Agriculture Reference
In-Depth Information
Composting of garden waste in windrows. Photograph by the author. See color insert.
Figure 5.10
dustrial sewage sludge, provided bulking-up material such as wood chips or saw-
dust is added. The ideal C:N ratio for successful composting of such mixtures is
about 20. The composting is done in heaps or windrows (fig. 5.10), where the
temperature should reach at least 55°C for 3 days to kill weed seeds and patho-
gens. Well-made compost should be odorless. Organic manures and compost are
best spread along the rows in winter when the vines are dormant. Compost can
serve as a mulch that reduces in-row soil temperatures and evaporation rates—an
important function in regions with hot summers.
“Compost tea” is an organic-rich liquid that drains from a compost heap. Al-
though it is sometimes applied as a foliar spray in organic vineyards, its benefits
are unproven.
Organic Fertilizers and Soil Amendments
. By-products from the animal pro-
cessing industry may be used under regulated conditions in organic viticulture.
The example of blood and bone is given in table 5.10. RPRs are an acceptable
source of P, but the conditions controlling their effectiveness should be observed
(section 5.4.2.1). For example, mixing RPR with lime is neither necessary nor de-
sirable because an increase in pH slows the rate of dissolution of the RPR, and
dissolution of the RPR itself has a liming effect. Further, because RPR is insolu-
ble in water, when used as a foliar spray, it is ineffective in supplying P to the
vines.
Cu supplied in Bordeaux Mixture for the control of downy mildew is ac-
ceptable in organic viticulture. Elemental S, which is used as a wettable powder
in sprays to control powdery mildew, is an acceptable source of S. Wood ash is a
suitable source of K (as is K
2
SO
4
, but not KCl). Ground rock dust can supply
Ca, Mg, and some of the micronutrients (table 5.10), but should be incorporated
into the soil. Proprietary brands of seaweed extract may also be used. Although
