The yield per acre of a certain crop depends on

The yield per acre of a certain crop depends on the amount of fertilizer used and the amount of rainfall during the growing season. The table in Figure 4.2(a) shows crop yields in bushels per acre under various conditions of fertilizer use and rainfall.

Figure 4.2

(a) Crop Yield (Bushels per Acre)                          (b)

    Fertilizer,               Inches of Rainfall

    Tons per

    Acre 5               10             15             20

    0    15               25             40             45

    1    35               45             60             65

    2    50               60             75             80

    3    60               70             85             90

    4    65               75             90             95

   a.   On the basis of the data given in the table, describe your theory of the relationship among crop yield, fertilizer use, and rainfall.

   b.   In Figure 4.2(b), draw a curve showing the relationship between fertilizer use and crop yield when there is <5 inches of rainfall. Label the curve “5 in.”

   c.   Now draw additional curves for 10, 15, and 20 inches of rainfall, labeling them appropriately.

   d.   In talking about your graph, how would you describe the effect on crop yield of an increase in rainfall? How would you describe the effect of fertilizer use, given 10 inches of rainfall?