Research Approaches to Sustainable Biomass Systems || Soil Fertility and Soil Microorganisms
Post on 19-Dec-2016
Organic Matter 118
5.2.1. Carbon Dynamics on
Continuous Cropping 129
5.4. Microbially Mediated Soil
EnvironmentalBiomass in Japanese
Agricultural Soils 133the Earth Scale 118
5.2.2. Factors in the Increase
and Decrease of SOC 118
5.2.3. Principle of
5.4.2. Nitrogen Cycles
Biomass in Soils 132
5.4.3. Nitrogen Cycle
Through Microbial5.2. Soil Management and SoilFertility 131
5.4.1. Productivity andRes
5.1.5. Improvement of
5.3.5. Soil Sickness due toProductive CapabilityClassification
5.1.4. Expression of109Classification
5.1.3. Factors Affecting the
5.1.2. Soil Potential
Productivity108Chapter Outline5.1. Soil Fertility
5.1.1. Definition of Soil108aruo Tanaka, Akane Katsuta, Kokiicroorganisms
oil Fertility andearch Approaches to Sustainable Biomass Systems. http://
yright 2014 Elsevier Inc. All rights reserved.Biomass 1
5.3.2. Habitats 1
5.3.3. Taxonomy 1
5.3.4. Microbial Functions 122
235.3. Soil Microorganisms 1
5.3.1. Abundance andModified RothC 120
22and Paddy Soils 1
5.2.5. Application of20RothC for Andosols5.2.4. Modification ofToyota and Kozue SawadaSoilChapter 5dx.doi.org/10.1016/B978-0-12-404609-2.00005-2
5.1. SOIL FERTILITY
In lassification (National Conference ofSo 1979) is used to evaluate soil fertility;th ificat yHa
108 Research Approaches to Sustainable Biomass SystemsJapan, Soil Potential Productivil Conservation and Survey Proe soil potential productivity classmazaki and Micosa (1991).Classification of soil potentiality Cject,sults of soil surveys. It is a practicalon their limitations or hazards for cropuctivity is a form of interpretinion is presented based on the report b
g thHaruo Tanaka
5.1.1. Definition of Soil Fertility
Soil fertility is defined as the quality of a soil that enables it to provide nu-trients in adequate amounts and in proper balance for the growth of specifiedplants or crops (Soil Science Glossary Terms Committee, 2008). It is not onlybased on the natural conditions or peculiar property that the soil has but also thehuman activities such as growing various crops by applying different cultiva-tion methods. Soil fertility is the most important factor to affect the productionof biomass in a field. Usually, sustainable high yields of biomass can beexpected from fertilized soil. For land that is not fertile, application of a largequantity of natural or chemical fertilizer with high labor demand is necessary tomaintain high biomass production.
An agro-ecosystem is viewed as a subset of a natural ecosystem. Tradi-tionally, the agro-ecosystem is characterized as having a simpler speciescomposition and simpler energy and nutrient flows than a natural ecosystem.The soil has the function as the decomposer in the agro-ecosystem to decom-pose the organic matter such as composts or plant residues applied to the soilinto inorganic matters biologically by animals and microorganisms inhabitingthe soil. However, excessive application of organic matter causes environ-mental pollution such as the groundwater contamination with ammonium. Inaddition, as a producer, the soil supports the growth of plants that absorbnutrients and water from the soil to grow under solar irradiation. Hence, soilproductivity is a synonym of soil fertility.
5.1.2. Soil Potential Productivity Classification5.4.4. Management of
a Crop Growth Period 136
5.4.5. Future Prospects 139
References 140method to grade or group soils basedproduction and/or risk of soil damage
to jeopardize crop production; all these concerns are closely related to soilsphysical and chemical properties. The objective of land capability classificationis to eliminate limitations for increasing crop productivity. There are four soilcapacity classifications, i.e. I, II, III, and IV, defined as follows:
l Class I Land has almost no limitations or hazards for crop productionand/or risks of soil damage.
l Class II Land has some limitations or hazards and/or risks of soil damage,and some improvement practices are required for normal crop production.
l Class III Land has many limitations or hazards and/or risks of soildamage, and fairly intensive improvement practices are required.
l Class IV Land has great natural limitations, so it is difficult to use as
more than 15 cm is classified as class I, because paddy or grassland crops are
109Chapter j 5 Soil Fertility and Soil Microorganismscapable of growing in thinner topsoil than upland or orchard crops.
TABLE 5.1 Thickness of Topsoil (t)
Paddy Upland Orchard Grassland
>25 I I I I
25e15 I II II I
TABLE 5.2 Effective Depth of Soil (d)
Paddy Upland Orchard Grassland
>100 I I I I
100e50 I II II I
50e25 II III III IeII
25e15 III III IV IIeIII
111Chapter j 5 Soil Fertility and Soil Microorganismsand their combinations. For example, soil texture is based on the classificationused in the ISSS system; textures of S, LS, SL, FSL, L, and SiL are classified asCoarse to medium; SCL, CL, and SiCL are classified as Fine; and SC, LiC,SiC, and HC are classified as Very fine.
TABLE 5.4 Ease of Plowing (p)
Class Criteriaa b c d
Easy to slightly difficult
aTexture of top soil (Coarse to medium: 1; Fine: 2; Very fine: 3).bStickiness of topsoil (Non-sticky to slightly sticky: 1; Sticky: 2; Very sticky: 3).cConsistence of topsoil when dry (Loose to soft: (2); Slightly hard: 1; Hard: 2; Very hard to extremely
hard: 3).dMoisture condition of topsoil (Dry to moderately dry: (2); Moist: 1; Wet: 2; Very wet: 3). Moisture
condition refers to the major part of the year and/or 2e3 days after considerable rainfall.e. Permeability Under Submerged Conditions (l; only for paddyfields; Table 5.5)
This soil permeability affects the movement of water in the soil, soil temperature,and leaching of nutrients or development of reduced condition of the soil. It isevaluated mainly by the combination of soil texture and the presence of acompact layer within 50 cm of the surface as dependent factors. The measure-ment of the water permeability coefficient and/or water requirement in depth hasbeen widely used, and hence the permeability data are handy for carrying out thesoil permeability classification. The dependent factors that are relevant to clas-sifying the soil are as shown in Table 5.5. This table shows similar classificationsof finest soil texture as in Table 5.4, but the ratings are different. To determine themaximum compactness within 50 cm of the surface, Yamanakas core pene-trometer is used. Value ranges of >24, 2411, and
112 Research Approaches to Sustainable Biomass SystemsTABLE 5.5 Permeability under Submerged Conditions (l; only for
paddy fields)of easily decomposable organic matter in topsoil, Contents of free ironoxides in topsoil, and Degree of gleyzation are used. Organic matter that iseasily decomposed is represented by NH4-N cg kg
1 in air-dried soil (A) andNH4-N cg kg
1 in soil after the soil sample has been incubated at 30C for4 weeks (B). The easily decomposable organic matter is classified as Low
(Paddy) Criteriaa b
1 1 I Poorly to imperfectly permeable1 2 I
2 2 II Moderately to well permeable3 2 II
3 3 III Well to excessively permeable
aFinest soil texture within 50 cm of the surface (Very fine: 1; Fine: 2; Medium to coarse: 3).bMaximum compactness within 50 cm of the surface (Very compact to compact: 1; Medium
to loose: 2; Very loose: 3).
TABLE 5.6 State of OxidationeReduction Potentiality (r; only for paddy
Dependent factors Class
(Risk of root damage)a b c
1 1 2 I None to weak1 3 2 I2 1 2 I
1 1e2 3 II Moderate to strong1 3 3 II2 1e2 3 II3 1 2 II
2 3 3 III Very strong3 2 2 III3 1 3 III3 3 2 III
aContents of easily decomposable organic matter in topsoil (Low: 1; Medium: 2; High: 3).bContents of free iron oxides in topsoil (High: 1; Medium: 2; Low: 3).cDegree of gleyzation (Weak: 1; Moderate: 2; Strong: 3).
(A < 10, B < 10), Medium (A: 1020; B: 1015), and High (A: >20; B:>15). If based on the content of free iron oxides (cg kg1), the topsoil can beclassified as High (>1.5), Medium (1.50.8), and Low (200 is High, 200100 is Medium, and
113Chapter j 5 Soil Fertility and Soil Microorganisms
2 1 2 I
114 Research Approaches to Sustainable Biomass Systemsh. Inherent Fertility of the Soil (f; Table 5.8)
1 2 3 II Medium2 1 3 II1 3 1 II1 3 2 II
1 3 3 IIIeII Infertileemedium3 1 1 III Infertile
2 4 2 IIIeII Infertileemedium
aNutrient holding capacity (High: 1; Medium: 2; Low: 3).bNutrient fixation power (Very low: 1; Low: 2; Medium: 3; High: 4).cBase status of the soil (Good: 1; Medium: 2; Poor: 3).TABLE 5.8 Inherent Fertility of the Soil for Upland, Orchard,
and Grassland (f)
Class Criteriaa b c
1 2 1 I FertileThe soils inherent fertility is evaluated by using combinations of thefollowing three dependent factors: nutrient-holding capacity, nutrient fixa-tion power, and base status. Nutrient-holding capacity is evaluated based oncation exchanged capacity (CEC; cmolc kg
1 soil) as High (>20), Me-dium (206), and Low ( 5.5), medium(pH between 5.5 and 5.0), and poor (pH < 5.0). Table 5.8 shows theclassification for upland, orchard, and grassland, while other tables are usedfor paddy fields.
i. Content of Available Nutrients (n; Table 5.9)
Available nutrients in topsoil are closely related to the inherent soilfertility, but evidently influenced by the combination of the followingdependent factors: contents of exchangeable Ca, exchangeable Mg,exchangeable K, content available P (determined by using the Truogmethod), available N and Si (for paddy), and micro-elements (evaluatedby using the risk of deficiency), as well as soil acidity as indicated by thepH (H2O) value.
115Chapter j 5 Soil Fertility and Soil MicroorganismsTABLE 5.9(b) Rating of Dependent Factors of Available Nutrients
1 2 3 4
Content of exchanged Ca (cmolc kg1) >7.1 7.1e3.6 1.2 1.2e0.5 0.32 0.32e0.17 44 44e9 20 20e10 15 15e5 6 6e5 5e4.5
TABLE 5.10 Hazard (i)
116 Research Approaches to Sustainable Biomass SystemsII Moderate
III FrequentTABLE 5.11 Frequency of Accidents (a)
Class Criteriadetermined based on the following two independent factors: risk of overheadflooding inundation (None to slight, Moderate, and Frequent), and risk of landcreep (None to slight, Moderate, and Frequent).
l. Slope of the Field (s; for upland and orchard; Table 5.12)
The natural slope is the main dependent factor; its classification is decided by acombination of natural slope, direction of slope, and artificial slope.
TABLE 5.12 Slope of the Field (s; for upland and orchard)
Slope (%) Rating Upland Orchard
47 5 IV IV
lowest class of factors. This code formula arranges briefly the information
117Chapter j 5 Soil Fertility and Soil Microorganismsregarding the kind and the degree of limitations with each class of land. Thecode II plrn means that the land is classified class II because the factorsp (ease of plowing), l (permeability under submerged conditions), r (state ofoxidationreduction potentiality), and n (content of available nutrient) aregrouped in class II. If the soil fertility of this land is to be improved, improvingall of these factors together is necessary.m. Erosion (e; for upland orchard; Table 5.13)
The degree of erosion or occurrence of rill or gully (Very slight, Slight,Moderate, and Severe), the power to resist water erosion for topsoil determinedusing the dispersion ratio (Strong, Moderate, and Weak), and the resistingpower wind erosion for topsoil determined using the soil bulk density (Strongand Weak) are pertinent here.
5.1.4. Expression of Productive Capability Class
The evaluation of these standard and dependent factors is expressed as either asimplified code formula or a detailed code formula. When a simplified codeformula, e.g. II plrn, is used, the productive capability class is placed in theTABLE 5.13 Erosion (e; for upland orchard)
I None or very slight
IV Very severe5.1.5. Improvement of Potential Productivity Classification
Soil Potential Productivity Classification, which is focused on crop produc-tion, represents the inhibitory factors of the crop production clearly with asimple code formula. Now that environmental conservation has become animportant issue, these issues may include prevention of nitrogen eluviation tothe groundwater, and prevention of the emission of greenhouse gasesincluding methane and nitrous oxide. The classification must include envi-ronmental conservation functions. In addition, as far as the current situation isconcerned, the classification must consider not only chemical and physicalfactors, but also biological factors such as activity or variety of the soilorganisms.
and reduce SOM contained in the soil lead to the loss of about 500 Pg SOC. The
118 Research Approaches to Sustainable Biomass Systemsamount of carbon released as a result of soil degradation is equivalent to doublethe amount of 230 Pg, which is the total quantity of carbon released byconsuming fossil fuels (Hakamata et al., 2000). If the soil degradation is restoredusing appropriate management practices, soil can become a huge sink ofatmospheric carbon through carbon sequestration. Much research has beenundertaken to study how to predict the quantitative change of SOC, and estimatethe carbon balance more accurately. This is also emphasized in the KyotoProtocol in order to prevent the expected global warming.
5.2.2. Factors in the Increase and Decrease of SOC
The SOC decomposition rate is affected by environmental factors as discussedin the following paragraphs:
1. In the range of natural temperature, both the microbial activity and the SOCdecomposition rate increase at higher temperature. Hence, tropical zoneshave less SOC than frigid zones due to the temperature difference.
2. Either higher or lower water content than the level for maximum microbialgrowth in the soil causes the SOC decomposition rate to slow down, so thatthe amount of SOC increases. If the soil water content is appropriate, micro-bial activity reaches the highest level so that more SOC is decomposed toresult in less SOC in the soil. In paddy fields, SOC accumulates becausethe paddy soil is fully submerged in irrigation water when rice is cultivated.
3. The quantity of SOC increases when the soil is clayey.4. Soil with extreme acidity or alkalinity inhibits the activity of soil microor-
ganisms, so that the SOC decomposition rate becomes slow, and SOC accu-5.2. SOIL MANAGEMENT AND SOIL ORGANIC MATTER
5.2.1. Carbon Dynamics on the Earth Scale
In recent years, the importance of soil organic carbon (SOC) in the carbon cycleon a global scale has attracted the attention of public and p...