Agriculture Reference
In-Depth Information
nitrogen-rich materials have a distinct advantage over their more distant
counterparts.
Newly established organic orchards and orchards transitioning from con-
ventional to organic systems are most likely to suffer nutrient deficiencies.
The problem is compounded by weed competition, which can greatly impair
the survival and growth of young trees. These facts emphasize the need for
careful and thorough preplant soil testing, applications of soil amendments,
corrections of soil pH, and weed management.
allow us to supply much of the needed nitrogen on-site using nitrogen -
fixing cover crops. While we still have much to learn in selecting and man-
aging cover crops, orchard floor management has great potential to reduce
the need for off-site nitrogen, while enhancing and maintaining soil structure
and biological activity.
Essential Elements
Plants take chemicals called “essential elements” from their environments
to create living tissues. We refer to them as essential because plants must
have them in order to complete their life cycles. Sixteen elements are gener-
ally considered necessary for normal plant growth and development. Among
them are carbon, hydrogen, and oxygen, which come from water and air and
combine to form cellulose, starches, sugars, and other carbohydrates that
make up the bulk of plant tissues. The remaining 13 essential elements (min-
eral nutrients) come from the soil and are divided into “macronutrients” and
“micronutrients.” Although both macro- and micronutrients are equally im-
portant, plants need larger amounts of macronutrients, which are normally
measured as percentages, by weight, of plant tissues. Micronutrients are
needed in tiny amounts, ranging from about 5 to 400 parts of micronutrients
and micronutrients, along with their recommended ranges for leaf tissues in
orchard crops.
