Yes, if you want to achieve your target to get 50% WHC, you should know WHC of your soil first, it is not necessary to know wilting point, then calculte the exact value of your 50%WHC and adjust your water content properly by adding corrresponding amount of water to your samples. For the exact steps, you should keep in mind that adding water carefully to make the soil sample aggregate because of unevenly spraying or dropping of water.  I hope my answer can help you a little bit.

You have to find the amount of water of your soil at 100% and 0% of the field capacity to be able to know the 50%.

To do so you can do the next:

- Take a certain volume of soil. Let's say 2 L. Make a certain number of repetitions and make it twice. One half will go to the oven to dry it completely (0% field capacity) and the other half is for bringing to 100% field capacity (when the soil can not take more water, leave it for a while to drain the free water).

- If you know the 0 and the 100 you can just calculate the percentage of your interest.

I hope it is clear. Good luck!

You need to determine the value of WHC.

To do so, you need to saturate one subsample of you soil by capillarity in a filtrant crucible and let it stabilized for 16 hours. If you let it drain, you will calculate a lower value (Field Capacity), not WHC

Procedure for MHC

ü  An empty perforated brass cup or keen Keen- Rackzowski box  containing filter paper was taken

ü  The cup was filled up with dry soil (

Take 1 Kg soil sample in dry condition. Add water in little measured quantities to saturate the soil and to know the 100% water holding capacity. To make the soil 50 % water holding capacity, take 1/2 Kg dried soil mix with 1/5 kg sand. Add 1/2 the quantity of water utilized for making to 100% water saturation to the soil mixture. This soil mixture will have only 50% water holding capacity of the original soil. Proportionate soil, sand and water has to be made for increased quantities.

Best wishes. 

Hello there.

I agree with the expert view of boys. All answers were very clear and complete.

Yes, is necessary to know the values of soil retention curve.

With this values (gravimetric moisture valuers), you can determine Field capacity moisture value or your WHC value.

Then solid mass formula could be useful to determine the amount of water to add and obtain the this value or WHC desired with a soil dried.

M s= M / (1+HG /100)

where M s= soil solids mass or soil oven dried mass

M = soil moist mass

HG % gravimetric moisture.

With the moisture value needed and soil dried mass you can determine the moist soil mass and then determine the amount of water to apply and get your WHC.

Greetings from Costa Rica.

Determine the saturation percentage of your soilsample which will be equal to 100 % WHC. To calculate 50 % WHC, just divide by two. It will be your 50% WHC. 

Ist determined the WHC by wetting and drying method it would by water content at 100% . Then decide by 2 and you will get 50%