SOILS-REVIEW-CH1-CH8 PDF

CHAPTER 8: SOIL CLASSIFICATION AND SURVEY Predict behaviour Identify best uses Soil survey - inventory of soil resource; By province (unit of...

CHAPTER 8: SOIL CLASSIFICATION AND SURVEY Predict behaviour Identify best uses Soil survey - inventory of soil resource; By province (unit of Estimate productivity publication) Extensive research results Order of soil survey 1st – very intensive, detailed; for experiments, bldg. site; LEVELS OF CLASSIFICATION: delineation of ≤1 ha i. order – based on major diagnostic horizon 2nd-intensive, detailed; agriculture, urban planning; 0.6-4 has. ii. suborder – divides order by moisture/temp. regime 3rd – extensive; rangeland, community; 1.6-16 has. iii. great group – division by arrangement etc. 4th – extensive, reconnaissance; broad land use; 16-252 has. iv. subgroup – typic, intergrades, transitional 5th – exploratory; regional planning; 252-4,000 has. v. family – division according to uses in plant growth vi. series – basic unit (400 in Philippines) SOIL TAXONOMY -based on USDA soil survey; grounded on; (i) SOIL PROPERTY; (ii) CONSIDERATIONS FOR LAND SUITABILITY CLASSES: READILY OBSERVABLE PROPERTY; (iii) SOIL PROPERTY AFFECTS SOIL 1. erosion/runoff GENESIS 2. wetness 3. limitations to tillage and plant rooting REASON: -organize knowledge about soils; -understand relationship among diff. soils; -for practical purposes: DIAGNOSTIC SUBSURFACE TEMPERATURE MOISTURE PARTICLE SUITABILITY SOIL ORDER HORIZON HORIZON REGIME REGIME SIZE CLASSES Mollic – soft, Argilic (white clay) - Pergelic - mean Aquic - Sand = 2 – Entisol - A: arable, no dark, basic illuvial horizon of clay annual temp is saturated and 0.05 um Youngest conservation YOUNG accumulation 3 Gellisol – D: suited for & water illuvial accum. of Al & 8oC - 15oC mos. ; moist ≥ immature pasture, but arable saturated Fe & OM 3 mos. because cold when conserved Ochric – thin, Oxic - very weathered Thermic - MAT = Xeric - MAT = Histosol - L: flat but light colored layer of Al & Fe & 1:1 15oC - 22oC dry summer, organic/ high wet/stony; for Clay wet winter OM; pasture/forestry FERTILE waterlogged Plaggen – man- Sombic - light-colored Hyperthermic - Mollisol – M: steep; eroded; made, due to with low % base- MAT > 22oC fertile soil shallow soil; for manure saturation (grasslands) pasture Placic (flat stone) - *add “iso-“ if Andisol – N: steep; eroded; thin, black to dark-red summer and Volcanic ash shallow soil; pan cemented by Fe winter differ by pastured if ACID Inorganic N -single-celled, aerobic Immobilization Inorganic N -> organic N -eats bacteria NH4+ --nitrosomonas--> NO2- --nitrobacter--> -binary fission Nitrification NO3- -Biomass: 100 kg/HFS NO3 -> N2, NO (Pseudomonas, Denitrification Achromobacter, Bacillus, Micrococcus); Bacteria largely inaerobic -most important Ammonification OM -> NH3 Based on Nutrition Symbiotic N-fixation Rhizobia in roots (N -> NH3) Heterotrophic Eats OM Non-symbiotic N- Azotobacter in soil (N -> NH3) Autotrophic Eats CO2, Inorganic matter fixation Photosynthetic Requires Sunlight Solubilization of Calcium Phosphate by: Chemosynthetic Eats chemicals Bacteria Fungi Based on O2 Requirement Pseudomonas Penicillin Aerobic Requires oxygen Mycobacterium Fusarium Anaerobic Cannot live in oxygen Bacillus Aspergillus Generally requires O2, but can Micrococcus Facultative live when not present Inorganic P Based on Temperature Solubilization Causes: Mesophilic 1.Organic acid Prod’n Thermopilic 2. Nitric Acid/sulfuric acid psychrophilic 3. Flooding (reduces ferric phosphate) -Biomass: 2,000 kg/HFS 4. Mycorrhiza ectotrophic: exterior mantle Fungi Endomycorrhiza – penetrate cells -most adaptable - sulphate form available -can decompose lignin, cellulose, and gum -microbial decomposition of S -Mycorrhizae: assists in P absorption - oxidation of inorganic S; Sulfide, -generally heterotrophic & aerobic thiosulfate, elemental S -Biomass: 8,000 Kg/HFS Microbial Sulfur - reduction of SO42- Transformation - Desulfovibrii & Desulfotomaculum: Actinomycetes reduces sulfate to sulfide -attack and simplify organic compounds -oxidation of elemental S leads to -intermediate between bacteria and fungi formation of great amounts of organic -produce antibiotic Acid -Biomass: 4,000 kg/HFS - Iron bacteria - ferrous oxidation from Fe2+ to Fe3+ Algae Iron Precipitation -Iron reduction -chlorophyll bearing -Iron Precipitation - excellent host for bacteria - 250 kg/HFS COMPOST & COMPOSTING SOIL ORGANIC MATTER Composting – creating humus-like organic materials -accumulation is affected by: Compost – finished product; C/N ratio: 14/1 – 20/1; pathogens are TEMPERATURE, MOISTURE, TEXTURE, CROPPING SYSTEM destroyed during thermophilic stage (50-75oC) - totality of all carbon-containing compounds in the soil Cellulose decomposition – -organic constitution of plants FUNGI BACTERIA Cellulose 15-60% Aspergillus Bacillus Hemicellulose 10-30% Fusarium Clostridium Lignin 5-30% Trichoderma Vibrio Water soluble fraction 5-30% Cytophaga* Protein Fats, oil wax *Abundant in Soil/straw/manure -SOM ∝ MOISTURE -more OM accumulated in grasslands than in forested due to FASTER TURNOVER OF VEGETATIVE MATTER & SHORTER GRASS LIFE CYCLE - OM declines by cultivation due to ENHANCED OXIDATION AND MICROBIAL ACTIVITY CHAPTER 4: CHEMICAL PROPERTIES Via Cmol, 1 Known: 1 𝑐𝑚𝑜𝑙 = 𝑡ℎ 𝑜𝑓 𝑎 𝑚𝑜𝑙𝑒 1000 Chemical nature of Soil Constituents Given: 1 𝑐𝑚𝑜𝑙 𝐶𝑎 = 0.40 𝑔; 1𝑐𝑚𝑜𝑙 𝐻 + = 0.01 𝑔; 2+ 1. Solid – skeletal framework 1 𝑐𝑚𝑜𝑙 𝐶𝑎2+ = 1 𝑐𝑚𝑜𝑙 𝐻 + 2. Liquid – soil solution 2 3. Gas – Soil Air, N2, O2, CO2 Solution: (by way of ratio & proportion) 0.02 𝑔 𝑥(𝐶𝑎2+ ) = ; 𝑥 = 20 𝑔 𝐶𝑎2+ Soil Colloid 0.001 𝑔 1 𝑔 (𝐻 + ) - 0.2 um; seat of various chemical reactions; high surface area per unit amount (specific surface area) CATION EXCHANGE CAPACITY (CEC) - increase w/ amount of clay % OM; ability to adsorb and exchange 1) Organic Colloid cations w/ the surrounding soil solution and plant roots 𝑐𝑎𝑡𝑖𝑜𝑛 𝑐𝑜𝑛𝑐𝑒𝑛𝑡𝑟𝑎𝑡𝑖𝑜𝑛 , 𝑐𝑎𝑡𝑖𝑜𝑛 𝑣𝑎𝑙𝑒𝑛𝑐𝑒 -humus: high molecular weight; stable; created via H+ dissociation -adsorption ∝ ℎ𝑦𝑑𝑟𝑎𝑡𝑖𝑜𝑛 𝑠𝑖𝑧𝑒 , 𝑖𝑜𝑛𝑖𝑐 𝑠𝑖𝑧𝑒 of carboxylic and phenolic functional groups @ high pH; enables -order of adsorption strength: adsorption & exchange of ions. (Al3+, H+)>Ca2+>Mg2+>K+>Na+ -comes in the form of Aluminum Silicate clays -in leached soils, strongly adsorbed cations will be left -CEC Calculation: add all given ME’s (milliequivalent) of adsorbed O+ O+ cations O + O+ Si Al PERCENT BASE SATURATION + O O+ O + O+ - degree by which exchange sites are occupied by basic cations O+ O+ - (alfisol) – high base saturation; (ultisol) – low base saturation 𝒃𝒂𝒔𝒆 𝑴𝑬 -formula: × 𝟏𝟎𝟎 𝑪𝑬𝑪 Silica tetrahedron Aluminum Octahedron* *Alumina octahedron makes up the aluminum sheet EXCHANGEABLE SODIUM PERCENTAGE -degree by which exchange sites are occupied by sodium ions 2) Inorganic Colloid 𝑵𝒂 𝑴𝑬 i) Crystalline Silicate Clays – composed of aluminosilicate; -formula: × 𝟏𝟎𝟎 𝑪𝑬𝑪 ratio of silica to aluminum sheet: 1:1 Non-expanding Kaolinite, Halloysite SOIL pH 2:1 Expanding Montmorillionite, smectite -referred to as soil reaction; degree of acidity/alkalinity 2:1 Limited expansion vermiculite -pH = -log[H+]; pH of Philippine soils: 5.5 – 6.5 pH 2:1 Non-expanding Illite -pH8.0: micronutrients become unavailable except Mo -Causes of soil acidity: ii) Amorphous Silicate Clays – amorphous hydrous oxides of Iron 1. base leaching and Al 2. OM decomposition: Fulvic acid, humic acid, carbonic acid -hematite -Goethite NOTES: -Limonite -inhibition of -Boehmite symbiotic N-fixation -Gibbsite & Nitrification -low pH: Fe, Al, Mn, Electrical Charges of Silicate Clays become toxic 1. Negative Charge – “Agri. soils are net-negative” -high pH: P is Negative charge arises because precipitated to i. exposed hydroxyls at the edge of crystal insoluble forms of ii. dissociation of H+ @ high pH (creation of humus) Fe & Al /Manganese iii. isomorphous substitutions of ions in silica/aluminum sheets Phosphate when rich - uses GENTIAN DYE to demonstrate negative charge w/ Mg oxides -adsorbed cations keeps it from washing away -high pH: P is complexed w/ Ca 2. Positive Charge To form precipitate – arise from the protonation/addition of H+ to OH groups in of Ca hydroxyapatite sesquioxides, allophone, kaolinite or Ca phosphate - arise from exchange of OH groups for other anions dehydtrate - use EOSIN to demonstrate positive charge SOURCES OF ACIDITY SOURCES OF ALKALINITY ION EXCHANGE i. H i. base forming cations + & Al3+ ions Ca, Mg, K, Na -reversible -CATION EXCHANGE: colloids attract cations ii. H2CO3 dissociation; ii. carbonates & bicarbonates- -ANION EXCHANGE: colloids attract anions (NO3-, PO4-, SO4-) CO2 + H2O -> H2CO3 (CO32-) & (HCO3-) iii. organic acid from OM 𝟏 -Liming ∝ 𝒎𝒊𝒄𝒓𝒐𝒏𝒖𝒕𝒓𝒊𝒆𝒏𝒕𝒔 MILLIEQUIVALENT/ CMOL decomposition 𝒎𝒐𝒍.𝒘𝒕.𝑪𝒂𝑪𝒐𝟑 iv. mineral weathering -𝑹𝑵𝑽 = × 𝟏𝟎𝟎 1 𝑚𝑒 = 𝐴𝑊/(𝑉 × 1000) 𝑴𝒐𝒍.𝒘𝒕.𝑳𝒊𝒎𝒆 v. acid rain - Limestone (CaCO3) Ex. K+ = 39/(1 × 1000) = 0.039 𝑔/𝑚𝑒 vi. heavy cropping removes -dolomite (CaMgCo3)2 basic cations - burned lime (CaO/MgO) Ex. How many (g) of Ca2+ is needed to replace 1 (g) H+ vii. long term use of acidifying 179% Given: 1 me Ca2+ = 1 me H+ fertilizer -slake lime (Ca(OH)2) 136% Known: 1 me Ca2+ = 0.02 g; 1 me H+ = 0.001 g; *Gypsum -for saline soil* Solution: (by way of ratio & proportion) ACIDIFICATION 0.02 𝑔 𝑥(𝐶𝑎2+ ) - more diff. than liming; achieved through OM add’n, ferrous = ; 𝑥 = 20 𝑔 𝐶𝑎2+ 0.001 𝑔 1𝑔 𝐻 + sulfate/sulfur BUFFERING CAPACITY - resistance due to drastic changes in pH; CEC ∝ BF ∝ liming; more lime is needed for acid clay soils than sandy ones. ACIDITY CALCAREOUS (HIGH LIME SALINITY (HIGH SALT SODIC SOILS IRON TOXICITY ZINC DEFICIENCY WATERLOGGED DRYLAND CONTENT) CONTENT) Liming using CaCO3, CaO, -Apply organic fertilizer -soils with toxic amount of -soils with excessive -Regular drainage to - Spray foliar fertilizers -Lowland/paddy soils -nutrients present in Ca(OH)2, soluble salt content amount of soluble oxidize iron and to reduce containing zinc like ZnSO4 oxidized state CaMg(CO3)2 -Dig holes and replace sodium (Na content toxicity problem of excess - anaerobic but w/ thin with top soil and clayey -EC>4 mmhos/cm >15% CEC) iron under flooded -Dipping of roots of rice oxidized layer - brown, yellowish brown, -Use ashes soils condition seedlings to 2 tbsp red brown -Apply organic -reclaim using gypsum ZnO/liter water (2% ZnO - NH4+, H2S, Mn2+, Fe2+, CH4 -Apply guano, apply -Spray plants with foliar matter/fertilizer (CaSO4) -Apply phosphatic solution) (reduced state) -OM decomposition yields phosphatic fertilizer fertilizers containing fertilizers and guano CO2 micronutrients -Irrigation and regular -Apply adequate level of -dark gray, bluish gray -Use urea rather than drainage to remove salts -Apply rice hull ash and compost -Dig holes to serve as water ammonium sulfate -Apply composts other forms of ashes like - OM decomposition yields catchment and to contain -Spray plants with foliar wood ash -Use Ammonium sulfate H2S, organic acids, alcohol, water for plant use -Use compost -Employ mulching fertilizers containing rather than urea ketones micronutrients -Use of tolerant rice -Use mulching with organic -May apply rice hull ash varieties to high level of -Occasional drainage to -Construct canals to drain materials tp prevent -Apply gypsum (CaSO4) iron in soils increase availability of excess water to maintain evaporation of soil - Apply mycorrhiza- zinc well-drained or aerobic soil moisture containing organic -Use Ammonium sulfate condition fertilizers to enhance rather than Urea -Use drought-tolerant crops availability of fixed -Employ raised-bed phosphorus -Use mulching with organic technology in planting -Apply organic materials shallow- and medium- fertilizers/compost -Acid Sulfate Soil: rooted crops occurs in low pH; can be -Deep plowing -Apply mycorrhiza as lows as 4.0; genus -Employ horticulture-on- containing organic Thiobacillus facilitate dikes to improve fertilizers to enhance sulfur oxidation productivity of availability of soil moisture waterlogged condition -Employ drip irrigation system with fertigation CHAPTER 3: PHYSICAL PROPERTIES OF THE SOIL SOIL PORE SPACE SOIL TEXTURE – (Sand, Silt, Clay) Micropore – holds H2O Macropore – holds air; for aeration and root growth Soil Separate Diameter Feel Sand 2.0 – 0.05 um Coarse, gritty BULK DENSITY BD = Ms/Vt FACTORS AFFECTING BD Silt 0.05 – 0.002 um Smooth, powdery (measures compaction) i. soil texture α BD Sand: 1.20 – 1.80 g/cm3 ii. OM α 1/BD Clay 1.13 g/cm3 Compact Low nutrition High nutrition 2.70 g/cm3 Heavy minerals -surface means higher OM ii. roll – knead to a rod magnetite, which means lower PD. iii. mechanical – hydrometer/pipette hornblende, zircon hematite) AB – transition C – weathered parent -carbonation: H2CO3 reaction (Calcite -> Calcium carbonate) R – bed rock -solution: H2CO3/H+ dissociation (silica is dissolved) STAGES OF SOIL FORMATION i. Physical weathering ii. particle rearrangement iii. OM addition iv. Chemical weathering v. Soil Horizon formation - FIVE FACTORS AFFECTING SOIL FORMATION (CT,R.L.O.R.PS,T.TY,O) Climate - Temperature: (10oC)T α (reaction)2 tropical soils weather faster because of T -Rainfall: causes hydrolysis/hydration, Leaching, & erosion Living organisms Causes bioturbation (soil mixing) Relief/topography -affects water movement Parent material - Sedentary (no movement) -Transported (ALMMVC) Alluvium (river) CHAPTER I: CONCEPT OF SOIL SOIL -medium of plant growth; mix of in/organic matter; non- renewable; natural body SOIL SURFACE - Soil upper limit SOIL INDIVIDUAL - PEDON – hexagonal (1-10m2); basic unit of soil POLYPEDON – multiple pedon APPROACHES IN SOIL STUDY 1. FERTILITY 2. PHYSICS 3. CHEMISTRY 4. MICROBIOLOGY 5. CONSERVATION & MANAGEMENT 6. SURVEY & CLASSIFICATION 7. MINERALOGY 8. LAND USE SOIL COMPONENT SOLID 1) MINERAL (45%) 2) ORGANIC (5%) GAS 1) N2 (78%) 2) O2 (20%) 3) CO3 (0.5%) LIQUID H2O (20 -30%)