Characteristics of soil which encourage a good response of crops to fertilizers

1. Characteristics of soil which encourage a good response of
crops to fertilizers
&
Saline, Alkali and Saline-alkali soils
Course No.: AGRON-608
(Soil conservation and watershed management)
Presented by:
Rohit Y. Karde
PhD 1st year
PGI, Dr. PDKV, Akola

2. Characteristics of soil which encourage a
good response of crops to fertilizers

3. Why are we studying this?
Crop response to fertilizer application depends
not only on the level of available plant nutrients
in the soil but is also related to crop physiology
and morphology, soil biological, physical and
chemical properties. For a well balanced
nutrition, the rate of nutrient supply to the
roots must correspond with the rate of nutrient
required for growth.
(K. Mengel, 1983)

4. How soil affects crop production?
• Soil is a living, breathing, natural entity composed of solids, liquids,
and gases. Soil has five major functions:
North Carolina Extension Gardener Handbook
Provides a
habitat for
organisms
Recycles
waste
products
•Filters water
•Serves as an
engineering
material
•Provides a
medium for
plant growth

5. The fifth function
• In this role, soil provides structural stability for plants and retains
and relinquishes water and the nutrients necessary for plant
growth.
• An ideal soil for plant growth contains 50% pore space and 50%
solids, with the pore space filled with equal parts air and water.
• This distribution rarely occurs because pore space varies with soil
texture and soil management. For example, tilling increases pore
space, while poor drainage and compaction reduce it.

6. North Carolina Extension Gardener Handbook

7. Characteristics of soil which encourage a good
response of crops to fertilizers
Soil Chemical
properties
Biological
properties
Moisture
Organic
matter
Physical
properties

8. Physical properties
• Physical properties are the most visible and can be
observed without using equipment.
• They are reflective of the solid soil particles such as
sand, silt and clay and the manner in which they are
arranged.
• They can be used to define and classify soil types and
horizons. In addition, they are very effective for
field/lab demonstrations. They include:
•Structur
e
Texture
•Infiltration
and
Permeability
•Porosity
•Aggregatio
n and
Aggregate
Stability
•Bulk
Density
•Crusting
•Compaction
•Water
Holding
Capacity and
Available
Water
•Temperatur
e

9. Directly and indirectly, soil structure impacts
on soil fertility and crop productivity…
Cooper, 2011

10. Soil health management suggestions for soil physical properties
S. No. Parameters Short term management Long term management
1 Available water
capacity
*Addition of stable organic materials
*Addition of biochar or compost
*Reduce tillage
*Rotation with sod crop
*Incorporate high biomass cover crop
2 Surface hardness
*Use of some mechanical soil loosers
(striptill, aerators, broadfork, spader)
*Grow shallow rooted cover crops
*Use a living mulch
*Shallow-rooted cover/rotation crops
*Avoid traffic on wet soils
*Avoid excess traffic/tillage/loads
*Use controlled traffic patterns
3 Sub-Surface hardness
*Use targeted deep tillage (subsoiler,
chiselplough, spader)
*Plant deep rooted cover crops
*Avoid disk plough that create pans
*Avoid heavy loads
*Reduce traffic when sun soil is wet
4 Aggregate stability
*Incorporate fresh organic matter
* Grow shallow rooted cover crops
*Add green manure and manures
*Reduce tillage
*Use a surface mulch
*Rotation with sod crops
5 Organic matter
*Addition of stable organic materials
*Addition of biochar or compost
*Reduce tillage
*Rotation with sod crop
*Incorporate high biomass cover crop
Urvashi et al., 2019

11. Biological properties
• Biological Properties represent the direct
and indirect influence of the living
organisms habituating a particular soil.
• Soil biological properties reflect how well-
suited a soil is to support life. Most of the
properties require specialized and high
powered equipment for observations or
measurements. They include:
•Active
and Total
Carbon
Organic
Matter
•Earthworm
s
•Enzymes
•Nematode
s
•Respiration
•Nitrogen
Fixation
•Fungi and
Bacteria
•Other
microorganis
ms

12. Lotus arise, 2021

13. Chemical properties
• Chemical properties represent the
complex chemical reactions and processes
occurring in the soils.
• They represent nutrient availability,
deficiency, toxicity, salinity and sodicity
just to name a few.
• Almost all of the properties require field
equipment or lab analysis for
measurement. They include:
•Electrical
Conductivity pH
•Cation
Exchange
Capacity
•Nutrient
Content
•Sodium
Adsorption
Ratio
•C:N
Ratio
•Exchang-
eable
Cations
•Base
Saturation
•Exchangea
-ble Acidity
•Trace
Elements
and Heavy
Metals

14. Nutrient
availability
according to
the soil pH
Roques et al., 2013

15. How does CEC and soil colloids affect plant
nutrition?
• Soil colloids are the most active constituent of the soil and they are important because
their surfaces attract soil nutrients dissolved in soil, water as positively charged mineral
ions, or cations.
• Some cations are needed for plant growth, including calcium (Ca++), Magnesium (Mg
++), Potassium (K+), and sodium (Na+). They need to be dissolved in a soil water solution
to be available to plants when they are in close contact with root membranes.
• The fertility of the soil-water solution for plants is based on the capability of the soil to
hold and exchange cations; this is referred to as the cation exchange capacity. Without
soil colloids, most vital nutrients would be leached out of the soil by percolating water
and carried away in streams.
Lotus arise, 2021

16. Lotus arise 2021

17. The “5th R”
• The 4Rs provide a really nice framework to achieve cropping system
goals. The right source. The right rate. The right time. And the right
place. However, UW-Madison soil fertility professor Carrie Laboski
believes a “5th R” should take priority – the “Right Data”.
eKonomics 2022

18. The 4Rs
eKonomics 2022
The 5thR

19. Conclusion
• Maintaining the soil health (Soil physical, chemical, biological
properties) should be our topmost priority to get the better response
of crops to fertilizer application. Incorporation of organic matter,
better drainage facilities and preventing soil compaction are the few
things to keep in mind other than fertilizer application during the crop
production, as they lead to better soil health and fertility.

20. Saline,
Alkali
and
Saline-
Alkali
soils

21. What are salt affected soils?
• Salt-affected soils (SAS) include saline, sodic, and saline-sodic soils- and many
sub-categories depending on the type of salts.
• Saline soils contain an excessive amount of soluble salts (calcium, magnesium,
potassium, sodium, chloride, carbonate, and sulfate) that reduces the ability of
plants to take up water from soil.
• Only specially adapted plants - halophytes and salt tolerant crops - can grow well
in these soils.

22. Global distribution of salt-affected land area.
Source: FAO 2015; Butcher et al., 2016; Zaman et al., 2018

23. Distribution of salt-affected land in India
Source: Mandal et al., 2009; Sharma and

24. Salt-affected soils of Purna valley in
Vidarbha region of Maharashtra
Kadam et al., 2013

25. Map of Purna Valley Tract in Vidarbha region of
Maharashtra
Kadam et al., 2013

26. Classification of salt-affected soils
Salt affected soil Soil pH (pHs) Electrical
conductivity(EC
e) (dS m-1)
Sodium
adsorption ratio
(SAR)
Exchangeable
sodium
percentage
(ESP)
Soil physical
condition
None < 8.5 < 4 <13 < 15 Flocculated
Saline < 8.5 >4 <13 < 15 Flocculated
Sodic > 8.5 < 4 >13 >15 Dispersed
Saline-sodic < 8.5 >4 >13 >15 Flocculated
Introductory Soil Science – D. K. Das

27. Saline Soils
• These salts can be made up of calcium, magnesium, potassium, sodium, chloride, carbonate, and sulfate.
Usually saline soils still have good physical structure and water infiltration and soil permeability is not
affected. Specific physicochemical characteristics include:
• Electrical Conductivity: >4 ds m-1
• Exchangeable Sodium Percentage: <15%
• Sodium Adsorption Ratio: <13%
• pH: <8.5
• Visual: white crusts on soil
• Because of the presence of excess salts and low amounts of Na+ ion on exchange sites, these soils are
usually in a flocculated state and their permeability is considered to be equal to or higher than the normal
soils. Most of these soils have salt efflorescence or white encrustation of soluble salts at the surface. In India,
these soils are known by different names such as ‘Thur’ in Punjab, ‘Reh’ in Uttar Pradesh and ‘Luni’ in
Rajasthan.
Choudhary and Kharche, 2018

29. Sodic Soils
• Sodic soils are similar to saline soils, however the soil solution of sodic soils are dominated by sodium which
tends to disperse soil particles leading to negative impacts on soil physical structure and reduced water
infiltration or if clay particles are dispersed and leach to a lower layer, reduced permeability may be seen
rather than reduced infiltration at the surface. Specific physicochemical characteristics include:
• Electrical Conductivity: <4 ds m-1
• Exchangeable Sodium Percentage: >15%³
• Sodium Adsorption Ratio: >13%
• pH: >8.5
• Visual: Dispersed, crusts, structure compromised, can be very dark in color
• When organic matter is dispersed and deposited on the surface, sodic soils appear brown-black and are
sometimes known as black alkali soils. These soils are also known as ‘Kallar’ in Punjab, ‘Usar’ in Uttar
Pradesh and ‘Kshar’ in Gujarat.
Choudhary and Kharche, 2018

30. A sodic soil in
Australia with
significant loss
of porosity due
to aggregate
instability.
(https://www.agric.wa.gov.au/dispersive-and-sodic-soils/identifying-dispersive-sodic-so

31. Saline-Sodic Soils
• Soils can be a combination of saline and sodic. Saline-sodic soils tend not
to be afflicted with poor physical structure as their soil solution is
concentrated with soluble salts that help floculate (not disperse) the
soil. Specific physicochemical characteristics include:
• Electrical Conductivity: > 4 4 ds m-1
• Exchangeable Sodium Percentage: >15%
• Sodium Adsorption Ratio: >15%
• pH: <8.5
• Visual: Not dispersed, okay structure, not usually dark in color.
Choudhary and Kharche, 2018

32. The difference between flocculated (aggregated) and dispersed soil structure. Flocculation (left) is
important because water moves through large pores and plant roots grow mainly in pore space.
Dispersed clays (right) plug soil pores and impede water movement and soil drainage.

33. The types of soil salinity and sodicity (FAO)

34. What Causes Soil Salinization?
• Soil salinization occurs
when soluble salts are
retained in the earth.
It happens either
naturally or because of
improper
anthropogenic
activities, particularly
farming practices.
Besides, some earths
are initially saline due
to low salt dissolution
and removal. Soil
salinization causes
include: (FAO)

35. Irrigation Salinity
• Irrigation salinity occurs where saline groundwater tables rise, under the direct
influence of irrigation, to a level which limits plant growth.
• The major causes of irrigation salinity are:
i. excess use of irrigation water
ii. inefficient water use
iii. poor drainage
iv. irrigation of inappropriate soils
v. seepage from irrigation channels, drains and water storages
• Any of these may lead to a rise in the water table. If the ground water is
inherently salty, or if there are salt stores in the soil below the root zone, saline
water can invade the root zone and result in irrigation salinity.

36. Schematic diagram of changes to the distribution of salt in the landscape due to change in
land-use (Department of Agriculture and Rural Affairs (1980) ‘Managing Salinity: Ensuring a
Farming Future’. The State of Victoria)

37. Effects of soil salinity on plants
Sahab et al. 2021

38. Water
absorption
in salt
affected
soils
FAO

39. Detailed
representation
of salt stress in
plants
Zorb et al. 2013

40. Maize plant
under salt
water
irrigation
Farooq et al., 2015

41. Salt stress effects on maize plant growth and yield (from Kaya et al., 2013). A: Effect
of salt stress on growth; B: cob length; and C: grain filling of maize.

42. Reclamation methods and practices for saline soil management
Sahab et al. 2021

43. Equivalent quantities of some common amendments for sodic soil
reclamation
Amendment Relative quantity
Gypsum (CaSO4 2H2O) 1.00
Calcium chloride (CaCl2.2 H2O) 0.85
Sulphuric acid (H2SO4) 0.57
Iron sulphate (FeSO4.7H2O) 1.62
Aluminium sulphate (Al2(SO4)3.18H2O) 1.29
Sulphur (S*) 0.19
Pyrite (FeS2*) - 30% Sulphur 0.63
Pressmud (Lime sulphur, 9% Ca, 24% S) 0.77
* Hundred per cent oxidation is assumed of materials like sulphur or pyrite in order
to be as effective as soluble calcium compounds. In practice, however, this does not
happen; thus their effectiveness is much lower.
Choudhary and Kharche, 2018

44. Effect of gypsum on plant growth
Choudhary and Kharche, 2018

45. Crop bed configurations to mitigate negative effects of
salinity on crop growth
Bernstein et al. 1955

46. Salt tolerance of some grass, grains, crops, and vegetables to saline soils.
Common Name Botanical name Salt Tolerance (dSm-1)
Barley Hordeum vulgare L. 8.0
Bean Phaseolus vulgaris L. 1.0
Cotton Gossyoium hirsutum L. 7.7
Sorghum Sorghum bicolor (L.) Moench 6.8
Soybean Glycine max (L.) Merrill 5.0
Sugar beet Beta vulgaris L. 7.0
Rice Oryza sativa L. 3.0
Wheat Triticum aestivum L. 6.0
Asparagus Asparagus officinalis L. 4.1
Cucumber Cucumis sativus L. 2.5
Spinach Spinacia oleracea L. 2.0
Cowpea Vigna unguiculate (L.) Walc. 4.9
Carrot Daucus carota L. 1.0
Pea Pisum sativum L. 3.4
Tomato Lycopersicon lycopersicum (L.) Karst. ex
Farw.
2.5
Alfalfa Medicago sativa L. 2.0
Rye grass Lolium perenne L. 5.6
Source: Qadir et al., 2000; Machado and Serralheiro, 2017

47. Conclusion
• The first step for ensuring crop production in salt-affected soils is to lower the salinity within
acceptable limits by leaching out the salts and maintain salt and water balance in the root zone.
It is important to ensure adequate drainage in the soil.
• For reclamation of sodic soil, application of appropriate amendment such as gypsum
(CaSO4.2H2O) is required to displace sodium ions from the exchange complex before initiating
leaching. Calcium supplied through gypsum or any other amendment will stimulate flocculation
and increase permeability of the soil to facilitate leaching of the replaced sodium and other
salts out of the root zone.
• Injudicious use of poor quality ground waters in many arid and semi-arid regions for irrigation
leads to the build-up of salinity and/or sodicity in soil and deterioration of soil health because of
which sustainability of crop production is adversely affected. Despite these harmful effects, the
poor quality waters can also become a valuable resource for irrigation and sustaining crop
production, when used and managed correctly.

48. Thank you!