Agriculture Reference
In-Depth Information
Besides crop residues, organic cereal crops may be fertilized with animal manure, especially
on poor soils, at rates of 4-10 t ha
-1
(up to content of 180 kg N ha
-1
year
-1
). Also legumes as
preceding crops improve nitrogen nutrition on subsequent winter wheat, e. g. the Nitrogen
Nutrition Index at flowering ( NNIf) = 0.51 +/- 0.12 for a crop rotation with a rate of legumes
over 37% vs. 0.41 +/- 0.11 for a crop rotation with a rate of legumes under 25% [3]. In the case
of comparing conventional animal production, organic animal production, and organic cereal
production residual fertility effects from the preceding crop produced higher yields in organic
animal production winter and spring wheat than in conventional. Cultivation of winter wheat
in organic animal production was a more efficient use of nitrogen resources than conventional
[21]. The findings that microbial properties and N availability with 182-285% increase in
potentially mineralizable N, for thus the yields of crops differed under different organic input
(regimes cotton gin trash, animal manure and rye/vetch green manure), [22].
Organic fertilizers may also be combined as phosphorus and potassium fertilizers which are
allowed (depending on the certification agency).
An additional nutrient dressing can be applied at the generative stages (EC 20-35) by disper‐
sion of dung (5-7 t ha
-1
) or slurry (20-40 m
3
ha
-1
). Higher rates of dung or slurry can cause
expansion of ruderal weeds (docks, goosefoot, hardship, scentless may-weed, barnyard grass,
etc.). Harmonious fertilization maintains the competitive strength of crops, promoting fast
foliage growth and better soil coverage.
Additional supply of nitrogen is possible by intercropped legumes. The data showed that
nitrogen content of the wheat grain and whole plant biomass significantly increased when the
density of beans in the intercrops increased; this was reflected in a significant increase in grain
protein at harvest of organically grown wheat [23]. The clear and significant differences in
wheat yield and protein content between the organic and conventional systems suggest a
limited supply of available N in the organic fertility management system which is also
supported by the significant interaction effect of the preceding crop on protein content [24].
Seed selection and sowing
According to EU regulations, if available, certified organically grown seed is required for
certified organic crop production (EU Regulation No. 834/2007). As sufficient certified organic
seeds of cereal crops and maize are on the market, European organic growers are bound to
use these seeds. The situation is different in North America and Canada, where grower-saved
seeds are often used, or commercial, conventionally grown seeds without fungicide coating.
The selected sowing rate should ensure an optimum stand density that results in soil shading
and weed suppression. Sowing at high density at a narrow row distance is more effective to
control weeds in a cereal crop than wide row spacing combined with mechanical weed control.
Early sowing is not as effective for weed control as sowing after repeated harrowing (preparing
a false seedbed to kill germinated weeds). Finally, the sowing depth is crucial: not too deep to
avoid root and foot diseases, and not too shallow to avoid drying of the seed.
Both, cereals and maize can be intercropped by legumes; in the case of maize intercropping
with climbing bean is suggested and in case of cereals with pea and beans. Sowing of obove
