Einfluß der N-Düngung von Apfelkulturen auf Nitratgehalte im Boden,stickstoffhaltige Reservestoffe im Baum und Ertrag

Effect of N-fertilization in apple orchards on soil nitrate contents, nitrogenous reserves in the tree, and crop yield It should be investigated how nitrate supply affects crop yields and incorporation and mobilization of nitrogenous reserves with Golden Delicious' apple trees on M 7 and M 9, and whether N fertilizer needs are influenced by N reserves in the trees. Two trials were carried out in 1981–1983. In the first one on al loess soil increasing N levels (0, 40, 80, 120 kg N/ha) were applied. In the second one, on a podsolic sandy soil, N was applied either in spring and/or in August (0/0, 80/0, 40/40, 0/80 kg N/ha). N fertilizers were applied to the herbicide strips only. Both orchards were in their best cropping age. Soil nitrate contents were mainly influenced by N-fertilization. Precipitation and drip irrigation caused translocation of nitrate and leaching from the soil layer investigated (0–90 cm). Thus, on the sandy soil almost no nitrate was left in spring, whereas on the loess soil various amounts of nitrate were still available in the subsoil depending on N fertilization in the preciding year. In plots where N fertilization was at optimum, the soil nitrate contents varied between 65 and 130 kg N per hectare herbicide strip over the main growing season (May–August). In the bark N reserves were mainly proteins, but almost equal amounts of protein and soluble N were found in the wood. N reserves were incorporated into the bark mainly between October and December, but even earlier than September in the wood. They were mobilized from April through July. Arginine was stored in the wood in considerably higher amounts than in the bark. Asparagine contents showed a sharp increase immediately after blossom time, particularly in the bark. There was almost no significant influence of the different fertilizer patterns on incorporation and mobilization of nitrogenous compounds. The N-reserves had no effect on crop weight. Highest crop yields were obtained whenever at least 40 kg N/ha were applied in spring. Additional N supply in August did neither increase incorporation of N-reserves nor crop yields. The nitrogenous reserves in the trees can be ignored in estimating N-fertilizer needs. On the other hand, the soil nitrate contents at bud break in April should be taken into account.     

Einfluß von Müllkompost und Eisenverbindungen auf die Eisen-, Zink- und Manganaufnahme von Sonnenblumen und Mais im Gefäßversuch

Influence of compost and Fe-compunds on the uptake of Fe, Zn and Mn by sunflower and maize in pot experiments The influence of compost and different iron compounds on the uptake of Fe, Zn and Mn from calcareous soils was investigated in a pot experiment using sunflower and maize. Regardless of the iron compounds applied, the addition of compost resulted in an increase of the Zn content in both plant species. The compost treatment without Fe, resulted in a lower Fe content in sunflower and maize. This effect was partly or completely counteracted by the addition of Fe compounds. Very high Zn contents were observed in the Fe – EDTA treatments. The Zn content was further increased when compost was also added. In treatments in which compost was omitted none of the Fe compounds applied increased the Fe content of the plants.     

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.     

Umsatz im Boden und Ertragswirkung rohphosphathaltiger Düngemittel

Turnover in soil and yield response of phosphate rock containing fertilizers Solubility of phosphate rocks is the better the higher the carbonate substitution in the given phosphate rock type. From the soil factors, pH is of importance. At soil pH < 5 phosphate rocks are fairly soluble and their yield effect equals that of fully processed fertilizers. In a soil pH range from 5 to 7, pH does not play such a decisive role as has been assumed. Other soil factors such as H⁺ buffer power of soil, Ca²⁺ and particularly the phosphate concentration in the soil solution are equally relevant for phosphate rock dissolution. The evaluation of numerous field experiments provided evidence that in the above cited pH range fully processed fertilizer phosphates are superior to phosphate rock containing fertilizers with regard to phosphate uptake, yield formation, and phosphate recovery. Also the residual effect of rock phosphate is poorer than that of fully processed phosphate fertilizers. There is some evidence that phosphate rocks show a relatively good response on deep rooting soils which allow a vigorous root growth and on soils with a sufficiently high level of soil moisture. In a soil pH range > 5 rock phosphate containing fertilizer are not suitable for maintenance fertilization, since under such conditions the phosphate concentration in the soil solution is relatively high thus suppressing the dissolution of phosphate rock.     

Nmin−Gehalt im Boden,mineralische N-Düngung und N-Entzug von Winterweizen im Internationalen Organischen Stickstoffdauerdüngungsversuch (IOSDV) Berlin-Dahlem

N_mim content in the soil, N-fertilization and N uptake of winter wheat in the international organic nitrogen long-term fertilization experiment (IOSDV) Berlin-Dahlem During the 9th and 10th year of the long-term IOSDV field experiment micro plots were put in three treatments. Labelled¹⁵ N (160 resp. 110 kg/ha N as ammonium sulfate) was fertilized to winter wheat subdivided into three portions. N_min in soil was determined five times during the season, plant biomass was harvested at different growth stages and N uptake was calculated. Using the¹⁵ N-technique permitted a discrimination between fertilizer-N and soil-N. Preferential uptake of fertilizer-N by the wheat crop but also immobilisation in soil were observed until June. Subsequently the immobilized N was remineralized and assimilated by wheat. But the native N_min of soil was minimaly utilized during the initial growth of wheat. Therefore the absolute amount of soluble N temporarily increased caused by a mineralisation of the organic matter.     

Stickstofffraktionen verschiedener Güllen und deren Wirkung im Pflanzenversuch

Fractions of Nitrogen in various types of slurry and their effects in vegetation trials Total Nitrogen in slurry of different animal species was separated by fractionating methods, and effectiveness of the organic N was then tested in pot trials. Total N content of cattle slurry was 0.44% based on 10% dry matter; pig and chicken slurry almost reached values twice as high. Ammonium-N amounted (in the same order) to 45–70% of total N. The C/N-ratio was 8–10 in cattle slurry, and about 4 in pig and chicken slurry which are richer in ammonium. The biggest part of the residual organic N is, “6 n HCl – hydrolyzable N”, mainly microorganism nitrogen, half of which could be analyzed as amino acid N. After fractionating of humus, 28 to 37% of organic N appeared as fulvic acid N, 32 to 44% as humic acid N, and 19–32% humine N. Mineralization of organic N (largely free of ammonium) in an incubation trial under controlled conditions was only 17% (pig slurry) resp. 22% (chicken slurry) resp. 27% (cattle slurry) within 40 weeks, in spite of a relatively small C/N-ratio (13). In short term vegetation trials with green maize and green oats in Neubauer- resp. rye grass in Mitscherlich experiments with a very intensive utilization (3 cuttings), all types of slurry gave only very small raises (max. 5–10 %) in yields and N removals as compared to the control on the basis of organic N. In one set of experiments with “aerated” cattle slurry, a somewhat better mineralization and utilization of organic N in vegetation trials could be observed.     

Calciumgehalte in Früchten von Paprika,Bohne, Quitte und Hagebutte im Verlauf des Fruchtwachstums

Calcium content in fruits of paprika, bean, quince and hip during fruit growth The Ca content and the Ca translocation into the fruits during their growth was determined in paprika and bean under controlled conditions (nutrient solution, growth room) and in quince and hip (Rosa rugosa Thumb.) under field conditions. Compared to leaves the Ca content in the fruits is very low in all 4 species and declines further during their growth. The K content, however, is similar in the leaves and in the fruits of all 4 species and remains nearly constant during fruit growth. The low Ca content of the fruits cannot directly be related to the cation exchange capacity (CEC) as there are no differences in the CEC between leaves and fruits. The generally low Ca content of the fruits and its decline during fruit growth is causally related in all 4 plant species to the low rate of Ca translocation compared to the rate of dry matter translocation into the fruits. There are, however, distinct differences between the 4 plant species in the course of the ratio Ca/dry matter translocation into the fruits: In paprika the Ca translocation into the fruits strongly declines during fruit growth and in bean the Ca translocation practically ceases with the onset of seed growth. In quince under field conditions the Ca translocation into the fruits rapidly declines at later stages and finally a translocation of Ca out of the fruit takes place (decrease in the amount of Ca/fruit). Only in hip the Ca translocation into the fruits remains constant during fruit growth. There is, however, a distinctly different distribution of Ca to the various parts within the hip fruits. The decline in Ca translocation during fruit growth can be explained in paprika and bean with a shift in water influx from the xylem (rich in Ca) to the phloem at the stage of high rates of dry matter influx into the fruit. In quince and hip, however, additional mechanisms (alternating water flux in the xylem, CEC) seem to be involved in the regulation of the Ca content of these fruits.     

Einfluß von Stroh und Nitrapyrin auf den verfügbaren Stickstoff im Boden,den Ertrag und den Stickstoffentzug von Lolium multiflorum

Effect of straw and nitrapyrin application on the nitrogen availability in the soil and the yield and nitrogen uptake of Lolium multiflorum. In pot experiments the effect of straw and nitrapyrin application on the turn-over of fertilizer NH and on the nitrogen availability in the soil was investigated. The investigation comprised two sections: an incubation experiment in which straw and nitrapyrin together with NH-N were incorporated into a brown podsolic soil and a subsequent pot experiment with ryegrass. Nitrapyrin inhibited the nitrification and reduced the nitrogen loss of the soil. Compared with the treatments without nitrapyrin application, nitrapyrin resulted in a lower dry matter yield and in a lower nitrogen uptake of the ryegrass. Straw application reduced the nitrate content in the soil significantly. This effect was particulary evident in the treatments which did not receive nitrapyrin. Accordingly, nitrogen uptake and yield of ryegrass were significantly lower in the ‘straw treatments’ as compared with the treatments without straw. It is suggested that the impared nitrogen availability in the ‘straw treatments’ was mainly due to nitrogen losses caused by denitrification.     

Wachstum und Ernährung von Eberesche,Buche und Fichte im Gefäßversuch mit immissionsbelasteten Bodensubstraten aus dem Erzgebirge

Influence of simulated sulphur and nitrogen depositions on biomass and nutrient relationships of mountain ash, European beech and Norway spruce in a pot experiment with two soil substrates from the Ore Mountains Growth and nutrient relationships of mountain ash (Sorbus aucuparia), European beech (Fagus sylvatica) and Norway spruce (Picea abies) were investigated in a pot experiment with the two substrates rhyolithe (acidic) and basalt (alkaline). Additionally, depositions of sulphur (S) and nitrogen (N) as expected to occur in the Ore Mountains (Saxonia, Germany) in the future were simulated in order to test the species′ suitability for forest regeneration. After two years, aboveground biomass was significantly higher on basalt compared to rhyolithe for all species. The amount of S given (0 and 100 kg ha^—1 a^—1) and the dominant form of N applied (NH₄⁺:NO₃^— = 1:4 and 4:1; total amount of N given 80 kg ha^—1 a^—1) were of minor influence only. The contents of N and K in leaves or needles were higher on rhyolithe, whereas P, Ca, Mg and Mn contents were higher on basalt. Nutrient contents were only slightly affected by the amount of S supply and the NH₄⁺:NO₃^— ratio. In contrast to mountain ash, beech saplings exhibited considerable growth on rhyolite. It is therefore concluded that beech may be a suitable species for forest regeneration even on acidic soils suffering heavily from S and N immissions, whereas spruce will not tolerate high S loads. However, increasing N depositions by stimulating growth may cause deficiencies of Mg and K in both species.     

Bodenstruktur und Regenwurm-Aktivität in einem Wiesenboden im Solling

Soil structure and earthworm activity in a meadow soil in the Soiling area The A-horizon of a Golden Oat Meadow (Trisetetum flavescentis OB) in the Solling was analyzed micromorphologically and micromorphometrically. Five tables with magnifications of the soil structure form an essential part of the presentation. The upper 8-10 cm of the soil consist mainly of earthworm castings with different density of deposition. By these a spongy structure, stable against water, was formed in the upper 3-5 cm of depth. But also in the deeper horizons the soil bulk is penetrated by a net of pores of different width, causing a favourable water capacity as well as allowing sufficient air for the roots.