How to dilute pesticides correctly? Calculation method of pesticide concentration and dilution

"the dilution of pesticides is directly related to the effectiveness of pesticides and the growth of crops. How can dilution be correct?" "can I understand what the expert said and what was written in the manual?" Similar problems often haunt farmers. After reading this article, you can understand the correct way to dilute pesticides.

1. Dilution method

The percentage concentration refers to the number of medicine and fertilizer in 100 parts of medicine fertilizer liquid or medicine fertilizer powder, expressed as "%".

For example, 2% urea means that there are 2 kg urea and 98 kg water in 100 kg urea solution.

two。 Multiple concentration

Refers to the multiple of water added to 1 serving of pesticide, which is often expressed by weight.

For example, the preparation of 700 times 50% carbendazim is made by mixing 1 part of 50% carbendazim and 700 parts of water.

3. Conversion method

The conversion formula from percentage concentration to ppm concentration is as follows:

The percentage of water added to 1 part of pesticide = the percentage of pesticide × 1000000 / the number of ppm to be prepared.

For example, 40% ethephon is compounded into 1 kg 2000ppm solution, and the amount of water added is 40 × 1000000 × 2000,200 phr.

4. Converted to multiple concentration

Divide the percentage by the ppm number and move the decimal point back 4 places to get the dilution multiple.

For example, when 40% ethephon 1000ppm is converted into multiple concentration, 40 / 1000 / 0.04 is used and the decimal point is moved back 4 places, which is 400 times.

5. Water mixing method

When several pesticides are mixed, water is not added for each drug, but all kinds of drugs are used: the same part of water is used to calculate the concentration.

For example, to prepare 500x urea plus 1000 times methyl topiramate, use 2 parts of urea plus 1 part of methyl topiramine plus 1000 parts of water. In addition, when mixing water, the mother liquid should be prepared first, that is, the drug should be liquefied with a small amount of warm water, and then the water should be added to the required concentration and fully dissolved to improve the efficacy and prevent drug damage.

How to dilute pesticides correctly?

I. the expression method of drug concentration

1. Percentage concentration: refers to the number of active ingredients in 100 parts of pesticides, often expressed as (%).

two。 Concentration per million: refers to the number of active ingredients in 1 million pesticides, the symbol is PPm (or micrograms per milliliter; milligrams per liter; grams per cubic meter, etc.).

3. Multiple method (that is, dilution multiple): refers to the multiple of adding water or other diluents (fine soil, particles, etc.) when commercial pesticides are diluted. Dilution 100 times or less than 100 times, the calculation should deduct 1 part of the original drug, such as: 50 times dilution, that is, 1 part of the original drug plus 49 parts of diluent. Dilution of more than 100 times, the calculation does not deduct the number of parts of the original drug, such as: dilution 600 times, that is, 1 part of the original drug plus 600 parts of diluent.

II. Conversion between concentration representations

1. Conversion between percentage concentration and millionth concentration: ppm = 10000 × ppm.

two。 The conversion between multiple method and percentage concentration: percentage concentration (%) = (original drug concentration / dilution multiple) x100.

Third, the calculation method when diluting pesticides

1. Calculated according to active ingredient

(1) ask for the amount of diluent (water or filler, etc.):

① dilution is less than 100x: diluent dosage = original reagent weight x (original agent concentration-agent concentration) / agent concentration.

② diluted more than 100times: diluent dosage = original reagent weight x original agent concentration / mixed agent concentration.

(2) the required dosage:

The dosage of the original agent = the weight of the agent x the concentration of the agent / the concentration of the original agent.

two。 Calculated according to the multiple method (without considering the content of active ingredients)

(1) dilution less than 100 times: diluent dosage = original reagent weight × dilution multiple-original reagent weight.

(2) dilution more than 100 times: diluent dosage = original reagent weight × dilution multiple.

(3) the dosage of the original drug = the weight / dilution multiple of the drug.

(4) calculate the dilution multiple:

The dilution multiple of ① is calculated from the concentration ratio: dilution multiple = the concentration of the original agent / the concentration of the agent.

② calculates the dilution multiple from the weight ratio: dilution multiple = the weight of the agent / the weight of the original agent.

3. Conversion according to concentration and concentration units:

Solution concentration: solution concentration can be divided into mass concentration (such as mass percentage concentration) and volume concentration (such as molar concentration, equivalent concentration) and mass-volume concentration.

(1) Mass percentage concentration

The concentration of the solution expressed as a percentage of the mass of the solute in the total solution is called the mass percentage concentration, expressed by the symbol%. For example, 25% glucose injection means that 100% glucose injection contains 25 grams of glucose.

Mass percentage concentration (%) = solute mass / solution mass 100%

(2) Volume concentration

① molar concentration: the concentration of a solution expressed by the number of moles of solute in a liter of solution is called mole concentration, denoted by the symbol mol. For example, if a liter of concentrated sulfuric acid contains 18.4mole of sulfuric acid, the concentration is 18.4mol. Molar concentration (mol) = number of moles of solute / volume of solution (liter).

② equivalent concentration (N): the concentration of a solution expressed by the number of grams of solute contained in a liter of solution is called equivalent concentration, represented by the symbol N. For example, if 1 liter of concentrated hydrochloric acid contains 12.0g equivalent hydrochloric acid (HCl), the concentration is 12.0N. Equivalent concentration = g equivalent of solute / solution volume (liter).

(3) Mass-volume concentration

The concentration expressed by the mass number of solutes per unit volume (1 cubic meter or 1 liter) of the solution is called the mass-volume concentration, represented by the symbol g/m3 or mg/L. For example, if the mass of hexavalent chromium in 1 liter of chromium-containing wastewater is 2 mg, the concentration of hexavalent chromium is 2 mg / L (mg/L).

Mass-volume concentration = mass number of solute (grams or milligrams) / volume of solution (cubic meters or liters).

4. Conversion formula of concentration unit

1) equivalent concentration = 1000.d mass percentage concentration / E

2) Mass percentage concentration = equivalent concentration Emax 1000.d

3) Molar concentration = 1000.d mass percentage concentration / M

4) Mass percentage concentration = mass-volume concentration (mg / L) / 104.d

5) Mass-volume concentration (mg/L) = 104% mass concentration

5. Ppm is the percentage of weight.

Ppm=mg/kg=mg/L

That is 1ppm=1ppm=1000ug/L

1ppb=1ug/L=0.001mg

In the formula: the gram equivalent of E-solute; the specific gravity of d-solution; the molar mass of M-solute.

4. PPM concentration conversion algorithm

PPM is a commonly used concentration unit in the world, because PPM is an acronym, not the name of the unit of calculation, that is, 1PPM = 1x10 ^-6, that is, 1PPM is 1/1000000.

The drug dilution 1000KG water with 100% drug concentration is the 1PPM concentration, and if the drug concentration effective ingredient is 50%, then the drug dilution 500KG water with 50% drug concentration is the 1PPM concentration.

For example: how many times does it take to dilute water for 500PPM GA3 (100%)?

100/500X10000=2000 times

That is, 1G dilution 2000G water is 500PPM concentration, and can be replaced by conversion formula: pesticide effective ingredient content (%) / liquid effective concentration (PPM) X10000 = dilution multiple of adding water.