Search

Winter annual cover crop use is limited in conservation management systems in the United States. Grazing cover crops could encourage cover crop adoption if returns offset establishment costs without reducing crop yields. A 4-yr field experiment was conducted near Watkinsville, GA, in which a rye (Secale cereale L.) cover crop was grazed by cattle or roller-crimped before planting cotton (Gossypium hirsutum L.). Cattle consumed about 2.4 Mg ha-1 of forage annually but amounts were variable due to weather conditions. Rye residue remaining at cotton planting averaged 6.7 Mg ha-1 for non-grazed compared with 1.7 Mg ha-1 for grazed treatments. Cotton yields tended to be better in the non-grazed treatment but were significantly different only in 2009 when yields were reduced in the grazed treatment due to soil compaction. Four-year average lint yield was 120 kg ha-1 greater for the non-grazed treatment. Cotton fiber quality parameters were generally better in the non-grazed treatment but not enough to change crop price. Differences between grazed and non-grazed returns ranged from $-26 to $355 and averaged $81 ha-1 when based on market year prices. The difference in average return increased to $110 ha-1 when based on 2012 market year prices. Although negative effects of soil compaction were observed the final year, returns from grazing have the potential to offset establishment costs of a rye cover crop and increase profits for cotton producers in the Southern Piedmont of the United States. [ABSTRACT FROM AUTHOR]

Flue gas desulfurization (FGD) gypsum is a byproduct of coal-fired power plants. Its application to agricultural fields may increase water infiltration, reduce soil erosion, and decrease nutrient losses from applications of animal manures. It may also reduce fecal bacterial contamination of surface waters. We tested the hypothesis that FGD gypsum applications would decrease the load of Salmonella and the fecal indicator bacterium Escherichia coli from poultry litter applications. Two rainfall simulation experiments were undertaken: one in spring 2009 and one in spring 2011. Six treatments consisted of four rates of FGD gypsum (0, 2.2, 4.5, and 9.0 Mg ha-1) with poultry litter (13.5 Mg ha-1 and two controls) in a randomized, complete-block design with three replications. Each replicate 4- X 6-m plot contained a single 1- X 2-m subplot that was delineated by metal plates and a flume that captured total overland flow or runoff. Rainfall was applied at ~64 mm h -1. Volume of overland runoff was measured and subsampled for analysis every 10 min for 1 h. Flow-weighted concentrations, total loads, and soil concentrations of E. coli were determined. Salmonella was not detected in runoff. No significant differences between treatments were observed for the 2009 rainfall simulation. However, after 3 yr of FGD gypsum applications, the highest rate of FGD gypsum resulted in decreased flow-weighted concentrations and total loads of E. coli. Flue gas desulfurization gypsum applications may be a management practice that reduces microbial contamination of surface waters from manure applied to agricultural fields in the southeastern United States. [ABSTRACT FROM AUTHOR]

High-quality surface-soil characteristics are important for developing environmentally sustainable agroecosystems. We evaluated the factorial combination of fertilization regime (inorganic and broiler litter) and tall fescue [Lolium arundinaceum (Schreb.) Darbysh.]--endophyte association (free, novel, and wild) with cattle grazing (plus a control treatment of inorganic fertilizer + novel endophyte with haying) on surface soil compaction and soil organic C and total N sequestration during 8 yr of management on a previously degraded Typic Kanhapludult in Georgia. Soil organic C and total N were sequestered with time at all depth intervals to 20 cm (0-3, 3-6, 6-12, and 12-20 cm). At a depth of 0 to 6 cm (surface zone most responsive to management), soil organic C sequestration was (I) greater with grazed than with hayed management (1.36 vs. 0.69 Mg C ha-1 yr-1, respectively), (ii) similar between broiler litter and inorganic fertilization, (iii) similar among endophyte associations, and (iv) similar among zones within a grazed pasture. At a depth of 0 to 20 cm, soil organic C and total N sequestration were not significantly affected by treatment variables, but high mean sequestration rates of 1.51 Mg C ha-1 yr-1 and 0.126 Mg N ha-1 yr-1 during managed grazing of tall fescue in addition to the previous decade of unmanaged herbaceous fallow (implied sequestration rates of 0.76 Mg C ha-1 yr-1 and 0.062 Mg N ha-1 yr-1) suggests that improved grazing management systems can have an enormous benefit to surface soil fertility restoration of degraded soils in the southeastern United States. [ABSTRACT FROM AUTHOR]

Soil water influences hydrological, biological, and biogeochemical processes that determine on- and off-site response of landscapes under different agricultural uses. There are relatively little detailed spatial and temporal soil water measurements to validate current representations of spatial and temporal soil water variability. Soil water was measured over 3 yr at 12 sites to a 1.2-m depth in a 7.8-ha pasture catchment in the Georgia Piedmont in southeastern USA. The Mahalanobis statistical difference was estimated between all pairs of measurement sites for soil water. Multidimensional scaling of the Mahalanobis differences showed that only a single statistical dimension was separating the observed soil water variations at measurement sites (r = 0.99). This statistical dimension was then found to be most closely correlated with the depth to the Bt and the depth of the Ap horizons for explaining the observed variation in soil water between sampling sites (r = 0.69 and r = 0.8, respectively). Those sites where the Bt, an argillic horizon, was close to the surface, even when higher up the landscape, were generally wetter than those in which the Bt was deeper, even in the lower part of the landscape. The depth to the Bt horizon may serve as an indicator of the portions of the watershed most likely to be primary sources of runoff in association with the depth of overlying coarse-textured soil. Volumetric soil water content was generally greatest in winter (22 to 30% average) and least in summer (8 to 12% except when influenced by intense summer storms). To fully understand the soil water dynamics of Piedmont or similar landscapes, it is important to know the spatial distribution of the depth to the Bt horizon. Improved understanding of the soil water dynamics could lead to improved land use decisions, erosion control, and management of water resources. This should be of interest to many researchers across many disciplines. [ABSTRACT FROM AUTHOR]