Sand - A TerraSoil Overview

Understanding Sand

Sand is a granular material composed of small mineral particles, ranging in size from 0.05 to 2.0 millimeters in diameter. Any type of mineral that is reduced to 0.05-2.0 millimeters can be classified as a sand so the chemical composition and usefulness varies greatly. It is characterized by its gritty texture and forms the largest component of soil particles in sandy soils. Overtime the sand particles are reduced to silt and clay through natural erosion mechanisms. Sand particles are typically derived from the weathering and erosion of rocks and minerals, transported by wind, water, or glaciers to deposit in various landscapes.

Formation of Sand

Sand is formed through the mechanical and chemical weathering of rocks and minerals over geological time scales. As rocks break down into smaller fragments through processes such as abrasion, erosion, and disintegration, sand-sized particles are produced and transported by natural agents such as rivers, waves, and glaciers.

Sand Examples

Benefits of Sand in Soil

1. Soil Aeration: Sand particles promote soil aeration and porosity, facilitating gas exchange and enhanced root respiration. This reduces the risk of root rot.

2. Drainage Improvement: Sandy soils have excellent drainage properties, allowing excess water to percolate freely through the soil profile. This reduces the risk of standing water.

3. Root Development: Coarse sand particles provide a loose, friable texture that promotes root penetration and exploration, enhancing nutrient uptake.

4. Soil Warming: Sand soils warm up quickly in spring, facilitating seed germination and early plant growth, particularly in cooler climates.

5. Soil texture: Sand can help break up compacted or heavy clay soils, shifting the texture towards the ideal loam.

Negatives of Sand in Soil

1. Nutrient Leaching: Sandy soils are prone to nutrient leaching, as water moves rapidly through the porous soil profile, carrying away soluble nutrients.

2. Low Water-Holding Capacity: Sand soils have low water-holding capacity, requiring frequent irrigation and management to sustain plant growth during dry periods.

3. Soil Erosion: Sandy soils are susceptible to erosion by wind and water, leading to soil degradation and loss of fertility over time.

4. Fertility Challenges: Sandy soils typically have low fertility due to their low nutrient-holding capacity and limited organic matter content, requiring supplemental fertilization.

5. Surface area: The reduced surface area of sand results in a reduced ability to retain nutrients or host large bacterial and fungal populations when compared to silt or clay fractions.

Optimum Level of Sand in Soil

The optimum level of sand in soil varies depending on factors such as soil texture, climate, crop type, and management practices. Typically a sand fraction of over 50% is considered the limit for loam type soil. Areas with heavier rainfall would want to have a higher sand content to reduce waterlogging. Equally, warmer climates would want a lower sand level to increase water retention. A balanced soil texture, containing a mixture of sand, silt, and clay particles, promotes optimal soil structure, drainage, and fertility.

Benefits of Adding Sand to Compost

Incorporating sand into compost can improve its texture, aeration, and drainage properties. Sand particles act as a bulking agent, enhancing compost structure and reducing compaction. The sand provides structure and in correct quantities increases porosity. Additionally, sand-amended compost provides a source of minerals and promotes microbial activity, enhancing decomposition and nutrient cycling.

Dangers of Using Sand and Appropriate PPE

Handling sand can pose health risks due to inhalation of fine particles and skin irritation. Appropriate personal protective equipment (PPE), including dust masks, gloves, and protective clothing, should be worn when working with sand to minimize exposure and ensure safety.

Sustainability of Using Sand

The sustainable use of sand in agriculture relies on responsible management practices that optimize its beneficial properties while mitigating potential drawbacks. The specific chemical composition of the sand has a large effect on the potential benefits being provided. The primary concerns for sand sustainability is regarding the extraction methods used and the specific mineral being used. Incorporating organic matter, practicing crop rotation, and implementing erosion control measures can enhance soil health and minimize environmental impact.

Conclusion

Sand, a crucial element of fertile soils, offers a way to increase resilience and adaptability in the face of environmental challenges. Through controlling the size of the sand fraction, Farmers can manipulate the soils characteristics and nutrient profile to better suit the local environment and plant species. Let us utilise the natural benefits sand can offer and cultivate a future where soil fertility thrives in harmony with nature's abundance.

References:

1.      Lal, R. (2015). Principles of soil physics. CRC Press.

2.      Brady, N. C., & Weil, R. R. (2016). The nature and properties of soils (15th ed.). Pearson.

3.      Hillel, D. (2004). Introduction to environmental soil physics. Elsevier Academic Press.

4.      Goldstein, A. H. (1994). Involvement of the quinoprotein glucose dehydrogenase in the solubilization of exogenous phosphate by Gram-negative bacteria. Soil Biology and Biochemistry, 26

5.      Scharenberg K., Demars B.O.L., Wildenschild D., Carminati A. (2017) Physical and Hydraulic Properties of Sandy Soils Amended with Biochar. Soil Science Society of America Journal. 81(5):1194-1203.

6.      Lal R. (2016) Benefits and Limitations of Biochar for Sustainable Soil Management. Frontiers in Plant Science. 7:1487.

7.      Kaur H., Singh B., Gupta S.R., Nain L. (2019) Effects of Sand Application on Soil Chemical Composition and Crop Yield in a Subtropical Region. International Journal of Agriculture and Biology. 21(6):1275-1280.

8.      Ghimire R., Norton J.M. (2018) Influence of Sand Addition on Soil Structure and Water Retention. Soil Science Society of America Journal. 82(3):561-569.

9.      Al-Wabel M.I., Usman A.R.A., Al-Faraj A.S., Ahmad M. (2016) Soil Amendments with Biochar and Sand: Impacts on Soil Texture and Crop Productivity. Geoderma. 289:29-39.