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Sradnick A.,University of Kassel | Oltmanns M.,Institute for Biodynamic Research | Raupp J.,Agriculture science.org | Joergensen R.G.,University of Kassel
Geoderma | Year: 2014

Long-term organic fertilization may control the accumulation of organic matter in subsoil. The objective of this study was to evaluate the effects of long-term farmyard manure application in comparison with mineral fertilization on the accumulation of amino sugars as indices for microbial residues down to 1. m depth at a sandy site that exhibits highly heterogeneous pH conditions. In relation to maximum values in topsoil at 90-100. cm depth, the SOC content decreased to roughly 24% and the total N content to 16% of the maximum values, leading to an increased soil C/N ratio from 11 to values around 16 in all treatments. The relative contribution of microbial residue C to SOC decreased with depth from 68% at 0-25. cm to 24% at 50-100. cm. In the subsoil, the stocks of microbial residue C were increased by manure in comparison with mineral fertilization, but not the stocks of SOC. This suggests that manure-induced priming effects increase the microbial turnover at 50-100. cm depth. Manure fertilization promoted the formation of bacterial residues in the topsoil at 0-25. cm depth, but not in the subsoil. Below the topsoil, the fungal C to bacterial C ratio decreased from 2.6 at 0-25. cm depth to 2.1 at 50-100. cm depth. Below the topsoil, the ratio of fungal to bacterial residues continuously decreased with depth from 2.7 to 1.7 at 90-100. cm depth, without fertilizer effects. Possible reasons for this decrease, such as effects of pH on the subsoil microbial community, a higher sensitivity of fungi to the absence of fresh organic matter or to an unfavourable composition of the subsoil atmosphere, need further investigations. © 2014 Elsevier B.V.


Ludwig B.,University of Kassel | Geisseler D.,University of Kassel | Michel K.,University of Kassel | Joergensen R.G.,University of Kassel | And 7 more authors.
Agronomy for Sustainable Development | Year: 2011

The study of sustainable land use is complex and long-term experiments are required for a better understanding of the processes of carbon stabilization. Objectives were (i) to describe for four long-term experiments the effects of fertilization and soil management on crop yields and the dynamics of soil organic carbon (SOC) and total N, and (ii) to discuss the usefulness of models for a better understanding of the underlying processes. Data of soil organic carbon and total N of four long-term experiments in Germany and China which studied the effect of fertilization (Bad Lauchstädt, Darmstadt) and tillage (Göttingen, Quzhou) were evaluated and soil organic carbon fractionation was carried out. The Rothamsted Carbon Model was used for a description and prediction of soil organic carbon dynamics as affected by fertilization and tillage in Bad Lauchstädt and Quzhou. The type of fertilizer added at common rates - either mineral N or farmyard manure - affected the crop yields only slightly, with slightly lower yields after manure application compared with mineral N fertilization. For both fertilization trials, manure applications at common rates had beneficial effects on soil organic carbon stocks in the labile pool (turnover time estimated as <10 years) and to a greater extent in the intermediate pool (turnover time estimated to be in the range of 10 to 100 years). A comparison of the effects of conventional tillage, reduced tillage and no-tillage carried out in Göttingen and Quzhou indicated only small differences in crop yields. Reduced tillage in Göttingen resulted in an increased C storage in the surface soil and C was mainly located in the mineral-associated organic matter fraction and in water-stable macro-aggregates (>0.25 mm). For Quzhou, no-tillage and conventional tillage had similar effects on total C stocks, with a greater spatial variability in soil organic carbon stocks in the no-tillage plots. Modeling required site-specific calibrations for the stock of inert organic matter for each of the sites, indicating that not all carbon stabilization processes are included in the model and that application of a model to a new site may also need site-specific adjustments before it can be used for predictions. After site-specific calibration, however, model predictions for the remaining treatments were generally accurate for the fertilization and tillage trials, which emphasizes the importance of temperature, moisture, soil cover and clay content on the decomposition dynamics of soil organic carbon and the significance of amounts and quality of carbon inputs in the soil for maintaining or increasing soil organic carbon stocks in arable soils. © INRA, EDP Sciences, 2010.


Heitkamp F.,University of Kassel | Raupp J.,Institute for Biodynamic Research | Ludwig B.,University of Kassel
Journal of Plant Nutrition and Soil Science | Year: 2011

The application of density fractionation is an established technique, but studies on short-term dynamics of labile soil fractions are scarce. Objectives were (1) to quantify the long-term and short-term dynamics of soil C and N in light fraction (LFOC, LFON, ρ ≤ 2.0 g cm-3) and microbial biomass C (Cmic) in a sandy Cambisol as affected by 28 y of different fertilization and (2) to determine the incorporation of C4-C into these labile fractions during one growing season of amaranth. The treatments were: straw incorporation plus application of mineral fertilizer (MSI) and application of farmyard manure (FYM) each at high (MSIH, FYMH, 140-150kg N ha-1 y-1) and low (MSIL, FYML, 50-60kg N ha-1 y-1) rates at four field replicates. For all three sampling dates in 2008 (March, May, and September), stocks of LFOC, LFON and Cmic decreased in the order FYMH > FYML > MSIH, MSIL. However, statistical significance varied markedly among the sampling dates, e.g., with LFOC being significantly different (p ≤ 0.05) in the order given above (sampling date in March), significantly different depending on the fertilizer type (May), or nonsignificant (September). The high proportion of LFOC on the stocks of soil organic C (45% to 55%) indicated the low capacity of soil-organic-matter stabilization on mineral surfaces in the sandy Cambisol. The incorporation of C4-C in the LFOC during one growing season of amaranth was small in all four treatments with C4-LFOC ranging from 2.1% to 3.0% of total LFOC in March 2009, and apparent turnover times of C3-derived LFOC ranged from 21 to 32 y for the sandy soils studied. Overall, our study indicates that stocks of LFOC and LFON in a sandy arable soil are temporarily too variable to obtain robust significant treatment effects of fertilizer type and rate at common agricultural practices within a season, despite the use of bulked six individual cores per plot, a common number of field replicates of four, and a length of treatments (28 y) in the order of the turnover time (21-32 y) of C3-derived LFOC. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Heinze S.,University of Kassel | Oltmanns M.,Institute for Biodynamic Research | Joergensen R.G.,University of Kassel | Raupp J.,Institute for Biodynamic Research
Plant and Soil | Year: 2011

The main objective of the second Darmstadt trial was to investigate the effects of vegetal fertilizers on soil properties and crop yield in comparison with farmyard manure. The experiment consisted of seven treatments: (i) inorganic fertilizers, (ii) vegetal organic fertilizers, (iii) vegetal organic fertilizers equivalent to biodynamic preparations, (iv) cattle farmyard manure, (v) cattle farmyard manure with addition of biodynamic preparations, (vi) high level of cattle farmyard manure, and (vii) high level of cattle farmyard manure with biodynamic preparations. The soil properties analyzed were pH, soil organic C, N, P, and S, soil microbial biomass C, N, and P, basal respiration and fungal ergosterol. The application of vegetal fertilizers had slightly negative effects on soil organic C, no effects on crop yield (potato, winter rye) and microbial biomass, but positive effects on ergosterol in comparison with farmyard manure. The increase in ergosterol was caused by straw return in the vegetal, but also in the inorganic fertilizer treatments. The biodynamic preparations did not affect the contents of soil organic C and total N. The low effectiveness of vegetal fertiliser in maintaining soil organic C levels is of particular importance for organic cropping systems and should be examined further under different site conditions. © 2011 Springer Science+Business Media B.V.


Geisseler D.,University of Kassel | Linsler D.,University of Kassel | Piegholdt C.,University of Kassel | Andruschkewitsch R.,University of Kassel | And 2 more authors.
Journal of Plant Nutrition and Soil Science | Year: 2011

A major challenge in sustainable crop management is to ensure adequate P supply for crops, while minimizing losses of P that could negatively impact water quality. The objective of the present study was to investigate the effects of long-term applications of different levels of mineral fertilizers and farmyard manure on (1) the availability of P, (2) the relationship between soil C, N, and P, and (3) the distribution of inorganic and organic P in size fractions obtained by wet sieving. Soil samples were taken from the top 20cm of a long-term (29 y) fertilization trial on a sandy Cambisol near Darmstadt, SW Germany. Plant-available P, determined with the CAL method, was little affected by fertilization treatment (p < 0.05) and was low to optimal. The concentration of inorganic and organic P extracted with a NaOH-EDTA solution (P NaOH-EDTA) averaged about 350 mg (kg dry soil) -1, with 42% being in the organic form (P o). Manure application tended to increase soil C, N, and P o concentrations by 8%, 9%, and 5.6%, respectively. Across all treatments, the C N P o ratio was 100 9.5 2 and was not significantly affected by the fertilization treatments. Aggregate formation was weak due to the low clay and organic-matter content of the soil, and the fractions > 53 μm consisted predominantly of sand grains. The different fertilization treatments had little effect on the distribution of size fractions and their C, N, and P contents. In the fractions > 53 μm, P NaOH-EDTA ranged between 200 and 300 mgkg -1, while it reached 1260 mgkg -1 in the fraction < 53 μm. Less than one third of P NaOH-EDTA was present as P o in the fractions > 53 μm, while P o accounted for 70% of P NaOH-EDTA in the smallest fraction (< 53 μm). Therefore, 16% and 28% of P NaOH-EDTA and P o, respectively, were associated with the smallest fraction, even though this fraction accounted for < 5% of the soil mass. Therefore, runoff may cause higher P losses than the soil P content suggests in this sandy soil with a weak aggregate formation. Overall, the results indicate that manure and mineral fertilizer had similar effects on soil P fractions. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Heitkamp F.,University of Kassel | Heitkamp F.,University of Gottingen | Raupp J.,Institute for Biodynamic Research | Ludwig B.,University of Kassel
Organic Agriculture | Year: 2011

One aim of organic and biodynamic agriculture is to improve soil fertility. Our objectives are to (1) explain previously reported differences in the soil organic matter levels between soils receiving farmyard manure (FYM) with or without biodynamic preparations (BD), (2) quantify the effect of three levels of FYM applications on microbial biomass and soil organic matter (SOM) pools with different stability, and (3) relate SOM pools to crop yields in a long-term experiment on a sandy soil at Darmstadt, Germany. Soils of the BD-FYM treatments had significantly higher Corg contents compared to soils of the FYM treatments. However, soil fractionation indicated that there was a greater storage of Corg in the intermediate and passive pools of the BD-FYM treatments, and the temporal course of Corg contents suggested a slow convergence of Corg stocks between FYM and BD-FYM with time. Thus, the observed differences between BD-FYM and FYM treatments were likely to have existed since the beginning of the experiment. Contents of labile C (70-114 g [kg Corg],-1 turnover time 462 days) and labile N (35-49 g [kg Nt]-1, turnover time of 153 days) were strongly related to the application rate and also to crop yields. Yield of potatoes, winter rye, and clover significantly increased in proportion to the application rate of FYM, while BD had no effect. Overall, the study showed that increasing rates of FYM increased C and N availability independent of the use of BD. Nevertheless, efficiency of C sequestration in a more stable form (intermediate pool) decreased with increasing rate. © 2011 Springer Science & Business Media BV.


Heinze S.,University of Kassel | Raupp J.,Institute for Biodynamic Research | Joergensen R.G.,University of Kassel
Plant and Soil | Year: 2010

In the Darmstadt long-term fertilization trial, the application of composted cattle farmyard manure without (CM) and with (CMBD) biodynamic preparations was compared to mineral fertilization with straw return (MIN). The present study was conducted to investigate the effects of spatial variability, especially of soil pH in these three treatments, on soil organic matter and soil microbial biomass (C, N, P, S), activity (basal CO2 production and O2 consumption), and fungal colonization (ergosterol). Soil pH was significantly lower in the MIN treatments than in the organic fertilizer treatments. In the MIN treatments, the contents of soil organic C and total N were also significantly lower (13% and 16%, respectively) than those of the organic fertilizer treatments. In addition, the total S content increased significantly in the order MIN < CM < CMBD. The microbial biomass C content was significantly lower (9%) in the MIN treatments than in the organic fertilizer treatments. Microbial biomass N and biomass P followed microbial biomass C, with a mean C/N ratio of 7.9 and a mean C/P ratio of 23. Neither the microbial biomass C to soil organic C ratio, the metabolic quotient qCO2, nor the respiratory quotient (mol CO2/mol O2) revealed any clear differences between the MIN and organic fertilizer treatments. The mean microbial biomass S content was 50% and the mean ergosterol content was 40% higher in the MIN treatments compared to the organic fertilizer treatments. The increased presence of saprotrophic fungi in the MIN treatments was indicated by significantly increased ratios of ergosterol-to-microbial biomass C and the microbial biomass C/S ratio. Our results showed that complex interactions between the effects of fertilizer treatments and natural heterogeneity of soil pH existed for the majority of microbial biomass and activity indices. © Springer Science + Business Media B.V. 2009.


Heitkamp F.,University of Kassel | Heitkamp F.,University of Gottingen | Jager N.,University of Gottingen | Flessa H.,University of Gottingen | And 3 more authors.
Archives of Agronomy and Soil Science | Year: 2012

Annual changes in stocks of soil organic carbon may be detected by measurement of heterotrophic respiration, but field studies of heterotrophic respiration in long-term fertilization experiments on sandy soils are scarce. Our objectives were to: (1)investigate the influence of fertilizer type on mineralization of soil organic carbon and crop residue, and (2) show how fertilization treatments affect the annual C balance (net ecosystem carbon balance, NECB; negative values indicate a CO2-source) in the sandy soil of the Darmstadt experiment. Treatments were long-term mineral fertilization with cereal straw incorporation (MSI) and application of rotted farmyard manure (FYM), both treatments receiving 14 g N m-2 year-1. This study used δ13C natural abundance after introduction of a C3 crop to distinguish between different sources of respiration. Mineralization derived from C3 sources was similar for MSI and FYM treatments (~270 g C m-2 year-1). The rate of residue mineralization in MSI treatments was higher, resulting in a mineralization of 49 and 37% of initial residue C in the soil of MSI and FYM treatments, respectively. The NECB (g C m-2 year-1) indicated the MSI treatment (approximately -190) as a stronger source compared with the FYM treatment (~-30). © 2012 Copyright Taylor and Francis Group, LLC.

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