Tackling Soil Remediation: Addressing the Impact of Drought, Soil Compaction, Alkalinity, and Salinity

Paolo Bravini

Business Development Manager Agrochemicals at IMCD

paolo.bravini@imcd.it

Soil, often regarded as the Earth's living skin, plays a vital role in supporting life on our planet. However, various factors such as drought, soil compaction, and salinity have significantly compromised its health and functionality. Soil remediation, the process of restoring contaminated or degraded soil to a healthy state, is essential to safeguarding agricultural productivity, environmental sustainability, and human health. In this article, we'll explore the challenges posed by drought, soil compaction, alkalinity, and salinity, and discuss effective strategies for soil remediation.

The Impact of Drought on Soil:

Drought, characterised by prolonged periods of dry weather and water scarcity, poses a significant threat to soil health. During droughts, soil moisture levels decrease, leading to desiccation and reduced microbial activity. This can impair nutrient cycling, decrease soil organic matter content, and compromise soil structure. As a result, drought-affected soils become less fertile and more prone to erosion.

The Impact of Soil Compaction:

Soil compaction, caused by over fertilization, heavy machinery, foot traffic, and natural processes, occurs when soil particles are pressed together, reducing pore space and restricting root growth. Compacted soils have poor aeration, drainage, and water infiltration capacity, which impairs plant growth and productivity.

The Impact of Soil Alkalinity:

Soil alkalinity, characterised by a high pH level, exerts a profound impact on plant growth and soil health. Alkaline soils often harbour excessive amounts of soluble salts, such as carbonates and bicarbonates, which can inhibit nutrient uptake by plants and impede root development. Additionally, the presence of alkaline compounds can alter soil structure, reducing water infiltration and drainage capacity, leading to waterlogging and root asphyxiation. In regions where alkaline soils prevail, agricultural productivity may be severely compromised, necessitating targeted soil management practices such as soil amendments and pH balancing to mitigate the detrimental effects of soil alkalinity and promote optimal plant growth.

The Impact of Soil Salinity:

Soil salinity, resulting from high levels of soluble salts in the soil, negatively impacts plant growth and productivity. Saline soils have poor water infiltration and drainage, leading to waterlogging and root damage. Excessive salinity can also disrupt nutrient uptake and inhibit microbial activity in the soil.

IMCD is an ideal partner for formulators of soil remediation and soil health products, offering expertise and resources in environmental science and agricultural technology. Within our portfolio, IMCD introduces novel ingredients for innovative solutions tailored to address soil complexities, leveraging advanced technologies and a deep understanding of soil microbiology and chemistry.

KANEKA Surfactin

Wetting agents, also known as surfactants, play a crucial role in soil management by enhancing water penetration and distribution within the soil profile. These compounds reduce the surface tension of water, allowing it to spread more evenly across the soil surface and infiltrate deeper into the soil matrix. By breaking down hydrophobic barriers and promoting uniform moisture distribution, wetting agents improve soil structure, increase water retention, and enhance nutrient uptake by plant roots. In agricultural settings, they are commonly used to combat soil water repellence, alleviate drought stress, and improve irrigation efficiency. Additionally, wetting agents can aid in the dispersion of pesticides and fertilizers, ensuring their uniform distribution and effectiveness in the soil.

In partnership with KANEKA, IMCD offers Surfactin, a biodegradable natural biosurfactant produced by Bacillus subtilis, which acts as an effective soil wetter by reducing the surface tension of water, thus promoting its infiltration into the soil (Fig. 2). Its unique properties make it a valuable tool in agriculture for enhancing soil moisture retention and improving water distribution, ultimately fostering healthier plant growth and crop yields. 

KANEKA Surfactin has a unique structure including a hydrophilic cyclic peptide part constructed by seven amino acids and a hydrophobic hydrocarbon chain (Fig. 1).

KANEKA Surfactin Key Characteristics:

• ECOCERT approved.

• Low dosing in formulation (0.05% w/w).
  

• Stable to heat and from acidic to weak alkaline conditions.
  

• Easily biodegradable (MITI test).
  

• Sustainable product made by fermentation under mild conditions. 
  

Figure 1: Chemical structure of KANEKA Surfactin.

Figure 2: Effect of Surfactin three minutes after dropping on water-repellent soil prepared by silica sand and octadecyl amine. Each water drop is 150 microliters.

SF: Surfactin. A: Organic wetting agent. B: Alcohol ethoxylated.

CrestHarvest™ 588 

CrestHarvest™ 588, an organic chemistry solution meticulously developed for soil salinity and alkalinity management, effectively unlocks essential nutrients such as calcium, magnesium, and phosphorus, thereby promoting soil health and fertility. In addition to its role in reducing sodium accumulation and mitigating soil salinity, CrestHarvest™ 588 also significantly enhances soil porosity, facilitating improved water infiltration and reducing the need for irrigation. Moreover, its phosphate-free composition maximises free calcium levels, leading to reduced gypsum usage and contributing to sustainable soil management practices. By optimising soil conditions and nutrient availability, CrestHarvest™ 588 minimises the reliance on nitrogen and phosphate fertilizers, thus mitigating runoff and reducing the risk of eutrophication in water bodies. 

CrestHarvest™ 588 initially ensures the availability of free fertilizer, subsequently unlocking bound nutrients for crop uptake. While some nutrients may become partially locked again over time, they are re-released before the next application (Fig. 3). Furthermore, the reduced consumption of urea facilitated by CrestHarvest™ 588 not only stabilises soil pH but also diminishes the potential for root diseases and eliminates the necessity for lime applications, underscoring its comprehensive approach to soil health enhancement and sustainable agriculture.

CrestHarvest™ 588 Key Characteristics:

• Reduces soil salinity and alkalinity to effectively reduce soil compaction.

• Improves germination, root growth, and plant establishment.
  

• Reduces usage of soil-applied fertilizers.
  

• Enhances quality of crops; higher yield attained with less agricultural chemicals and phosphate fertilizers used.
  

• It is inherently biodegradable.
  

CrestHarvest™ 588 can be incorporated into formulations for soil remediation meant to be applied by drip irrigation or used as a stand-alone product diluted in irrigation water systems. 

Figure 3: Effect on free nutrient and available fertilizers.

K-Huminate and Pure Humic Acid

The decrease in organically bounded carbon in soil is now a global problem that can be solved with humic acid. The soil organic carbon is linked to many important ecosystem services of the soil, such as filtering and storing water, building and maintaining soil structure, securing nutrient supply, and fixing and breaking down pollutants.

Humic substances are naturally occurring, bio-genic, organic molecules that arise as degradation products during the decomposition of plant remains. They represent the most important component of the humus layer, therefore playing a fundamental role in maintaining soil fertility and promoting sustainable play regular farming. Humic substances are divided into three different groups of substances: the humins, which are neither water-soluble in the acidic nor in the basic range, the humic acids, which are water-soluble in the basic range, and the fulvic acids, which are water-soluble in the acidic and basic ranges. The humic acids currently available on the market are obtained from Leonardite via alkaline extraction and, depending on their genesis, have very different molecular sizes and often a high level of heavy metal contamination. Using a new hydrothermal process, humic acids could be obtained from rapidly renewable plant raw materials under relatively mild conditions. By controlling the process, the molecular size can be managed, thereby always ensuring consistent quality. In addition, the humic acids produced in this way have a very low heavy metal concentration compared to the humic acids available on the market. The humic acids stabilise the soil structure through the formation of clay-humus complexes by increasing clumping, aeration, permeability, and storage capacity (Fig. 4).

Thanks to their composition, the products can be applied at a low dose of around 4 kilograms per hectare in crops.

The products are eligible for FiBL listing and can be used on their own or in combination with other ingredients to obtain the right formulation for each customer need.

K-Huminate and Pure Humic Acid Key Characteristics:

• Improves soil structure and increases humus formation.

• They promote aggregation, which improves soil structure, porosity, and aeration.
  

• Promotes root growth.
  

• Reduces the risk of soil erosion.
  

• Promotes soil life.
  

• Increases fertilizer efficiency.
  

• Reduces soil compaction.
  

• Improves the buffering capacity of the soil.
  

• Increases cation exchange capacity and thereby offers better binding and storage of plant nutrients.
  

• Improves water retention capacity.
  

• Absorbs heavy metals such as As, Cd, Ni, Cu.
  

• Increases the availability of macro and micronutrients and their transport into plant roots, resulting in stimulated plant growth.
  

• Increases soil temperature due to a dark soil surface.
  

• Balances pH value in (strongly) acidic and basic soils.
  

• Improves soils contaminated with salt and pollutants.
  

• Increases resistance to abiotic stress, e.g. drought, heat, UV radiation, frost, saline soils, nutrient deficiency, and pH value.
  

• Secures the harvest in quantity and quality.

Figure 4: The preparation scheme of artificial humic substances.¹

Bio-Hydrogel

IMCD has access to a new technical innovation, a biological water storage granulate based on a natural raw material - a bio-based super water-absorbing hydrogel. This 100% wood-based gel absorbs and stores water during rain and slowly releases it back to the plants during dry periods. The product is made from wood, a natural precursor of humus that converts non-fertile soils, including sand, into productive soils.

This granular hydrogel can be used alone or in combination with other ingredients in any form of irrigation, improving water footprint and reducing energy and labour. It helps save up to 40% water by reducing the frequency of irrigation (Fig. 5). It comes in the form of granules for in-furrow applications and in powder form for formulated applications like delivery of microbials to the soil or for solutions against drought.

Bio-Hydrogel Key Characteristics: 

• The first long-lasting bio-based hydrogel made from 100% wood.

• 100% peat free.
  

• Improves the soil texture and thus the exchange of soil gases.
  

• Active for at least five years, depending on soil.
  

• Increases the soil water-holding capacity.
  

• Protects plants and crops from drought.
  

• Degrades into humus, thereby increasing soil fertility.
  

• Converts non-fertile soils, including sand, into productive soils.
  

• Captures and stores fertilizer/nutrients and slowly releases them to plants.
  

• Prevents leaching of fertilizers and thus environmental pollution.
  

• Helps reduce water, fertilizer, irrigation, and labour costs.
  

• Approved for conventional and organic farming without restrictions.
  

Figure 5: Bio-Hydrogel after rehydration.

Conclusion

Drought, soil compaction, and salinity pose significant challenges to soil health and productivity, threatening global food security and environmental sustainability. However, through the application of innovative soil remediation products, we can restore degraded soils, ensure their long-term viability, and thus safeguard their health for future generations.

References: 

1.Fan Yang, Shuaishuai Zhang, Kui Cheng, Markus Antonietti. A hydrothermal process to turn waste biomass into artificial fulvic and humic acids for soil remediation. Science of The Total Environment, 2019.

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