Nitrogen and sulphur management: challenges for organic sources in temperate agricultural systems

A current global trend towards intensification or specialization of agricultural enterprises has been accompanied by increasing public awareness of associated environmental consequences. Air and water pollution from losses of nutrients, such as nitrogen (N) and sulphur (S), are a major concern. Governments have initiated extensive regulatory frameworks, including various land use policies, in an attempt to control or reduce the losses. This paper presents an overview of critical input and loss processes affecting N and S for temperate climates, and provides some background to the discussion in subsequent papers evaluating specific farming systems. Management effects on potential gaseous and leaching losses, the lack of synchrony between supply of nutrients and plant demand, and options for optimizing the efficiency of N and S use are reviewed. Integration of inorganic and organic fertilizer inputs and the equitable re-distribution of nutrients from manure are discussed. The paper concludes by highlighting a need for innovative research that is also targeted to practical approaches for reducing N and S losses, and improving the overall synchrony between supply and demand

LANCELOT (Lake Nyos carbon emission lowering by olivine treatment)

A catastrophe hit Lake Nyos in Cameroon in August 1986, when a dense cloud of CO2 erupted from the lake and rolled down the slope of the volcano, killing more than 1,700 people. To prevent a repetition, a geyser-like system has been installed, which lifts the bottom waters. When the pressure diminishes, bubbles of CO2 nucleate and bubble upward, thus preventing the accumulation of this greenhouse gas in the bottom waters. In this note, another way of tackling the problem is proposed, by which the CO2 is transformed into bicarbonate in a layer of olivine spread over the lake bottom. Although the volume of the gas is modest at Nyos, the approach can function as a model for other and more voluminous CO2 emissions in the world, to prevent their escape into the atmosphere