Advances and challenges for nutrient management in china in the 21st century.

Managing agricultural nutrients to provide a safe and secure food supply while protecting the environment remains one of the great challenges for the 21st century. The fourth International Nutrient Management Symposium (INMS), held in 2011 at the University of Delaware, addressed these issues via presentations, panel sessions, and field tours focused on latest technologies and policies available to increase nutrient use efficiency. Participants from the United States, Europe, Canada, and China discussed global trends and challenges, balancing food security and the environment in countries with struggling and emerging economics, nutrient management and transport at the catchment scale, new technologies for managing fertilizer and manure nutrients, and adaptive nutrient management practices for farm to watershed scales. A particular area of interest at the fourth INMS was nutrient management progress and challenges in China over the past 40 years. China's food security challenges and rapidly growing economy have led to major advances in agricultural production systems but also created severe nutrient pollution problems. This special collection of papers from the fourth INMS gives an overview of the remarkable progress China has made in nutrient management and highlights major challenges and changes in agri-environmental policies and practices needed today. Lessons learned in China are of value to both developing and developed countries facing the common task of providing adequate food for an expanding world population, while protecting air and water quality and restoring damaged ecosystems.

The driving forces for nitrogen and phosphorus flows in the food chain of china, 1980 to 2010.

Nitrogen (N) and phosphorus (P) use and losses in China's food chain have accelerated in the past three decades, driven by population growth, rapid urbanization, dietary transition, and changing nutrient management practice. There has been little detailed quantitative analysis of the relative magnitude of these driving forces throughout this period. Therefore, we analyzed changes in N and P flows and key drivers behind changes in the food (production and consumption) chain at the national scale from 1980 to 2010. Food (N and P) consumption increased by about fivefold in urban settings over this period but has decreased in rural settings since the 1990s. For urban settings, the integrated driving forces for increased food consumption were population growth, which accounted for ∼60%, and changing urban diets toward a greater emphasis on the consumption of animal products. Nutrient inputs and losses in crop and animal productions have continuously increased from 1980 to 2010, but the rates of decadal increase were greatly different. Increased total inputs and losses in crop production were primarily driven by increased crop production for food demand (68-96%) in the 1980s but were likely offset in the 2000s by improved nutrient management practices, as evidenced by decreased total inputs to and losses from cropland for harvesting per nutrient in crop. The contributions of animal production to total N and P losses to waters from the food chain increased by 34 and 60% from 1980 to 2010. These increases were caused mainly by decreased ratios of manure returned to cropland. Our study highlights a larger impact of changing nutrient management practice than population growth on elevated nutrient flows in China's food chain.

c-Abl and Arg are activated in human primary melanomas, promote melanoma cell invasion via distinct pathways, and drive metastatic progression.

Despite 35 years of clinical trials, there is little improvement in 1-year survival rates for patients with metastatic melanoma, and the disease is essentially untreatable if not cured surgically. The paucity of chemotherapeutic agents that are effective for treating metastatic melanoma indicates a dire need to develop new therapies. Here, we found a previously unrecognized role for c-Abl and Arg in melanoma progression. We demonstrate that the kinase activities of c-Abl and Arg are elevated in primary melanomas (60%), in a subset of benign nevi (33%) and in some human melanoma cell lines. Using siRNA and pharmacological approaches, we show that c-Abl/Arg activation is functionally relevant because it is requiredfor melanoma cell proliferation, survival and invasion. Significantly, we identify the mechanism by which activated c-Abl promotes melanoma invasion by showing that it transcriptionally upregulates matrix metalloproteinase-1 (MMP-1), and using rescue approaches we demonstrate that c-Abl promotes invasion through a STAT3 → MMP-1 pathway. Additionally, we show that c-Abl and Arg are not merely redundant, as active Arg drives invasion in a STAT3-independent manner, and upregulates MMP-3 and MT1-MMP, in addition to MMP-1. Most importantly, c-Abl and Arg not only promote in vitro processes important for melanoma progression, but also promote metastasis in vivo, as inhibition of c-Abl/Arg kinase activity with the c-Abl/Arg inhibitor, nilotinib, dramatically inhibits metastasis in a mouse model. Taken together, these data identify c-Abl and Arg as critical, novel, drug targets in metastatic melanoma, and indicate that nilotinib may be useful in preventing metastasis in patients with melanomas harboring active c-Abl and Arg.

The phosphorus footprint of China's food chain: implications for food security, natural resource management, and environmental quality.

Efficient use of phosphorus (P) for producing food, preventing water pollution, and managing a dwindling rock P reserve are major challenges for China. We analyzed P stocks and flows in the Chinese food chain to identify where P use efficiency can be improved, where P leaks to the environment, and the research, technologies, and policies needed to improve P use. We found a high degree of inefficiency; of 6652 Gg P entering the food chain, only 1102 Gg P (18%) exit as food for humans. The greatest inefficiencies were a large build-up of soil P (3670 Gg P yr; 52% of P inputs) and high P losses to the environment from animal production (1582 Gg P yr; 60% of excreted P). Improving P use in China must focus on national-scale nutrient management strategies, better animal nutrition, and adoption of technologies and policies to reduce P discharges from the animal sector and recycle P as manures in agriculture.

Nitrogen mass flow in China's animal production system and environmental implications.

China's economic boom in recent decades has stimulated consumer demand for animal products and consequently, a vast expansion in animal production. From 1978 to 2006, the number of animals increased by 322% for pigs, 209% for poultry, and 2770% for dairy cattle. The objective of the present study was to quantify nitrogen mass flow in China's animal production system at the national scale and to elucidate potential environmental implications. A comprehensive analysis was performed combining statistical records with data from the scientific literature and supplemental survey information. Results indicate that approximately 18 Mt of N flowed through the Chinese animal production system in 2006. Nitrogen input to the system was from various feed materials, including 6.8 Mt (38% of total) from roughage, 4.4 Mt (24%) from byproducts, 2.3 Mt (13%) from cereal grains, and 1.6 Mt (9%) each from crop residues and oilseed cakes, with the remaining N (16%) obtained from other feedstuffs. Nitrogen outputs from the system included edible animal products (2.4 t, 13% of total), nonedible animal parts (e.g., bones, skins) (3.8 Mt, 21%), and excreta (12 Mt, 66%). At the national level, the excreta would average 28 Mg (as excreted) and 90 kg N ha(-1) of cropland. However, at the provincial level, it varied from 1 Mg ha(-1) (5 kg N ha(-1)) in Qinghai to 97 Mg ha(-1) (243 kg N ha(-1)) in Sichuan. In regions with excreta in the intermediate rate (e.g., Hebei Province, 115 kg N ha(-1)) or high rare (e.g., Sichuan Province, 243 kg N ha(-1)), animal manure contributes significantly to nutrients polluting groundwater and/or surface waters. It is crucial for China to develop and implement proper management practices to maximum the beneficial use of the 12 Mt excreta N while minimizing its environmental footprint.

Aggressive breast cancer cells are dependent on activated Abl kinases for proliferation, anchorage-independent growth and survival.

Mutant Abl kinases (such as BCR-Abl) drive the development of leukemia; however little is known regarding whether Abl kinases contribute to the development or progression of solid tumors. We recently demonstrated that endogenous Abl kinases (c-Abl, Arg) are activated by deregulated ErbB receptors and Src kinases, and drive invasion of aggressive breast cancer cells. In this study, we examined whether activation of endogenous Abl kinases affects transformation, proliferation and survival, which are major contributors to breast cancer development and metastatic progression. Using a pharmacological inhibitor and RNAi, we demonstrate that activation of endogenous Abl kinases dramatically promotes breast cancer cell proliferation and anchorage-independent growth in serum, as well as survival following nutrient deprivation. Activation of Abl kinases mediates phosphorylation of STAT3, and promotes proliferation by accelerating G(1) --> S progression. Moreover, we identify IGF-1R as a novel upstream activator of endogenous Abl kinases, and demonstrate that Abl kinase activation is required for IGF-1-stimulated cell cycle progression in breast cancer cells. Since activation of Abl kinases affects multiple steps of breast cancer development and progression, Abl kinase inhibitors are likely to be effective agents for the treatment of breast cancers containing highly active Abl kinases.

Defining the sources of low-flow phosphorus transfers in complex catchments.

Nutrient transfers from the land to rivers have the potential to cause persistent eutrophic impacts at low flows even though the transfers may constitute a minor percentage of total annual fluxes. In rural catchments, the contribution from agricultural soils during storm events can be particularly large and untangling the relative contributions from multiple sources that vary in time and space is especially problematic. In this study, the potential for domestic septic tank system pollution during low flows was investigated in 3 small catchments (3 to 5 km(2)) using an integrated series of methods. These included septic system surveys, continuous (10 min) total phosphorus (TP) monitoring at the outlet of each catchment, repeated low-flow water quality surveys in sub-catchments upstream of the catchment outlets and single day river-walk water quality surveys. A series of faecal matter and grey-water fingerprinting techniques were also employed. These included determining sterol ratios in stream sediments, monitoring the presence of proteins, E. coli and enterococci bacterial signatures and boron. The total density and density of poorly maintained septic systems mirrored the magnitude of frequent TP concentrations in the catchments although this relationship was less apparent in the nested sub-catchments. The exception was possibly related to the simple hydraulics in one particular catchment and indicated temporary effluent attenuation in the other catchments. Repeated low-flow and river-walk water quality surveys highlighted discrete areas and reaches where stepped changes in nutrient concentration occurred. Bio-chemical fingerprinting showed that between 7% and 27% of sediments were contaminated with human faecal material and correlation matrices indicated that, at least during low flows, P fractions were positively correlated with some markers of faecal and grey-water contamination.

Dietary strategies for reduced phosphorus excretion and improved water quality.

Cost effective feeding strategies are essential to deal with P surpluses associated with intensive animal agriculture and the consequent impact on water quality. Reduction of P overfeeding, use of feed additives to enhance dietary P utilization, and development of high available phosphorus (HAP) grains have all been shown to decrease fecal P excretion without impairing animal performance. Much progress has been made, but more research will be needed to refine these strategies to maximize reductions in P excretion while maintaining animal performance. Recent research has focused on the impact of modifying dietary P on the forms of P excreted and the mobility of P in soils amended with these manures, with strong treatment trends becoming evident in the literature. In general, dietary strategies have been developed that can effectively reduce the total P concentration in manures produced, and combining strategies usually leads to greater reductions than individual practices. However, the impact of different approaches on the solubility of P in manures and amended soils has been more variable. Soluble P remains of particular concern due to links between solubility of P in manure and P losses from manure-amended soils. In this paper, we outline the major strategies for reducing dietary P in different species, review the literature on the impact of these approaches on P forms in manures and amended soils, and discuss the potential beneficial effects on animal agriculture and the environment.

Phytase supplementation and reduced-phosphorus turkey diets reduce phosphorus loss in runoff following litter application.

Concerns about regional surpluses of manure phosphorus (P) leading to increased P losses in runoff have led to interest in diet modification to reduce P concentrations in diets. The objectives of this study were to investigate how dietary P amendment affected P concentrations in litters and P losses in runoff following land application. We grew two flocks of turkeys on the same bed of litter using diets with two levels of non-phytate phosphorus (NPP), with and without phytase. The litters were incorporated into three soils in runoff boxes at a plant-available nitrogen (PAN) rate of 168 kg PAN/ha, with runoff generated on Days 1 and 7 under simulated rainfall and analyzed for dissolved reactive phosphorus (DRP) and total P. Litters were analyzed for water-soluble phosphorus (WSP) and total P, while soils in the runoff boxes were analyzed for WSP and Mehlich-3 phosphorus (M3-P). Formulating diets with lower NPP and phytase both decreased litter total P. Phytase had no significant effect on litter WSP at a 1:200 litter to water extraction ratio, but decreased WSP at a 1:10 extraction ratio. Using a combination of reducing NPP fed and phytase decreased the total P application rate by up to 38% and the P in surplus of crop removal by approximately 48%. Reducing the NPP fed reduced DRP in runoff from litter-amended soils at Day 1, while phytase had no effect on DRP concentrations. Increase in soil M3-P was dependent on total P applied, irrespective of diet. Reducing overfeeding of NPP and utilizing phytase in diets for turkeys should decrease the buildup of P in soils in areas of intensive poultry production, without increasing short-term concerns about dissolved P losses.

Influence of phytase addition to poultry diets on phosphorus forms and solubility in litters and amended soils.

Diet modification to decrease phosphorus (P) concentration in animal feeds and manures can reduce surpluses of manure P in areas of intensive animal production. We generated turkey and broiler litters from two and three flock trials, respectively, using diets that ranged from "high" to "low" in non-phytate phosphorus (NPP) and some of which contained feed additives such as phytase. Phosphorus forms in selected litters were analyzed by sequential chemical fractionation and solution (31)P nuclear magnetic resonance (NMR) spectroscopy. Selected litters were also incubated with four contrasting soils. Reducing dietary NPP and using phytase decreased total P in litters by up to 38%. Water-soluble phosphorus (WSP) in litters was decreased 21 to 44% by feeding NPP closer to animal requirement, but was not affected by phytase addition. Solution (31)P NMR spectroscopy showed that feeding NPP closer to requirement decreased orthophosphate in litters by an average of 38% and that adding phytase to feed did not increase the concentration of orthophosphate in litters. Phytase also decreased phytate P in litters by 25 to 38%, demonstrating that it increases phytate P hydrolysis. Incorporation of litters with soils at the same total P rate increased WSP in soils relative to the control; this increase was correlated to soluble P added with litters at 5 d, but not by 29 d. Changes in soil Mehlich-3 phosphorus (M3-P) were related to total P added in litter, rather than soluble P. We conclude that feeding NPP closer to requirement and using feed additives such as phytase decrease total P concentrations in litters, while having little effect on P solubility in litters and amended soils.

Determination of phosphorus source coefficients for organic phosphorus sources: laboratory studies.

Phosphorus losses in runoff from application of manures and biosolids to agricultural land are implicated in the degradation of water quality in the Chesapeake and Delaware Inland Bays. We conducted an incubation study to determine the relative P solubility and bioavailability, referred to as P source coefficients (PSCs), for organic P sources, which are typically land-applied in the Mid-Atlantic USA. Nine organic and one inorganic (KH2PO4) P amendments were applied to an Evesboro loamy sand (mesic, coated Typic Quartzipsamments) at a rate of 60 mg P kg(-1) and incubated for 8 wk with subsamples analyzed at 2 and 8 wk. There was an increase in Mehlich-3 P (M3-P), water-soluble P (WS-P), iron-oxide strip extractable P (FeO-P), and Mehlich-3 P saturation ratio (M3-PSR) with P additions, which varied by P source. The trend of relative extractable WS-P, FeO-P, and M3-P generally followed the pattern: inorganic P > liquid and deep pit manures > manures and biosolids treated with metal salts or composted. We found significant differences in the availability of P from varying organic P sources. The use of PSCs may be beneficial when determining the risk of P losses from land application of manures and other organic P sources and could be used in risk assessments such as a P site index. These PSCs may also be useful for determining P application rates when organic P sources are applied to P deficient soils for use as a fertilizer source.

Phosphorus feeding levels and critical control points on dairy farms.

A viable and cost-effective approach to managing P on dairy farms is to minimize excess P in diets, which in turn leads to less excretion of P in manure without impairing animal performance. A questionnaire survey was conducted, coupled with on-site feed and fecal sample collection and analysis on dairy farms in New York, Pennsylvania, Delaware, Maryland, and Virginia. The purpose was to assess dietary P levels and to identify critical control points pertaining to P feeding management. Survey responses, 612 out of 2500 randomly selected farms, revealed a wide range of dietary P concentrations for lactating cows, from 3.6 to 7.0 g/kg of feed DM. The mean was 4.4 g/kg, which was 34% above the level recommended by the NRC for 27.9 kg milk/d, the mean milk yield in the survey. Higher P concentrations in diets were not associated with higher milk yields (n = 98, R2 = 0.057 for the survey farms; n = 92, R2 = 0.043 for farms selected for on-site sampling). However, higher dietary P led to higher P excretion in feces (n = 75, R2 = 0.429), with much of the increased fecal P being water soluble. Phosphorus concentrations in diet samples matched closely with P concentrations in formulated rations, with 67% of the feed samples deviating <10% from the formulations. On 84% of the survey farms, ration formulation was provided by professionals rather than producers themselves. Most producers were feeding more P than cows needed because it was recommended in the rations by these consultants. In conclusion, P fed to lactating cows averaged 34% above NRC recommendations; to reduce excess dietary P, ration formulation is the critical control point.

On-farm evaluation of aluminum sulfate (alum) as a poultry litter amendment: effects on litter properties.

Aluminum sulfate [alum; Al2(SO4)3] amendment of poultry litters has been suggested as a best management practice to help reduce the potential environmental effects of poultry production. Past research has shown that alum treatment reduced NH3 emissions from litters, decreased the loss in runoff of P and trace metals from litter-amended soils, improved poultry health, and reduced the costs of poultry production. We conducted a large scale, "on-farm" evaluation of alum as a poultry (broiler) litter amendment on the Delmarva peninsula to determine the effect of alum on (i) litter properties and elemental composition and (ii) the solubility of several elements in litter that are of particular concern for water quality (Al, As, Cu, P, and Zn). Alum was applied over a 16-mo period to 97 poultry houses on working poultry farms; 97 houses on other farms served as controls (no alum). Litter samples were analyzed initially and after approximately seven alum applications. We found that alum decreased litter pH and the water solubility of P, As, Cu, and Zn. Alum-treated houses also had higher litter total N, NH4-N, and total S concentrations and thus a greater overall fertilizer value than litters from the control houses. Higher litter NH4-N values also suggest that alum reduced NH3 losses from litters. Thus, alum appears to have promise as a best management practice (BMP) for poultry production. Future research should focus on the long-term transformations of P, Al, As, Cu, and Zn in soils amended with alum-treated litters.

Solid-state speciation of natural and alum-amended poultry litter using XANES spectroscopy.

While alum amendments have shown to be effective in lowering water-soluble phosphate levels in poultry litter, the mechanism by which this occurs is not fully known. To determine the solid-state speciation of phosphate in litter samples, experiments were conducted with X-ray absorption near edge structure (XANES) spectroscopy. XANES analysis reveals that, in unamended samples, phosphate is present as weakly bound inorganic as well as some organic phosphate, with some dicalcium phosphate-type calcium phosphates also present. When alum is applied in the houses, XANES results suggest that it precipitates out as amorphous Al(OH)3 and then reacts with phosphate via an adsorption mechanism. No evidence was found of aluminum phosphate precipitation in any samples.

Effect of mixing soil aggregates on the phosphorus concentration in surface waters.

At any time, the phosphorus (P) concentration in surface waters is determined by a complex interaction of inputs of soluble P and sorption-desorption reactions of P with sediments. This study investigated what factors control P in solution when various soil aggregates were mixed, seen as being analogous to selective soil erosion events, transport, and mixing within river systems. Fifteen soils with widely differing properties were each separated into three aggregate size fractions (2-52 microm, 53-150 microm, and 151-2,000 microm). Resin P, water-soluble phosphorus (WSP), and the phosphorus buffer capacity (PBC = resin P/WSP) were measured for each aggregate size fraction and WSP was also measured for 11 mixes of the aggregate fractions. The smallest aggregates tended to be enriched with resin P relative to the larger aggregates and the whole soils, while the opposite was true for WSP. As the PBC was a function of resin P and WSP, the PBC was greatest in the 2- to 52-microm aggregate size fraction in most cases. When two aggregate size fractions were mixed, the measured WSP was always lower than the predicted WSP (i.e., the average of the WSP in the two individual aggregates), indicating that WSP released by one aggregate fraction could be resorbed by another aggregate fraction. This resorption of P may result in lower than expected solution P concentration in some surface waters. The strength with which an eroded aggregate can release or resorb P to or from solution is in part determined by that aggregate's PBC.

Relationships between biosolids treatment process and soil phosphorus availability.

Laws mandating phosphorus (P)-based nutrient management plans have been passed in several U.S. Mid-Atlantic states. Biosolids (sewage sludge) are frequently applied to agricultural land and in this study we evaluated how biosolids treatment processes and biosolids P tests were related to P behavior in biosolids-amended soils. Eight biosolids generated by different treatment processes, with respect to digestion and iron (Fe), aluminum (Al), and lime addition, and a poultry litter (PL), were incubated with an Elkton silt loam (fine-silty, mixed, active, mesic Typic Endoaquult) and a Suffolk sandy loam (fine-loamy, siliceous, semiactive, thermic Typic Hapludult) for 51 d. The amended soils were analyzed at 1 and 51 d for water-soluble phosphorus (WSP), iron-oxide strip--extractable phosphorus (FeO-P), Mehlich-1 P and pH. The biosolids and PL were analyzed for P, Fe, and Al by USEPA 3050 acid-peroxide digestion and acid ammonium oxalate, Mehlich-1, and Mehlich-3 extractions. Biosolids and PL amendments increased extractable P in the Suffolk sandy loam to a greater extent than in the Elkton silt loam throughout the 51 d of the incubation. The trend of extractable WSP, FeO-P, and Mehlich-1 P generally followed the pattern: [soils amended with biosolids produced without the use of Fe or Al] > [PL and biosolids produced using Fe or Al and lime] > [biosolids produced using only Fe and Al salts]. Mehlich-3 P and the molar ratio of P to [Al + Fe] by either the USEPA 3050 digestion or oxalate extraction of the biosolids were good predictors of changes in soil-extractable P following biosolids but not PL amendment. Therefore, the testing of biosolids for P availability, rather than total P, is a more appropriate tool for predicting extractable P from the biosolids-amended soils used in this study.

Vertebroplasty in patients with severe vertebral compression fractures: a technical report.

Vertebroplasty is a procedure in which polymethlymethacrylate (PMMA) is injected into a vertebral body compression fracture. It has been suggested that fractues greater than 65% to 70% of the original vertebral body height are too compressed to be treated successfully with this procedure. We describe six patients with severe compression fractures that were successfully treated with vertebroplasty in which the trocar was inserted in the far lateral aspect of the vertebral body, because of the typical morphology of severe compression fractures.

Management and utilization of poultry wastes.

Waste by-products such as excreta or bedding material that are generated by the worldwide annual production of more than 40 million metric tons (t) of poultry meat and 600 billion eggs are generally land applied as the final step of a producer's waste management strategy. Under proper land application conditions, the nutrients and organisms in poultry wastes pose little environmental threat. Environmental contamination occurs when land application of poultry wastes is in excess of crop utilization potential, or is done under poor management conditions causing nutrient loss from environmental factors such as soil erosion or surface runoff during rainfall. Environmental parameters of concern are N, P, and certain metals (Cu and Zn in particular), as well as pathogenic microorganisms that may be contained in poultry waste. The biochemical cycle of N is very dynamic, and N contained in poultry waste may either be removed by crop harvest, leave the animal production facility, waste treatment lagoon, or application field as a gas (NH3, NO, NO2, N2O, or N2), or, due to its mobility in soil, be transported in organic or inorganic N forms in the liquid state via surface runoff or leaching into groundwater. Elevated concentrations of NO3-N in groundwater used for human consumption is a health risk to infants that are susceptible to methemoglobinemia. An environmental impact resulting from elevated NO3-N is eutrophication of surface waters. Ammonia loss from poultry waste is an environmental concern because of volatilized wet and dry deposits of NH3 into nitrogen-sensitive ecosystems. Phosphorus in poultry wastes may contribute to environmental degradation by accelerating the process of eutrophication. Unlike N, P is very immobile in soil and must first be transported to a surface water environment to have an environmental impact. It is generally accepted, however, that this nutrient affects receiving waters via transport in eroding soil as sediment-bound P or in surface runoff as soluble inorganic or organic P. Numerous studies have reported that excess P contained in land-applied manures may contribute to eutrophication. Soils containing P concentrations that greatly exceed the agronomic potential of crops may require years or even decades to return to levels that are crop limiting for this nutrient. Environmental concerns include the capacity of such soils to adsorb new P and the amount of P loss from these soils from erosion, runoff, drainage, or leaching to groundwater. Although much information is available regarding the loss of P from agricultural fields from erosion and runoff, less information is available regarding P losses from fields receiving poultry wastes. However, studies have shown that there are many challenges to controlling P losses from fields receiving manures. In addition, subsurface transport of P resulting from repeated application of poultry manure onto soils that are artificially drained is an environmental concern where drainage waters enter or interact with water bodies sensitive to eutrophication. Trace elements such as As, Co, Cu, Fe, Mn, Se, and Zn are often added in excess to poultry feed to increase the animal's rate of weight gain, feed efficiency, and egg production and to prevent diseases. Because most of the excess trace elements are not absorbed by the bird, the concentration of elements excreted in the manure will reflect dietary overformulation. Because trace elements are generally required in very small quantities for crop growth and, like P, are immobile in most soil types, their concentrations will increase with repeated land application of poultry wastes. Of particular concern are accumulations of Cu and Zn in certain soil types utilized for certain crops. Copper and Zn toxicity for some crops have been documented in some areas receiving repeated land-applied poultry wastes. A potential environmental concern relative to poultry litter and trace elements in receiving soils involves the transpor

A speech-to-noise ratio measurement algorithm.

An algorithm to measure speech-to-noise ratios has been implemented on a minicomputer. The algorithm attributes the energy within each consecutive 20-ms frame of a speech-plus-noise waveform to either a speech or noise source. This discrimination process is based upon the known characteristics of frame energy histograms of such waveforms. In response to observed inaccuracies of this discrimination process in cases of low speech versus noise separation, a method of estimating the speech Vrms of the signal is incorporated which attempts to recover speech energy, "masked" by noise. The algorithm's ability to track known speech-to-noise ratios on a decibel-for-decibel basis down to a ratio of approximately 5 dB has been demonstrated by experimentation.