Contribution of nitrogen and phosphorus to subsurface drainage
water from intensely cropped mineral and organic soils in Ontario, Journal of Environmental Quality 8(1):41-48.
Due to these poorly drained soils, extensive subsurface drainage
systems are installed to help increase agricultural crop production (USDA 1969).
Management practices to reduce [NO.sub.3]-N concentrations in subsurface drainage
include rate, method, form/additives, and timing of N applications.
The field inspection indicated that a subsurface drainage
tile system had been installed in the northwest region of the watershed several years ago.
According to a 1985 USDA-Economic Research Service survey, Midwestern states have about 31 million acres (12.5 million hectares) of mostly cropland containing subsurface drainage
The subsurface drainage
intensity decreases with increasing ditch spacing; it is inversely proportional to the square of the ditch spacing.
Completion of the subsurface drainage
network at Al Tawil Al Bahari fourth zone serving 3,460 feddans land.
Adding subsurface drainage
systems to this area has created some of the most productive agricultural land in the country.
DRAINMOD was developed for shallow water table soils and has been used to design water management systems (16), to simulate the performance of subsurface drainage
systems (11), and to simulate crop response to surface and subsurface drainage
Two tenders for the request of offers from Eligible bidders for the rehabilitation/ replacement of subsurface drainage
networks at both Sandala Zone 2 A & 2 B serving 2,100 feddans and 2,700 feddans respectively.
The news release said that over the next four years, over $2 billion will be spent on streets and subsurface drainage
projects around the city.
'Sewage water is currently coming back to the shore and it's not getting diluted,' she said, adding that with the subsurface drainage
system, the sewage water could be diluted into the sea.