Micron - manufacturers of specialist spraying equipment

Language: english french spanish = English
 

The Advantages Of Controlled Droplet Application (CDA)

The advantages of Controlled Droplet Application  within the plantation sector are well known but are worth reiterating.  They are chiefly:


Increased work rates

Because of the low volumes which are possible using Controlled Droplet Application spraying  typically 10-20 litres of spray mix per hectare compared with the 250-300 litres needed if spraying with a conventional knapsack sprayer, the amount of time and effort – both physical and logistical which needs to be spent fetching and carrying water is vastly reduced.  In 1983 it was estimated (Jollands et al, 1983, Juan, 1985) that this increase in productivity results in a labour cost saving of around 60% when Controlled Droplet Application is compared with knapsack spraying.

Table 1 Cost and productivity comparisons of Controlled Droplet Application and knapsack sprayers (from Jollands et al 1983)
 
 

   Chemical (kg ai/ha)
 Chemical
 Water Labour Cost Changes (%)
Paraquat
          
LOK 0.16  100 100 100  
Herbi
 0.16 100
 10 20 -26%
Herbi 0.08 50 10 20 -60%
2,4-D
          
LOK 0.20 100 100 100  
Herbi 0.20 100
 10
 20
 -26%
Herbi 0.10 50
 10
 20
 -60%
Glyphosphate          
LOK
 0.27 308
 100   100
 +242%
Herbi 0.10 123 10 20 -10%
Herbi 0.06 68 10 20 -47%

At current costing, assuming a daily labour rate of RM 16.5, labour costs for Controlled Droplet Application application can be calculated at RM3.67 per hectare.  This compares with RM 11 per hectare using knapsack spraying techniques.  In oil palm estates for example it is possible to treat 500 tree circles in a day which is four times the work rate of a conventional knapsack sprayer.


Reduced operator effort

The reduced physical effort needed for Controlled Droplet Application treatment has significant advantages over and above the reduction in labour costs discussed above.   Because strenuous pumping is not necessary the task of spray application  is one which can be carried out more easily by both men and women.  Management of the weed control programme is therefore improved.


Increased chemical efficacy

It is understood that low volume, CDA, application of certain herbicides (particularly those based on the active ingredient glyphosate) increases the efficacy of the product.  This is due, in part, to the improved coverage and retention of Controlled Droplet Application spraying but more importantly due to the fact that the herbicide is present in a higher concentration.  Glyphosate, as an active ingredient, is only poorly absorbed by plant leaves.  To assist in its uptake, it is generally formulated with tallow amine surfactants which, when present in higher concentrations (as in low volume spraying), are more effective resulting in increased uptake and activity of the glyphosate active ingredient.  While it is not the intention to discuss, chemical dose reduction in this paper,  the increased efficacy afforded by Controlled Droplet Application spraying using glyphosate has undoubtedly led to many chemical cost savings (Jollands et al 1983, Aun and Fee, 1985) and was a major factor in the successful introduction of glyphosate in plantation agriculture in south east Asia.


Safety

Controlled Droplet Application spraying also offers significant advantages in improved  operator safety.  Various studies (Aun and Fee 1985, Thornhill et al 1995) have shown that due to the lower volumes employed and  reduction in the number of very small sized droplets, Controlled Droplet Application spraying leads to significantly less operator contamination during the spraying process than high volume application.  Additionally, because Controlled Droplet Application spraying is less arduous than high volume knapsack spraying workers are less likely to make errors in the spraying operation due to fatigue They are also more inclined to wear protective clothing in hot and humid climatic conditions.

Studies have shown (Craig and Mbevi, 1993) that the highest levels of operator contamination occur during the preparation of the spray mix,  As there are fewer mixing and filling operations needed for CDA application, there are fewer instances where contamination can occur.  It also means that chemical mixing and measuring can be carried out centrally by trained staff who can be better equipped to wear the correct protective clothing and appreciate the importance of accurate measurement and sprayer calibration.

Back to Controlled Droplet Application (CDA)