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Soil Salinity: Repairing the world’s agricultural soils.

How do we bring our soils back to life for the next generation?

Of all of the world’s natural resources, the upper most layer of our soil is one of our most precious reserves. We grow 95% of our food in this highly valuable topsoil.

It is estimated that Mother Nature takes 1,000 years to generate just 3 mm of topsoil, so it is vital that we protect it. In the last 150 years, we have lost almost half of our productive, agricultural land. The UN’s Food and Agricultural Organisation reports that if we continue at the current rate of degradation, all topsoil will be gone within 60 years’ time – our descendants will pay the price.

Soil salinity one of the biggest threats to our global agricultural soils, the world’s largest industry and the wider food system. It is estimated that 20% of the world’s irrigated farmland is salt-affected. In 2018, the Intergovernmental Science Policy Platform of Biodiversity and Ecosystem Sciences, (IPBES) completed a global assessment of land degradation. The report revealed that soil salinization was one of the main factors reducing plant growth and agricultural productivity worldwide.

The annual global economic cost of lost crop production is US $27.3 billion.

Land affected by high levels of salinity totals 2.4 billion acres (or 1 billion hectares). That farmland generates 40% of the planets food. The UN university states that since the 1990’s, 5,000 acres have been lost, daily. We must urgently find cost-effective solutions for salinization to ensure we have enough to eat, to protect our environment and ensure our very existence on earth.

What is soil salinization?

Soil salinization is the most common land degradation processes caused by the salt levels in water. Salinization is the excessive accumulation of the soluble salts on the surface and in the sub-soil.

The amassing of salts in soil is a natural process; it is more prevalent in arid and semi-arid regions. In river basins where there is no outlet, run-off can collect and evaporate, leaving the salt behind. However, secondary salinization has accelerated the process substantially; this includes poor irrigation practices, the use of saline rich or brackish water to irrigate and poor land drainage. The irrigation water carries the dissolved salts directly to the root zone. This toxicity is detrimental to the plant and creates significant productivity concerns for the farm.

The salt accretion places the plant under Osmotic Stress, which affects the crops ability to absorb water, even if it is present. Horizontal salt crusts at the surface and vertical salt walls channel water away from the plant’s root system, restricting the water infiltration. The Osmotic pressure also interferes with the plants Nitrogen uptake and harmful Ions found within Chloride and Sodium creates a toxic effect. This Ionic Stress inhibits other positively charged Ions, which are essential for healthy plant growth.

The combination of these processes not only results in slow plant development, it can suffocate the crops and lead to complete crop failure as the soil turns into ‘sand’. This results in soil hyper-salinity, soil erosion, and desertification. The secondary impacts on our global food and nutrition security, poverty and negative migration are far reaching - leading to concerns about the sustainability of irrigated agriculture.

The effects of climate change exacerbate salinization. Erratic precipitation, drought, high evaporation rates of shallow groundwater, flooding, and sea level intrusion only adds to the crisis. Although not fully understood as yet, crop scientists widely agree that soil salinity also increases Nitrous Oxide emissions – a greenhouse gas that remains in our atmosphere for 114 years and is 300 x more potent that CO2.

Agro-ecosystems are very sensitive to soil salinization, both yield and produce quality deteriorating rapidly within this growing environment. Destroying the structure of the soil, it strips the nutrients, minerals and vast soil biodiversity that support healthy plant growth. A 2004 study published in the Journal of the American College of Nutrition showed significant declines in Protein, Calcium, Iron and Vitamin C and B2 between 1950 and 1999.

Farm yields can be reduced by as much as 30%.

Solutions for agricultural soil salinization.

Secondary salinization is estimated to affect 190 million acres of land. (77 m. ha). The good news is that rehabilitation of our agricultural soils is possible. The earlier detection of high concentrations in farm soils, the better the changes for recovery.

Improve sub-surface drainage.

Fresh irrigation water can be applied to flush the excess salts away from the root zone but without the improvements to the sub-surface drainage, the land will become waterlogged and erode further. The installation of drainage tech is an effective method, but requires significant investment. In India, implementation of irrigation schemes without complementary drainage plans have resulted in large-scale salinization in the Uttar Pradesh state with 14 million acres (5.7 m.ha) damaged.

The vast majority of the world’s 537 million farms are less than two acres; 90% are run by individuals or families. These smallholdings simply don’t have access to the resources required for this more expensive solution.

Optimize water distribution.

The use of continuous drip irrigation systems can improve water distribution efficiency. By slowing the delivery of water, plants can absorb it more effectively. However, as above, the low incomes of farms limits the ability to invest in and maintain new irrigation systems.

Farms can also save valuable fresh irrigation water by adding mulch, manure or crop residue as a cost-effective way to reduce evaporation and boost the saline soil’s low organic matter.

Implement Halophyte crop rotation.

Saline tolerant crops can be grown on rotation to absorb the salts present; this can be followed by other crops or left fallow for intermittent periods to aid recovery. Whilst Halophytes, such as Quinoa are seeing some market growth, demand for human consumption of Halophytes is still relatively low despite them being rich in antioxidants, fatty acids and amino acids. Salt-tolerant varieties are considered an alternative solution to the food and nutrition security crisis, fresh water scarcity and salinization.

Sustainable water treatment technology.

Whilst the reduction of irrigation with saline-rich water is in itself a solution, in many arid and semi-arid regions the only accessible water source is hard, saline or brackish water. An emerging water treatment for agriculture means that farmers can use this available high salinity water without harming soil biodiversity or causing long-term structural damage to their soil. In fact, this advanced agri innovation actually repairs the soil, breaking down salt crusts and walls, improving water infiltration and plant absorption. The chemical-free, solar powered treatment for water reduces salinity by up to 50%, improving the quality of irrigation water. The sustainable treatment also saves up to 20% water and reduces the need for synthetic fertilizers, which are known to increase salinity further. This reduces costs for both, which is good news for farmers that now have to pay for their fresh irrigation water.

Recognising that farmers do not have vast finance reserves to pay for agricultural innovations in full, manufacturers of sustainable water technologies such as ALVÁTECH have made their technology available on a subscription basis to global farmers.

In the world’s drylands in particular, our reliance on irrigation systems to produce enough food for the global population grew, and so too did the salt-affected soils areas of the world. According to the UN University, this area increased by 111 million acres (45 m.ha) between the 1990’s and 2014 – an area the size of France. The study by IPBES suggests that approximately 190 million acres (76 m.ha) or irrigated land has already been permanently lost to salinization.

It is hoped that the global Governments, NGO’s and policy makers can assist by incentivising irrigation best practice. The use of precision agriculture farming technology alongside sustainable practices, such as crop rotation will pay dividends for our future generations. However, we must start now to keep our soil healthy and avoid serious global food and water shortages.

About the author.

Yuval Chen

Chief Agronomist

ALVÁTECH Water Revolution.

An international arid land agronomy expert, Yuval brings decades of experience working with research centres and global corporates whilst being an advisor to national governments & farmers. Always seeking to the at the leading edge of innovation, Yuval’s substantial knowledge in the field means that he has effectively united the needs of farmers with science & practicality to create ALVÁTECH's solutions.


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