Sandy soils RG.pptx

Problematic soils

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

5. 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.

6. 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.

7. 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

8. 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 .

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

10. 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.

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

12. 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.

13. 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 .

14. 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

15. 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.

16. 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

17. 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

18. 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

19. 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

20. 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.

21. 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 )

22. Available water for various sandy soil textures

23. 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.

24. Methods of Irrigation Scheduling

25. Classification of Irrigation Scheduling

26. 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 .

27. 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.

28. 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 .

29. 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 .

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

31. 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 .

32. 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.

33. 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

34. 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)