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).     

Einfluß der Löslichkeit verschiedener Phosphatdüngemittel auf die Phosphataufnahme und den Ertrag von Sommerweizen

Solubility of various phosphate fertilizers in a brown podzolic soil and their effect on phosphate uptake and yield of spring wheat. The solubility of various phosphate fertilizers (Superphosphate, Rhenaniaphosphate, Novaphos, Carolonphosphate and Hyperphosphate) was studied in an incubation experiment, and P uptake and yield effect of these fertilizers were investigated in a pot experiment. The soil used was a carbonate free brown podzolic earth (C horizon) with a neutral pH and low in available phosphate and humus. The quantities of P extracted from the soil by the EUF technique were the lower, the higher the amount of non processed phosphate of the incubated P fertilizers. This clear differentiation in the solubility of the various P-fertilizers was not obtained by the DL extraction. The P uptake of plants was highly correlated with the P quantities extracted by EUF (r = 0,95***), while the correlation between P uptake and the P of the DL extract was less narrow (r = 0,64*). The yield, particularly the grain yield, decreased with an increase of the non processed P in the fertilizers tested. Grain yield and EUF extractable P were highly correlated (r = 0,86***); while the relationship between grain yield and the DL extractable P was poorer (r = 0.62*). The experiments have shown that mainly the easily soluble phosphate is of decisive importance for the yield formation.     

Auswirkungen von Bodenverdichtungen auf die Dynamik von Boden- und Düngerstickstoff unter Winterweizen

Effect of soil compaction on the dynamics of soil and fertilizer nitrogen under winter wheat In 1987 and 1988 the effect of severe soil compaction before sowing on the dynamics of soil and fertilizer nitrogen under winter wheat was studied in a field trial at the experimental station of Roggenstein. According to the course of soil nitrate values before winter soil compaction caused a loss of 34 kg N/ha in the first year whereas no such effect could be seen in the second year. During winter vertical nitrate movement was slower on the compacted plots because of the smaller volume of macropores. Without additional N-Fertilizer net N-mineralization during the vegetation period was 22 kg N/ha (32 %) lower in the compacted than in the well structured soil. Total N-yield at harvest was 95 kg N/ha on the control plots and 68 kg N/ha on the compacted plots. The unfavourable soil structure also led to a lower N-fertilizer efficiency, especially in the wet year of 1987, when about 20 % of the fertilizer-N was lost by denitrification whereas in 1988 all fertilizer nitrogen was found in the plant-soil system at harvest. Denitrification on the untreated soil was negligible in both years. The results showed that, besides a weakly developed root system, reduced N-mineralization and increased denitrification losses are responsible for nitrogen deficiency symptoms of plants growing in compacted soils.     

Zum Einfluß von pH und organischem Kohlenstoffgehalt auf die Löslichkeit von Eisen,Blei, Mangan und Zink in Waldböden

Influence of pH and organic carbon content on the solubility of iron, lead, manganese and zinc in forest soils Several soil factors determine the solubility of heavy metals in soils. The contents of exchangeable and in consequence potentially plant available heavy metals are mainly influenced by the pH and the content of organic carbon. Samples of the A_h-horizon from the stemflow area and from soil not influenced by stemflow water were investigated in beech forests. The solubility or iron, lead, manganese and zinc is described in relation to the pH and the content of organic carbon. Exchangeable iron and lead appear in significant amounts at pH below 3.5 and 4.5, respectively, regardless to the content of organic carbon. Manganese and zinc are exchangeable at pH below 5.0 and are leached for about 90% from the A_h-horizon at pH values below 3.0. The effects of higher soluble iron and lead contents on the distribution of herbaceous plants are discussed.     

Der Einfluß agrochemischer Substanzen auf den Stroh- und Zelluloseabbau im Boden

The influence of agrochemical compounds on the decomposition of straw and cellulose in soil Supplementary to earlier investigations the decay of large amounts of straw-material with normal quantities of pesticides and normal amounts of straw-material with large quantities of pesticides was proved in a gasanalytical instrument and in pot-experiments. At the same time the straw-decay was tested in pot-experiments. The soil used in these pots has been untreated or treated for several years with different kinds of plant-Protecting-solutions. Finally there was made a test about the decay cellulose (KOZOVA 1963) with the same and different investigation materials. The results are as follows: 1. The use of plant-protection in wheat does not diminish the decay of straw even if the double quantity of straw treated with a medium-quantity of pesticides is added and normal quantities of straw treated with high quantities of pesticides are added to the soil. 2. Agricultural soils, which are cultivated for many years by using pesticides, do not show less straw-decay. 3. The decay of pure cellulose in the laboratory tested by the method of Kozova (1963) was diminished in soils, which had been treated for many years with herbicides and herbicides added with other plant-protection-means. This restriction seems to depend on unfavorable food-conditions for microorganisms eating cellulose in a soil without weed, since the direct dipping of cellulose in herbicid-liquid is not causing any decay-restriction. 4. On the other hand the direct sprinkling of the cellulose-filter-discs with fungicid-solutions of normal concentration diminished the decay strongly. However the decay was not restricted under field-conditions. This seems to be due to the fact that in the growing plants the fungicides have been transformed to a large extend and only small amounts could reach the soil.     

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.     

Einfluß von Bodenreaktion,Redoxbedingungen und organischer Substanz auf die Phosphatgehalte der Bodenlösung

Influence of soil reaction, redox conditions and organic matter on the phosphate content of soil solutions Samples of seven agriculturally used soils of different composition (A_p-horizons), one marine underwater soil and two garbage composts were adjusted in suspensions (soil-water-ratio 1:3) to different pH values between 3 and 8 by additions of NaOH or HCl. By a different degree of aeration the redox potential was kept constant at selected values between +600 and ?300 mV. After an incubation period of 22–24 days under controlled E_h-pH-conditions the content of total phosphate and orthophosphate was measured in the equilibrium solutions. At oxidizing conditions all soil and compost samples show the lowest phosphate content in solution at pH S6. At higher and lower pH values the phosphate content increases. The results indicate that the phosphate concentration is determined by adsorption/desorption processes – mainly connected with iron oxides – and not by dissolution or precipitation of definite phosphorus compounds. Under reducing conditions the phosphate content increases in the equilibrium solutions of all samples. Especially in samples with high content of sulphides a considerable increase of the phosphate concentration could be measured at Eh values below +300 mV at pH 5, +200 mV at pH 6, and ± 0 mV at pH7 and 8. Below these values phosphate containing iron(II1) oxides were reduced and – with further decreasing redox potentials – transformed to iron sulphides. In samples without sulphide formation the phosphate mobilization is much lower. With increasing amount of soluble organic matter the phosphate content of the solutions also increases because of phosphate desorption by organic anions or complexation of aluminium and iron from phosphate adsorbing compounds. But also the content of soluble organically bound phosphate increases and may amount to 70 % of the total phosphate content in solution.     

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.     

Einfluß von Bodeneigenschaften,Bodennutzung und Bodentemperatur auf die N-Mobilisierung von Kulturböden

Influence of soil characteristics, agricultural use and soil temperature on the N-mobilization of cultivated soils A new N-mobilization model, which considers also the short term and seasonal N-supplying capacity of soil is presented. At a fixed time the potential mobilizable N (N-MOB) is a sum of difficultly mobilizable N (N-MOB_s) originating from the pool of difficultly mobilizable N (N_s) and the easily mobilizable N (N-MOB₁) originating from the pool of easily mobilizable N (N₁). It is possible to characterize soil according to their M₁, N-MOB_s and v (N-MOB_s per day) values. Usefulness of these parameters in N-nutrition and ground water burden from N has been discussed. Basic parameters of this model have been experimentally determined independently with the help of two different experiments i. e. laboratory incubation and column lysimeter using surface soil samples. The easily mobilizable N pool (N₁) values were found in the range of 142 to 814 kg N ha^?1 which corresponded to 1.2 to 7.4 % of organic N content of these soils. The difficultly mobilizable N per day (i. e. v = N-MOB_s per day) in an incubation experiment (35°C) were found in the range of 1.5 to 24kg N ha^?1. However, in the column lysimeter experiment, in contrast, these values at 10°C ranged between 0.05 to 0.9 kg N ha^?1. These values correspond to N-MOB_s values in the range of 11–182 kg N·ha^?1 for a period of 200 days which approximate to a vegetation period. For practical purposes, the N₁ and v values could be calculated by just measuring 3–4 points after 14 days of incubation at 35°C. The results show that N-MOB_s values strongly correlated compared to N₁ values to total N, organic carbon and clay content and non significantly to pH and silt content. The results of an laboratory incubation experiment carried out to assess the effect of temperature on N-mobilization show that even at 0°C there was N-mobilization. The results revealed that in the temperature range of 0–8°C (a range of soil temp. usually observed in winter months) and in the range of 25–40°C (range of summer months temp. for surface arable soil), a small change in the soil temperature would result in enormous increase in the quantity of mobilized N. The highest mobilized N quantity was found above 60°C.     

Wirkungen technogener Druckbelastung auf die Spannungsverteilung und das Bodengefüge einer Schwarzerde aus Löß

Effect of wheeling on stress distribution and changes in the macro- and microstructure of a cambic phaeozem derived from loess The determination of stress induced changes in the poresystem due to repeated wheeling of a cambic phaeozem derived from loess as well as in the aggregate size distribution, arrangement, and stage are reported. It could be shown, that repeated wheeling always results in a further stress distribution to deeper depths and that the vertical stresses dominate with repeated wheeling. Furthermore the octahedral shear stresses and mean normal stresses exceed the maximum strength defined by the Mohr Coulomb failure line and define a further soil deformation. The process of aggregate deterioration can be verified by radiographs from which not only the changes in bulk density on a mesoscale can be derived but from which also the crack patterns can be defined for the different stages of structure deterioration. Under the well known assumption that pore water pressure is increased due to wheeling, soil compaction and consecutive soil homogenisation by kneading can be differentiated. The consequences for ecological parameters will be discussed.     

Alterung von wasserlöslichem Düngerphosphat bei verschiedenen Bodentypen

Aging of phosphate fertilizers in different soil types With ten different soils the effect of the contact time between soil and phosphate fertilizer on the availability of the fertilizer (superphosphate) was investigated. For this purpose phosphate fertilizer application was carried out at different times: six month and three months before sowing and directly before sowing. Sowing of rye-grass (Lolium perenne L.) in Mitscherlich pots was carried out at the same time for the three treatments. On most soils phosphate uptake of the grass was significantly higher in the treatment with phosphate application directly at sowing as compared with applications three and six months before. In 13 from 16 cases phosphate application three months before sowing yielded higher phosphate uptake than the application six months before. The reduction in phosphate availability (phosphate aging) was also reflected in phosphate quantities extracted from the soil by three different soil test methods (electroultrafiltration = EUF, double lactate = DL, calcium acetate lactate = CAL). Soil test data obtained by these three methods were significantly correlated with phosphate uptake of the crop. Phosphate aging was severest in an acid brown earth, weakest aging was found in a rendzina (subsoil with 67 % CaCO3). Additional laboratory experiments support the assumption, that aging of fertilizer phosphate originated from a binuclear phosphate adsorption. This process is the stronger the more acid a soil. Phosphate adsorption occurs during a relatively short time, while the transformation of solüble phosphate fertilizer to apatite is supposed to be a longer lasting process.     

Einfluß löslicher organischer Inhaltsstoffe auf die photometrische Analyse von Nitrat,Chlorid und Sulfat in Sickerwässern

Influence of DOC on the photometric analysis of nitrate, chloride and sulfate in seepage water Investigations on the applicability of photometric sulfate and chloride analysis in seepage water are showing strong influences by DOC, causing a raised detection of these anions. Interactions can be reduced, but not completely removed by solid phase extraction with reversed phase material. The photometric detection of nitrate is not influenced by DOC.     

Einfluß verschiedener Substanzen auf den Eindringwiderstand von Bodenpasten

Effect of different substances on the resistance of penetration of soil pastes A preliminary study was carried out to test for to what extent the molecular forces of a soil may be influenced. Soil pastes treated with Alginure', Ca(OH)₂, NaCl, KCl, organic matter, or ferrihydrite, were prepared from topsoil samples of two eroded Typic Hapludalfs derived from loess (A_p within the A_l and B_t horizon, resp.). Following airdrying and breaking the pastes, the penetration resistance of 8–12 mm aggregates was measured at 4 different applied water suctions. These resistances to penetration are correlated with the applied water suction by lg(resistance) = ?a+b*(suction) and with the aggregate water content by lg(resistance) = a-b*lg(water content). The resistances to penetration of the B_t-pastes are constantly higher than those of the A_l-pastes. If any change due to treatment occurred, adding a substance decreased the resistance to penetration of the B_t-pastes whereas those of the A_l-pastes were increased. As differences due to parent material and treatments occured at >10kPa and >30kPa applied water suction, resp., it is assumed that they essentially effect the surface tension of the soil water, which on its part influences the force of cohesion of the water menisci. This force of cohesion affects the degree of aggregation and thereby among others the resistance to penetration of a soil.     

Einfluß von Kationenaustauscherharz auf die Schwermetallaufnahme von Reben und anderen Kulturpflanzen aus kontaminierten Böden

The effect of a cation exchange resin on the uptake of heavy metals by grapevines and other cultivated plants grown in contaminated soils The effect of a cation exchange resin on the growth and heavy metal content of grapevine, sun flower, cress, wheat and Italian rye-grass was investigated in potted vineyard soil, contaminated by the long application of Cu-containing pesticides (total Cu content of the soil: 628 ppm), or a soil contaminated artificially with 20 ppm Cd. Roots of cress seedlings grown in a vineyard soil mixed with a cation exchange resin were 2.2 times longer than in the untreated soil. Rye-grass was not injured, whereas grapevine, sun flower and wheat showed varying degrees of growth reduction, chlorosis and necrosis when grown in untreated vineyard soil. However, wheat and sunflower grown in vineyard soil containing a cation exchange resin showed no injury and grapevines exhibited markedly reduced symptoms. The Cu content of the test plants decreased as follows: The Zn and Cd content of the plants also decreased considerably, whereas their Fe and Mn content was not influenced. Grapevine, grown in a calcareous soil contaminated with 20 ppm Cd, contained 447 ppm Cd in the roots (untreated: 1,9 ppm) and 0,20 ppm Cd in the leaves (untreated: 0,04 ppm). The Cd content of the roots declined to 113ppm, that of the leaves to 0,15 ppm when grown in the contaminated soil containing a cation exchanger.     

Einfluß von Düngemaßnahmen auf die Stickstoffauswaschung bei mehrjährigem Silomaisanbau

Influence of fertilization on nitrogen leaching after cultivation of maize for silage over four successive seasons In a field trial, nitrogen leaching from soil was determined between February 1983 and May 1986 by analyzing soil water from 50, 80 and 110 cm below the soil surface every 14 days. On a Stagno-gleyic Luvisol, maize after maize was cultivated over four successive seasons. Nitrogen was applied either minerally in spring according to N_min or as a semiliquid cattle manure. The time of application (autumn and/or spring), application rate and use of nitrification inhibitor dicyandiamide (DCD) were varied. Under very low N-fertilization (underground fertilization only), nitrate nitrogen losses by leaching dropped from 100 kg N/ha in the first year to 33 kg N/ha in the 3^rd. Nitrogen leaching from the various treatment plots depended on the maize growth and rainfall conditions. Because of an intensive and long lasting seepage of gravitational water, nitrogen leaching from the root zone ranged from 113 to 208 kg N/ha during the fall and winter seasons of 1983/84 and 1984/85. Under the more balanced infiltration conditions of the leaching period 1985/86, and after a high yield of maize in 1985, losses due to leaching were reduced to values between 69 to 108 kg N/ha. Under these experimental conditions (deliberately high quantities of semiliquid cattle manure; DCD-application in autumn) no reduction in nitrogen losses could be proved due to the addition of dicyandiamide.