18.1: Introduction
- Page ID
- 25223
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)The purchase of plant food is an important matter, but the use of a [fertilizer] is not a cure-all, nor will it prove an adequate substitute for proper soil handling.
—J.L. Hills, C.H. Jones and C. Cutler, 1908
Most of the essential nutrients for plants, animals and humans are derived from weathered minerals in the soil. But plants also absorb carbon, oxygen and hydrogen from the air and water. Nitrogen is derived from the atmosphere by legumes, but other plants absorb it from the soil. Of the 17 elements needed by all plants (Table 18.1), only three—nitrogen (N), phosphorus (P) and potassium (K)—are commonly deficient in soils. Deficiencies of sulfur (S) are less prevalent but not uncommon. Other nutrients, such as magnesium (Mg), zinc (Zn), boron (B) and manganese (Mn), can be lacking in certain regions. Deficiencies of sulfur, magnesium and some micronutrients may be more common in regions with highly weathered minerals, such as the southeastern United States and many parts of the tropics, or those with high rainfall, such as portions of the Pacific Northwest. Sulfur deficiency is especially common on the sandy soils on the coastal plains of the Southeast and has become more common in areas with low organic matter soils with the decrease in sulfur air pollution from coal burning power plants. Keep an eye out for deficiencies of iron, zinc, copper and manganese on higher-pH calcareous soil, especially in drier regions. Low phosphorus availability is also common in calcareous soils. In contrast, in locations with relatively young soil that contains minerals that haven’t been extensively weathered by nature, such as glaciated areas with moderate to low rainfall like the Dakotas, K deficiencies are less common.
Environmental concerns have resulted in more emphasis on better management of N and P over the past few decades. While these nutrients are critical to soil fertility management, their mismanagement also causes widespread environmental problems. In many regions of the United States and other countries, surface and groundwater pollution has been caused by poor soil management, overuse of fertilizers, mishandling of manures, sewage sludges (biosolids) and composts, and high animal numbers on limited land areas. Because N and P are used in large quantities and their overuse has potential environmental implications, we’ll discuss them together in Chapter 19. Other nutrients, cation exchange, soil acidity (low pH) and liming, and arid and semiarid region problems with sodium, alkalinity (high pH), and excess salts are covered in Chapter 20.