Download Managing the Soil

Section 4.2
 The
nutrients plants require are found in
the soil
• Potassium
• Nitrogen
• Phosphorous
 As
plants grow they take in these
nutrients
 As plants are harvested these nutrients
are removed from the ecosystem
 Natural:
• From plant/animal waste
• Compost
• Manure
 Synthetic:
• Manufactured by
chemical processes
• Farmers started using
them in 1960s and saw
increased crop yields
 Synthetic
fertilizers are very
concentrated so they change the
community of soil organisms
 Can leach out of the soil and enter the
water system.
 Fertilizer
in water
systems causes an
increase algae, which
then dies and
decomposes
 The bacteria involved in
decomposition use up a
lot of dissolved oxygen
which kills fish and other
organisms
 Farmers
often use
irrigation to add water
to crops
 If there is too much
water then drainage
must be added
 If
soil is compacted it has decreased
oxygen levels and water will have
difficulty passing through.
 Pg. 128
#3, 4, 6, 8
 Read Black Gold – page 129