L.E. Lanyon, K.E. Arrington, C.W. Abdalla, and D.B. Beegle
X.-C. Zhang
G.J. Gascho and R.K. Hubbard
C.A. Murphy, B.L. Foster, M.E. Ramspott, and K.P. Price
C. Cantero-Martinez, D.G. Westfall, L.A. Sherrod, and G.A. Peterson
P.B. DeLaune, B.E. Haggard, T.C. Daniel, I. Chaubey, and M.J. Cochran
Y.A. Popova, V.G. Keyworth, B.E. Haggard, D.E. Storm, R.A. Lynch, and M.E. Payton
Performance assessment of wood strand erosion control materials among varying slopes, soil textures, and cover amounts
K.A. Yanosek, R.B.Foltz, and J.H. Dooley
ABSTRACT: Two blends of manufactured wood strands with different lengths were tested for effectiveness in controlling erosion. Wood strand blends were tested on two soils, two slopes, and at three coverage amounts. Laboratory rainfall simulations were conducted to evaluate runoff and sediment loss. Wood strands were effective in delaying runoff, reducing runoff volume, and reducing sediment loss. There was no statistically significant difference between the two wood strand blends with respect to runoff or sediment loss. In comparison to bare soil with no cover, sediment loss was reduced by at least 70 percent for all cover amounts tested and among each soil type, slope and flow event. In comparison to estimates of sediment loss reductions due to agricultural straw (Burroughs and King, 1989), wood strand materials were equally effective on coarse grained soils and superior to straw on fine grained soils. In contrast to agricultural straw, manufactured wood strands are inherently weed and pesticide free. Consequently, wood-based materials may be a more appropriate material for erosion mitigation, especially in areas where introduction of non-native species is of great concern.
Keywords: Mitigation, runoff, soil erosion control, straw mulch, water quality
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Phosphorus budgets for Pennsylvania cropland: 1939 to 2002
L.E. Lanyon, K.E. Arrington, C.W. Abdalla, and D.B. Beegle
ABSTRACT: Historically phosphorus (P) was applied to cropland based on expected crop response and to correct soil nutrient deficiencies. As these deficiencies have become less common and animal production has intensified in many regions, concerns about surplus cropland P becoming a water resource pollutant have replaced historical concerns. To understand spatial and temporal changes in P surpluses, P budgets were developed for Pennsylvania cropland at approximately ten-year intervals from 1939 to 2002. The P balance, the difference between inputs to crop land (manure and fertilizer) and outputs (harvested crops), estimates the change in soil P storage plus P losses through runoff, erosion and leaching. Although the state-level P balance decreased since 1949, in 20 counties the maximum excess
P occurred since 1992. Nutrient budgets, such as those developed for P in this research, can contribute to more informed strategies to reduce or prevent cropland P surpluses and thus reduce the risk to water quality.
Keywords: Fertilizer, manure, nutrient budgets, Pennsylvania, phosphorus
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Spatial sensitivity of predicted soil erosion and runoff to climate change at regional scales
X.-C. Zhang
ABSTRACT: Impacts of climate change on natural resources need to be evaluated in a range of geography and agricultural systems for better conservation planning. The objectives of this paper were to evaluate spatial sensitivity of predicted soil loss and runoff to climate change at large scales, and to simulate the “regional” impacts of climate change on soil erosion on the southern Great Plains. Relative climate changes at three spatial scales between 1950 to 99, and 2070 to 99, projected using HadCM3 under the A2a, B2a, and GGa1 emission scenarios, were used to generate changed climates for Chickasha, Oklahoma. The Water Erosion Prediction Project (WEPP) model was run for each climate scenario at three spatial scales with three tillage systems. The HadCM3 predicted a general decrease in precipitation and an increase in the east-west precipitation gradient on the Southern Great Plains over the century. The decrease in precipitation resulted in general decreases in predicted runoff and soil loss. Percent changes, compared to the present climate, ranged from -33 to -3 percent for runoff and from -33 to 0 percent for soil loss. Variability of predicted runoff and soil loss over spatial scales was comparable to that between climate change scenarios. This finding suggests that the climatic impacts should be assessed at the spatial resolution at which global climate models have predictive skill, or at multiple spatial scales if the skillful resolution is unknown. The latter would yield additional information on uncertainty of predicted impacts due to uncertainty of spatial scales of climate input.
Keywords: Climate change, soil conservation, soil erosion
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Long-term impact of broiler litter on chemical properties of a Coastal Plain soil
G.J. Gascho and R.K. Hubbard
ABSTRACT: Broiler chicken (Gallus gallus) production is increasing rapidly in the southern Coastal Plain where there is an abundance of agricultural crops. The litter (mainly manure and bedding material) is a proven source of crop nutrients. We measured the pH, carbon (C), and extractable nutrient elements to a depth of 90 cm (3 ft) prior to and following seven years of an irrigated conservation-tilled double-cropped rotation. Litter was surface-applied to each crop at four rates (0, 4.5, 9.0, and 13.5 Mg ha-1 yr-1; 0, 2, 4, and 6 t-1 ac-1 yr-1) during the first five years of the rotation. Concentrations of extractable nutrient elements from the applied litter remained below levels of environmental concern during this seven-year study. Several trends in the data suggest that there will likely be problems with longer-term applications at high rates in the intensive crop rotation. Increases of extractable phosphorus (P), zinc (Zn), and copper (Cu) (contained in broiler feed) are of greatest concern. Phosphorus, extracted by Mehlich-1, increased >100 mg kg-1 ( >100 ppm) in the surface soil due to the greatest BL rate. Many crops will thrive when soil P is high, but depending on slope and other soil properties, potential exists for losses of P via surface runoff or leaching. Such losses have been correlated with extractable P. Potassium from litter appeared to move to depths beyond the rooting zone of some crops. Concentrations of Cu increased four-fold and Zn five-fold in the top soil at the greatest rate of litter. Continuance of the applications at high rates will eventually lead to toxicity, particularly Zn toxicity in peanut (Arachis hypogaea L.). Nitrate-nitrogen concentration remained low through the soil profile. Potential benefits from broiler litter were attained by the maintenance of pH and an increase of 2.7 Mg C ha-1 (1.2 t C ac-1) in the top 15 cm (6 in). Results of the study suggest that litter can be utilized well, without negative environmental effects when it is applied at conservative rates.
Keywords: Agriculture, broiler litter, coastal plain, poultry manure, runoff, soil testing
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Effects of cultivation history and current grassland management on soil quality in northeastern Kansas
C.A. Murphy, B.L. Foster, M.E. Ramspott, and K.P. Price
ABSTRACT: Management regimes of varying types and intensities can have profound impacts on grassland soil quality. Plus, there has recently been increased interest in finding soil quality indicators that are reflective of historical and current land management. We surveyed soil quality of privately owned grasslands in northeastern Kansas differing in their cultivation histories and current land-use (cool-season hay and grazed, warm-season native hay and grazed, and Conservation Reserve Program). We found significant differences in individual soil characteristics among management regimes when using both chemical and physical soil quality indicators. Principal components analysis showed that cultivation history and current land-use of these fields could be reflected by overall soil quality. Also, within cultivated fields, overall soil quality significantly increased with time since last cultivation. Our results suggest that using soil quality indicators such as nitrogen, carbon and organic matter are reflective of historical land use, but are not as useful when trying to determine current land use.
Keywords: Conservation Reserve Program, cultivation, grassland, grazing, hay, land-use, prairie, soil quality
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Long-term crop residue dynamics in no-till cropping systems under semi-arid conditions
C. Cantero-Martinez, D.G. Westfall, L.A. Sherrod, and G.A. Peterson
ABSTRACT: The presence of crop residue is an important component of dryland cropping systems management in the semiarid environment where soil erosion by wind is a major soil degradation process. Residue also affects precipitation capture and runoff. Long-term residue quantity dynamics of different cropping systems has not been studied in the semi-arid environment of the western Great Plains. Long-term studies were conducted to determine the interaction of no-till cropping systems, soils, and climatic gradient on the production, retention, and disappearance of crop residue over a 12-year period. The cropping systems evaluated were winter wheat (Triticum aestivum)-summer fallow (WF), winter wheat-corn (Zea Mays) or sorghum (Sorghum bicolor)-summer fallow (WC/SF), winter wheat-corn/sorghum-millet (Panicum miliaceum)-summer fallow (WC/SMF), and continuous cropping (CC). A soil surface residue base was achieved in a few years (four to five) and changed little over time. However, as cropping intensity increased the total crop residue retained on the soil surface increased as the proportion of fallow time decreased; a general trend was for residue levels to increase slowly. However, in the winter wheat-summer fallow system residue levels showed a trend to decrease after the initial base was achieved. Greater residue production and retention occurred on the toeslope soil position because these soils are deeper, have greater water holding capacity, and receive run-on water from upslope positions. Residue disappearance was less in the fallow period before corn planting compared to before wheat planting due to the greater fallow period, which included summer fallow in the wheat system. Residue loss was greater during the crop production periods as compared to the fallow periods. The levels of residue present on the soil surface in our intensive no-till cropping systems were generally adequate to control erosion by wind. However, at our high potential evapotranspiration site the residue levels were “marginal” for adequate wind erosion abatement, particularly in the winter wheat-summer fallow system. A combination of no-till management and increased cropping intensity (greater than winter wheat-summer fallow) is the key to sustainable production and soil conservation in this semi-arid environment.
Keywords: Cropping systems, crop rotations, dryland
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The Eucha/Spavinaw phosphorus index:
A court mandated index for litter management
P.B. DeLaune, B.E. Haggard, T.C. Daniel, I. Chaubey, and M.J. Cochran
ABSTRACT: Phosphorus (P)-based management strategies have been adopted in state planning standards nationwide, as most states have modified and adapted the original P index approach to better assess local landscape characteristics and management practices. However, P-based management strategies and environmental issues have become the focus of legal action within and between the states of Arkansas and Oklahoma due to differing management strategies in trans-boundary watersheds. A court settlement agreement was reached between parties in July 2003 requiring the development of a new P index by January 1, 2004 for use in writing nutrient management plans throughout the entire Eucha/Spavinaw watershed. The University of Arkansas found it most appropriate to modify the existing P index already in use in Arkansas to meet terms of the settlement agreement and to better reflect landscape characteristics and management practices specific to the Eucha/Spavinaw watershed. Hence, the Eucha/Spavinaw P index was developed and submitted to the court. By court decree, nutrient management plans in the watershed were written using the Eucha/Spavinaw P index beginning in February 2004. The Court issued further modifications to the Eucha/Spavinaw P index prior to release because the court felt that the specific P index did not fully comply with the settlement agreement. Through 2004, it was reported that the implementation of the Eucha/Spavinaw P index resulted in recommended litter application rates that were approximately one-third the rates that were common before the implementation of the Eucha/Spavinaw P index. Litter application rates recommended by the Eucha/Spavinaw P index were as much as 60 percent lower than application rates that would be recommended with the Arkansas phosphorus index for pastures as currently used.
Keywords: Court settlement, Eucha/Spavinaw watershed, lawsuit, phosphorus index, poultry, water quality
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Stream nutrient limitation and sediment interactions in the Eucha-Spavinaw Basin
Y.A. Popova, V.G. Keyworth, B.E. Haggard, D.E. Storm, R.A. Lynch, and M.E. Payton
ABSTRACT: Water-quality concerns at lakes and reservoirs often force watershed managers to focus on nutrient sources within the catchment, particularly nutrients applied to the landscape and direct input of nutrients from wastewater treatment plants. When nutrients from these sources enter stream systems, nutrient molecules begin a spiraling process, moving downstream and interacting in various in-stream processes that temporarily retain and transform nutrients. The objectives of this study were to evaluate: 1) the limiting nutrient of periphytic algae using a passive diffusion periphytometer; 2) the content of easily exchangeable and bioavailable nutrients in sediments; and 3) sediment and water column dissolved phosphorus equilibrium in streams draining the Eucha-Spavinaw Basin in northeast Oklahoma and northwest Arkansas. Stream nutrient concentrations were generally not limiting algal growth because nutrient enrichment did not elicit a significant increase in periphytic chlorophyll-a concentration at most locations and in most seasons; however, two streams did show evidence of P limitation of algal growth during summer. Nutrient concentrations in the select Ozark streams increased with an increase in pasture land use in the catchment (p<0.05). Sediment nutrient content and equilibrium P concentrations generally also increased with the proportion of pasture, but these parameters were more strongly influenced by wastewater treatment plant effluent discharge than catchment land use. In the Ozarks, it appears that the effects of wastewater treatment plants on stream water chemistry and sediment nutrient content were much greater than that from potential nonpoint sources and catchment land use.
Keywords: Algal nutrient limitation, phosphorus, nitrogen, sediment nutrient content, wastewater treatment plants, water quality
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