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It was the objective of this study to compare the suitability of different extractants for predicting the availability of sulfur (S) in natural grassland in a sulfur response trial on three different soil types in the Inner Mongolia steppe of China. For soil analysis, seven different extractants have been employed. The inorganic SO4–S concentration was determined by ion chromatography. Additionally, in the Ca(H2PO4)2 extract the total soluble S was determined employing turbidimetry. Weak salt solutions (0.15% CaCl2, Ca(H2PO4)2, and KH2PO4) extracted similar amounts of SO4–S. Extraction with 0.025 M KCl provided the lowest SO4–S values. Deionized water dissolved significantly more SO4–S in the control plots than most weak salt extractants. The concentration of soluble organic S decreased in the control plots after 100 days of plant growth, indicating that the organic S pool contributed significantly to the S nutrition of the forage crops. Significant relationships among the SO4–S in the soil deter...

To clarify the response of soil organic carbon (SOC) content to season-long grazing in the semiarid typical steppes of Inner Mongolia, we examined the aboveground biomass and SOC in both grazing (G-site) and no grazing (NG-site) sites in two typical steppes dominated by Leymus chinensis and Stipa grandis, as well as one seriously degraded L. chinensis grassland dominated by Artemisia frigida. The NG-sites had been fenced for 20 years in L. chinensis and S. grandis grasslands and for 10 years in A. frigida grassland. Aboveground biomass at G-sites was 21–35% of that at NG-sites in L. chinensis and S. grandis grasslands. The SOC, however, showed no significant difference between G-site and NG-site in both grasslands. In the NG-sites, aboveground biomass was significantly lower in A. frigida grassland than in the other two grasslands. The SOC in A. frigida grassland was about 70% of that in L. chinensis grassland. In A. frigida grassland, aboveground biomass in the G-site was 68–82% of that in the NG-site, whereas SOC was significantly lower in the G-site than in the NG-site. Grazing elevated the surface soil pH in L. chinensis and A. frigida communities. A spatial heterogeneity in SOC and pH in the topsoil was not detected the G-site within the minimal sampling distance of 10 m. The results suggested that compensatory growth may account for the relative stability of SOC in G-sites in typical steppes. The SOC was sensitive to heavy grazing and difficult to recover after a significant decline caused by overgrazing in semiarid steppes.

The use of depleted uranium (DU, 238U) as ammunition is currently a major topic for discussion. DU is the main by-product from the processing of nuclear fuel (235U). It is considered to be less radioactive than natural uranium, but despite this, there is still a serious hazard due to the alpha-radiation that is emitted. U like other heavy metals is a threat to both health and the environment because of its pronounced toxicity. Significant amounts of uranium have been released in the last decade with armor piercing ammunition that was manufactured from DU, not only during major conflicts but also on numerous military shooting ranges all over the world. The paper describes methods for the extraction of plant available DU from soils, digestion processes for plant material and the determination of 238U by Inductively Coupled Plasma-Quadrupole Mass Spectrometry (ICP-QMS) in soils, plants and waters.

The influence of nitrogen (N) and sulphur (S) fertilizer on yield and quality of spring oats and the N and S metabolism of sheep was determined. Eighteen crossbred wether lambs (about 30 kg) were fed oats fertilized with N (0, 138 kg N/ha as of urea) and S (0, 30 and 60 kg S/ha as gypsum) assigned randomly to six treatments in an experiment of 2×3 factorial design. On S-deficient soils, S and N fertilization increased dry matter (DM) by 10.5 and 71.9%, and crude protein (CP) yield of oats by 11–13 and 94.5%, but there was no interaction between N and S fertilizer. S fertilization increased S content of oats from 0.14 to 0.29% and significantly reduced the N:S ratio from 14.4 to 7.22. There was a significant interaction between N and S on N content. N and S fertilization significantly increased apparent DM digestibility of oats by about 4%, but did not affect intake (g/kg BW0.75), DM intake being almost 60 g/kg BW0.75 for all treatments. N increased average daily gain of lambs by 62.4–78.6% if S was supplied, being twice the gain without S supply but no interaction between N and S was observed. N retention was affected by interaction between N and S fertilization. N retention and N utilization were positively correlated with S intake. N:S ratio in oats was positively correlated with N metabolism. S fertilization increased N utilization efficiency and vice versa. The critical levels of total S in oats were 0.20 and 0.23%, and the critical levels of N:S ratio were 17.0 and 15.7 for maximum DM and CP yield, respectively. The critical levels of S content and N:S ratio for maximum average daily gain of lambs were 0.26% and 10.5, respectively. Therefore, in the diagnosis of S status in soil–forage–animal systems, the use of total S and N:S ratio in the forage tops for the maximum CP yield is preferable to that for the maximum DM yield because the values are more closely related to the requirements for maximum daily gain of lambs; similarly, the use of a combination of total S and N:S ratio is preferable to the use of N:S ratio alone.

Coca Cola® has been found to be an excellent extractant for micronutrients in soils, particular for manganese (Mn). The main ingredients of Coca Cola®, phosphoric acid, reducing sugar and carbon dioxide are well proven in common extraction recipes. The overall extraction force of Coca Cola® was similar to that of commonly used phosphoric acid methods. Compared to DTP A, Coca Cola® extracted only 27% of iron (Fe), 38 % of copper (Cu), and 86% of zinc (Zn), but 165% of Mn. Correlation coefficients for the relationship between Coca Cola®‐extractable Fe, Zn, and Cu in soils and element concentrations in plants were the same as by means of the DTPA method. For Mn 49% of the variability in Mn concentrations observed in field grown winter wheat plants could be explained by Coca Cola®‐extractable soil Mn, but only 39% when employing DTPA. The critical value for available Mn and Zn on the investigated inceptisols was 17.8 mg/kg Mn and 1.3 mg/kg Zn for Coca Cola® and 9.4 mg/kg Mn and 1.8 mg/kg Zn for DTPA....

Germany is reported to be an iodine deficient region of the world. Therefore investigations of the iodine concentration in plants and soils are of particular importance. The low concentration of iodine (μg and ng levels) in plant and soil samples, can be determined by photometry based on the SANDELL‐KOLTHOFF‐Reaction, the reduction of Ce(IV) by As(III) catalysed by iodine. The reaction, essentially depending on time and temperature, can also be affected by the ions, such as: Cl% NO2 ‐, SCN‐, Fe2+, BrO3 ‐, MnO4 ‐, Ag+, CN‐, Hg+ and metals like Os. Using the alkaline dry ashing method by adding KOH and ZnSO4, the digestion with the calorimetric bomb and the SCHONIGER digestion arc gives reliable results for iodine determination for use in conjunction with photometric analytical techniques. For this investigation, the influence of iodine fertilisation on the iodine concentration of cress (Lepidium sativum) was determined by a pot experiment in which different amounts of iodine were added. The iodine...

Uranium (U) is a toxic heavy metal. The background values of natural soils differ between 0.79–11 mg kg−1 U. U is accumulated in the A horizons and its plant availability is influenced by both natural soil properties and anthropogenic activities. Recently, the use of phosphorus fertilizers in agriculture will be reported as a longer-term risk for the soil-plant-system. An alien source of environmental pollution results from military operations. Soil fertility, pH value and nutrient supply can effect the U content of crops growing on U contaminated soils.

Schwefelmangel ist mittlerweile eine der bedeutendsten Ernahrungsstorungen in der pflanzenbaulichen Produktion Nordeuropas. Daher besteht ein zunehmender Bedarf an prazisen und zuverlassigen Methoden zur Bestimmung des Schwefelversorgungsgrades landwirtschaftlicher Nutzpflanzen und Boden. Fur die Prognose der Schwefelversorgung wurde sich die Bodenanalyse anbieten, es konnte jedoch keine Beziehung zwischen den Schwefelgehalten in den Pflanzen und dem mobilen (extrahierbares Sulfat plus extrahierbarer organischer Schwefel) Schwefelgehalt im Boden festgestellt werden. Die Ursachen fur die Unzulanglichkeit herkommlicher Bodenuntersuchungsmethoden scheinen im Wasser- und Schwefelhaushalt der Boden zu liegen, so das standortbezogene Modelle fur eine Prognose des Schwefelversorgungsgrades landwirtschaftlicher Kulturpflanzen entwickelt werden mussen.

Processing, recycling and use of plant nutrients from industrial processes are central concepts in waste avoidance. However, pressure to use agriculture as a way of disposing of industrial wastes may conflict with requirements to maintain the rural environment and guarantee food quality. Sustainable agriculture should use any resource in such a way that does not compromise the way in which the present and future human needs for food or other agricultural goods are satisfied, and ensures that the quality of the environment and natural resources remains preserved.

The analysis of samples in a graphite furnace directly from the solid state can be attractive for a number of reasons already discussed in Chapter 1 in detail. Langmyhr [629] pointed out what the solid sampling technique of atomic spectrometry can do: ”As compared to other methods for the quantification of trace elements the direct analysis of solids by atomic absorption spectrometry offers some definite advantages: being direct the method involves only three steps, viz. the sampling, the sample preparation and measurement, the time-consuming decomposition step can be omitted, and the analysis can be carried out without addition of reagents and without any separation and concentration steps; the risks of introducing contaminants and of losing the elements to be determined are thus considerably reduced”

Die Moglichkeit der Direktbestimmung von Hg in biologischen Materialien wurde im Graphitrohrofen eines Zeeman-Atomabsorptionsspektralphotometers (ZAAS) erprobt. Die hohe Untergrundkompensation des ZAAS ermoglicht die Trennung der spezifischen Hg-Absorption von dem unspezifischen Rauchsignal. Es werden die Bedingungen beschrieben, unter welchen die Direktmessungen von Hg in Proben mit mehr als 0,2 μg/g i.TS. durchfuhrbar sind. Diese Grosenordnung ist bei biologischen Proben wie Mullkomposten, Klarschlammen, Pilzen und Regenwurmern zu finden. Ohne vorangehenden chemischen Aufschlus konnen bis zu 1 oder 2 mg der Probe im Graphitschiffchen direkt ohne Veraschungsstufe im Graphitrohrofen bei 1700° C atomisiert werden. Zur Kalibrierung wird ein Klarschlammreferenzmaterial mit einem zertifizierten Gehalt an Hg von 3 μg/g i. TS. eingesetzt.

Fur die Methodik zur Auswertung der einen Zustandsgraphen reprasentierenden Daten ist es unwichtig, welche Steuerungsaufgaben durch einen Zustandsgraphen beschrieben sind. Bei der Betrachtung eines einzelnen Graphen erkennt man, das sich dieser in einzelne Elemente, den Zustanden und den Ubergangsbedingungen, zerlegen last. Die getrennte Behandlung der einen Zustandswechsel auslosenden Bedingungen und der an die Zustande gebundenen Aktionen ist vorteilhaft fur den Entwurf geeigneter Algorithmen. Allerdings ist hierfur ein Strukturabbild des Graphen notwendig, damit sich die einzelnen Elemente wieder zu einem Ganzen zusammenfugen lassen.

Ausgangspunkt und Grundlage fur die vorliegende Arbeit ist die Darstellung von Steuerungsaufgaben mit Zustandsgraphen. Diese Beschreibungsform war aufgrund erweiterter Aufgabenbereiche (z.B. Fehlerdiagnose) in den letzten Jahren einer stetigen Wandlung unterworfen, als Folge ergaben sich uneinheitliche Darstellungen.

Die Hilfsmittel fur Inbetriebnahme und Test von Steuerprogrammen fur SPS auf Basis von Zustandsgraphen mussen sich direkt an die Beschreibungsform der problemorientierten Eingabesprache anlehnen konnen. Dies ist notwendig, um bei der Fehlersuche eine systematische Vorgehensweise auf der Ebene dieser Eingabesprache zu erhalten. Die Reihenfolge der Inbetriebnahme von Teilfunktionen einer Anlage orientiert sich dabei streng an der hierarchischen Struktur des mit Hilfe von Zustandsgraphen entworfenen Steuerprogramms.

Fur die Erstellung eines Steuerprogramms mit Zustandsgraphen ist eine Programmier- und Testeinrichtung (PuTE) notwendig, die sich direkt an die Beschreibungsform des Entwurfsmittels ‚Zustandsgraph‘ anlehnt.

Die Darstellung eines Steuerprogramms mit einer prozessorunabhangigen Datenstruktur bildet die gemeinsame Datenbasis sowohl fur die Programmier- und Testeinrichtung als auch fur die Steuerung. Bild 6.1 zeigt das Gesamtsystem, das aus der PuTE und der SPS mit den zugehorigen Systemprogrammen besteht.