Temperate Climate Of Central Europe Research Articles

From sediment to soil: floodplain phosphorus transformations at the Danube River

Substantial transformations of biogeochemical phosphorus (P) fractions can occur within a few hundreds of years under humid and tropical conditions; however, slower changes are expected under dry and temperate climate. The objective of this study was to infer P transformations over time by comparing suspended sediments in the Danube River to floodplain soils developed from such sediments over different time periods in the continental climate of Central Europe. We analyzed suspended sediments from 20 flood events between 1990 and 2006, and floodplain soils from seven sites along a chronosequence covering about 500 yrs. The studied flood sediments had similar characteristics over the 16-yr observation period. Total phosphorus (TP) averaged 732 mg kg−1, and biogeochemical fractionation yielded important primary mineral contributions (apatite phosphorus, AP, ~80% of TP). The TP concentrations of the floodplain soils were in the range of the Danube sediments and showed little variation along the chronosequence. However, the distribution of P among biogeochemical fractions changed considerably in less than 500 yrs of soil development. The youngest soils (<20 yrs) were dominated by AP, as was observed for the Danube sediments. In less than 250 yrs of pedogenesis, AP markedly decreased and organic phosphorus (OP) increased, and in less than 500 yrs, OP reached AP levels. This shows that while P biogeochemistry in very young floodplain soils is strongly related to the river sediments, significant transformations can occur in less than 250 yrs of soil development in the dry and temperate climate of Central Europe.

Soil and atmospheric nitrogen uptake by lentil ( Lens culinaris Medik.) and barley ( Hordeum vulgare ssp. nudum L.) as monocrops and intercrops

Three morphologically different varieties of lentil ( Lens culinaris Medik.) and one cultivar of naked spring barley ( Hordeum vulgare ssp . nudum L.) were studied as monocrops and in a substitutive mixture in a 2-year field experiment. Plants were grown on a brown warp soil in the temperate climate of Central Europe. The growth habit of the lentil type (spreading or erect habit) had no marked influence on growth, soil N and atmospheric N 2 acquisition of monocropped and intercropped lentil. Yield advantage of the mixture over both monocrops was only apparent in one year when mineral soil N (N min-N) was low. The yield advantage of the barley–lentil mixture seems to be based on two effects: the greater crop growth rate (CGR) of barley in the early growth period due to the efficient use of soil N min-N which compensates for the lower CGR of lentil in the early growth stages and the N 2 fixation of lentil which compensates for the nitrogen limitation in the soil so that the CGR of the mixture reaches the CGR of monocropped lentil in later growth stages. At maturity the level of symbiotically fixed N 2 was 154/117 kg N ha −1 (2000/2001) in monocropped lentil and 95/41 kg N ha −1 in intercropped lentil. The amounts of N taken up from the soil were 58/61 kg N ha −1 (2000/2001) and 17/8 kg N ha −1 for monocropped and intercropped lentil, respectively. Monocropped lentils took up N min-N almost exclusively from the top 0.6 m soil layers and showed a great N sparing effect. At final harvest monocropped lentil left up to 52 kg N min-N ha −1 more in the soil than intercropped lentil and barley. Harvest indices of DM and N of the crop stands increased in the order: monocropped lentil<mixture<monocropped barley. The N balances of the crop stands were in the reverse order. The higher N min-N supply and the drier growth conditions in 2001 increased uptake of N from soil by barley, the competitive ability of barley in the mixture and the harvest indices of all crop stands and led to a reduction in N balances. It was concluded that under a temperate climate, high N use efficiency in legume-based cropping systems can be achieved by managing the cereal–lentil intercrops to enhance the symbiotic N 2 fixation without reducing the soil N uptake efficiency. It can also be achieved by growing follow-on crops before winter which have a high nitrogen uptake ability to minimize the risk of losses from the high residual N min-N left after growing monocropped lentil.