P. Gurumurthy, M.Sc.(Ag.), Ph.D. Professor & Head Soil Science & Agricultural Chemistry Acharya N.G. Ranga Agricultural University Agricultural College, Naira-532 186 Andhra Pradesh
1. Introduction ....................................................................................... 1
1.1 Soil Analysis .......................................................................................... 1
1.2 Plant Nutrients ...................................................................................... 3
1.3 Fertilizer Technology .......................................................................... 10
1.4 Irrigation Water................................................................................... 18
2. Analytical Principles ..................................................................... 21
2.1 Stoichiometry ....................................................................................... 21
2.2 Mole Concept....................................................................................... 22
2.3 Gravimetric Analysis .......................................................................... 24
2.4 Titration ............................................................................................... 30
2.5 Hardness of Water .............................................................................. 32
2.6 Empirical Formula and Molecular Formula .................................... 33
2.7 Working Principles of Laboratory Instruments ............................... 33
2.7.1 pH meter ................................................................................. 34
2.7.2 Conductivity meter ................................................................ 36
2.7.3 Kjeldhal Assembly................................................................. 38
2.7.4 Colorimeter/Spectrophotometer .......................................... 39
2.7.5 Flame photometer .................................................................. 42
2.7.6 Atomic Absorption Spectrophotometer(AAS) ................... 45
3. Analytical Methods of Soil .......................................................... 47
3.1 Analytical Methods of Soil Physical Properties .............................. 47
3.1.1 Description of soil profile in the field .................................. 47
3.1.2 Studies of Capillary rise phenomenon of waterin soil column ............................................................................. 50
3.1.3 Determination of soil texture by feel method ...................... 54
3.1.4 Determination of soil texture by laboratory method .......... 55
3.1.5 Determination of Bulk density of soil .................................. 60
3.1.6 Determination of Particle density of the soil....................... 63
3.1.7 Determination of soil moisture content ............................... 66
3.1.8 Determination of soil watertension .................................... 67
3.1.9 Determination of soil colour................................................. 69
3.1.10 Determination of Infiltration rate of soil ............................. 71
3.1.11 Determination of soil strength.............................................. 74
3.1.12 Determination of soil structural stability ............................ 76
3.1.13 Measurement of heat transfer in soils and recording diurnal variations in soil temperature ................................ 79
3.1.14 Determination of volume expansion and maximum water holding capacity of soil .............................................. 82
3.1.15 Assessment of Coefficient of Linear Extensibility .............. 84
3.2 Analytical Methods of Soil Chemical Properties ............................. 85
3.2.1 Collection and preparation of soil sample .......................... 85
3.2.2 Determination of soil pH ...................................................... 89
3.2.3 Determination of soil EC ....................................................... 91
3.2.4 Determination of pH and EC of saturation extract of soil .......................................................................... 93
3.2.5 Determination of exchangeable acidity of soil ................... 96
3.2.6 Determination of soil organic carbon .................................. 99
3.2.7 Fractionation of soil organic matter by particle size ........102
3.2.8 Fractionation of soil humus ...............................................104
3.2.9 Determination of minerlizable Nitrogen in soil ...............109
3.2.10 Determination of extractable Phosphorus in soil by Olsen method ..................................................................111
3.2.11 Determination of extractable Phosphorus in soil by Brays’s method ...............................................................114
3.2.12 Determination extractable Phosphorus in soil by Resin bag method ................................................................116
3.2.13 Determination of available or Exchangeable Potassium in soil .................................................................119
3.2.14 Determination of available Sulphur in soil ......................121
3.2.15 Determination of exchangeable Calcium and Magnesium in soil ...............................................................124
3.2.16 Determination of available Micronutrients in soil ...........127
3.2.17 Determination of available Boron in soil ..........................132
3.2.18 Determination of available Molybdenum in soil..............136
3.2.19 Determination of Cation Exchange Capacity of soil ........137
3.2.20 Determination of Gypsum requirement of sodic soil .......140
3.2.21 Estimation of Lime requirement of Acid soil ....................142
3.2.22 Determination of ESP of sodic soil .....................................144
3.2.23 Estimation of Calcium carbonate content of soil ..............146
3.2.24 Rapid Soil Test Kit ...............................................................149
3.3. Analytical Methods of Soil Biological Properties ..........................155
3.3.1 Estimation of soil microbial biomass carbon ....................155
3.3.2 Estimation of microbial population in soil .......................156
3.3.3 Estimation of Soil Dehydrogenase Activity ......................161
3.3.4 Estimation of Soil Urease activity ......................................162
3.3.5 Estimation of soil Phosphotase activity ............................163
4. Analytical Methods of Plant .....................................................165
4.1 Plant sampling and processing.......................................................165
4.2 Digestion or Ashing of plant sample ..............................................168
4.3 Determination of Nitrogen content in plant...................................170
4.4 Determination of Phosphorus content in plant ............................172
4.5 Determination of Potassium content in plant ................................174
4.7 Determination of Calcium content in plant....................................176
4.8 Determination of Magnesium content in plant..............................177
4.9 Estimation Sulphur content in plant ..............................................178
4.10 Determination of Manganese, Copper, Zinc and Iron content in plant .................................................................................180
4.11 Determination of Boron content in plant........................................185
4.12 Determination of Molybdenum content in plant ...........................188
4.13 Rapid plant tissue tests for N, P and K ...........................................191
5. Analytical Methods of Organic Manures ..............................195
5.1 Collection and handing of manure sample ....................................195
5.2 Estimation of organic matter and ash content of organic manure and compost ..........................................................200
5.3 Estimation of Nitrogen content in organic manure .......................201
5.4 Estimation of Phosphorus, Potassium and Sulphur in organic manure .................................................................................204
5.4.1 Estimation of total phosphorus content in organic manure Principle .................................................................205
5.4.2 Estimation of total potassium content in organic manure Principle .................................................................206
5.4.3 Estimation of total Sulphur content in organic manure Principle ................................................................ 207
6. Analytical Methods of Fertilizers ............................................213
6.1 Collection of fertilizer sample ..........................................................213
6.2 Determination of Nitrogen in Urea .................................................217
6.3 Determination of NH4 -N in Nitrogenous fertilizers: Ammonium sulphate ........................................................................220
6.4 Determination of nitrate nitrogen in nitrogenous fertilizer ..........223
6.5 Determination of Phosphorus content in phosphatic fertilizer DAP ................................................................226
6.6 Determination of water soluble phosphorus in single super phosphate (SSP) ................................................................................229
6.7 Determination of Potassium content in Potassic Fertilizer...........233
6.8 Determination of Sulphur content in Sulphate fertilizer ..............235
6.9 Quick tests kits for quality control of fertilizers .............................238
6.10 Quick tests foridentification of known fertilizer salts ..................239
6.11 Identification of anion and cation in unknown fertilizer .............246
7. Analytical Methods of Water....................................................249
7.1 Collection of Irrigation water sample .............................................249
7.2 Determination of pH of irrigation water.........................................252
7.3 Determination of Salinity hazard of irrigation water ...................253
7.4 Determination of Residua Sodium Carbonate (RSC) of irrigation water .............................................................................254
7.5 Determination of Sodicity hazard (SAR) of irrigation water........258
7.6 Determination of Chloride concentration in irrigation water ......262
7.7 Determination of Boron content in irrigation water......................263
7.8 Determination of Biological Oxygen Demand (BOD) of water....265
7.9 Determination Chemical Oxygen Demand (COD) of water .........267
7.10 Determination of Sulphates content in water ................................269
7.11 Determination of Nitrates content in water....................................271
7.12 Quality parameters in irrigation water..........................................272
8. Interpretation of Soil, Plant, Manure and Water Analysis Data ...................................................................279
8.1 Interpretation of soil analysis data .................................................279
8.2 Interpretation of plant analysis data ..............................................291
8.3 Interpretation of manure analysis data ..........................................301
8.4 Interpretation of fertilizer analysis data .........................................304
8.5 Intrpretation of water analysis data ...............................................309
References .....................................................................................319
Appendices ....................................................................................323
Appendix-1: Laboratory safety measures ...............................................323
Appendix-2: Electric wiring and Earthing in Laboratories ...................326
Appendix-3: Error, Precision and Accuracy in laboratory analysis ....329
Appendix-4: Washing and cleaning of laboratory glassware ..............330
Appendix-5: Equivalent weight and Molecular weight of some chemical compounds ..............................................................332
Appendix-6: Units of measurements and conversions ..........................333
Appendix-7: Colour changes due to pH change in the presence of pH indicators ................................................................................339
Appendix-8: Nutrient concentrations in fertilizers ................................340
