Agriculture Reference
In-Depth Information
1.1.3. Cereal crops management practice
Variety selection
The main criteria for selection of cereal crops and varieties for organic production are:
suitability for the certain location, yielding ability, stability and plasticity, large rooting and
nutrients uptake ability (especially of nitrogen), resistance to fungal diseases, high competitive
ability towards weeds, and stress tolerance (drought, water logging, extreme temperatures).
The lower internodes should be relatively short to prevent lodging, but the upper internodes
long to support higher ability of assimilation during the period of grain forming, even if the
leaves are damaged by fungal diseases. Mid-height and bearded varieties seem to be optimal
as these produce good grain yields with fewer productive stalks but with more grains per
spike. It is important to select varieties with resistance or tolerance to fungal diseases prevailing
at the particular location, as synthetic fungicides are prohibited in organic cereal production,
and copper fungicides are generally not used on these crops. In case of maize the special
attention must be done to the sowing appropriate FAO groups of hybrids, depending on
geographical latitudes (FAO classification valid for Corn Belt in USA, number of growing days
for each group growth out of this latitude are longer) and other production demands, and also
to the target type of grains (dent, flint, semi dent or flint, pop, sweet) due to it's potential use.
Older varieties of cereals usually have favourable features to low pretentiousness of produc‐
tion inputs, with possible respect to grain quality, but lower productivity. Such varieties can
be used for particular contracts with processors, where the price of a specific product balances
lower yields.
Preparatory soil cultivation
Soil cultivation is primarily needed for destruction of crop debris and stubble of a previous
crop, weed control and mineralization of nutrients, but also to enhance porosity for aeration
and water and root penetration. Several cultivation operations can be distinguished, each with
their own objectives, for example: ploughing to turn the soil so that crop residues, weed seeds
and plant pathogens are buried below the immediate rooting zone, tillage to loosen the soil
without turning it, harrowing to prepare a loose seedbed (4-5 cm deep), and hoeing to remove
weeds.
The timing of cultivation is extremely important, because the wrong timing can destroy the
soil structure, and nullify the benefits of proper organic matter management. This was shown
for a biodynamic farm, where soil had been ploughed in a too wet condition, leading to soil
compaction. The soil structure was not significantly better than that of a neighbouring
conventional farm in comparison to the much better soil structure of permanent grassland. For
winter cereals, the soil is obviously prepared for seeding in the fall, but for summer cereals
and maize there is a choice of fall or spring soil preparation, depending on the climate. When
springs are generally wet, for example in land climates with heavy snow fall, fall ploughing
may be the only option, even for spring crops.
