Croda: The role of soil adjuvants in the planet’s sustainable future

Laura Weatherhead, Applications Team Leader at Croda, explores how the design of their sophisticated soil adjuvant, Hydravance 200™ can increase crop yields while minimising negative effects on our environment, particularly around availability and sustainable management of water. This directly contributes to helping to achieve multiple UN sustainable development goals (SDGs).

There is increasing pressure on farmers today to carefully manage their water usage. The Food and Agricultural Organisation (FAO) of the United Nations states that “Agriculture tends to have a much lower water use efficiency compared to other productive sectors. Increasing agricultural water productivity is therefore a key intervention for improving water use efficiency.”

As innovators of agrochemicals, we can all play our part to collectively design products that contribute to achieving the 17 UN SDGs and therefore relieving some pressures on farmers. An example of this is our sophisticated soil adjuvant (Hydravance 200) that contributes to four of the UN SDGs which I will highlight throughout this article.

To learn more about Croda’s strategy and commitment to sustainability, click here.

The role of soil adjuvants in agriculture and land management

It is well understood that one of the biggest challenges the world will see in the next century is being able to meet the demands of the growing population. It is forecasted that by 2050 we will require one hectare of land to yield enough food for six people, in comparison to only two people in 1960. This challenge must be met with a multifaceted approach if we are to succeed and within this soil will play a critical role in how it contributes to our ability to achieve the goal of feeding the world.

Within agriculture, the most common and effective way to optimise agricultural yields is through the application of chemical pesticides, of which pre-emergent herbicides and soil applied insecticides play an important role. There is increasing pressure to carefully manage applications, particularly of pre-emergent herbicides, as many of these are made directly to the soil and can potentially enter waterways, causing harm to the environment. When applying a spray solution to soil, it will follow the path of least resistance, moving around water repelling hydrophobic regions, leaving pockets of untreated soil. This causes some areas to remain untreated, and in combination with surface run-off may allow the establishment of weed germination, diseases and insect infestations. Adjuvants can be used to increase the efficacy of soil applied herbicides, insecticides and liquid fertilisers by facilitating root uptake mechanisms. It is important to optimise and balance multiple surfactant modes of action, to ensure the adjuvant can deliver improvements in efficacy when applied in the field.

Whilst yields can be optimised through the application of chemical herbicides, it is arguably important to acknowledge the role that soil health can play in managing and maintaining land output. A significant portion of soil erosion is the unintentional side effect of land-use practices such as tillage and clear cutting. It is critically important to minimise the erosion of agricultural soils and restore the productivity of soils that have already been degraded if we are to meet the demands of the growing population. Poor soil quality can result from inadequate soil fertility, infrequent crop rotation or over farming of the same land.

Furthermore, poor soil management can lower the nutritional content of soil and increase the requirement for the addition of fertiliser. Two key issues that fall into this bracket which can be impacted by adjuvant application include, soil hydraulic conductivity (the ability of soil to manage, hold and drain water) and soil nutrient management. Soil compaction can frequently occur in intensively farmed land, resulting in compression of pores that would otherwise transport water and air. This can impede root growth of crops and can cause oxygen deficiency. By reducing the number of applications required to the land, the impact of soil compaction can be reduced. Flooding and precipitation leaches nutrients out of the soil and often erodes the top layer of soil itself. Facilitating surface water penetration can maintain and protect soil and nutrient erosion caused by excessive rainfall.

Additionally, heavy rainfall onto dry soils can result in significant run-off and thus poor use of water resources. This is likely to become more of an issue with the changing climate (more drought, heavier rain bursts etc).

Introducing Hydravance 200:

Hydravance 200 is a soil adjuvant designed by Croda to deliver four key modes of action to address better soil management and permit a more sustainable approach to farming.

Table 1: Physical properties of Hydravance 200

Table 2: Regulatory information of Hydravance 200

Modes of action of Hydravance 200

Hydravance 200 has four key modes of action. Here we will explore how these are technically addressed and their impact relating to the SDG.

1. Hydravance 200 increases soil penetration

It can be difficult for water to penetrate soil due to a high natural surface tension, particularly when it is dry. Rapid and complete absorption of irrigation water into the ground is essential to achieving optimised crop growth as plants require water to remain healthy. Additionally, pre-emergent agrochemical treatments are typically applied using water-based delivery systems so need to penetrate into the soil to deliver the target action. Hydravance 200 reduces surface tension of spray solutions, which allows it to be readily absorbed into the hydrophobic soil, increasing penetration. By modifying the surface tension of the spray solution, the soil adjuvant reduces surface run-off and pooling, delivering the product into the soil where it needs to be effective.

Figure 1: The effect of Hydravance 200 on surface tension and soil penetration

Figure 1 depicts a spray droplet with and without the inclusion of Hydravance 200. The application of Hydravance 200 lowers the interfacial tension between the ground water and soil surface resulting in increased wetting. This reduces water repellency and therefore improves infiltration.

Reducing surface-run off, is not only good for the effectiveness of the treatment but it is one of the major sources of environmental contamination (leaching). If more of the spray solution penetrates the soil it is less likely to enter waterways and contaminate them. Surface run-off can be exacerbated by climatic events such as droughts as it causes soil to become more hydrophobic and therefore more difficult to penetrate. However, Croda’s soil adjuvant can improve infiltration even in these harsh conditions.

2. Hydravance 200 facilitates an even distribution in the soil profile

Hydravance 200 improves the distribution of water-based applications throughout the soil profile, helping them to move into, and through, micro and nano-pores in the soil, normally avoided by water alone due to unfavourable hydrophobic interactions of compositional matter.

Soil applied agrochemical treatments are most effective when they are evenly distributed throughout the soil. An even coverage and distribution of application eradicates dry or unprotected spots in the soil profile.

Figure 2: Schematic depicting improved soil coverage with Hydravance 200

Figure 3: Dehydrated soil plugs after application with water, a standard surfactant and Hydravance 200

Figure 4: Video demonstration of how Hydravance 200 improves soil coverage

For further video demonstrations click here.

Figures 2 and 3 shows the effect of spray solutions with and without the inclusion of Hydravance 200. Without a soil adjuvant, spray solutions that are simply mixed with water, follow the path of least resistance usually forming channels. This results in poor distribution, leaving dry or unprotected spots in the soil profile. However, Hydravance 200 ensures homogeneous wetting of the soil profile by interacting favourably with both water and the lipophilic components within soil. When using Hydravance 200 alongside irrigation, each seed or plant receives a uniform amount of water which is beneficial for growth and development.

When included as part of a chemical application, the soil adjuvant ensures more even distribution of the plant protection active ingredient, contributing to better coverage and protection. This ultimately leads to improved efficacy and a more sustainable contribution to agricultural productivity.

3. Hydravance 200 reduces evaporation rate

Hydravance 200 slows down the evaporation of water from the soil profile. This helps to conserve water whilst improving bioavailability of nutrients and treatments by maintaining them in solution for longer.

There is increasing pressure on farmers to conserve water and use it in the most efficient way. Low humidity, high temperature and lots of sunlight all increase the rate of evaporation of soil moisture and water loss from plants.

Figure 5: Schematic depicting how soil adjuvants retain moisture in soil

Figure 6:  Water retention study in soil plug profiles

The favourable bridging interaction Hydravance™ 200 imparts on water and soil components slows down the dehydration of the soil profile. This helps to conserve water whilst improving bioavailability of nutrients and treatments by maintaining them in solution for longer. Experimental data shows that the rate of evaporation of water can be reduced from 1.58% per hour to 0.55% per hour, almost three times longer with the inclusion of Hydravance 200.

4. Residual wetting properties

One application of Hydravance 200 is expected to improve the performance of subsequent non-adjuvanted treatments due to its residual wetting properties. The design of Hydravance 200 carefully considers the biodegradability and ecological persistence of the material, where based on component data the product is expected to be biodegradable.

Figure 7: Schematic depicting the extended performance of Hydravance 200

Once a field had been sprayed with Hydravance 200, subsequent applications that do not contain an adjuvant also benefit from the performance provided by a previous application of Croda’s soil adjuvant due to its enduring effect in the field. As a result, some irrigation requirements may be reduced which can contribute towards using natural resources, such as water, in a more sustainable and efficient way. Due to this extended performance some irrigation requirements may be reduced which links to SDG goal target 6.4 and 12.2 about using natural resources (water) in a sustainable way.

Closing remarks

The UN SDGs have been described as closest thing to a strategy for planet Earth that humanity has ever generated. The agrochemical industry has a large part to play in taking every step to minimise our impact so that the world can continue to support generations to come. Hydravance 200 is an example of how we can help achieve these SDGs within our industry.

Hydravance 200 enhances the penetration of water into hydrophobic soil, improving the wetting and percolation of water throughout the soil profile. By improving penetration into the root zone and evenly distributing the treatment the application is more effective. Hydravance 200 helps to retain moisture within the soil, maintaining agrochemical treatments in solution for longer, nurturing seed and plant development and improving treatment bioavailability. These benefits contribute to sustainable management and efficient use of natural resources as well as demonstrating lower potential for persistence in soil and ecological impact.

For more information on Hydravance 200 click here.

To order your free sample of Hydravance 200 email cropcare@croda.com or contact your local Croda sales team.

Contact：

Laura Weatherhead

Applications Team Leader 

Croda Europe Ltd

Email: cropcare@croda.com

www.crodacropcare.com

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