Der Einfluß langjähriger Düngungsmaßnahmen auf die Dynamik der Bodenstruktur

The influence of a long term fertilizer experiment on the dynamic of soil structure In a long term manurial experiment at Dikopshof the dynamic of the structure of a Luvisol from loess during the growing seasons 1981 and 1982 was investigated. Farmyard manure effected the greatest variations in pore volume, amount of pores > 50 μm, air and water permeability, aggregate stability and dehydrogenase activity. Higher amounts of mineral fertilizer, that is additional mineral fertilization equivalent to the mineral contents of farmyard manure, could change the soil structure only for a short period. The yield of winter wheat was in close relation to the pore volume, the amount of pores > 50 μm and the dehydrogenase activity of the topsoil.     

Einfluß von Meliorationsmaßnahmen auf die kleinräumliche Variation von Waldbodeneigenschaften

Influence of amelioration procedures on the small scale spatial variation of forest soil properties After clearcutting, a podzol-pseudogley derived from silty loam covering clay and a podzolic brown forest soil of sandy texture were treated as follows: CaPMg-fertilization either alone or combined with tilling (after herbicide spray) or ploughing (after mechanical stump extraction); planting of young pines, fertilization with N in the third growing season. Eight years after initiation of the trials, the coefficients of variation for stoniness and bulk density didn't differ between treatments. On the other hand there was clear evidence, that the clearcutand the subsequent amelioration techniques had increased the variability of the organic floor weight as well as of the pH, the carbon and nitrogen contents of the top mineral soil. These effects presumably are due to an irregular mixing of fertilized raw humus and A-horizon material with subsoil layers by harvesting procedures, tilling or ploughing and bioturbation.     

Einfluß von Stickstoffernährung und Wuchsstoffapplikation auf die Knolleninduktion bei Kartoffelpflanzen

Influence of nitrogen nutrition and application of growth regulators on tuber initiation in potato plants In water culture the effect of continuous and discontinuous N-nutrition on tuber initiation was investigated. Additional applications of growth regulators on growing stolon tips were carried out. Continuous supply of nitrate or ammonium inhibited completely the tuber initiation in S. tuberosum varieties ?Ostara”? and ?Clivia”?, The inhibition was compensated by application of CCC and ABA on the stolon tip. In contrast to this stolon application of kinetin and root application of CCC were ineffective. Temporarily damaging of the root system led to tuber initiation even when nitrogen was supplied continuously. In S. andigena grown under short day continuous N supply only delayed the tuber initiation but could not prevent it. Discontinuous N supply promotes tuber initiation in S. tuberosum. A sudden increase in N supply caused ?re-growth”? of the tuber, i.e. a stolon was formed on the tuber apex. GA₃ application on the growing tuber had the same effect. The effect of N nutrition on tuber initiation can be explained via changing the balance of endogenous growth regulators in general and the physiological aging of the leaves in particular. Discontinuous N supply seems to reduce cytokinin production in roots and therefore accelerates the aging of the leaves. This in turn favours the formation of inhibitors and/or presumably reduces the GA production in the shoot, which will change the balance of the growth regulators in the stolon tip in favour to tuber initiation.     

Wirkungen organischer Substanzen auf Boden- und Düngerphosphat. Teil 2: Einfluß verschiedener organischer Stoffe auf die Mobilität von Dünger-P

Effekt of various organic substances on the mobility of fertilizer P Using model trials, studies were carried out on the influence of long-term organic manuring as well as incubation with rotted straw, maize roots, and slurry, on both the diffusion of ³²P from added (NH₄)₂H³²PO₄ in a ‘soil block’and the fixation rate of fertilizer phosphate in the soil. 1. In the “soil block experiment”, preincubation for 7 days with slurry (added to a low-P brown earth soil at a rate of 5% D. M.) increased diffusion of P as compared to an equivalent amount of added inorganic P. Preincubation with rotted straw resp. maize roots had only insignificant effects. 2. Long-term organic manuring with farmyard manure (P-long-term field trials Weihenstephan) had a significant positive effect on the diffusion of P in the soil block in contrast to annual application of mineral P. Effects of straw manuring were markedly less. 3. Addition of maize roots (5% D. M. to a non P-treated or P-enriched brown earth soil) resulted in a reduced fixation of labelled fertilizer phosphate (by 2–8%), longer preincubation periods, however, increased fixation. Preincubation with rotted straw increased P fixation by 2 to 4% as compared to an equivalent addition of inorganic P (diammonium phosphate).     

Wirkungen organischer Substanzen auf Boden- und Düngerphosphat Teil 1: Einfluß von Stroh- und Maiswurzelextrakten auf die Löslichkeit von Boden-und Dünger-P

Effects of organic substances on soil- and fertilizer phosphate Part 1: Influence of straw or maize-root extracts on the solubility of soil and fertilizer P The effects of straw and maize-root extracts on the solubility of soil and fertilizer phosphate were tested in incubation trials. The following results were obtained. 1. Addition of an extract of unrotted straw (10 g straw/100 g soil) to incubate a brown-earth soil, (high or low in P) for 1–14 days did not have any significant effects on the H₂O and CAL P-fraction as compared to a KH₂PO₄ control, but markedly increased transformation of ‘easily soluble’Fe- and Al-phosphates (?15 to ?40 ppm) into ‘less soluble’forms (+15 to +20 ppm). Addition of an extract of rotted straw decreased the amounts of water extractable P and ‘easily soluble’Fe- and Al-phosphates but CAL-extractable P and ‘less soluble’Fe- and Al-phosphates were increased. 2. Incubation of the same soil (P-enriched) with an extract of maize roots (roots: soil = 1:3) for 1 day resulted in a reduction in the fixation of fertilizer phosphate (34 as compared to 42%) and in a decrease of fertilizer P recovered as ‘less soluble’Fe- and Al-P (from 31 to 11%); however, fixation was markedly increased after 14 days.     

Einfluß langjähriger Düngung mit verschiedenen N-Formen auf die Phosphat-Dynamik einer Ackerbraunerde

Influence of long-term application of different nitrogen sources on the dynamics of phosphate in an arable brown earth In a long-term field experiment parameters of the soil phosphate status were determined after 53 years. Soil characteristics of the arable brown earth are: sandy silt loam; pH 5,9–6,6; total carbon 0,9%; CEC 13–15 meq/100 g soil; effective field capacity 160 mm unto 150 cm. The following results were obtained: Total P content was slightly higher in the plots without mineral N and with farm manure (90 and 93 mg P/100 g soil resp.) than in the plots with mineral N supply (Ø 85 mg P/100 g soil). Application of farm yard manure and ammonium sulfate caused higher proportions of ?Fe and Al phosphates”? (56–57% of inorganic phosphate) whereas calcium cyanamide, calcium nitrate and ammonium sulfate with annual liming led to higher a content of Ca-phosphate (52–56% of inorganic phosphate). When pH was brought to 6,5 by liming, P uptake of rye grass and green oats/green rape-seed in a pot experiment depended on the soil content of ?Fe- and Al-phosphates”?. Without liming, P uptake was lower in the plot with ammonium sulfate, however, in the calcium cyanamide plot P uptake was higher than expected from the content of ?Fe- and Al-phosphate”?.     

Einfluß von NaCI-Salinität auf die CO2-Assimilation und auf den Einbau von 14C in verschiedene Inhaltsstoffe bei jungem Sommerweizen

Effect of NaCI salinity on CO₂ assimilation and incorporation of ¹⁴C in various chemical fractions of young wheat plants The effect of an increasing NaCI salinity on CO₂ assimilation and on the distribution of ¹⁴C in various chemical fractions of young wheat plants was studied. Increasing salinity restricted growth and in particular ¹⁴CO₂ assimilation being measured at the end of the experimental period. Correspondingly the amounts of ¹⁴C found in the various chemical fractions (amino acids, organic anions, carbohydrates, proteins, lipids, insoluble residue) were decreased with an increase in salinity. The relative distribution of ¹⁴C in the chemical fractions also was affected by salinity. At low salinity level a relatively low ¹⁴C concentration was found in the low molecular fractions, while the high molecular fractions showed a relatively high ¹⁴C concentration. At high salinity level this tendency was only weakly evident. Increasing salinity had no major impact on the nutrient concentrations (N, P, K, Ca, Mg) in the shoots, whereas the concentration of Na and especially of CI was remarkably raised. It is assumed that this excessive Na and CI concentrations in the shoots are resulting in the yield depression.     

Einfluß langjähriger Düngung mit verschiedenen Phosphatdüngerformen auf die Phosphatverfügbarkeit in der Rhizosphäre von Raps

Influence of long-term application of different P-fertilizers on phosphate availability in the rhizosphere of rape The residual P effect was investigated in soils from a 10 years' lasting field trial (North of Hessia, Alfisol-Udalf, pH 5.7) in which different P-fertilizer types had been applied with a rate of 111 kg P₂O₅ ha^?1 a^?1. Soil analysis showed that basic slag phosphate had increased the content of CAL-, H₂O- and EUF extractable P in the soil to a higher extent than Novaphos (partially acidulated phosphate rock) or Hyperphos (phosphate rock). In the latter treatment the highest content of DL soluble P was found as compared with the other P-fertilizer types. Pot experiments with rye-grass, rape and maize showed that P recovery was highest from the soil with the basic slag treatment and lowest in the treatment with Hyperphos, Novaphos taking an intermediate position. This finding demonstrates that the DL-method does not provide a reliable information on the P-availability of a soil, if treated with rock phosphate. The level of water soluble P in the rhizosphere of rape was investigated with a particular technique (Kuchenbuch and Jungk, 1982). It could be shown that the P level in the rhizosphere of the Hyperphos treatment was only slightly higher than the P level of the P₀ treatment (without P fertilizer) while in the Novaphos – and particularly in the basic slag treatment much higher levels of soluble P were found. It thus becomes evident that even in the rhizosphere the solubility of Hyperphos was poor. The levels of water soluble P in the rhizosphere followed a depletion curve. The steepest gradient was found for basic slag, followed by the Novaphos-, Hyperphos- and the P₀ treatment.     

Einfluß von Ammonium- und Nitratstickstoff auf die Entwicklung von Buchenjungpflanzen

Influence of ammonium and nitrate nitrogen on the growth of young beech plants Young beech plants were grown in aerated nutrient solutions with NH₄ or NO₃ nitrogen for a period of 12 weeks. pH-changes caused by the source of nitrogen were corrected every second day. Absorption of NH₄-N was higher than of NO₃-N. NH₄-N was superior for shoot growth and development of lateral roots, NO₃-N for growth of the main root. Nutrient solution containing both sources of nitrogen was the most favorable.     

Der Einfluß von Fungiziden auf die mikrobielle Aktivität eines Bodens

The influence of fungicides on microbial activity in soil The objective of this work was to investigate the influence of the fungicides copper, sulfur, mancozeb, captan-folpet-folcid, quintozene and benomyl on CO₂-evolution and on the dehydrogenase-, xylanase- and urease-acitivities of an acid soil. The investigations showed that a recommended dosage of fungicide caused an increase in CO₂-evolution. After the second and third fungicide application this ‘stress reaction’ was followed by a decrease in CO₂-release below the value of the untreated control soil. Up to the tenth week after pesticide application again an increase of the activity could be shown. This increase might be explained by an inactivation of fungicides, a selection of resistant species, a decreasing competition of microorganisms and mineralization of dead organisms. Finally, after 10 to 14 weeks the activity returned to the value of the untreated soil, that was probably due to the recovery of the affected microflora and/or a new adapted microflora. The various enzyme activities did not follow this scheme exactly. The course was influenced by the mode of action of the particular compound used. Brassicol (Quintozene) differed because of the severe and continous inhibition of the xylanase activity. It can be concluded that the fungicides applied to the soil influence both the CO₂-release and the activities of the soil enzymes tested. Consequently litter decomposition and metabolic activities may be affected for 3 to 4 months.     

Einfluß organischer Düngungen auf bodenphysikalische Parameter

Influence of organic amendments on soil physical properties The effect of applying crop residues additionally to fertilzers or farmyard manure on soil structure was studied in Upper Bavaria. Crop residues were applied each year for 13 years before sampling. The Aquic Hapludalf, derived from loess underlain by Tertiary fine sand, was cropped with vegetables. Resistance to penetration, saturated hydraulic conductivity (k_f), pore size distribution, and aggregate stability (AS) were determined. The application of residues and/or manure increased the organic matter content of the top soil, resulting in increases in AS and k_f. However, both of these parameters were higher following residue application rather than that of manure. Only the application of residues improved the plant available water capacity by about 10 mm within 70 cm depth of soil profile. The other properties were not significantly affected, probably because they were also influenced by the weather and soil management practices. The values for these properties must therefore be considered as only momentary.     

Der Einfluß von Bormangel und von mechanischer Zerstörung des Spitzenmeristems auf die Zellteilung bei Sonnenblumen

Influence of boron deficiency and destruction of the apical meristem on the cell division in sunflowers With a severe, nearly absolute boron deficiency metabolism and formation of tissues are so disturbed that the primary symptom of boron deficiency can not be recognized with certainty. Investigations here had to clarify if cutting the tops or destruction of the apical meristem with a red-hot needle will induce symptoms similar to those of boron deficiency or how symoms develop under mild boron deficiency. With the red-hot needle technique, it was possible to obtain cambial enlargement in plants with a normal boron nutrition. Cutting off the tops also, induced an enlargement of the hypocotyl. In this case the enlargement was however due to an enlargement of the cortex by formation of an aerenchymlike tissue. A boron supply near the deficiency level caused development of deficiency symptoms in growing plants (chlorosis, inhibited enlargement of the stem, small deaf' blades, small-celled xylem, malformed and discoloured cell walls and appositions on the young cell walls). As long as the shoot apex displayed growth, enlargement of the cabium did not appear as a rule. This symptom seems to be a secondary symptom of boron deficiency caused by damage to the shoot apex and, thus disturbed auxin metabolism.     

Einfluß von Bikarbonat auf die subzelluläre Verteilung von blatt- und wurzelappliziertem Eisen bei Sonnenblumen (Helianthus annuus L.)

Influence of bicarbonate on the subcellular distribution of iron applied to roots or leaves of sunflower (Helianthus annuus L.) 18 days old sunflower seedlings were transferred and cultivated for 9 days ( untill chlorosis appeared) in nutrient solutions. After that Fe concentration of roots and shoots and the subcellular distribution of Fe in the cytoplasm of the young leaves was determined. Bicarbonate in the nutrient solution with Fe reduced the concentration of Fe and chlorophyll in the young leaves of the plants, also the concentration of Fe and protein in the chloroplast fraction of the cytoplasm, but the subcellular distribution for Fe remained unchanged compared with the control. Leaf spray with Fe-EDTA to plants in nutrient solution without Fe + bicarbonate resulted in higher Fe but unchanged chlorophyll concentrations in the young leaves, while the cytoplasm fractions of these leaves had higher concentrations of iron and protein compared with the control. An inactivation of leaf iron by bicarbonate in the nutrient medium could not be demonstrated. There was no significant lowering of the concentration of disolved Fe in the nutrient solution by bicarbonate, indicating a disturbance of Fe-up-take rather than an insufficient Fe-supply as a factor for iron chlorosis. The physiological activity of leaf applied Fe was not diminished by bicarbonate in the nutrient solution. This observation too points to a primary effect of bicarbonate in the root area. The pH of the cytoplasm from young leaves remained unchanged after leaf spraying with Fe-EDTA. In spite of this there might be a local effect of sprayed solution (with pH 5,1) on the pH of solutes in the apoplast, influencing the mobility of leaf applied Fe.     

Der Einfluß von P-Ernährung und pH auf die Phosphataseaktivität von Zuckerrübenwurzeln

The influence of phosphorus nutrition and pH on phosphatase activity of sugar beet roots For the determination of acid phosphatase activity (P_ase) of sugar beet roots (cultivar: Reka), plants were cultivated in nutrient solution with 1 or 100 μM P in a growth chamber for 12, 18, 24, 30, 36 and 42 days. The phosphatase activity of intact roots was measured in buffer solutions with pH 4 to 7.2 and 14 mM p-Nitrophenylphosphate (NPP) after 10 min of incubation at 20°C. The influence of P nutrition on P_ase activity was significant at all intervals. At P deficiency the activity was increased by a factor of 4 to 20. During the experimental period the pH optimum was 6. At pH 5 and 7.2 the P_ase activity reached only 63 and 64% respectively of the optimum value. At P deficiency (1 μmol P L^—1) the absolute rate of NPP-hydrolysis at pH 6 was 144 nmol min¹ m¹ root length (day 12 to 36). The plants which received optimum P supply showed only 10% of this value. Sugar beet roots with P deficiency have a high potential of P_ase activity from the acid to the neutral pH-range. Therefore, under this condition they may effectively use dissolved organic phosphorus compounds.     

Der Einfluß von Klärschlamm auf die mikrobielle Tätigkeit im Boden

The influence of sewage sludge on microbial activity in soil The effect of untreated, pasteurized and irradiated sewage sludge on soil biology was studied in model and field experiments. Sewage sludge from the sewage plant Geiselbullach in the west of Munich city was used for these experiments. The investigations were performed with 4 soil types according to the different locations. All the results demonstrate that there is an increase in biomass after application of sewage sludge while there were definite influences from the location. No significant relation could be observed according to sewage sludge treatment. Under favourable lab conditions the mineralization of the organic matter applied to the soil with higher amounts of sewage sludge induces in short time a definite decrease in pH. In accordance with these changes in pH there is a corresponding decrease in microbial biomass. Early results on the influence of microbial N-cycle demonstrated that amounts of sewage sludge applied under practical conditions brought an increase in denitrification capacity of the soil. In the experiment with soils nitrification rate was doubled after sewage sludge application.     

Einfluß verschiedener Bodeneigenschaften auf die mikrobielle Toxizität von Blei und Cadmium

Effects of different soil properties on the microbial toxicity of lead and cadmium Effects of different soil properties on the microbial toxicity of lead and cadmium were investigated in laboratory experiments on ten arable and nine preserve area soils. Microbial activity was measured by means of the dehydrogenase and the arginine-ammonification tests. The latter was not suitable to show the microbial toxicity of both metals. Effects of lead on dehydrogenase activity were mainly influenced by its concentration in soil solution (r = 0,79). Thus, all soil properties which determined the adsorption of lead correlated significantly with the relative dehydrogenase activities of the contaminated soils. The most important abiotic factors influencing the toxicity of lead were the soil pH and the CEC. Cd solubility and Cd toxicity were influenced by soil pH in a contrary way. Low Cd concentrations caused greater inhibitions of dehydrogenase activity at neutral and slightly alkaline soil reaction than under acidic conditions. Therefore, correlations between Cd concentrations of soil solutions or clay content and dehydrogenase activity were only significant if partial correlation analysis (constant pH) was used.