Problematic soils

1. Characteristics and
Management of Sandy soils
Presented by
Rathinaguru.E
1st PG-AGRON

2. • Also known as light soils.
• Prevail mostly in drylands.
• Sand or sandy soils are formed by the smallest
or fine particles of weathering rocks.
• Sandy soils are usually formed by the
breakdown or fragmentation of rocks like
granite, limestone and quartz.
• Sand is the largest among soil particles.
• Finer than Gravel grains and coarser than silt
grains

3. • Natural vegetation is often formed of grasses
and woodlands –profitably utilised for a range
of grains and vegetables via imaginative and
intensive management.
• Ideal for Drainage systems
• pH range between 7.00 and 8.00

4. Characteristics: Textural Nature of soil
• It is the largest among soil separates.
• Sand is very gritty to touch. They are 2mm in
size
• Sand grains will not stick to each other.
• Sandy soils are coarse textured soils.

6. Colour of sandy soil
• Sandy soils are often light coloured
• Based on mineral matter present the sandy
soils are coloured.
• Mostly the colours of soil are white to yellow
or light pink.
• As organic matter content of soil is low it
does not shows the dark coloured
appearance.

8. Soil porosity
• Sandy soils have large number of macropores
and fewer number of micropores.
• Soil porosity determines the water and nutrient
retention condition of soils (Improves soil
drainage)
• It is the important phenomena contributes to the
most of physical reactions of the soils.

9. Structure
• Sandy soils have very loose soil structure.
• Soft soil surface(non hardsetting which may be difficult
to wet)
• Sub soil horizons which usually have a brighter colour
than the surface soil horizons
• Sandy soils does not hold together well(not sticky and
lacks cohesion) and needs to be amended with organic
matter to give it better structure

10. Water and nutrient holding capacity
• Sandy soils have poor water holding capacity.
• Due to large particle size of sandy soils it has
numerous macropores through which the
water is easily leaked out.
• It can’t withhold the nutrients or water as it is
leached through pores.
• Sandy soils have good drainage properties.

11. Hydraulic Conductivity
• Hydraulic conductivity of sandy soil are very
high.
• The water easily and fastly moves through the
soil column

12. Cation exchange capacity of soil
• The CEC of the soil is very low because sandy
soils contains very less amount of Organic
matter.
• Sand has no capacity to exchange cations as it
has no electrical charge.
• CEC can be improved in sandy soils by organic
matter amendments.

13. Plasticity and consistency
• Sandy soils have no plasticity.
• The plasticity index of sandy soils is zero

14. Swelling and shrinkage
• Sandy soils doesn’t shrink well. It is prone to
to erosion if proper drainage isn’t in place. The
sand will erode and settlement will occur.
• Swelling is never a property of sandy soils as
it does have any clay content.

15. Important problems of sandy soils
• High macroporosity
• Excessive drainage or less retention of irrigation
water.
• High percolation rate
• High evaporation and leaching.
• Low soil organic matter content
• Low fertility or low retention of added nutrient
• High erodability.

16. Management of sandy soils
• Application of organic matter can supply
nutrients in slowly available forms and
improve soil physico-chemical properties.
(Vermiculite, peat moss,coconut coir)
• For tillage to be really effective, it has to be
done at the earliest possible time after
irrigation or rainfall when the evaporation rate
is still high.
• Strip cropping ,Crop rotations

17. • Lay down a layer of mulch- Enchance water
retention by preventing excessive evaporation.
• Grow Cover crops – G.M crops improve the
soil health by moisture and nutrient retention
• Overgrazing on coarse textured soils must be
avoided.The introduction of rotational grazing
helps helps to combat this hazard. It might be
better no to permit grazing but to use fodder
cut on feed lots.
• Afforestation with selected trees and shrubs
is complementary measures.

18. Suitable crops for sandy soils
• Carrots, Radishes,beets,onions, Potatoes,
Lettuce, Collard greens, Tomatoes, Zucchini,
Corn, Asparagus, Watermelon, Beans, and
Cucumber are suitable crops.
• Herbs : Thyme and Rosemary

19. • Establishment of shelter belts and
windbreaks are some of the protective
measures to counter the high susceptibility of
sandy soils to erosion.
• Drip irrigation system Installation- water the
soil with shallow frequent waterings.
Consistently moist throughout the warm
season

20. Irrigation decision factors
Phy. characteristics
• Soil depth –soil is deep with low gravels at a
depth more than 50cm. If depth more than 3
ft,rooting depth and available water for plants
is decreased …so more irrigation
• Texture- tends to be light, fast leakage of
nutritional elements occurs when water is
added at short intervals – O.M To improve
WHC

21. • Infiltration rate
Downward entry of water into soil. Unit inch/hr.
Allows through the soil profile .
But soil storage is important – root uptake,plant
growth, habitat for soil organisms
Hence more infiltration cause leaching or surface
runoff which leads to erosion
If erosion – nutrients and chemicals washed out –
reduce soil productivity-diminished water quality

23. • Soil Moisture content – Reservoir of water
(weathering, cation exchange, organic matter
decomposition, fertilization)important process
depends on this soil solution
• Bulk density – LOW as it is light textured
• Porosity- The porosity or pore space is that space
between the soil particles, which is equal to the
ratio of the volume of voids either filled with air
or with water to the total volume of soil,
including air and water. The porosity or pore
space of sandy soils is less than for clay soils.

24. Chemical Properties
• Salinity and sodicity - The most common cations
in arid and semi-arid areas are calcium,
magnesium and sodium. Each of these cations is
base-forming, meaning that they contribute to an
increasedOH- concentration in the soil solution
and a decrease in H+ concentration.
• They typically dominate the exchange complex
of soils, having replaced aluminum and
hydrogen. Soils with exchange complexes
saturated with calcium, magnesium and sodium
have a high base saturation and typically high pH
values
(Flocculation and deflocculation )

26. Available water for various sandy soil textures

27. Irrigation scheduling
• It enables the farmer to schedule water cycles among
the various fields to minimize cropwater stress and
maximize yields.
• It lowers fertilizer costs by holding surface runoff and
deep percolation (leaching) to a minimum.
• It increases net returns by increasing crop yields and
crop quality.
• It assists in controlling root zone salinity problems
through controlled leaching.
• It results in additional returns by using the “saved”
water to irrigate non-cash crops that otherwise would
not be irrigated during water-short periods.

28. Methods of Irrigation Scheduling

31. Classification of Irrigation Scheduling

32. Irrigation using wireless sensors
• To determine the actual crop water need through
sensing soil moisture using wireless techniques.
• Used in precision agriculture to assist in precise
irrigation where it can provide a potential
solution to efficient water management through
remotely sensing soil water conditions in the field
and controlling irrigation systems on the site.
• Sensors consists of radio frequency transceivers,
sensors, and microcontrollers.

33. • Infrared light, point-to-point communications,
wireless personal area network (WLAN),
Bluetooth, ZigBee, multi-hop wireless local area
network, and log-distance cellular phone systems
such as GSM/GPRS and CDMA.
• New wireless irrigation used a new system with
Single Board Computer (SBC) using Linux
operating system to control solenoids connected
to an individual or group of nozzles. The control
box was connected to a sensor network radio,
GPS unit, and Ethernet radio.

34. • Designed a Bluetooth wireless communication
in-field sensor and control software using four
major design factors that provide real-time
monitoring and control of both field data and
sprinkler controls. The system successfully
enabled real-time remote access to the field
conditions and site-specific irrigation.
• Smart sensors developed and evaluated a
remotely controlled automatic irrigation
system for an area using WLAN network. They
were able to save 30-60% of water usage.

35. • Developed a mobile field data acquisition
system to collect information for crop
management and spatial-variability studies
including available soil water and plant water
status and other field data.
• There is great potential for the
implementation of wireless sensors in the
irrigation of sandy soil, in which greater water
use efficiency will be achieved. The main
advantage of these technologies is to save
water use in agriculture sector.

36. Wireless sensor in the field that detects soil water
status at various depths

37. Case study
• Sandy terraces developed in poor eolian sands have been
discovered in the Glomma river valley, Hedmark, south-
eastern Norway, during the last two decades.
• These are of a specific morphological type which has not
been found elsewhere in Norway. Some of them have been
excavated and dated, stimulating an intense debate among
Norwegian archaeologists as to whether they are of
natural or anthropogenic origin, and whether or not they
were used for agriculture.
• One of these sandy terraces was investigated using
conventional radiocarbon dating, morphological
descriptions, pollen analysis and soil micromorphology in
connection with archaeological excavations.

38. • The pollen results were rather
poor, but the
micromorphology analysis,
combined with radiocarbon
dating, was able to reveal that
the terrace had developed
under strong anthropogenic
impact since c. AD 400–560
• The sandy soils had probably
been improved and used for
cultivation, interrupted by
lengthy fallow periods or
abandonment.
• Soil improvement seems to
have been intensified from c.
AD 1025–1220 onwards,
possibly for cultivating crops
with growth requirements that
matched these soil properties.

39. Conclusion
Sandy soils drain quickly (low WHC).
O.M helps plants get an extra boost of nutrients
by Improving soil nutrients and WHC.
Drip irrigation is a promising method but its cost
is still quite high. It is recommended to setup
field trials before embarking on large scale
developments with drip irrigation.
Wireless sensors in this can improve the water use
efficiency

40. References:
• https://www.masterclass.com/articles/sandy-soil-
guide
• https://prep.in/news/e-492-sandy-soils-
agriculture-notes
• www.fao.org/soil-management
• Mohamed S.Alhammadi and Ali M.Al-Shrouf,
(Irrigation of Sandy soils,Basics and
Scheduling),Intech-Open science
• Ingunn Holm& Barbara M.Sageidet (Origin of the
sandy terraces at Grundset, Elverum,South-
Eastern Norway)