Depth suggestions for soil moisture sensors to effectively measure the root zone.
Application of irrigation water should be limited to an amount that will penetrate only to the effective root zone depth. Applications in excess of this amount will result in waste of water and added pumping cost. To have a better understanding of the water content the sensor must be placed in the effective root zone which is dependent on the type of crop.
The effective root zone depth is the depth of soil used by the main body of the plant roots to obtain most of the stored moisture. It is not the same as the maximum root zone depth(which is the max extension of the roots). About 70% of the moisture extracted by the root is obtained in the top half of the root zone; about 20% from the third quarter; and about 10% from the soil in the deepest quarter of the root zone.
Sensor depth suggestions
The suggested sensor depth is defined based on 3 variables:
- Specific Crop root zone depth
- Sensor dimensions
- Experience based on Growers use cases
|
Crop type |
Effective Root zone depth*[cm] |
Suggested Sensor depth [cm] |
|
Asparagus |
60 |
30 |
|
Beets |
45 |
22 |
|
Broccoli |
45 |
22 |
|
Cabbage |
45 |
22 |
|
Carrots and Parsnips |
45 |
22 |
|
Cauliflower |
45 |
22 |
|
Celery |
30 |
15 |
|
Chives |
15 |
10 |
|
Collards |
45 |
22 |
|
Corn |
60 |
30 |
|
Cucumbers |
45 |
22 |
|
Eggplant |
45 |
22 |
|
Lettuce, Escarole, Endive |
15 |
10 |
|
Fennel |
15 |
10 |
|
Kale |
30 |
15 |
|
Kohlrabi |
45 |
22 |
|
Beans |
45 |
22 |
|
Melons & Watermelons |
60 |
30 |
|
Okra |
45 |
22 |
|
Onions & Shallots |
15 |
10 |
|
Peas |
45 |
22 |
|
Peppers |
30 |
15 |
|
Potatoes and Sweet Potatoes |
45 |
22 |
|
Pumpkins |
60 |
30 |
|
Radish |
15 |
10 |
|
Rutabagas |
45 |
22 |
|
Spinach |
15 |
10 |
|
Chard |
30 |
15 |
|
Tomatoes |
45 |
22 |
|
Turnips |
45 |
22 |
|
Barley, Millet, Oats, Rye and Sorghum and Wheat |
60 |
30 |
|
Soybeans |
60 |
30 |
|
Fruit trees |
60 |
30 |
|
Strawberries, Blueberries & Cranberries |
15 |
10 |
|
Grapes |
90 |
45 |
|
Alfalfa |
76 |
38 |
|
Annual Flowers |
15 |
10 |
|
Ericaceous ornamental plants (azalea, etc.) |
30 |
15 |
|
Gladioli, Peonies, Iris |
30 |
15 |
|
Other bulb or corn plants |
30 |
15 |
*Please be aware that the effective root zone depth might vary due to specific soil type.
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