‣ the number and volume of dry or unprotected spots in the soil profile . Figure 2 shows the effect of spray solutions with and without the inclusion of a soil adjuvant . Without one , spray solutions that are simply mixed with water follow the path of least resistance , usually forming channels . This results in poor distribution of the solution , leaving dry or unprotected spots in the soil profile . Incorporating an adjuvant ensures homogeneous wetting of the soil profile by driving favourable interactions between water and the lipophilic components within the soil . When using the adjuvant in conjunction with 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 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 .
Reduced evaporation
The soil adjuvant slows the evaporation of water from the soil profile . This helps to conserve water while also improving the bioavailability of nutrients and treatments by maintaining them in solution over longer periods . 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 thus of water loss from plants . The favourable bridging interaction the soil adjuvant imparts on water and soil components slows down soil dehydration . Experimental data shows that the rate of evaporation of water can be reduced threefold with the inclusion of the soil adjuvant .
Residual wetting properties
One application of the soil adjuvant is expected to improve the performance
Figure 3 – How soil adjuvants retain moisture in soil
of subsequent treatments without adjuvants , due to its residual wetting properties . The design of Hydravance 200 takes into account both biodegradability and a lower potential for persistence and ecological impact . Subsequent applications that do not contain an adjuvant also benefit from the performance advantages of a previous application of the soil adjuvant , due to its residual effect in the field . As a result , the need for irrigation may be reduced . This in turn ensures that natural resources , like water , are being used in a more sustainable and efficient way .
Closing remarks
When considering what to apply on cultivated areas , growers should pursue the most efficient , sustainable and cost-effective means . Even more importantly , choices for applications made to the soil will fundamentally impact what is available to target crops through their growth cycles . In this context , soil-applied adjuvants can play a vital role in modulating these systems through improved delivery of chemical and biological treatments . Their effective placement within soil management programmes can significantly improve the seasonal bioavailability of the water and nutrients essential for more efficient management of limited natural resources . Soil adjuvants improve the delivery of agrochemical treatments through
reduced levels of surface run-off and enhanced penetration into soil . This results in more effective treatments , as applications are distributed more evenly throughout the soil to create a more favourable environment for uptake into root systems . The use of a soil adjuvant increases the efficiency of water use through reduced pooling , run-off and evaporation . More rapid and complete movement of surface water into soil with slower loss over time increases the available moisture in the soil over longer periods . Enhanced soil moisture increases the availability of water and nutrients to growing plants . The use of effective soil adjuvants enables growers to access these benefits for a higher , more consistent yield . •
* - Hydravance is a trade name of Croda
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Laura Weatherhead
APPLICATIONS TEAM LEADER
22 SPECIALITY CHEMICALS MAGAZINE ESTABLISHED 1981