Sediment and nutrient retention was studied in a seasonally flooded lakeside wetland as a natural mechanism for preventing water quality deterioration. Both wetland and upland soils in the watershed had comparable concentrations of inorganic P on a per‐volume basis, while NH4+‐N and organic forms of N and P were much higher in the wetland soils. Nitrate concentrations expressed in a per‐volume basis were lower in the wetland soils than in the upland soils.The distribution of sediment and nutrients in the wetland was correlated with distance from a small stream flowing through the wetland. Deposition patterns were affected by recent stream channel migrations.The accumulation of nutrients and sediment delivered from the upland to wetland soils was estimated in two ways: (i) by calculating the volume of alluvium deposited in low natural levees adjacent to the stream; and (ii) by estimating nutrient and ash enrichment of histic surface soils farther away from the stream. Although the levees constituted only about 20% of the wetland surface area, they accounted for 81% of the sediment, 84% of the N, and 67% of the P retained by the wetland.The depth of Cs‐137 in the soil was used to estimate net sedimentation rates. Average annual accumulations over the wetland as a whole were: 2.0 kg sediment m−2 yr−1, 2.6 g P m−2 yr−1, and 12.8 N g m−2 yr−1. Since these values exceed those published for average annual storage by wetland plants, soil mechanisms are more important than vegetative uptake for long‐term nutrient and sediment retention in the White Clay Lake wetland.

The goal of this study was to improve understanding of the factors that influence runoff generation during non-frozen ground periods in small agricultural watersheds in southwestern Wisconsin where the landscapes are controlled by dolostone bedrock in order to provide agricultural producers with a manure management tool. Six small watersheds (ranging from 6 to 17 ha) within two southwestern Wisconsin farm sites (Discovery Farms Program (DFP) and Pioneer Farm (PF)) were instrumented, and surface runoff was continuously monitored from 2004 to 2007. The soils in all watersheds were formed in deep (~1 m) loessial sites. A direct-plant management strategy and corn-soybean crop rotation were utilized within watersheds at DFP. A conventional tillage system (chisel plow in the fall followed by soil finisher in the spring) and a corn-oat-alfalfa crop rotation were utilized within watersheds at PF. At PF, the amount of precipitation leaving the landscape as surface runoff (1.8%) was two times greater compared to DFP (0.9%), indicating that the direct-plant management system was better at retaining precipitation than the chisel plow/soil finisher system. Using breakpoint regression analysis, a non-linear response in runoff generation with antecedent soil moisture (ASM) was observed with a threshold ASM of 0.39 cm 3 cm À3 (approximately 80% of total porosity) for all six watersheds. Below this threshold, runoff coefficients were near zero. Above this threshold, runoff coefficients increased with ASM. A non-linear response in runoff generation with maximum 30 min rainfall intensity (I30) was also observed, and threshold I30 values increased as ASM decreased and as crop cover increased.

] in any year) and any statistical differences in sediment concentrations among basins were not related to the presence or absence of manure or the amount of runoff. Concentrations and losses of total nitrogen and total phosphorus were significantly increased in basins that had either manure type applied less than one week preceding runoff. These increases occurred despite relatively low application rates. Lower concentrations and losses were measured in basins that had manure applied in fall and early winter and an extended period of time (months) had elapsed before the first runoff event. The highest mean, flow-weighted concentrations of total nitrogen (31.8 mg L -1 ) and total phosphorus (10.9 mg L -1 ) occurred in winter 2003 to 2004, when liquid-dairy manure was applied less than one week before runoff. On average, dissolved phosphorus accounted for over 80% of all phosphorus measured in runoff during frozen-ground periods. The data collected as part of this study add to the limited information on the quantity and quality of frozen-ground runoff at field edges, and the results highlight the importance of manure management decisions during frozen-ground periods to minimize nutrients lost in surface runoff.

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The morphological and physical properties of a fine‐loamy, mixed, frigid Aquic Fragiochrept at two locations in Taylor County, Wisconsin were examined. At both sites, the fragic zone occurs in bisequal soils beneath eluvial horizons and transgresses a lithologic discontinuity where the loess cap grades into a dense sandy loam till. This study evaluated the utility of several field and laboratory tests for demarcation of the fragipan, and it examined the morphological and physical features of the fragipan in relation to its potential origin. Bulk density was measured using the saran‐coated clod and Uhland ring methods. The upper boundary of the fragipan was distinguished from the overlying horizons by its higher bulk density with the Uhland ring method. Hydraulic conductivity (Ksat) of saturated soil was measured using two methods (falling‐head permeameter and Guelph permeameter). Although Ksat values were low in the fragic zones (10−5.06–10−7.60 m s−1), they were not significantly lower than those measured in underlying nonfragic, dense till horizons. Soil strength tests showed that the site with >10% clay in its fragic horizons had twice the strength of the site with <10% clay. Various macro‐ and micromorphological features indicate that the upper part of the second parent material may be a debris flow sediment, rather than dense basal till and that the fragic zone may have been influenced by permafrost. This influence is seen by the presence of a suite of characteristics associated with permafrost such as vesicular porosity, platy structure, reverse sorting, and silt coatings superimposed on clay coatings or papules.