Effects of different management practices on surface water quality from rice fields in south Louisiana

Water samples collected in the Mermentau River Basin over several years at Louisiana Department of Environmental Quality monitoring sites contained high levels of total solids and nutrients during the spring that were highly correlated to pre- and post-plant discharges from rice fields. This study was developed to evaluate the potential of selected management practices (MP's) for reducing total solids, nutrients and pesticides from discharge water in order to improve the surface water quality in southwest Louisiana. Five rice plots located on the Rice Research Station in Crowley, LA represented the different MP's to be evaluated. The five water seeding MP's were: a.1-no till; a.2-water cultivation with 30-day settling, a.3-dry cultivation with clear water planting; a.4-mudding-in with vegetated filter, and b-mudding-in (control). Quality of discharged water from rice fields in the Mermentau River Basin was clearly affected by the different MP's. From the first year of data, all the MPa's were better than the mudding-in (MPb). The concentrations of the total solids (kg/ha) in the discharged water (initial + final drain) for the different MP's were in the order: MPb(4860) > MPa.3(3906) > MPa.4(3412) > MPa.2(3068) > MPa.1(1807). The Mpa.3, Mpa.4 and MPb had no detectable amounts of pesticides being released. The 30-day holding period (Mpa.2), clear water planting (MPa.3) and the mudding-in with vegetated filter (MPa.4) were similar as far as TDS, TSS and TS with the no-till (MPa.1) being the least. The 30-day holding period (Mpa.2) and the no-till (MPa.1) had less nutrients, but more pesticides released. Depending on the priority of the stream problems, different MP's may be more advantageous than others. All of the selected MP's were better than the control (MPb), and therefore, should help to improve water quality.