Phosphorus in Finnish soils in the 1900s with particular reference to the acid ammonium acetate soil test

Comprehensive research into phosphorus (P) in soils and crops began in Finland in the early 1900s. The average amount of total P in the ploughed topsoil layer of mineral soils was about two tonnes per hectare in the 1930s, before the abundant use of fertilisers. The main chemical fractions of P in mineral soils were organic matter, primary apatite and secondary complexes of the hydrous oxides of Al and Fe. Of the smaller amounts of P in light peat soils, as much as 80% was present in stable organic compounds. Field experiments showed that the native P reserves of Finnish soils are poorly available to plants, and that P fertilisers are inefficiently utilised because of the strong fixation of applied phosphate in soils. In evaluations before the late 1950s, all simple chemical tests appeared to be rather unreliable indicators of the supply of P from soils to plants, but later research has shown that the results were impaired by errors implicit in the research materials. Some soil test P values (STP)obtained from old samples stored for more than ten years evidently were too high, particularly for organic soils, and many of the soils studied were strongly acidic and therefore biologically less fertile than the chemical P tests indicated. The acid ammonium acetate method (pH 4.65) was introduced in the early 1950s and has since been used in routine soil testing in Finland, not only for P but for all macronutrients except N. In later evaluations of different methods used for estimating the requirement of P fertilisation, the acid ammonium acetate method has proven equal or superior to any other simple chemical method

Changes of yield responses and soil test values in Finnish soils in relation to cumulative phosphorus and potassium balances

Field experiments with five rates of annual P fertilisation were carried out at 24 sites in Finland 1977-1994. A summary of the yield results was calculated on the basis of the amounts of P recommended to cereals according to STP in early 1990s. The effects of repeated K fertilisation were studied at 21 sites in 1977-1994

Estimating bioavailable reserves and potential leaching of soil P by simple chemical tests

The amounts of P extracted with acid ammonium acetate are significantly correlated with the bioavailable P reserves of Finnish soils. Together with clay percentage the simple extraction method is fairly reliable. In routine soil testing clay% can be estimated visually. Additional improvement in accuracy is possible by extraction with a strong acid. Leaching losses of P are also significantly correlated with acetate-extractable soil P, but the concentration of dissolved phosphate at a certain soil test P value varies with other soil properties and increases with decreasing pH

Compiling Esterel into Static Discrete-Event Code

Executing concurrent specifications on sequential hardware is important for both simulation of systems that are eventually implemented on concurrent hardware and for those most conveniently described as a set of concurrent processes. As with most forms of simulation, this is easy to do correctly but difficult to do efficiently. Solutions such as preemptive operating systems and discrete-event simulators present significant overhead. In this paper, we present a technique for compiling the concurrent language Esterel into very efficient C code. Our technique minimizes runtime overhead by making most scheduling decisions at compile time and using a very simple linked-list-based event queue at runtime. While these techniques work particularly well for Esterel with its high-level concurrent semantics, the same technique could also be applied to efficiently execute other concurrent specifications

Compiling Linguistic Constraints into Finite State Automata

International audienceThis paper deals with linguistic constraints encoded in the form of (binary) tables, generally called lexicon-grammar tables. We describe a unified method to compile sets of tables of linguistic constraints into Finite State Automata. This method has been practically implemented in the linguistic platform Unitex