Author
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Fouss, James |
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Submitted to: Irrigation Association Conference Proceedings
Publication Type: Proceedings Publication Acceptance Date: 11/1/1999 Publication Date: N/A Citation: N/A Interpretive Summary: Soil-water management on cropland in the southern U. S. depends upon several factors. If shallow water table exists in the soil during the late spring months, a water table control (WTC) system may be feasible. This approach is well suited in level coastal zones of the S.E. A common method of WTC is a dual- purpose subsurface conduit system for controlled-drainage and subirrigation to maintain root-zone soil-water content. In coastal areas, where gravity drainage outlets are often not possible, WTC systems can be connected to sumps to control the water level by pumps rather than an overflow weir at a gravity outlet. Water is pumped out of the sumps for subdrainage and into them for subirrigation. Management of WTC in the S.E. is difficult because of the erratic rainfall distribution. Both excess and deficit soil-water conditions often occur during the same year. System operation can be improved if the % chance of rain in weather forecasts is used to schedule periods for subirrigation. The forecasts can also be useful to avoid applying pesticides and fertilizer before predicted rain, thus minimizing the risk of their losses in runoff. Thus, operation of WTC systems can be in harmony with the environment if weather forecasts are used to aid the farmer manage the system. Technical Abstract: Soil-water management on cropland in the southern U. S. may be accomplished by a dual-purpose subsurface conduit system for water table control (WTC), if a shallow water table exists in the soil profile during much of each spring. The subsurface conduits are used forc ontrolled-drainage and subirrigation of the soil to maintain the root-zone water content via water table depth control. This approach is well suited in level coastal zones of the S.E.,but gravity drainage outlets are often not possible. WTC systems can be connected to sumps to control the water level by pumps rather than an overflow weir at a gravity outlet. Water is pumped out of the sumps for subdrainage and into them for subirrigation. Management of WTC in the S.E. is difficult because of the erratic spatial and temporal rainfall distribution. Both excess and deficit soil- water conditions often occur during the same season. System operation can be improved if the probability of rain in weather forecasts is used to schedule subirrigations. The forecasts can also be useful to avoid applying pesticides and fertilizer before predicted rain, minimizing the risk of their losses in runoff. Thus, WTC systems operation can be in harmony with the environment if weather forecasts are used to help manage them. |
