An enhanced software tool to support better use of manure nutrients: MANNER‐NPK

MANNER‐NPK (MANure Nutrient Evaluation Routine) is a decision support tool for quantifying manure (and other organic material) crop available nutrient supply. The user‐friendly design of an earlier version of MANNER was retained, but in response to user and stakeholder feedback, additional functionality was included to underpin new and revised nitrogen (N) transformation/loss modules (covering ammonia volatilization, nitrate leaching and nitrous oxide/di‐nitrogen emissions, and organic N mineralization) and also to estimate manure phosphorus (as P₂O₅), potassium (as K₂O), sulphur (as SO₃) and magnesium (as MgO) supply. Notably, MANNER‐NPK provides N availability estimates for following crops through the mineralization of organic N. Validation of the crop available N supply estimates was undertaken by comparing predicted values with data from more than 200 field experimental measurements. For cattle, pig and poultry manures, there was good agreement (P < 0.001) between predicted and measured fertilizer N replacement values, indicating that MANNER‐NPK provides robust estimates of manure crop available N supply and N losses to the wider environment.     

The chemistry of pedogenic thresholds

Pedogenesis can be slow or fast depending on the internal chemical response to environmental forcing factors. When a shift in the external environment does not produce any pedogenic change even though one is expected, the soil is said to be in a state of pedogenic inertia. In contrast, soil properties sometimes change suddenly and irreversibly in a threshold response to external stimuli or internal change in soil processes. Significant progress has been made in understanding the thermodynamics and kinetics of soil-property change. Even in the open soil system, the direction of change can be determined from measures of disequilibrium. Favorable reactions may proceed in parallel, but the most prevalent and rapid ones have the greatest impact on product formation. Simultaneous acid–base, ion exchange, redox and mineral-transformation reactions interact to determine the direction and rate of change. The nature of the governing reactions is such that soils are well buffered to pH change in the alkaline and strongly acid regions but far less so in the neutral to slightly acid zones. Organic matter inputs may drive oxidation–reduction processes through a stepwise consumption of electron acceptors (thereby producing thresholds) but disequilibrium among redox couples and regeneration of redox buffer capacity may attenuate this response. Synthesis of secondary minerals, ranging from carbonates and smectites to kaolinite and oxides, forms a basis for many of the reported cases of pedogenic inertia and thresholds. Mineralogical change tends to occur in a serial, irreversible fashion that, under favorable environmental conditions, can lead to large accumulations of specific minerals whose crystallinity evolves over time. These accumulations and associated “ripening” processes can channel soil processes along existing pathways or they can force thresholds by causing changes in water flux and kinetic pathways.     

Terrestrial ecosystem sensitivity to acidic deposition in developing countries

Acidic deposition is considered a problem in Europe and North America but the potential for ecosystem damage from this pollution is also increasing rapidly in many developing countries. It is therefore important to assess current and future risks of ecosystem effects due to acidic deposition in these areas. It is possible to indicate risk areas by linking an assessment of sensitivity to net acidic input rates derived from deposition estimates for sulphur and nitrogen compounds and base cations. A method to assess and map a relative scale of terrestrial ecosystem sensitivity using international datasets is presented. The assessment relies on the determination of buffering mechanisms that prevent effects related to acidic deposition. Land-cover data, edaphic and climate datasets are combined using a GIS. Large areas are assessed as highly sensitive to acidic deposition in tropical regions of Asia, South and Central America and Africa, and also in the Boreal forests of northern Asia. Sensitive areas cover forest and non-forest ecosystems and some areas of agricultural production. Critical loads are not evaluated in this project but initial estimates will be applied to sensitivity classes at a further stage which will allow estimation of areas at risk by comparison with deposition.     

Energy use,emissions, and air pollution reduction strategies in Asia

In contrast to Europe and North America, air pollution in Asia is increasing rapidly, resulting in both local air quality problems and higher acidic depositions. In 1989, an east-west group of scientists initiated a multi-institutional research project on Acid Rain and Emissions Reduction in Asia, funded for the past two years by the World Bank and the Asian Development Bank. Phase I, covering 23 countries of Asia, focussed on the development of PC-based software called the Regional Air Pollution INformation and Simulation Model (RAINS-ASIA). A 94-region Regional Energy Scenario Generator was developed to create alternative energy/emission scenarios through the year 2020. A long-range atmospheric transport model was developed to calculate dispersion and deposition of sulfur, based upon emissions from area and large point sources, on a one-degree grid of Asia. The resulting impacts of acidic deposition on a variety of vegetation types were analyzed using the critical loads approach to test different emissions management strategies, including both energy conservation measures and sulfur abatement technologies.