APES 2011 #4

(c) Soil quality is a critical factor in agriculture. Identify TWO physical and/or chemical properties of soils and describe the role of each property in determining soil quality.

-Soil Compaction: reduces amount of oxygen/ aeritaion needed for organisms and for respiration for plants. prevents from holding water. -Presence of organisms/organic matter/ leaf litter/humus/mulch/ crop residue • Organic matter provides nutrients to the topsoil, O Horizon (thick leaf litter prevents large amounts of water from evaporizing from topsoils).

(d) Describe TWO viable strategies for reducing the amount of land needed for agriculture

Increasing crop yield: -• Cover-cropping/intercropping/strip farming/strip cropping/alley cropping/polycultivation/ allowing for multiple crops to be grown on the same plot of land/etc. could increase crop yield by using the same plot of land during different seasons/growing noncompetitive crops together to use the space between rows/inhibiting crop diseases or pests/etc Decreasing the demand for agricultural land: • Urban/home/rooftop gardens utilize urban/residential space for growing food

(a) On the graph below, plot the data from the table above and draw a smooth curve.

X-axis/ years : 40 years apart 4 cubes in between y-axis/land area needed: start at 0 go up by 1's 4 cubes in between

(b) Assume that the maximum arable land area on Earth is 4.00 billion hectares. Using the smooth curve that you created above, determine the year in which the human population is likely to run out of arable land for agriculture

the year is 2048

(ii) Describe one method to prevent or remediate soil salinization.

• Plant vegetation/crops that remove salt from the soil (e.g., saltbush, barley, oats).

(e) One problem that can result from agriculture is soil salinization. (i) Describe how salinization occurs.

• Salinization can occur when irrigation water evaporates (or is used by plants), leaving the salts behind in the soils.