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
Organic C and total N dynamics in soil in an organic pig farm
DAVIDE BOCHICCHIO*, MICHELE COMELLINI, ROSA MARCHETTI,
GILDA PONZONI AND GIACINTO DELLA CASA
Agricultural Research Council (CRA), Swine husbandry research unit (SUI). San Cesario sul Panaro
(MO), Italy. *Corresponding author: davide.bochicchio@entecra.it
Key words: organic pig, soil, fertility, pasture, C, N.
Abstract
One of the challenges of including pigs in a sustainable farming rotation is to preserve soil fertility.
In fact, without a correct rotation of the paddocks, grazing pigs cause, with their normal feeding
behaviour, excavations, destruction of the sward and soil structure damage, with negative influence
on soil fertility. The aim of this study is to investigate soil fertility dynamics throughout one year in
an organic outdoor pig farm. An on-farm study was carried out in the south of Tuscany, in Italy.
The experimental design included 6 plots hosting different crop sequences. Grazing pigs were periodically
moved among the plots. Soil organic C (SOC) and total N (Ntot) were selected as fertility
indicators, and their contents were measured in the top 0-20-cm soil layer, in 12 dates, in the period
between June 2010 and September 2011. Mean SOC and Ntot contents were remarkably different
depending on the plot. However, for a given plot, they increased or did not vary during the
sampling period, with exception of the sorghum plot, where a slight decrease in C content was observed.
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.
Introduction
According to the European organic regulation (EC N. 834/2007) organic stock farming is a landrelated
activity and animals should have, whenever possible, access to open air or grazing areas. At
the same time, organic production should contribute to maintaining and enhancing soil fertility as
well as preventing soil erosion. One of the challenges of including pigs in a sustainable farming
rotation is to preserve soil fertility. Without a correct rotation of the paddocks grazing pigs cause,
with their normal feeding behaviour, excavations, destruction of the sward and soil structure damage
(Quintern and Sundrum 2006). Consequently these actions may negatively affect soil fertility.
The aim of this study is to investigate soil fertility dynamics throughout one year in an organic pig
farm. An on-farm experiment was used for this purpose (S.S.C. 1998).
Material and methodology
An on-farm experiment was carried out in the south of Tuscany, in an organic outdoor pig farm, at
Paganico (GR) 20 m a.s.l. The experimental design included 5 side by side strip plots hosting different
crops or crop sequences (Table 1): polyfita meadow (Vicia sativa L., Trifolium alexandrinum
L., Avena sativa L.); barley (Hordeum vulgare L.) followed by meadow; forage sorghum (Sorghum
bicolor L.); vegetable crops (Solanum lycopersicum L. and Solanum tuberosus L.); old lucerne
stand (Medicago sativa L.). The thermal regime is mediterranean. Annual temperatures vary between
-3 and 35°C. Mean annual precipitation range is 711 mm. A herd of 50 pigs (including lactating
sows, suckling piglets, weaned, growing and finishing pigs) were periodically moved among the
plots, during the experimental period, using electric fences. As a rule, pigs were let to graze in plots
free from growing crops, with exceptions for plots with crop re-growth (Table 1). Soils were a silty
loam (meadow and barley plots), a sandy loam (sorghum and vegetable plots) and a loam (old lucerne
stand). Soil sampling was carried out in 12 dates, in the period between June 2010 and Sep-
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