Mitigating manure contaminated drain discharge with controlled drainage
Authors: Geohring, L, Aa Royem, Mt Walter, S Kramer, E Young
Description: Land application of liquid manure can result in contamination of subsurface (tile) drain discharge and may cause environmental impact to receiving water. This contamination occurs rapidly following manure application, especially on soils exhibiting preferential flow characteristics and when precipitation follows shortly after manure application. Laboratory and field studies were initiated to better understand preferential flow processes and to quantify the extent of tile effluent contamination from liquid manure application. The laboratory leaching study consisted of replicated soil columns constructed with three different pore-size arrangements, and applying three different nutrient (liquid manure)application treatments. The field studies entailed adjusting controlled drainage structures to temporarily retain and control the tile drain discharge during the time of manure spreading. The laboratory study indicated phosphorus was leached most rapidly from soil columns with 3 mm diameter artificial macropores and from the liquid manure application with 3.5 percent solids, as opposed to no and 1 mm diameter macropore arrangements with applications of liquid manure containing 7 percent solids or with inorganic phosphorus fertilizer. Although peak phosphorus loss from the soil columns was only 0.14 kg/ha, the peak concentration of total phosphorus was 3.1 mg/L. The primary benefit of temporarily raising the drainage weir control in the field studies appears to be one of delaying the drain discharge rather than having much effect on the effluent concentration. This implies the contaminant load can be reduced somewhat, the extent of which depends on the antecedent soil moisture condition and the timing of precipitation after manure application. The soil column leaching and drain effluent quality following manure application experiments will be discussed during this presentation along with current efforts to identify vulnerable drained soils and implement controlled drainage on livestock farms.
Keywords: controlled drainage, water quality, preferential flow, phosphorus, nutrient management
Technical field: technical_fields_app7
Session name: Soil and water