Agriculture Reference
In-Depth Information
5.
Higher infestation rates by leaf diseases and lower nitrogen supply to the crop under the
organic system caused a decrease of total grain protein content compared to that under
conventional system. Spelt Schwabenkorn produced grains with the highest protein
content.
3.2. Estimation of spring wheat varieties suitability for cultivation in organic farming
In organic farms spring wheat is much more popular than winter wheat. The reason for that
is that weed infestation in spring wheat is easier to control than in winter wheat, also fungal
diseases in spring wheat are less common. Moreover, it is sown after late-harvested proceeding
crops (vegetables, potatoes, fodder crops and intercrops). Spring wheat is also a valuable
protective crop for undersown papilionaceous plants and grasses [29].
In organic system the yield of spring wheat, mean for 9 tested varieties, ranged from 4.7 t
ha
-1
in 2008, when the weather was favourable for plant growth, to 2.8 and 3.1 t ha
-1
in other
years (Table 13). The higher yield of spring wheat in 2008 than in the other two years of the
study could be caused by higher rainfall in autumn and winter. The sum of rainfall for 6 months
of 2007/2008 (X 2007 - III 2008) reached 146 mm, whereas in the subsequent years it reached
approximately 220 mm (Table 2). This could cause leaking of mineral nitrogen into the deeper
layers of soil resulting in an impaired nitrogen supply to plants. The effects of deficiency
became especially manifest in the springtime period of rainfall shortage, when intensity of
biological processes slowed down. Such weather conditions prevailed in 2009 and 2010.
Cvs. Nawra and Bryza had the lowest yields while Tybalt, Żura, Zadra and Vinjett were the
highest yielders (Table 13). Among those varieties Żura showed the most stable yields (3.31 -
4.86 t ha
-1
), whereas Tybalt's yields were the most differentiated (6.16 - 2.43 t ha
-1
). An extremely
high plant density as well as grains weight was the main reason of high wheat yields in 2008.
Likewise the weed infestation in this year was very low (Table 15).
During the 3-year period of research, yields of spring wheat cultivated in organic farm‐
ing system were on average lower by 1.86 t ha
-1
(34%) than those in conventional farm‐
ing system (Table 13-14). The difference in yields from organic vs conventional system
across the years ranged from 30% in 2008 (high yields) to 36% in 2009 (very low yields).
Yield comparison between organic and conventional system showed that Parabola's yield
was the most influenced by the farming system (38%) while the yields of the other varieties
differed from 32 to 33%.
A lower yields in the organic farming system was caused by lower ear density and inferior
grain weight (Table 13-14). Ear density was lower on average by 16% (from 14-15% in cvs.
Bombona and Vinjett to 20% in cv. Tybalt). Thousand grain weight of wheat cultivated in
organic farming was also lower by 16% than that in conventional farming system. Thousand
grain weight of Tybalt was reduced only by 9% while that of Parabola showed decrease by
22% (when in organic vs. conventional farming system).
