A. L. Page

Bio: A. L. Page is an academic researcher. The author has contributed to research in topics: Soil type & Soil test. The author has an hindex of 1, co-authored 1 publications receiving 13793 citations.

Study and Interpretation of the Chemical Characteristics of Natural Water

Abstract: The chemical composition of natural water is derived from many different sources of solutes, including gases and aerosols from the atmosphere, weathering and erosion of rocks and soil, solution or precipitation reactions occurring below the land surface, and cultural effects resulting from human activities. Broad interrelationships among these processes and their effects can be discerned by application of principles of chemical thermodynamics. Some of the processes of solution or precipitation of minerals can be closely evaluated by means of principles of chemical equilibrium, including the law of mass action and the Nernst equation. Other processes are irreversible and require consideration of reaction mechanisms and rates. The chemical composition of the crustal rocks of the Earth and the composition of the ocean and the atmosphere are significant in evaluating sources of solutes in natural freshwater. The ways in which solutes are taken up or precipitated and the amounts present in solution are influenced by many environmental factors, especially climate, structure and position of rock strata, and biochemical effects associated with life cycles of plants and animals, both microscopic and macroscopic. Taken together and in application with the further influence of the general circulation of all water in the hydrologic cycle, the chemical principles and environmental factors form a basis for the developing science of natural-water chemistry. Fundamental data used in the determination of water quality are obtained by the chemical analysis of water samples in the laboratory or onsite sensing of chemical properties in the field. Sampling is complicated by changes in the composition of moving water and by the effects of particulate suspended material. Some constituents are unstable and require onsite determination or sample preservation. Most of the constituents determined are reported in gravimetric units, usually milligrams per liter or milliequivalents

Nutrient availability and leaching in an archaeological Anthrosol and a Ferralsol of the Central Amazon basin: fertilizer, manure and charcoal amendments

Abstract: Soil fertility and leaching losses of nutrients were compared between a Fimic Anthrosol and a Xanthic Ferralsol from Central Amazonia The Anthrosol was a relict soil from pre-Columbian settlements with high organic C containing large proportions of black carbon It was further tested whether charcoal additions among other organic and inorganic applications could produce similarly fertile soils as these archaeological Anthrosols In the first experiment, cowpea (Vigna unguiculata (L) Walp) was planted in pots, while in the second experiment lysimeters were used to quantify water and nutrient leaching from soil cropped to rice (Oryza sativa L) The Anthrosol showed significantly higher P, Ca, Mn, and Zn availability than the Ferralsol increasing biomass production of both cowpea and rice by 38–45% without fertilization (P<005) The soil N contents were also higher in the Anthrosol but the wide C-to-N ratios due to high soil C contents led to immobilization of N Despite the generally high nutrient availability, nutrient leaching was minimal in the Anthrosol, providing an explanation for their sustainable fertility However, when inorganic nutrients were applied to the Anthrosol, nutrient leaching exceeded the one found in the fertilized Ferralsol Charcoal additions significantly increased plant growth and nutrition While N availability in the Ferralsol decreased similar to the Anthrosol, uptake of P, K, Ca, Zn, and Cu by the plants increased with higher charcoal additions Leaching of applied fertilizer N was significantly reduced by charcoal, and Ca and Mg leaching was delayed In both the Ferralsol with added charcoal and the Anthrosol, nutrient availability was elevated with the exception of N while nutrient leaching was comparatively low

The vegetation N:P ratio: a new tool to detect the nature of nutrient limitation

Abstract: Nutrient limitation (mostly N or P) is a driving force in ecosystem development. Current techniques to determine the nature of nutrient limitation use laborious fertilization experiments. It was hypothesized that the N:P ratio of'the vegetation directly indicates the nature of nutrient limitation on a community level (N vs. P limitation). This hypothesis was tested by reviewing data on fertilization studies in a variety of European freshwater wetland ecosystems (bogs, fens, wet heathlands, dune slacks, wet grasslands). In a subset of the data (dune slacks) between-site intraspecific variation and within-site interspecific variation in nutrient content and N:P ratio was studied in five plant species. A review of 40 fertilization studies reveals that an N:P ratio >16 indicates P limitation on a community level, while an N:P ratio < 14 is indicative of N limitation. At N:P ratios between 14 and 16, either N or P can be limiting or plant growth is colimited by N and P together. In only one out of 40 fertilization studies, the N:P ratio gave a false indication of the nature of nutrient limitation. Measuring the N:P ratio of the vegetation is a simple and cheap alternative to fertilization studies. The method can only be used under conditions where either N or P controls plant growth. The dataset contains a large variety of vegetation types and plant species, and 11 I of the 40 sites were near-monocultures. This suggests that interspecific differences in critical N:P ratios among species may be insignificant. However, a rigorous test of this hypothesis is required. A survey in 18 dune slacks showed large within-site variation in N:P ratio among five species (Calamagrostis epigejos, Phragmites australis, Lycopus europaeus, Mentha aquatica and Eupatorium cannabinum). The N:P ratios of the five species suggested that within plant communities species can be differentially limited by N or P. Moreover, species with an N:P ratio that suggested P-limitation were found at sites where N controlled community biomass production, and vice versa. Between-site intraspecific variation in N and P contents and N:P ratios was also large, and about equal for the five species. This illustrates the plasticity of plant species with respect to N and P contents, probably in response to differences in N and P supply ratios. The vegetation N:P ratio is of diagnostic value and its use may increase our understanding of numerous facets of physiological, population, community and ecosystem ecology.

Role of nitrifier denitrification in the production of nitrous oxide

Abstract: Nitrifier denitrification is the pathway of nitrification in which ammonia (NH 3 ) is oxidized to nitrite (NO 2 − ) followed by the reduction of NO 2 − to nitric oxide (NO), nitrous oxide (N 2 O) and molecular nitrogen (N 2 ). The transformations are carried out by autotrophic nitrifiers. Thus, nitrifier denitrification differs from coupled nitrification–denitrification, where denitrifiers reduce NO 2 − or nitrate (NO 3 − ) that was produced by nitrifiers. Nitrifier denitrification contributes to the development of the greenhouse gas N 2 O and also causes losses of fertilizer nitrogen in agricultural soils. In this review article, present knowledge about nitrifier denitrification is summarized in order to give an exact definition, to spread awareness of its pathway and controlling factors and to identify areas of research needed to improve global N 2 O budgets. Due to experimental difficulties and a lack of awareness of nitrifier denitrification, not much is known about this mechanism of N 2 O production. The few measurements carried out so far attribute up to 30% of the total N 2 O production to nitrifier denitrification. Low oxygen conditions coupled with low organic carbon contents of soils favour this pathway as might low pH. As nitrifier denitrification can lead to substantial N 2 O emissions, there is a need to quantify this pathway in different soils under different conditions. New insights attained through quantification experiments should be used in the improvement of computer models to define sets of conditions that show where and when nitrifier denitrification is a significant source of N 2 O. This may subsequently render the development of guidelines for low-emission farming practices necessary.

The role of soil organic matter in maintaining soil quality in continuous cropping systems

Abstract: Maintenance and improvement of soil quality in continuous cropping systems is critical to sustaining agricultural productivity and environmental quality for future generations. This review focuses on lessons learned from long-term continuous cropping experiments. Soil organic carbon (SOC) is the most often reported attribute from long-term studies and is chosen as the most important indicator of soil quality and agronomic sustainability because of its impact on other physical, chemical and biological indicators of soil quality. Long-term studies have consistently shown the benefit of manures, adequate fertilization, and crop rotation on maintaining agronomic productivity by increasing C inputs into the soil. However, even with crop rotation and manure additions, continuous cropping results in a decline in SOC, although the rate and magnitude of the decline is affected by cropping and tillage system, climate and soil. In the oldest of these studies, the influence of tillage on SOC and dependent soil quality indicators can only be inferred from rotation treatments which included ley rotations (with their reduced frequency of tillage). The impact of tillage per se on SOC and soil quality has only been tested in the ‘long-term’ for about 30 yrs, since the advent of conservation tillage techniques, and only in developed countries in temperate regions. Long-term conservation tillage studies have shown that, within climatic limits: Conservation tillage can sustain or actually increase SOC when coupled with intensive cropping systems; and the need for sound rotation practices in order to maintain agronomic productivity and economic sustainability is more critical in conservation tillage systems than conventional tillage systems. Long-term tillage studies are in their infancy. Preserving and improving these valuable resources is critical to our development of soil management practices for sustaining soil quality in continuous cropping systems.