Nitrogen and Sulfur Economy of Soils PDF

The Nature and Properties of Soil Fifteenth Edition, Global Edition CHAPTER 13 Nitrogen and Sulfur...

The Nature and Properties of Soil Fifteenth Edition, Global Edition CHAPTER 13 Nitrogen and Sulfur Economy of Soils The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved 13.1 Influence of nitrogen on plant growth and development Nitrogen (N) is major part of all proteins— including the enzymes, which in turn control virtually all biological processes. – Other critical nitrogenous plant components include the nucleic acids and chlorophyll. Nitrogen is also essential for carbohydrate use in plants. The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved  Plants deficient in N tend to exhibit chlorosis (yellowish or pale green leaf colors), a stunted appearance, and thin, spindly stems. – The older leaves are the first to turn yellowish. – Low shoot-to-root ratio – Mature more quickly than healthy plants – The sugar content is usually high The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved  When too much nitrogen is available, excessive vegetative growth occurs, the cells of the plant stems become enlarged but relatively weak, and the top-heavy plants are prone to falling over (lodging) with heavy rain or wind. Low levels of sugar and vitamin level, flower production in ornamentals is reduced in favor of abundant of foliage. Growth-inhibition environmental conditions can exacerbate the accumulation of nitrate in tissues. The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved  Forms of nitrogen taken up by plants Ammonium NH4+àlower the soil pH Nitrate NO3- àhigher the soil pH Dissolved organic nitrogen (proteins, amino acids, urea) The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved  Figure 13.5 Soluble organic nitrogen (SON) is comprised of compounds that can be easily dissolved in water or mild salt solutions. It is a small portion of the total organic N. The SON is potentially subject to leaching loss and—in case of the smaller soluble molecules—to absorption by plant roots. The measured size of the SON pool depends on the particular lab method used to extract it from the soil. The portion of the SON that is actually dissolved in the soil solution at a given time is termed the dissolved organic nitrogen (DON). Thus the DON measured in soil solution or leachates in the field is part of a larger pool of SON which can be measured by lab extraction, and which in turn comprises a few percent of the total organic nitrogen in a soil. (Diagram courtesy of Ray R. Weil) 0.1-3% of TN The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved  Chemical makeup of DON Microbial and root exudates and litter leachates, hydrolyzed insoluble organic matter. The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved Figure 13.1 Symptoms of too little and too much nitrogen. (a) The nitrogen-starved bean plant (right) shows the typical chlorosis of lower leaves and markedly stunted growth compared to the normal plant on the left. (b) The oldest leaves at right near the base of this potted cucurbit vine are chlorotic because N has been transferred to the newest leaves on the left which are dark green. (c) The oldest bottom corn leaves yellowed, beginning at the tip and continuing down the midrib—a pattern typical of nitrogen deficiency in corn. (d) Asian rice heavily fertilized with nitrogen. The traditional tall cultivar in the left field has lodged (fallen over), but the modern rice cultivar at right yields well with high nitrogen inputs because of its short stature and stiff straw. (Photos courtesy of Ray R. Weil) The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved  bean plant The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved  cucurbit vine The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved  lodged (fallen over) The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved Figure 13.2 The movement of nitrogen between Earth’s atmosphere (mainly N≅N ), land masses (terrestrial ecosystems), and oceans (marine ecosystems). The arrows are labeled with the general processes they represent and the numbers in each arrow indicate the estimated global annual nitrogen flux in Tg/yr (teragrams or 1012 g per year) via each process. The three main anthropogenic processes are labeled in yellow. (Redrawn and recalculated from data in Canfield et al. (2010)) The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved Figure 13.3 The nitrogen cycle encompasses many translocations and transformations. Here it is shown emphasizing the primary cycle in aerobic soils (thick olive green arrows) in which microbes mineralize organic nitrogen from plant residue, plants take up the mineral nitrogen, and eventually return organic nitrogen to the soil as fresh plant residues. In this regard N is like any of the other plant nutrients that cycle through soils. However, because nitrogen exists in many valence states and in all three phases of matter (gas, liquid, and solid), its interactions and cycling pathways are much more complex than just this basic cycle. The boxes represent various forms of nitrogen. The arrows represent processes by which one form is transformed into another. The name of a process (e.g., Mineralization or Anammox) is given alongside the arrow. Note the processes by which nitrogen is lost from the soil and by which it is replenished (bright green arrows). The blue arrows represent anaerobic processes. Soil organisms, whose enzymes drive most of the reactions in the cycle, are represented as rounded boxes labeled “SO.” (Diagram courtesy of Ray R. Weil) The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved  Fate of NH4+ Immobilization by micro-organisms Removal by plant uptake Anammox Volatilization Nitrification Denitrification Fixation or strong sorption in the interlayers of certain 2:1 clay minerals The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved  (5) dissimilatory reduction by microbes to ammonium; and (6) loss to groundwater by leaching in drainage water. We will discuss these N transformations in subsequent sections of this chapter. Immobilization and mineralization 13.3 IMMOBILIZATION AND MINERALIZATION Most (95–99%) soil nitrogen exists in large organic molecules that protect it from loss but also leave it unavailable for uptake by plant roots. Microbial decomposition breaks these large, Mineralization is an insoluble N-containing enzymatic organic process molecules into smaller and smaller of unitsnitrogen from organic with the eventual 4 nitrogen of simple amino compounds, or amine groups (R—NH2). Then the amine groups compound production are hydrolyzed, and the nitrogen is released as ammonium ions (NH4+ ), which can be oxidized In most of the to the nitrate form. soils of that The enzymes natural bring aboutvegetation, or mainly this process are produced the the soils with relative by micro- high organisms levels (but some are produced by plant roots and soil animals) and include hydrolases and of organic matter, the supply is sufficient for plant. deaminases that break C—H and C—NH2 bonds. The enzymes may carry out the reactions inside microbial cells, but most often they are excreted by the microbes and work extracel- lularly in the soil solution or while adsorbed to colloidal surfaces. This enzymatic process termed mineralization (Figure 13.3) may be indicated as follows, using an amino compound Biotic (R—NH2) as an example of the organic nitrogen process source: deaminases, hydrolases Mineralization +2H2O +O2 +1/2O2 – + + – R NH2 OH + R OH + NH4 4H + energy + NO2 energy + NO3– –2H2O –O2 –1/2O2 Immobilization (13.1) Biotic and abiotic process 4 Amino acids such as lysine (CH2NH2COOH) and alanine (CH3CHNH2COOH) are examples of these simpler com- pounds. The R in the generalized formula represents the part of the organic molecule with which the amino group ICD-10-CM/PCS The Nature and Properties Coding: A of MapSoil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. (NH2) is associated. Lorraine Ray M. For R. Weil example, for lysine, the R is CH2COOH. Papazian-Boyce | Nyle C. Brady All Rights Reserved Figure 13.4 The rate of immobilization of 15N-labeled nitrate added in solution to samples of forest soils where either pine or hardwood stands prevailed. Very rapid immobilization took place in both soils during the first hour, apparently by nonbiological (abiotic) processes. The nitrates probably reacted chemically with the soil organic matter. This fast reaction was followed by the more commonly observed slower immobilization in response to biological reactions stimulated by soil microorganisms. This graph suggests that both biological and abiotic reactions must be taken into consideration in studying the nitrogen-retentive capacity of forest soils. (Redrawn from data in Bernston and Aber (2000)) The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved  Carbon to nitrogen ratio determines the net effect of the nitrogen balance. The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved  Box 13.1 Calculation of Nitrogen Mineralization The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved  Ammonium fixation by clay minerals Negative charged surfaces of clay and humus More in 2:1-type clay minerals Greater in subsoil than in top soil The release of the fixed ammonium is often too slow to be of much practical value for fast growing annual plants. Low in highly weathered soils, high in some forest soils 15 The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved  Table 13.1 Total Nitrogen Levels of A and B Horizons of Four Cultivated Virginia Soils and the Percent age of the Nitrogen Present as Nonexchangeable or Fixed NH4+. The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved  Ammonia volatilization ental increases on nitrogen deposition from the atmosphere (see Section 13.12). nia gas is in equilibrium with ammonium ions according to the following rever n: NH4+ + OH– H2O + NH3 (1 Dissolved ions Gas From Reaction (13.3) we can draw two conclusions. First, ammonia volatilization - e pronounced at high pH levels Plant residue, (i.e., OH q ionspHdrive the reaction to the right); sec Soil nia gas–producing animal excrement amendments or the q Soil OMofand addition clay will drive the reaction t water fertilizers q Deep fertilizers placement sing the pH of the solution in which they are dissolved. oil colloids, both clay and humus, adsorb ammonia gas, so ammonia losses are gre The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved Figure 13.6 Ammonia volatilization is markedly affected by temperature and pH. Here, urea fertilizer (NH2— CO—NH2) was applied to a silt loam soil surface. Urea absorbs moisture from the air or soil and then hydrolyzes to form ammonia. The loss of ammonia gas is especially rapid when pH exceeds 7 and temperature exceeds 16 °C. Ammonia loss can be even faster from animal feces (manure) than from urea. Ammonia-forming amendments should not be left on the surface of warm, high pH soil for more than a day. [Redrawn from Glibert et al. (2006) using data in Franzen (2004)] The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved Figure 13.7 Irrigation or rain water can wash surface applied fertilizer into the soil and greatly diminish losses to the atmosphere of nitrogen as NH3 gas. In the research depicted here, 112 kg N/ha as urea fertilizer (H2N–C–NH2) was broadcast on the surface of an Adkins fine sandy loam (Xeric Haplocalcid) in eastern Oregon. The pH of the soil was 6.5, and that of the irrigation water was 7.8. Without the addition of irrigation water, 60% of the applied N was lost as NH3 gas within two weeks of fertilization. The application of only 7.6 mm of water reduced the loss to 17% of that applied. [Redrawn from Holcomb et al. (2011)] The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved  ammonium to nitrite. Molecular research has shown that certain archaea (Crenarchaeota) may ays. Every second day, soil be active samples ammonia-oxidizing organisms 150 in soils. In other soils, a specific group of autotrophic NH4 -N ! Nitrogen, mg/kg various forms of nitrogen. Note that N) almost mirrored the decline in any case, the nitrite so formed is then Nitrification bacteria of the genus Nitrosomonas is thought to carry out most of the ammonia oxidation. In immediately acted upon 100 NO3by-N a second group of autotrophs " for the small amount of nitrite-N (NO2−-N) + (the best known etween day 2 and 10. This pattern is being the bacteria of the genus Nitrobacter). Therefore, when NH 4 is re- - leased into the soil cess depicted by Eqs. (13.4) and (13.5). it is usually converted 50 rapidly into NO 3 (see Figure 13.8). The enzymatic oxidation e study. [Data selected releases from Khalil energy and may be represented very simply as follows: et al. (2004)] NO2 -N " Step 1 Step 1 0 0 2 4 6 8 10 12 14 ++ 1 Nitrosomonas Nitrosomonas – – + + NH4 4 ++11/12/O NH 2O 22 bacteria NO NO + 2H 2 2 + 2H + days Time, H O +O275 +2H 2 kJ energy + 275 kJ energy (13.4) bacteria Ammonium Ammonium Nitrite Nitrite Step Step22 – Nitrobacter NO2 –+ 1/12/O2 Nitrobacter NO3– +– 76 kJ energy (13.5) NO2 + 2O2 bacteria NO3 + 76 kJ energy bacteria Nitrite Nitrate Nitrite Nitrate So long as conditions are favorable for both reactions, the second transformation is thought to follow the AD2232_04_SE_C13.indd 611 first closely enough to prevent accumulation of much nitrite. This is fortunate, because even at concentrations ICD-10-CM/PCS The Nature and Properties Coding: A of Map Soil, to 15e, of just a few mg/kg, nitrite is Copyright Success Global Edition quite ©toxic to most 2017 Pearson Education, Ltd. plants. When oxygen Ray supplies Lorraine R. Weil are marginal, the nitrifying bacteria may also produceAll Rights M. Papazian-Boyce | Nyle C. Brady some Reserved  60% Autotrophic: Bicarbonates and CO2 20~30 ˚C The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved Figure 13.8 Transformation of ammonium into nitrite and nitrate by nitrification. On day zero, the silt loam soil was amended with enough (NH4)2SO4 to supply 170 mg of N/kg soil. It then underwent a warm, well-aerated incubation for 14 days. Every second day, soil samples were extracted and analyzed for various forms of nitrogen. Note that the increase in nitrate-N (NO3 −-N) almost mirrored the decline in ammonium-N (NH4 +-N), except for the small amount of nitrite-N (NO2 −-N) that accumulated temporarily between day 2 and 10. This pattern is consistent with the two-step process depicted by Eqs. (13.4) and (13.5). No plants were grown during the study. [Data selected from Khalil et al. (2004)] The Nature and Properties ICD-10-CM/PCS Coding: A of Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. Lorraine Ray R. Weil M. Papazian-Boyce | Nyle C. Brady All Rights Reserved  So long as conditions are favorable for both reactions, the second transformation is thought to follow the first closely enough to prevent accumulation of much nitrite. This is fortunate, because even at concentrations of just a few mg/kg, nitrite is quite toxic to most plants. When oxygen supplies are marginal, the nitrifying bacteria may also produce some NO and N2O, which are potent greenhouse gases (see Sections 12.9 and 13.8). The chemical When reaction below (Eq.oxygen (13.6)), supplies are marginal, which combines steps 1 andgreenhouse 2, illustrates the production of hy- droxylamine gases may beproduction and possible also produced: of N2O gas between the initial oxidation of NH4+ and the production of nitrite and nitrate during nitrification N2O N2O ½O2 ½O2 NH4+ NH2OH NO2- NO3- (13.6) hydroxylamine Nitrite oxidation O2 Ammonia oxidation H2O + 2H+ Regardless of the source of ammonium (i.e., ammonia-forming fertilizer, sewage sludge, animal excreta, or any other organic nitrogen source), nitrification will significantly increase soil acidity by producing H+ ions, as shown in Reaction (13.6). See also Sections 9.6 and 13.14. The Nature and Properties ICD-10-CM/PCS Lorraine Ray R. Weil Coding: A of M. Papazian-Boyce | Nyle C. Brady Map Soil, to 15e, Success Global Edition Copyright © 2017 Pearson Education, Ltd. All Rights Reserved  large numbers. They are mostly facultative anaerobic bacteria in genera such as Pseudomonas, Gaseous losses by denitrification and Bacillus, Micrococcus, and Achromobacter. However certain archaea and fungi are also known to carry out denitrification. Most denitrifying organisms are heterotrophs, which obtain their en- anammox ergy and carbon from the oxidation of organic compounds. Other denitrifying bacteria are autotrophs, such as Thiobacillus denitrificans, which obtain their energy from the oxidation of sulfide. The exact mechanisms vary depending on the conditions and organisms involved. In the reaction, NO 3- [N(V)] is reduced in a series of steps to NO 2- [N(III)], and then to nitro- gen gases that include NO [N(II)], N2O [N(I)], and eventually N2 [N(0)]: –2O –2O –O –O 2NO3– 2NO2– 2NO N2O N2 (13.7) Nitrate ions Nitrite ions Nitric oxide gas Nitrous oxide gas Dinitrogen gas (+5) (+3) (+2) (+1) (0) Valence state of nitrogen Although not shown in the simplified reaction given here, the oxygen released at each q Facultative step wouldanaerobic bacteria: be used to form CO2 from Pseudomonas, organic carbon (or SO 42 - from sulfides if Thiobacillus is Bacillus,theMicrococcus, nitrifying organism).Achromobacter For these reactions to take place, sources of organic residues should be available to provide q Heterotroph, the energyuse OM and the denitrifiers need.produce The soil air inCO the 2microsites where denitrification occurs should q O2 < 10% contain no more than 10% oxygen, and lower levels of oxygen are preferred. Optimum tempera- tures for denitrification are from 25 to 35 °C, but the process will occur between 2 and 50 °C. q 25-35 ˚C Very strong acidity (pH 6 5.0) inhibits rapid denitrification and favors the formation of N2O. q Very strongGenerally, acid (pH when