# Water Penetration

Author: Meghan Sindelar

Added: 08/09/2016

279
Plays

0
Comments

3.97 MB

## Searchable Transcript

Toggle between list and paragraph view.
- [00:00:01.481]Hello, this is Dr. Meghan Sindelar,
- [00:00:03.887]and we have a soil physical properties calculation here
- [00:00:08.634]looking at water penetration.
- [00:00:11.671]This video kind of assumes
- [00:00:14.281]that people understand water content and field capacity
- [00:00:21.646]as being the upper limit of water storage,
- [00:00:25.471]and that any water beyond that would freely drain away.
- [00:00:29.179]So, the idea here is to calculate
- [00:00:31.031]how deep will applied water drain?
- [00:00:34.357]'Cause if it wets a certain depth up to saturation
- [00:00:36.759]then it'll move down, so each depth will only be wetted
- [00:00:39.647]up to field capacity and any excess water continues
- [00:00:42.478]to move into the profile.
- [00:00:44.731]This might be something you would want to calculate
- [00:00:47.638]if you were trying to encourage deep rotting.
- [00:00:50.721]You needed to get water to a certain depth for,
- [00:00:55.241]you were planning to compact the top 12 inches say,
- [00:00:59.235]or you had a fertilizer band you wanted
- [00:01:02.330]to make sure was wetted.
- [00:01:06.325]Various reasons.
- [00:01:09.177]So, here would be the sorta input data we would use.
- [00:01:12.309]Basically, we would need to know the water content
- [00:01:14.971]at field capacity and then our current water content,
- [00:01:20.608]so we will add water to go from the current
- [00:01:22.693]up to field capacity and once that's reached,
- [00:01:24.969]water will then move farther down into the profile.
- [00:01:29.242]So for this example, we're going to add one inch of water
- [00:01:35.364]to the soil.
- [00:01:38.864]So, we'll start with this basic formula
- [00:01:42.815]that we have used before, where you can calculate
- [00:01:45.460]the depth of water in the soil profile
- [00:01:48.741]using the water content and the soil depth,
- [00:01:51.474]but we're gonna rethink about this formula
- [00:01:53.981]from another perspective.
- [00:01:56.266]So now, we wanna rework this so that we can think about
- [00:01:59.621]what is the soil depth to which a given amount
- [00:02:03.909]of water will move if we add, okay?
- [00:02:08.221]So, we will know our depth of water.
- [00:02:11.465]Okay, that's how much we add, so think of it
- [00:02:14.344]as depth of water added.
- [00:02:19.100]So, based on the water content, and so here let's think
- [00:02:23.262]of this as volume room
- [00:02:29.437]for more water,
- [00:02:34.286]and that's gonna be the difference
- [00:02:35.942]between current water content and field capacity, right?
- [00:02:39.814]And then that will allow us to solve for a soil depth
- [00:02:44.862]of penetration.
- [00:02:48.344]Okay, so if we take our depth of water
- [00:02:54.156]as water content times soil depth
- [00:03:01.008]and now we just wanna solve,
- [00:03:02.329]so we divide by water content both sides.
- [00:03:11.057]Okay?
- [00:03:12.764]So, here then is our formula to go.
- [00:03:14.633]Soil depth on this side.
- [00:03:16.603]Depth of water added divided by volume content
- [00:03:22.896]for more water, so room for more water
- [00:03:27.077]in this case will be field capacity minus current,
- [00:03:33.277]so that's .4 minus 0.27 equals 0.13 centimeters cubed
- [00:03:40.981]per centimeters cubed.
- [00:03:43.160]So, our depth of penetration will be the one inch
- [00:03:49.775]of water added divided by 0.13 volumetric room
- [00:03:58.301]for more water.
- [00:04:00.987]So, one divided by 0.13 is
- [00:04:07.181]7.7 inches, all right?
- [00:04:13.968]So for this soil, which can be wetted at field capacity
- [00:04:20.292]up to 40% water is currently at 27% water.
- [00:04:25.180]If we add one inch of water it will move 7.7 inches
- [00:04:31.374]into the profile, okay?
- [00:04:35.501]That is the depth at which the water will penetrate.

The screen size you are trying to search captions on is too small!
You can always jump over to MediaHub and check it out there.

## Description

This recording captures the author working calculations to determine how deep into a soil profile water will penetrate based on water content data.

Log in to post comments

### Embed

## Comments

0 Comments