Tackling the future challenges of Organic Animal Husbandry - vTI

RAHMANN G & GODINHO D (Ed.) (2012): Tackling the Future Challenges of Organic Animal Husbandry.
Proceedings of the 2 nd OAHC, Hamburg/Trenthorst, Germany, Sep 12-14, 2012
Table 2. Mean organic carbon (SOC) and total nitrogen (Ntot) contents in soil of the experimental
plots during the sampling period. Standard deviation (SD) is also reported,
when available. For date code meaning see table 1.
Date codes 1 2 4 5 6 7 8 9 10 11 12 Mean/SD
Plot N SOC (g C kg-1 dry soil)
1-Meadow 15.6 16.2 15.6 17.5 18.5 14.2 14.2 13.9 10.6 15.1/2.30
2–Barley +me. 14.0 12.3 16.3 14.8 17.3 14.9/1.98
3-Sorghum 11.8 10.4 9.8 10.5 9.8 9.2 7.8 9.9/1.24
4-Vegetables 12.2 12.4 12.5 10.3 11.9/1.03
5-Old lucerne 18.3 17.5 17.9/0.58
Mean 13.8 10.4 12.6 13.7 13.6 14.7 17.5 14.2 14.2 10.8 10.6
SD 1.9 2.6 2.7 3.3 4.6 4.3
N tot (g kg-1 dry soil)
1-Meadow 1.50 1.63 1.58 1.76 1.74 1.55 1.56 1.55 1.25 1.6/0.15
2-Barley +me. 1.39 1.37 1.54 1.43 1.57 1.5/0.09
3-Sorghum 1.27 1.22 1.16 1.22 1.09 1.10 1.22 1.2/0.07
4-Vegetables 1.19 1.28 1.22 1.06 1.2/0.09
5-Old lucerne 1.90 2.12 2.0//0.15
Mean 1.38 1.22 1.34 1.41 1.38 1.47 2.12 1.55 1.56 1.38 1.25
SD 0.12 0.21 0.18 0.29 0.38 0.24
Table 3. Mean organic C content in soil (SOC) of the meadow and sorghum plots during
the sampling period, in the presence (yes) or absence (no) of pig grazing.
Date codes 1 2 4 5 6 7 9 10 11 12 Mean SD
Plot SOC (g C kg-1 dry soil)
1-Meadow no 16.2 15.6 17.5 18.5 14.2 15.3 10.6 15.4 2.56
yes 15.6 13.7 13.9 14.4 1.04
3-Sorghum no 12.2 9.2 7.8 9.7 2.26
yes 11.4 10.4 9.8 10.5 9.8 10.4 0.68
Discussion
The inclusion of leguminous crops and grasses into the cropping system of this on-farm experiment
has permitted an overall enrichment of the soil organic matter reserve. In fact grasslands and legume-cropped
soils have usually higher C and N content than soils under arable crops (Conijn and
Taube 2003). SOC and Ntot content may have been influenced by the length of time the pigs were
allowed to graze in the plots, before sampling. In outdoor husbandry, pig manure supplies to soil
large amounts of organic matter, especially N. In fact, higher amounts of C and N were observed in
the autumn 2010 under barley (Table 2), in the presence of pig pasture (Table 1). Piñeiro et al
(2010) studied effect of grazing on SOC stocks in grasslands, and found that SOC increased, decreased,
or remained unchanged under contrasting grazing conditions across temperature and precipitation
gradients, which suggests that grazing influences the factors that control SOC accumulation
in a complex way. These preliminary results support the hypothesis that soil fertility is not negatively
affected by outdoor pig grazing, with the cropping system adopted by the organic farm hosting
this experiment. However, greater data availability is required, in order to establish the significance
of the effects of these treatments. Further sampling will be carried out to check fertility differences
in the long-term.
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