maize production. Weed
seedbank size was larger under the organic system of maize production than conventional
system; and for example differences among maize management systems depends mainly upon
weed control efficacy rather than upon tillage effects [25].
The most problematic weed species in cereal production are couch-grass and creeping thistle.
Application of herbicides is impossible and thus different ways of weed regulation must be
used. The aim of such regulation is not to completely destroy weeds, but to keep their coverage
under the damage threshold. The emphasis is put on prevention of introduction and spread
of regenerative organs of weeds (seeds, stolons, etc.), and on indirect control like promoting
optimal growing conditions for the crops that enhance their competitive strength against
weeds. Among the preventive measures belong selection of a location that is suited to a crop's
demands, a varied and well-balanced crop rotation including fodder crops, proper soil
cultivation, use of barnyard manure, harmonic fertilization, proper choice of species and
varieties, proper sowing, prevention of weed introductions, optimum time and way of
harvesting as well as post-harvest operations. Finally, care must be taken that noxious weeds
don't spread from field margins and surrounding natural vegetation.
If the preventive measures are not effective enough, direct weed control treatments must be
applied: mechanical, physical and biological methods. Harrowing using different harrow
types (weeders, net harrow, and spike harrow) can be used for deep-rooted crops (maize,
sorghum) before the plants sprout but after germination of weeds. A second harrowing can
be applied shortly after the stage of 2-3 true leaves (Maier code 21-23). Line weeding (with
brush cultivators or deer-tongue cultivators) can be applied in wide-row cereal crops on heavy
soils (row spacing over 15 cm) or to combat overgrown weeds when cultivation was delayed,
for example due to wet conditions. Thermal weed control (using propane-butane burners) can
be used to eliminate all weeds before sprouting of the crop, or to put down dicotyledonous
weeds in wide-row crops like maize. Biological weed control by plant pathogens or insect pests
is still hardly used in organic agriculture.
Harvesting, post-harvest treatments and storage
Organic grains need to be harvested and stored separately from conventional grains. Perfect
threshing and pre-cleaning of the grain is a basic expectation for proper harvesting of cereals.
Grain needs to be dried to 13.5 - 14% moisture. Drying of grain is performed gradually,
removing only about 2% water at a time if it originally had moisture content over 20%.
Organically grown grain should be dried like seed material, preventing too high temperatures,
because sprouted grains can be used for human consumption.
Grains of cereals and maize can be infected by fungi that produce mycotoxins (primarily
Fusarium
species), which can seriously affect human and animal health. Therefore mouldy
grain should not be used, not even for feeding purposes. To prevent mould infection, grain
