Agriculture Reference
In-Depth Information
weight gain, they are likely to place greater emphasis on pasture manage-
ment than non-organic producers.
Managed grazing is not exclusive to organic livestock producers; how-
ever, due to the pasture rule organic dairy producers are far more likely to
use intensive grazing management practices than are non-organic dairy
operations. Rotational grazing and strip grazing are ruminant manage-
ment strategies common to both organic dairy and beef farms, in regions
and seasons where environmental and forage conditions allow. Rotational
stocking is a method that uses recurring periods of grazing and rest among
three or more pastures [15]. Rotational stocking can ensure intake of high
quality forage for livestock throughout the grazing season, distribute for-
age growth optimally over time, and lengthen the grazing season [16].
Strip stocking is a variation of rotational stocking that may employ annual
crops such as cereal grains or summer annuals (e.g., triticale, Austrian
winter pea, sorghum-sudangrass) that are cultivated for grazing. Animals
progress across a fi eld, allotted a specifi c amount of feed for a short time,
controlling feed intake and optimizing feeding effi ciency [15]. Rotational
and strip grazing are two of the most common grazing management prac-
tices utilized in grazing ruminant production systems; however, there are
many other specifi c management practices in use across various regions.
4.2.1 SOIL FERTILITY IN ORGANIC AGRICULTURAL SYSTEMS
In a meta-review of soil and environmental quality studies conducted in
New Zealand, Switzerland, and the Great Plains of the US, Condron et al.
[17] determined that soil organic matter and soil biological activity were
consistently higher in organic systems compared to non-organic systems.
Soil structure, cation exchange capacity, respiration and the soil content of
mineralizable nitrogen relative to organic carbon were higher in organi-
cally farmed New Zealand soils, as was the number of earthworms [18].
However, soil pH and the content of phosphorus and sulfur were lower.
This is consistent with other studies cited by Condron et al. [17], such as
Liebig and Doran [19] and Nguyen et al. [20], who demonstrated that the
imbalance between outputs and inputs, which were minimal for phospho-
rus and sulfur in the organic systems evaluated, lead to deficiencies over
 
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