This document provides information on various methods and reagents used for analyzing soil and water properties. It discusses methods for analyzing available nitrogen, phosphorus, potassium, calcium, magnesium and other nutrients in soil. It also outlines methods for analyzing phosphorus, sulfur, micronutrients and other elements. Further, it provides classifications for water quality based on electrical conductivity, sodium absorption ratio, residual sodium carbonate and chloride concentration.

6. 2. Mineralized nitrogen (Kenny and Driman)- Incubation method.
Reagent: 2% KCl + Devarda’s alloy.
Devarda’s alloy = Cu: Al: Zn = 50:45:5.
Al- reducing agent.

8. METHOD COMPOSITION pH
1. Troug 0.02 N H2SO4 + (NH4)2SO4 3.0.
2. Mehlich. 0.5 N HCl +0.025 M H2SO4 1.22
3. Igner. Lactic acid + Ammonium lactate 3.8
4. Morgan 10% sodium acetate + 3% acetic acid.
(Universal extractant for acid soil)
4.8
5. Bray and Kurtz
No 1.
0.03 N NH4F +0.025 N HCl <5.5
6. Bray and Kurtz
No 2.
0.03 N NH4F + 0.1 N HCl 1.2
7. Olsen 0.5 M NaHCO3 8.5

9. CHLOROSTANOUS METHOD ASCORBIC ACID
Plant phosphorus Soil phosphorus
pH = 2.0 pH = 5.0
Reagent = SnCl2 Reagent = Ascorbic acid
Yellow colour formed (>10 ppm P) Blue colour formed (<2 ppm P)
Wavelength = 660 nm Wavelength = 730-850 nm
Colour stands for 8-10 minutes Colour stands for extended period.

17. Mohr method Volhard method
Direct method Indirect method
Titrated by Ag2CrO4 Titrated by AgNO3
Indicator: K2CrO4 Indicator: K2SO4. FeSO4.24H2O
End point: Brick red End point: Intense red.

18. Element Reagent
Fe Orthophananthroile (Orange colour)
Mn Potassium periodate (Red)
Zn Dithiozone (Red)
Cu Diethyl diethiocarbamate (Golden brown)
Mo Thiocyanate
B Bioquinoline

19. ELEMENT INSTRUMENT
Available N Micro Kjeldahl apparatus and titration
Available P Spectrophotometer (Absorption
spectroscopy)
Available K and Na Flame photometer (Emission spectroscopy)
Available Ca and Mg Titration
Hot water soluble B Spectrophotomter
Available S Spectrophotometer
Micronutrients
(Zn, Cu, Fe, Mn)
Atomic absorption spectrophotometer

20. Element Wavelength (nm)
1. Phosphorus (P ) in Morgan method 882
2. P in Bray and Kurtz method 882
3. P in Olsen method 660
4. Sulphur 420
5. Molybdenum 470
6. Zn 213.8
7. Cu 224.8
8. Fe 248.3
9. Mn 278.9

21. Indicator pH Colour in acid medium Colour in basic medium
1. Cresol Red 0.2-1.8 Red Yellow
2. Thimol blue 1.2-3.8 Red Yellow
3. Methyl orange 3.8-4.4 Red Orange
4. Methyl Red 4.2-6.3 Red Yellow
5. Paranitrophenol 5.6-6.6 Colourless Yellow
6. Phenyl red 6.8-8.4 Yellow Red
7. Thimol Blue 8.0-9.6 colourless Reddish pink
8. Phenopthalein 8.5-10.0 Colourless Pink
*pH of UNIVERSAL INDICATOR = 3-10.

22. PROPERTY OF INDICATOR EXAMPLE
1. Strong acid medium Mehyl red, methyl orannge
2. Strong basic medium Phenolpthalein.
3.Absorption indicator Starch, Eosin, Fluroresin
4. Self indicator KMnO4 (***)
5. Redox indicator Orthophenon chlorine, FeSo4
6. Precipitation indicator K2Cr2O7, Fe alam.
7. Metal indicator SBT, EBT, Muroxide.
8. Internal indicator Diphenyl amine, Ferroin.
9. Acidic dye Fluororesin, Eosin.
10. Basic dye Rhodamine.
11. BOD test Starch.
12. COD test Ferroin, K2Cr2O7.
13. Carbonate Phenolpthalein.
14. Bicarbonate Methyl orange

23. NUTRIENT LOW MEDIUM HIGH
Organic carbon (%) <0.5 0.5-0.75 >0.75.
Available nitrogen (kg/ha) <280 280-560 >560
Available phosphorus (kg/ha) <22.50 22.50-56.33 >56.33
Available potassium (Kg/ha) <141 141-336 >336
Available calcium Less than 25% of CEC
or <1.5 meq of Ca /100
g soil
Available magnesium Less than 15% of CEC
or <1 meq of Mg / 100 g
soil.
Available sulphur (ppm) <10 10-20 >20
Available Zn (ppm) 0.6
Available Cu (ppm) 0.2
Available Fe (ppm) 4.5
Available Mn (ppm) 3.0
Available B (ppm) 0.5
Available Mo (ppm) 0.02

33. Water class EC (mSm-1) Salt concentration
(g/l)
Remarks
Low salinity 0-25 <0.16 Can be used safely
Medium salinity 25-75 0.16-0.50 Moderately safe
High salinity 75-225 0.50-1.50 Unsafe
Very high salinity 225-500 1.50-3.0 Toxic

34. Water class SAR Remarks
Low Na hazard 0-10 No hazard
Medium Na hazard 10-18 Moderate hazard
High Na hazard 18-26 Unsafe
Very high sodium
hazard
>26 Unsafe

35. RSC VALUE REMARKS
<1.25 Good quality
1.25-2.50 Moderate quality
>2.50 Unsafe

36. Class Sensitive
crops
Semi tolerant
crops
Tolerant crops Remarks
Very low <0.33 <0.67 <1.00 Safe
Low 0.33-0.67 0.67-1.33 1.00—2.00 Little
management
required
Medium 0.67-1.00 1.33-2.00 2.00-3.00 Unsafe
High 1.00-1.25 2.00-2.50 3.00-3.75 Unsafe
Very high >1.25 >2.50 >3.75 Unsafe

37. Cl- concentration Quality of water
4 Excellent
4-7 Moderate
7-12 Unsafe
12-20 Not suitable
>20 Toxic