N2O-Freisetzung auf gemähtem Dauergrünland in Abhängigkeit von Standort und N-Düngung

N₂O Emissions from True Meadows Dependent on Location and N Fertilization Agricultural production is thought to be a main anthropogenic emitter of nitrous oxide (N₂O), which contributes to global warming and the destruction of the ozone layer. There is still considerable uncertainty about the amount of N₂O emission, and the site‐specific parameters that affect N₂O emission. From October 1995 until March 1998 experiments were conducted at established field plots (true meadows) at three different sites, i.e. low mountain range (Eifel), lowland (Niederrhein), and moist meadows (Münsterland). Plots were fertilized with calcium ammonium nitrate (CAN) at nitrogen equivalents ranging from 0 to 360 kg N ha^–1. N₂O fluxes were measured throughout the whole year using the closed‐chamber method. In addition, data on temperature, water‐filled pore space and precipitation were collected. N₂O emission rates (mg N₂O‐N ha^–1 h^–1) were highest either after fertilizer application or in winter during frost, depending on the experimental site and N dosage. The annual amount of N losses due to N₂O emission was dependent on the experimental site and the type and dosage of fertilizer. Disregarding the 360 kg N ha^–1 level of the CAN treatments, the N losses in this experiment were less than 1.5 kg N₂O‐N ha^–1 yr^–1. At low fertilizer dosage there was no reliable correlation between the amount of N that was applied and the amount of N₂O that was emitted. However, with high fertilizer levels the N₂O emissions increased gradually. Finally, N₂O emissions were more influenced by the amount of CAN than by the site.     

Clinical and patho-morphological investigation of spontaneously occurring Seriodontal isease in dogs

Diagnostic evaluation of, and treatment planning for, different periodontal diseases of dogs are a common problem in veterinary dentistry. Therefore the aim of the present study was to propose a classification for inflammatory periodontal disease. One hundred and twenty-three male and female poodles (from two to over 12 years) were used for the clinical investigations; 120 periodontitis teeth were analysed for pathomorphological signs of inflammation. The recorded data made it possible to differentiate five forms of gingivitis (gingivitis simplex, hyperplastica, ulcerosa, granulomatosa and desquamativa) and three forms of periodontitis (juvenile, rapidly progressive adult and chronic adult periodontitis). The pathomorphological investigations allowed a differentiation between acute progressive inflammation, chronic nonprogressive inflammation, chronic proliferative inflammation and chronic resorptive inflammation. It is concluded that standardised diagnoses as well as the pathomorphological background may be helpful tools for providing effective treatment strategies.     

Energy requirements of pregnant and lactating sows

The energy requirement of pregnant and lactating sows is derived on the basis of extensive experimental studies of the energy metabolism (indirect calorimetry, slaughtering) according to the factorial method. For the first reproduction cycle (RC) 0.41 MJ metabolizable energy (ME) or 0.29 MJ net energy fat, pig (NEFpig) resp. were necessary for energy maintenance requirement for pregnant and lactating sows and, depending on age, 0.44 MJ ME or 0.31 MJNEFpig in the second or third RC and 0.47 MJ ME/kg LW0.75.d or 0.33 MJ NEFpig/kg LW0.75.d in the 4th-8th RC. A linear increase of up to 6% of the energy requirement caused by pregnancy between the 85th and 115th day of pregnancy is taken into consideration. Energy requirement per 1 MJ retention both in pregnancy and lactation is 1.45 MJ ME or 1.03 MJ NEFpig, per 1 MJ milk yield it is 1.33 MJ ME or 0.91 MJ NEFpig. 1 MJ body energy for milk yield corresponds to 1.20 MJ ME or 0.82 MJ NEFpig. Equations describing energy retention in the products of conception, uterus and udder are established as well as equations characterizing the connections between live weight gain or loss and energy content of the gain or loss.     

Nitrogen mineralization in loamy arable soils after increasing the ploughing depth and ploughing grasslands

Abstract. Increasing the ploughing depth and ploughing in grassland has been common in Germany during the past 20 years. Incubation studies were conducted with topsoils from luvisols and gleysols at different times after change of management in order to assess its influence on nitrogen mineralization and its kinetic parameters.
The results show that deep ploughing slows the mineralization of nitrogen. The difference between earlier (1967–72) and more recently (1980–82) deepened topsoil has become smaller after a further three years of cultivation, however. The preceding crops (wheat or sugar beet), the amount of N fertilizer as well as clay and nitrogen contents cause a variation in N mineralization. The results indicate a continuing approach of an'equilibrium'organic matter and nitrogen content. The enrichment capacity of intensively managed soils may be replenished within 10 years.
Gleysols formerly under grass mineralize more nitrogen than'traditionally'ploughed soils, even 27 years after the ploughing-in. While nitrogen from easily decomposable materials decreases within the first 10 years, the resistant fraction is a long-lasting determinant for N mineralization. Both processes need to be considered when applying fertilizer to minimize nitrate leaching.     

Influence of soil temperature and soil compaction on growth and P uptake of sugar beet

Sugar beet growth is often impaired by cold and compacted soil. The aim of this study was to determine the effect of soil temperature and soil compaction on the growth and function of sugar beet roots. For this purpose a pot experiment with sugar beet (Beta vulgaris) was conducted in a growth chamber in which the soil temperature was kept constant either at 10°C or 20°C and air temperature at 20°C. The soil was uncompacted (1.30 g cm^?3) or compacted to a bulk density of 1.65 g cm^?3. In order to find out whether growth restriction was caused by insufficient P supply of the plant the experiment was run without and with P application (300 mg per kg soil). Root growth was much smaller at 10°C compared to 20°C, whereas root/shoot ratio was not affected by soil temperature. Hence, root and shoot growth was inhibited to the same extent. P content of the plants was not reduced, neither by cold nor by compacted soil, although parameters of acquisition such as root length and morphological root properties were altered. Soil temperature strongly affected P influx, whereas compaction did not. The calculation with a simulation model showed that at 10°C soil temperature the predicted P uptake of the plants agreed with the measured P uptake irrespective of compaction and P application. However, at 20°C the model underestimated the P influx at low soil P availability even if allowance was made for root hairs. It is concluded that under conditions of high shoot P demand and low P availability in soil P has been mobilized by mechanisms not taken into account by the model.     

Einfluß der Mineralstoffversorgung auf die Prädisposition von Phaseolus vulgaris gegen Colletotrichum lindemuthianum (Sacc. et Magn.) Br. et Cav. I. Wirkung verschiedener Nährstoffe und des Blattalters auf die Symptomausprägung

Influence of mineral nutrition on the predisposition of Phaseolus vulgaris against Colletrotrichum lindemuthianum (Sacc.et Magn.) Br.et Cav. I. Effects of different mineral nutrients and leaf-age on the disease severity 1. The N-concentration between 2–12 mMol N/I did hardly influence the disease, higher concentrations up to 52 mMol/I led to a severe disease increase. Potassium at concentrations of 5–10 mMol/I showed little effect on disease, higher concentrations up to 50 mMol also strongly increased the predisposition. 2. Calcium had a remarkable influence on symptom expression. Lower concentrations (1.15–0.25 mMol/I) increased the symptoms, higher concentrations up to 4.25 mMol/I reduced the disease, but only at a high disease level resulting from high N- or K-concentration. 3. The influences of Mg, P and Fe were of minor importance. 4. Usually, bean-leaves show resistance against C. lindermuthianum when the leaves are old. This is prevented by high N- and K-concentrations. 5. The change of predisposition related to the N- and K-concentration in the nutrient solution was confirmed with 3 additional bean varieties (‘Comtessa’ ‘Perry Marrow’, ‘Pizzaro’). No further increase of disease severity could be achieed with variety ‘Wavero’ which was generally very sensitive. 6. The monogenic resistance of incompatible combinations (‘Titan’/δ and ‘Titan’/λ) could not be changed with high N- or K-concentrations.