Einfluß unterschiedlicher Düngung auf pH,N, C und die Gehalte an CAL-extrahierbarem K und P im Boden

Influence of different fertilization on pH, N, C and CAL-extractable K and P in the soil The influence of different fertilization (mineral fertilizer, different kinds and quantities of farmyard manure and biocompost, horn meal) on soil properties was studied during 8 years of cultivation. The plots were planted and harvested as practised under local farming conditions. The pH of the non-fertilized plots decreased from 5.84 to 5.69, while it was increased by fertilization with farmyard manure or biocompost. N_t in the soil was not influenced by different fertilization. C_t was increased by high biocompost application, stayed constant on the other fertilized plots but decreased on the nonfertilized plots from 1.08 to 0.99%. Without fertilization, plant available nutrients were diminished from 7.3 to 4.3 mg P(CAL) 100 g^?1 and from 22.5 to 13.9 mg K(CAL) 100 g^?1. However, if the plots were fertilized with mineral or organic fertilizer, the nutrient content remained on the initial level. Storing farmyard manure under roof or covering with straw or polyethylene sheet did not affect the criteria of soil studied.     

Diminution of acetylene reduction during assay of detached soybean nodules

Initial rates of acetylene reduction were observed to decline after about 2 h at a given ratio of detached soybean nodule mass to assay vessel vol. Such decreases occurred despite final concentrations of oxygen at 20–30 per cent. and could not be attributed to depletion of acetylene or to accumulation of hydrogen or carbon dioxide. Nodules held briefly at high nodule mass to container vol. ratio gave evidence of progressive inactivation with holding time when subsequently assayed. A search for possible gaseous inhibitors revealed several unknown products that occurred consistently during prolonged acetylene reduction assay. One product observed during assay gave a peak on the gas chromatogram that was determined by the initial concentration of oxygen, and varied inversely with the ethylene peak. The compound responsible for this peak was identified as ethanol. Ethanol vapor added to the assay system inhibited acetylene reduction after 2 h. A high initial oxygen concn depressed somewhat the inhibitory effect of ethanol.     

Lignin turnover in arable soil and grassland analysed with two different labelling approaches

When modelling the carbon dynamics of temperate soils, soil organic carbon (SOC) is often represented by three kinetic pools, i.e. fast, slow and passive/inert. Lignin is often considered to be relatively resistant to decomposition, thus possibly contributing to the passive SOC pool. One way to assess SOC turnover under natural conditions is to follow the fate of ¹³C-labelled biomass in soils. We used compound-specific isotope analysis to analyse CuO oxidation products of lignin from grassland topsoils and from an arable topsoil that had received a natural (by C3-C4 vegetation change) or an artificial (by fumigation with labelled CO₂) isotopic label for 9–23 years. Results indicate faster apparent turnover for lignin (5–26 years in grassland, 9–38 years in arable soil) compared with bulk SOC (20–26 years in grassland, 51 years in arable soil). Although these calculated lignin turnover times cannot be extrapolated to the whole soil profiles, this paper provides isotopic evidence that lignin in soils is not preferentially preserved, which is a consistent result from both ways of isotopic labelling. It also demonstrates, however, that a considerable proportion of lignin in temperate soils can be stabilized for at least a few decades.     

Differential effects of potassium and molybdenum deficiency and fertilization on nitrogen metabolism in Norway spruce (Picea abies)

A field study on mineral nutrition of 12 year old Norway spruce (Picea abies (L.) Karst.) was carried out on a Lower Triassic region in the Eifel mountains in a plantation where the juvenile trees exhibited marked visual differences on adjacent plots, thus indicating a patchy pattern concerning the fertility status of the soil. This was confirmed by geological, pedological and chemical analyses, including X-ray diffraction analyses of the clay minerals and soil water as well as needle element analyses. A combined K and N deficiency was diagnosed for those trees, which exhibited growth retardation and small, rigid, and yellowish-green needles. Chlorophyll and protein content and glutamine synthetase activity were reduced while triphenyltetrazoliumchloride (TTC) reduction was enhanced in the sick trees as compared to adjacent healthy looking trees of the same age and provenance. A diagnostic fertilization treatment with K and Mo, respectively, yielded the following results. One year after administration of Mo a marked increase in total N content of the needles was observed, due to an increase of the storage pools for soluble (nonprotein) nitrogen, namely the basic amino acids arginine, histidine and lysine and also of ornithine. Yet, no visual recovery of the trees was observed. On the other hand, K fertilization caused an improvement of all biochemical parameters, except protein content and soluble N storage pools. The relationships between Mo dependent nitrate reduction, potassium content and nitrogen metabolism are discussed.     

Die Seefiefer (Sternkiefer, Igelf?hre)

Ohne Zusammenfassung     

Abwehr sch?dlicher Forstinsekten

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Abwehr sch?dlicher Forstinsekten

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Advantages of seed selection in wheat aneuploid studies

Summary Aneuploid studies in wheat often involve progenies which segregate for monosomics and disomics. In situations where only monosomics are needed, data are presented to show that their frequency can be increased by selecting wrinkled seeds for planting. Conversely, a higher proportion of disomics results from using the plumpest seeds from a cross- or self-pollination involving a monosomic parent.Published with the approval of the Director as Paper No. 2712, Journal Series, Nebraska Agric. Expt. Station.