Crop Fertilization on East Texas Soils.

4 p

Fragipan Horizon Fragmentation in Slaking Experiments with Amendment Materials and Ryegrass Root Tissue Extracts

Slaking experiments were conducted of fragipan clods immersed in solutions of poultry manure, aerobically digested biosolid waste (ADB), fluidized bed combustion byproduct (FBC), D-H2O, CaCO3, NaF, Na-hexa-metaphosphate, and ryegrass root biomass. The fragipan clods were sampled from the Btx horizon of an Oxyaquic Fragiudalf in Kentucky. Wet sieving aggregate analysis showed significantly better fragmentation in the NaF, Na-hexa-metaphosphate, and ryegrass root solutions with a mean weight diameter range of 15.5-18.8 mm compared to the 44.2-47.9 mm of the poultry manure, ADB, and FBC treatments. Dissolved Si, Al, Fe, and Mn levels released in solution were ambiguous. The poor efficiency of the poultry manure, ADB, and FBC treatments was attributed to their high ionic strength, while the high efficiency of the NaF, Na-hexa-metaphosphate, and rye grass root solutions to their high sodium soluble ratio (SSR). A slaking mechanism is proposed suggesting that aqueous solutions with high SSR penetrate faster into the fragipan capillaries and generate the critical swelling pressure and shearing stress required to rupture the fragipan into several fragments. Additional fragmentation occurs in a followup stage during which potential Si, Al, Fe, and Mn binding agents may be released into solution. Field experiments testing these findings are in progress

Evaluation of ductile-brittle transition temperature of anisotropy material by small punch test with U-shaped notch

Miniature and standard specimens, were cut from the anisotropy materials with axial, central and radial directions to study the mechanical property. In the paper, main research focused on the small punch test (SPT) with un-notched and U-shaped notched specimen in low temperature. Through the small punch energy variation with temperature, the ductile-brittle transition temperature by the small punch test (TSP) can be determined. The results indicated that there was no obvious difference among three different directions in transformation temperature of SPT with un-notch specimens, and it cannot represent upper plateau impact energy of three different directions. And the SPT with U-shaped notched specimens can determine the differences of upper plateau fracture energy of three different directions. Therefore, SPT with U-shaped notch specimens was more useful to evaluate the material anisotropy

Crop Fertilization on East Texas Soils.

4 p

Crop Fertilization on East Texas Soils.

4 p

Detecting Recent Crop Phenology Dynamics in Corn and Soybean Cropping Systems of Kentucky

Accurate phenological information is essential for monitoring crop development, predicting crop yield, and enhancing resilience to cope with climate change. This study employed a curve-change-based dynamic threshold approach on NDVI (Normalized Differential Vegetation Index) time series to detect the planting and harvesting dates for corn and soybean in Kentucky, a typical climatic transition zone, from 2000 to 2018. We compared satellite-based estimates with ground observations and performed trend analyses of crop phenological stages over the study period to analyze their relationships with climate change and crop yields. Our results showed that corn and soybean planting dates were delayed by 0.01 and 0.07 days/year, respectively. Corn harvesting dates were also delayed at a rate of 0.67 days/year, while advanced soybean harvesting occurred at a rate of 0.05 days/year. The growing season length has increased considerably at a rate of 0.66 days/year for corn and was shortened by 0.12 days/year for soybean. Sensitivity analysis showed that planting dates were more sensitive to the early season temperature, while harvesting dates were significantly correlated with temperature over the entire growing season. In terms of the changing climatic factors, only the increased summer precipitation was statistically related to the delayed corn harvesting dates in Kentucky. Further analysis showed that the increased corn yield was significantly correlated with the delayed harvesting dates (1.37 Bu/acre per day) and extended growing season length (1.67 Bu/acre per day). Our results suggested that seasonal climate change (e.g., summer precipitation) was the main factor influencing crop phenological trends, particularly corn harvesting in Kentucky over the study period. We also highlighted the critical role of changing crop phenology in constraining crop production, which needs further efforts for optimizing crop management practices

Characterization of Environmental Nano- and Macrocolloid Particles Extracted from Selected Soils and Biosolids

Environmental nanoparticles found in soil systems and biosolids may pose a considerable risk to groundwater quality as contaminant carriers. Little effort has been invested in the characterization of natural nanocolloids compared to corresponding macrocolloids. This study involved physicochemical, mineralogical, and morphological characterizations of nanocolloids and macrocolloids fractionated from three Kentucky soils and one biosolid. Particle size and morphology were investigated using scanning/transmission electron microscopy and dynamic light scattering. Mineralogical composition was determined by X-ray diffraction and thermogravimetric and Fourier-transform infrared spectroscopy analyses. Zeta potentials and cation exchange capacities assessed surface charge and chemical reactivity. The estimated average hydrodynamic diameter of nanoparticles was nearly twice the ideal 100 nm range, apparently due to irregular particle shapes and partial aggregation. Nanoparticles were also found attached to surfaces of macrocolloids, forming macro-nano aggregates and obscuring some of their physical and chemical characteristics. However, nanocolloids exhibited greater surface reactivity, likely due to their smaller size, poor crystallinity, and morphological shape distortions. In spite of some behavior modification due to nanoaggregation phenomena, nanocolloids appeared to be much more potent vectors of contaminant transport in subsurface environments than their macrosize fractions. Nevertheless, their heterogeneous nature brings to light important considerations in addressing pollution prevention and remediation challenges

Fragipan Horizon Fragmentation in Slaking Experiments with Amendment Materials and Ryegrass Root Tissue Extracts

Slaking experiments were conducted of fragipan clods immersed in solutions of poultry manure, aerobically digested biosolid waste (ADB), fluidized bed combustion byproduct (FBC), D-H2O, CaCO3, NaF, Na-hexa-metaphosphate, and ryegrass root biomass. The fragipan clods were sampled from the Btx horizon of an Oxyaquic Fragiudalf in Kentucky. Wet sieving aggregate analysis showed significantly better fragmentation in the NaF, Na-hexa-metaphosphate, and ryegrass root solutions with a mean weight diameter range of 15.5–18.8 mm compared to the 44.2–47.9 mm of the poultry manure, ADB, and FBC treatments. Dissolved Si, Al, Fe, and Mn levels released in solution were ambiguous. The poor efficiency of the poultry manure, ADB, and FBC treatments was attributed to their high ionic strength, while the high efficiency of the NaF, Na-hexa-metaphosphate, and rye grass root solutions to their high sodium soluble ratio (SSR). A slaking mechanism is proposed suggesting that aqueous solutions with high SSR penetrate faster into the fragipan capillaries and generate the critical swelling pressure and shearing stress required to rupture the fragipan into several fragments. Additional fragmentation occurs in a followup stage during which potential Si, Al, Fe, and Mn binding agents may be released into solution. Field experiments testing these findings are in progress

Integrating climate change mitigation and adaptation in agriculture and forestry: opportunities and trade-offs

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.International audienceAlthough many activities can jointly contribute to the climate change strategies of adaptation and mitigation, climate policies have generally treated these strategies separately. In recent years, there has been a growing interest shown by practitioners in agriculture, forestry, and landscape management in the links between the two strategies. This review explores the opportunities and trade-offs when managing landscapes for both climate change mitigation and adaptation; different conceptua-lizations of the links between adaptation and mitigation are highlighted. Under a first conceptualization of 'joint outcomes,' several reviewed studies analyze how activities without climatic objectives deliver joint adaptation and mitigation outcomes. In a second conceptualization of 'unintended side effects,' the focus is on how activities aimed at only one climate objective—either adaptation or mitigation—can deliver outcomes for the other objective. A third conceptualization of 'joint objectives' highlights that associating both adaptation and mitigation objectives in a climate-related activity can influence its outcomes because of multiple possible interactions. The review reveals a diversity of reasons for mainstreaming adaptation and mitigation separately or jointly in landscape management. The three broad conceptualizations of the links between adaptation and mitigation suggest different implications for climate policy mainstreaming and integration