Talk:Field capacity

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There is an important cultural story in the wide-scale rejection of use of a field or plot's field capacity in scheduling irrigation. In 2010, our collective awareness of our impacts to the environment, due in degrees of magnitude greater in agriculture than in any other societal enterprise, one can only make one wonder "why didn't they irrigate with greater precision? A new study by the USGS estimates that 50% - 70% of the water applied to landscapes and farms is not beneficially used by the plants. Additionally, nitrogen fertilizers are leached and rendered unavailable to the plants above, while often polluting the water tables and aquifers below. The 1938 Agricultural Yearbook (pg. 708) admonishes irrigators to know and use field capacity to time irrigation. .

Because determining the field capacities, which generally becomes a permanent field characteristic, take work, mankind has sought out short-cut methods for timing irrigation. These methods utilize complex algorithms to calculate what balance of available water remains after the last irrigation. These methods possess sufficient error that they must be corrected periodically, re-set to an actual field-measured soil cmoisture content, then manually inserted in place of the "running water balance" which the model has predicted. Many would argue, that if you must continually correct the model with ground-truth data, why bother to caluculate it at all? It would be like calculating the fuel remaining in the gas tank instead of just measuring it directly. Fortunately, new, practical soil moisture monitoring technologies which transmit the data via wireless networks appears to be gaining some attention. That does not excuse the 70 years where probably fewer than 10% of the irrigation managers globally timed their irrigations with regard to soil moisture content, which is based upon field capacity. — Preceding unsigned comment added by 72.208.178.86 (talk) 23:18, 9 February 2010 (UTC)

References

Maximum water hoiding capacity of a soil there all the pores are filled with water and is held with a force of 1/3 atm — Preceding unsigned comment added by 136.233.20.195 (talk) 10:22, 6 October 2019 (UTC)

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Redirection of water holding capacity

Water holding capacity (WHC) is redirected to this article. The problem is that WHC is used for more than soil, for instance WHC of snow and of meat. JohannaSorensen (talk) 09:01, 8 February 2022 (UTC)

Drainage does not cease once a soil drains to field capacity

Most drainage is unsaturated flow. Unsaturated flows continue at soil moisture levels below field capacity. This flow rate is driven by the matric potential gradient. The practical intent driving the need to identify field capacity is to achieve reasonable water use efficiency. Avoiding filling a soil to above field capacity controls drainage losses, but it does not cause drainage to fully cease. Hopefully the macropore qualifier added to the article works for the other editors. -- Paleorthid (talk) 07:13, 26 August 2024 (UTC)