Chapter 1.3, Problem 22E

Reminder Round all answers to two decimal places unless otherwise indicated.

Protein Content of Wheat Grain Protein content of wheat grain is affected by soil moisture and the amount of available nitrogen (among other things). Figure $1.45$ shows" the percent of protein content of wheat grain versus pounds of nitrogen per acre applied in three separate situations. In each case, soil moisture refers to moisture at the soil depth of 2 inches to $12$ inches.

■ Situation 1: Irrigation was used when soil moisture dropped to $49\%$.

■ Situation 2: Irrigation was used when soil moisture dropped to $34\%$.

■ Situation 3: Irrigation was used when soil moisture dropped to $1\%$.

a. If irrigation begins when soil moisture reaches $49\%$, what application of nitrogen will result in the lowest percentage of protein in wheat grain?

b. If irrigation begins when soil moisture reaches $34\%$, what application of nitrogen will result in the same protein content of wheat grain as beginning irrigation when soil moisture reaches $1\%$?

c. If you irrigate when soil moisture reaches $34\%$, how much nitrogen should you apply to achieve a $13\%$ protein content in wheat grain?

d. Does Figure $1.45$ indicate that, for nitrogen levels at $45$ pounds per acre or higher, increased protein content in wheat grain is associated with higher or lower soil moisture?

FIGURE $1.45$ Protein content versus availability of nitrogen