High distribution uniformity and low application rate, at
frequent irrigation cycles, provide maximum control and
monitoring of the wetted and aerated soil profile, which is
essential for the shallow root system of the lettuce.
Low application rate (3-5 mm/h): allows optimal absorption
of water into the soil with no run-off, even on slopes.
Low droplet impact: preserves soil structure and prevents
crust formation to allow perfect germination and development.
Moisture deficiencies occurring early in the crop cycle
may delay the maturity season and reduce yields.
Shortages later in the season often lower quality, as
well as yields. However, irrigation surplus, especially
late in the season, can reduce both the quality and the
post-harvest life of the crop.
Uneven or surplus irrigation, above the amount
required to replace evapotranspiration, causes nitrate
leaching below the root system and the ability of
the crop to recover from the nitrogen deficiency
Enormous increases in agricultural productivity can properly be associated with
the use of chemicals. This statement applies equally to crop production through
the use offertilizers, herbicides, and pesticides, as to livestock production and the
associated use of drugs, steroids, and other growth accelerators. There is,
however, a dark side to this picture and it is important to balance the benefits
which flow from the use of agricultural chemicals against their environmental
impacts, which sometimes are seriously disadvantageous.
The presence of substances in groundwater may be affected by naturally occurring processes
as well as by actions directly associated with human activities. Naturally occurring processes
such as decomposition of organic material in soils or leaching of mineral deposits can result in
increased concentrations of several substances. Those of health concern include arsenic,
fluoride, selenium, uranium, nitrate, metals, and radionuclides such as radon. Problems of
aesthetic quality and acceptance may be caused by iron, manganese, sulphate, chloride and
organic matter. ...