See the patterns

It’s one thing to put soil water monitoring equipment into the ground. It’s quite another to understand what the numbers means.

 

Soil water data is usually shown in one of two ways: 1) the fraction of the soil volume that contains water, normally shown as a percentage or 2) the suction the plant must overcome to extract water from the soil.

If data is shown as volume percentage, then you still need to find out the number at which to start and stop irrigating. This number is different for every soil.

If the data is shown as ‘suction’, it is easier to interpret because it tells us what the plant is experiencing, regardless of the soil type.

We show the data as suction, but instead of giving a number we give a colour. Blue means the soil is wet, red is dry and green is moist. We measure at three or four depths. When these colours are plotted each day, we get patterns. The patterns show us the level of water ‘stress’ the plant is experiencing, how deeply the roots are extracting water, the times we irrigate and how deeply the water penetrates.

Some example data below come from different beds in the garden. At the moment I upload the data to the ‘cloud’ and then the water colour patterns are automatically generated. At each site the water is measured at four depths; 15 cm, 30 cm, 45 cm and 60 cm.

Here are some current examles from my garden

Oats 2

Why so much red?? Well this is a cover crop, so its job is to pull the water and nutrients out of the soil. These nutrients can then be slowly released to the next crop. This crop is finished now.

Onions

Why so much blue?? Have a look under the Chameleon menu for the videos on ‘How deep are the roots?’ and ‘Irrigation and root disease’. You will find the answer there. Soon to harvest the onions.

Satsuma

One of my favourite plums, but in the driest part of the garden. It does get irrigated and the recent rain finally has things nice and wet.

Nectarine

Why do we seeing drying at the lowest soil levels before the middle? These trees are irrigated regularly, so the top soil water is frequently replenished.