Agricultural News
Keeping Track of Water Usage in Peanuts
Tue, 03 Jul 2012 14:35:12 CDT
Well-watered peanuts will use as much as 25 inches of water per season, says Chad Godsey, oilseed cropping specialist with OSU. The effective rainfall in the major peanut growing areas of the state during the season is approximately 10 inches in a normal growing season. This means as much as 15 inches of irrigation water could be required to keep the crop in a well-watered condition.
There are three stages in the peanut life cycle when excess moisture stress will cause a reduction in the quantity or quality of nuts produced. The first stage is germination and emergence. The second stage, peak flowering and pegging, occurs about 45 to 60 days after planting, which happens to be the current stage for most of the peanut fields in SW Oklahoma. This is the period of maximum susceptibility to drought stress for peanuts. The crop will normally require about 0.25 to 0.30 in/day of water at this stage (Figure 1), but the demand may be higher on extremely hot, windy days. At this time the crop must not be allowed to deplete more than half of the stored soil moisture in the root zone or a reduction in the number of fruiting sites and a resulting yield reduction will occur. Pegs will not develop in soil that is too warm or too dry, so adequate irrigation at this stage of growth is critical. Moisture stress while the pods are filling will also result in slower pod growth and smaller pods. During the third stage, nut maturation, the demand for water gradually declines to about 0.10 in/day or less immediately before harvest. Though lesser quantities are required, water is important at this stage to maintain nut quality. Stress at this stage can increase susceptibility of the crop to disease. However, too much water can increase the possibility of disease so close attention should be paid to irrigation scheduling.
One online tool to help estimate crop water use can be found at the AgWeather Mesonet website. You can get up-to-date estimates of crop water usage on a daily basis by clicking here..
In order to do a good job with irrigation scheduling you need to make sure you understand the water holding capacity of your soil in the surface 3 to 4 feet, which is the effective rooting zone where the plant will utilize water from during the growing season. Applying more water than the soil can hold is a waste of resources and cash. Also, make sure your sprinkler is applying what you think it should. Place several rain gauges around the field and check for accuracy. In a summer like last year and this year, irrigation scheduling makes a big difference in determining final yield.
You can read Godsey's article with tables and charts by clicking here.
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