Intensive biomass production in emerging bioenergy systems could increase nonpoint-source sediment and nutrient losses and impair surface and groundwater quality. Recycling biochar, a charcoal byproduct from pyrolysis of biomass, provides potential sources of mineral nutrients and organic carbon for sustaining biomass productivity and preserving soil and water. Yet, research is needed to verify that recycling of pyrolysis biochars will enhance crop growth and soil and environmental quality similar to black carbon or biochar derived from burning of biomass in tropical or Terra Preta soils. The experimental design of this study consisted of 3 replications and four biochar rates (0, 4, 16, and 64 Mg ha-1) incorporated in both a sandy loam and clay soil with and without fertilizer sources of N, P, and K. The sandy loam and clay soils were studied in separate experiments within a set of 24 box lysimeters seeded with switchgrass. Simulated rain was applied at 50 percent and 100 percent establishment of switchgrass for each soil type. Runoff and leachate were collected and analyzed for total and dissolved N, P, K and organic C. After the second rain event, each soil type and the accumulated switchgrass was sampled and analyzed. In the Boonville soil, biochar applied at 64 Mg ha-1 decreased switchgrass emergence from 42 percent to 14 percent when compared to soil alone. In the Burleson soil, 64 Mg ha-1 biochar had no effect (P > 0.05) on biomass production or leaf area index (LAI). Fertilizer N, P, and K had no effect (P > 0.05) on switchgrass emergence for either soil, but did increase (P < 0.001) N, P, and K uptake, biomass production, and LAI. Increasing rates of biochar increased (P < 0.001) runoff concentrations of DRP during each rain event for both the Boonville and Burleson soils. Four rates of biochar receiving supplemental N, P, and K fertilizer also resulted in greater runoff concentrations of DRP. Emergence tests under increased heat showed electrical conductivities of soil-water solutions to be as high as 600 microS cm-1, even after biochar was washed with acetone and water to remove residual oils and tars and soluble salts. Increasing biochar rates decreased soil bulk density and increased pH and SOC in the 0- to 5-cm depth of soil. As a result of high nutrient recovery during pyrolysis (58 percent of total N, 86 percent of total P and 101 percent of total K), high rates of biochar applied at 64 Mg ha-1 increased mass losses of TN, TP, and TK from both soils. Yet, the mass balance of nutrients showed a surplus of N, P, and K at 64 Mg ha-1 biochar, which suggests some nutrient inputs are not plant available and remain in soil. Careful management of biochar, especially at high rates with these high nutrient contents, is critical when trying to improve soil fertility while protecting water quality.

The top-down effects of consumers and bottom-up effects of resource availability are important in determining community structure and ecological processes. I experimentally examined the roles of consumers — both detritivores and predators — and habitat context in affecting nutrient cycling using the detritus-based insect community in bromeliad leaf wells. I also investigated the role of multiple resources in limiting plant productivity using meta analyses. The insect community in bromeliads only increased nitrogen release from leaf detritus in the presence of a predator trophic level. When only detritivores were present, the flow of stable isotope-labeled nitrogen from detritus to bromeliads was statistically indistinguishable from that in bromeliads lacking insects. I suggest that emergence of adult detritivores constitutes a loss of nitrogen from bromeliad ecosystems, and that predation reduces the rate of this nutrient loss. Hence, insects facilitate nutrient uptake by the plant, but only if both predators and detritivores are present. Moreover, predators can affect nutrient cycling by influencing the spatial scale of prey turnover. This mechanism results in a pattern opposite to that predicted by classic trophic cascade theory. Increasing habitat complexity can have implications for nutrient cycling by decreasing the foraging efficiency of both predators and their prey, and by affecting the vulnerability of predators to intraguild predation. Along a natural gradient in bromeliad size, I found that, depending on the relationship between community composition and habitat size, habitat complexity interacts with the changing biotic community to either complement or counteract the impact of predators on nutrient uptake by bromeliads. In contrast to the existing emphasis on single-resource limitation of primary productivity, meta-analyses of a database of 653 studies revealed widespread limitation by multiple resources, and frequent interaction between these resources in restricting plant growth. A framework for analyzing fertilization studies is outlined, with explicit consideration of the possible role of multiple resources. I also review a range of mechanisms responsible for the various forms of resource limitation that are observed in fertilization experiments. These studies emphasize that a wider range of predator and nutrient impacts should be considered, beyond the paradigm of single resource limitation or classic trophic cascades.

The purposes of this study are to investigate the sources, distributions, fluxes and phosphorus burial efficiency (PBE) of particulate phosphorus in the Gaoping (GP) coastal sea. The GP River carried about 3.14 ¡Ñ 104 ton yr-1 (1.03 ¡Ñ 109 mol yr-1) particulate P into the GP coastal sea. The total P flux was primarily determined by the river runoff during the May-yu (monsoon) and typhoon seasons. The river P was approximately consisted of 90.8% particulate inorganic-P (PIP), 7.4% particulate organic-P (POP), 1.5% dissolved inorganic-P (DIP) and 0.3% dissolved organic-P (DOP). The particulate-P existed mainly in 10-63 £gm particles. In the GP costal sea, particulate P in surface sediments was found to be 80-90% as PIP and 10-20% as POP. The highest distribution of PIP was located on the flanks of GP Canyon at the upper slope (200-600 m) region. This distribution may be caused by plumes of river sediments or turbidity currents overflowing the canyon. The sedimentation rates of sediments ranged from 0.032 to 1.62 g cm-2 yr-1 in the GP coastal sea and the highest rates were also located on both sides of the GP Canyon. The burial fluxes of total phosphorus (TP) ranged from 0.02 to 0.84 g cm-2 yr-1, consisted approximately by 88% PIP and 12% POP. The burial fluxes of this study area were generally similar to those in other continental margins (Bohai Sea, Yellow Sea, Mississippi Delta). The total depositions of sediment and TP were approximately 6.6 ¡Ñ 106 ton yr-1 and 4227 ton yr-1, respectively, in the study area. The burial TP was equivalent to 0.06% of deposited sediments. The buried TP can be proportionate approximately into 15% in the continental shelf (< 200 m), 69% in the continental slope (200-1000 m), and 16% in the slope basin (> 1000 m). The continental shelf (<200 m) region was apparently influenced by wave and tidal processes and prevented from sediment accumulation. The burial efficiency of TP (PBE) in the GP costal sea is estimated accordingly to PBE (%) = 100 ¡Ñ PBF / (PBF+JP), where PBF is the burial flux of TP and JP is the diffusion flux of TP from porewater. The PBE decreases with the depth of sampling location and the maximum PBE locates on the station of southern canyon (779-1), the station of northern canyon (791-L18) and the station within the canyon (732-38). The PBE(s) are similar to those found in the Nazar&#x00E9; Canyon, showing a high PBE in coastal and/or canyon regions. The budget model shows that the major sources of particulate-P are derived from the GP River and the net ecosystem production (NEP) from the euphotic zone of study area. The annual river load and NEP input to the study area are 1.03 ¡Ñ 109 mol P yr-1 and 1.5 ¡Ñ 108 mol P yr-1, respectively. However, annual TP accumulation in the GP costal sea is just 1.48 ¡Ñ 108 mol P yr-1, corresponding to 12.5% of river load and NEP input. In addition, about 80% of GP River loads do not deposit into GP sediments and may be exported out of the study area.

Thesis (M.S. in soil sciences)--Washington State University, December 2009. / Title from PDF title page (viewed on Jan. 25, 2010). "Department of Crop and Soil Sciences." Includes bibliographical references.

Title from PDF of title page (University of Missouri--Columbia, viewed on Feb 18, 2010). The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Thesis advisor: Dr. Laura McCann. Includes bibliographical references.

Thesis (Ph. D.)--Lehigh University, 2003. / Includes vita. Includes bibliographical references (leaves 100-104).

Fertilizer phosphorus (P) application rate and method are anticipated to have important influences on crop utilization and concentration and distribution of residual P in soil. This, in turn, can influence the amount of P removed in run-off water. The objective of this thesis work was to assess the influence of fertilizer P application method and rate on soybean (Glycine max (L.)) emergence, yield, and P uptake. Additionally, the forms and distribution of residual soil P following a season of crop growth, and the off-site export of applied P in simulated snowmelt run-off water was assessed. In a controlled environment study, soybean could tolerate up to 20 kg P2O5 ha-1 placed in the seed-row without significant reduction in emergence. Soybean was grown in a field study in 2014 in south-central Saskatchewan. Two sites were utilized within the same wheat stubble field (Downslope and Upslope) where fertilizer P was soil applied in the spring (seed-placed, deep band, and broadcast and incorporated) at 20 kg P2O5 ha-1 and broadcast at three rates (20, 40, and 80 kg P2O5 ha-1), along with a control treatment receiving no fertilizer P. At the Downslope position, in-soil application of fertilizer P resulted in a greater soybean yield and P uptake than broadcast application. After harvest, higher labile P concentrations were found in the zone of fertilizer P placement in the soil. Elevated concentrations of water soluble P were noted near the soil surface with broadcast P application compared to in-soil placement methods, attributed to immobility of P and lower plant utilization. A simulated snowmelt run-off event was conducted on intact soil slabs removed from the Upslope position treatments. Fertilizer P application method had a significant influence on P export with the greatest export occurring with broadcast application. Phosphorus XANES spectroscopy provided further evidence that, qualitatively, fertilizer P application method influenced speciation of fertilizer P reaction products in calcareous soil common to the Canadian prairies. Overall, it is concluded that in-soil placement of P fertilizer is a beneficial management practice in a prairie soil to maximize agronomic benefit while minimizing potential transport of fertilizer P off the field in snowmelt run-off water.

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