Untitled - Agriculture and Agri-Food Canada

order that fragments will not flow back together into masses when they are wet
again.
DRAINAGE
Poorly drained soils are relatively unproductive. It is possible for grass crops
to survive and frequently flourish under extremely wet conditions but most cultivated
plants cannot remain long in soils that are saturated with water.
The drainage of the soil depends upon topography and permeability. Inadequate
drainage most often occurs in areas of level or depressional topography
but may also occur on undulating areas where slowly permeable materials
exist. Often there is little evidence in the surface soil alone of poor drainage beneath.
The conditions of soil drainage are indicated fairly reliably by color of the
subsoil. Bright, uniform brown or yellow subsoil indicates fairly good drainage, but
gray and mottled subsoil indicates poor drainage.
A summary of the drainage condition of the soils in Dufferin County is given
in the following Table 5.
TABLE 5
DRAINAGE OF DUFFERIN COUNTY SOILS
Drainage Class Acreage Per Cent of Total Area
Good 24 1,700 68.0
Imperfect 4 1,200 11.6
Poor 38,600 10.9
Very Poor 33,600 9.5
Thirty-two per cent of the land is inadequately drained. The method of drainage
improvement must be determined for each individual field. Where open ditches
and high crowns may be satisfactory for one field, tile drainage may be essential for
another. In all cases, the cost of installation and maintenance of a drainage system
in relation to the price of the crop produced should be considered.
NUTRIENTS
One of the most important conditions required for good plant growth is that
there be a balance of plant nutrients in the soil. All plants take at least 12 essential
elements from the soil. The elements most commonly deficient are nitrogent, phosphorus
and potassium. These are the elements contained in mixed fertilizers. Calcium
and mapesium are included in liming materials and small amounts are usually
present in mixed fertilizers. The other elements used in lesser amounts and usually
adequate in most soils are sulphur, iron, boron, manganese, copper, zinc, and
molybdenum.
The inorganic or mineral fraction makes up the bulk of most soils. It is derived
from rocks of various kinds and their degradation products. The nutrient supplying
power of the larger particles - that is the sand and silt - are quite different from
those of the fine particles or clay fraction. Since the nutrient elements are held in
the soil mainly by the finer particles, clay textured soils are commonly considered to
have a higher nutrient supply than coarser textured soils.
In order to estimate the amounts of fertilizer that it is necessary to apply to
achieve a balance of plant nutrients in the soil, several things need to be determined:
the nutrients already in the soil, plus those normally added in manure;
the general requirements of the plants to be grown; and the amounts of the nutrients
contained in the various fertilizer materials available for use. A soil test provides a
sound basis for selecting the most profitable fertilizer treatment.
47