Follow your discussion i want to know.

I have a question in the same point

https://www.researchgate.net/post/How_to_know_the_available_water_holding_capacity_of_clay_soil

Hi, apart from agreeing with Fulvio, I just wanted to add that FC is defined at different suctions. While in the US more often pF 2.5 (0.33 bars) is used, Europeans usually refer to pF2 (0.1 bars or 100 cm). In search for a simple model, I came across BUDGET (soil water balance model), which allowed for multiple modifications, but also provided all basic input data necessary.

Thanks for all your responses.

After the crap i have been reading in the literature its reassuring to find other out there who know what they are talking about.

To me water holding capacity has always meant the plant available water content between field capacity and the permanent wilting point, which i have always measured between -10 kPa by desorption on large intact cores and -1500 kpa measured by pressure chambers on sieved disturbed soil. I accept the notion of a field capacity to be arbitrary and a little absurd, but still somehow useful.

Im currently reviewing the literature on biochar and its effects on soil properties. Ive been amazed and disappointed to see time and again poor understanding and use of terms such as water holding capacity, field capacity and the like.

When are plant scientists and agronomists going to learn that pot experiments do not drain to field capacity, or that the field capacity, density, porosity or PAWC of a repacked soil in a pot depends on how you repacked it not the actual soil properties, or that values of FC, PAWC, total porosity of pots have nothing to do with real field soils which have bugs, and worms, they freeze and shrink and get run over by tractors.

Here are some examples of water holding capacity from the biochar literature........not one of them got it right or used the term PAWC, they describe AWC as....

* the soil moisture content at -100 kPa (Streubel et al., 2011),

* moisture content after gravitational drainage (Dugan et al., 2010; Karhu et al., 2011), * between 0 and - 100 kPa (Gaskin et al., 2007),

* between -0.1 and -100 kPa (Kameyama et al., 2012),

* between 5 - 60 kPa (Novak et al., 2012).

Im still looking for a real reference that describes the water holding capacity as being between field capacity and the permanent wilting point. IF YOU KNOW OF ONE PLEASE LET ME KNOW

Love to hear what you reckon

Marcus

Hej Marcus,

for such basic principles I would usually refer to a textbook, eg: Brady, N. C. and Weil, R. R. 2008. The nature and properties of soils. 14. In my edition the concept is elaborated on pp 204-206.

Hope that helps, Marie