Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 1, 2001
Publication Date: February 8, 2002
Interpretive Summary: High amounts and intensity of rainfall (59 in./yr.) in the Lower Mississippi River Valley (LMRV) on slowly permeable alluvial soils can cause serious problems in conducting farm field operations for tilling, planting and harvesting (e.g., for corn and sugarcane). Field work can be stopped for several days following rainfall because heavy equipment can become bogged down causing not only damage to soil structure, but losses in crop quality and farmer profits. Research is being conducted to determine the potential benefits of controlling water table (WT) depth in the soil with subsurface drainpipes for removing excess soil-water after rain. The research focus is to compare the abilities to conduct field operations on plots with WT control and on plots with surface drainage only. Surface drainage is the common practice used in the LMRV. Field test results showed that three days after a 1.2 in. rain a tractor-mounted mower could be operated in the plots with WT control, whereas for the surface drained only plots operations could not begin until day 4. These results may be important for sugarcane growers because heavy cane combine (chopper-type) harvester and transport wagons are now in use throughout the LMRV. Thus, current drainage ditches should be maintained to provide better WT control for sugarcane fields.
Technical Abstract: A field experiment was conducted on a alluvial Commerce silt loam soil near Baton Rouge, LA, to study the effects of drainage on soil trafficability for two different drainage methods: surface drainage only and subsurface drainage. Following a 30-mm rainfall event there was a significant difference in the rate of decrease of soil moisture at a 10-cm depth directly above the subsurface drainpipes versus mid-way between drain lines that were spaced 15 m apart. Trafficable conditions were satisfactory for a tractor-mounted mower on the third day after rainfall for subsurface drained plots when the water table depth had increased to 87 cm, soil moisture content had decreased to 23.5%, and the average soil strength had increased to 1,550 kPa. Differences in soil moisture content between the two drainage methods were not statistically significant, however, the plots with subsurface drainage reached trafficable conditions one day sooner than the surface drained only plots. The soil strength above the drains was consistently higher (1,600 kPa) than at the mid-point between drains (1,300 kPa). These results may be important for sugarcane growers because heavy chopper-type harvester and cane transport wagons are now in widespread use. Current drainage ditches must be maintained to provide better WT control for sugarcane fields.