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Corg content (% DM) in the topsoil (0-25 cm) after 18 years of fertilization with composted manure with (CMBD) and without (CM) biodynamic preparations and with mineral fertilizer (MIN), each at 3 fertilization intensities; averages of 4 fields (Raupp, 2001)   CM CMBD MIN average low medium high 0.83 0.93 0.98 0.95 0.99 1.07 0.79 0.79 0.80 0.86 a 0.90 b 0.95 c average 0.91 b 1.00 c 0.79 a LSD05=0.05 The LSD refers to the interaction between fertilization type and intensity (p<0.05). Means of a factor with different letters are significantly different (p<0.05).

The treatment with manure fertilization plus application of biodynamic preparations still has the highest organic carbon content in the soil.
The lowest contents were found for mineral fertilization. The values for the manure treatment without preparations were at a medium level. Altogether, compared to previous periods, the values remained at simliar levels. In soils treated with organic fertilizers, higher fertilizer input resulted in more organic carbon. But this could not be confirmed for soils treated with mineral fertilizer.

 

Light fraction of POM in topsoil after spring wheat by type and rate (1-3) of fertilizationRaupp & Oltmanns (2002)
Heavy fraction of POM in topsoil after spring wheat by type and rate (1-3) of fertilization; Raupp & Oltmanns (2002)

In addition to the global parameter C_org content, it is important to have an idea about the composition of soil organic matter and its different turnover intensity to get a better understanding of nutrient cycles and nutrient supply to crops. The soil's particulate organic matter (POM) can be divided in different size and density fractions, which differ in age, origin and material composition. Manure fertilized plots displayed lower contents of the light POM fraction (mainly crop residues, hardly decomposed organic fertilizer) than the minerally fertilized plots. This indicates that crop residues were decomposed faster in the manure fertilized, biologically more active soils.

Similar differences between the fertilizer treatments as for C_org were found for the heavy POM fraction (materials which are more decomposed by soil organisms): plots fertilized with farmyard manure plus preparations displayed the highest values, minerally fertilized plots the lowest. This finding emphasized the better humification in manure fertilized soils.


References:
RAUPP, J. (2001): Manure fertilization for soil organic matter maintenance and its effects upon crops and the environment, evaluated in a long-term trial. In: Rees, R.M.; Ball, B.C.; Campbell, C.D.; Watson, C.A. (eds.), Sustainable management of soil organic matter. CAB International, Wallingford UK; 301-308  Download the PDF file

RAUPP, J.; OLTMANNS, M. (2001): Auswirkung langjähriger Rottemist- und Mineraldüngung sowie der Vorfrucht auf die partikuläre organische Substanz des Bodens. Mitt. Ges. Pflanzenbauwiss. 13, 59-60  Download the PDF file

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	Total hydrolyzable protein amino acids (μmol g-1 soil) in topsoil after 19 years with farmyard manure without (CM) and with biodynamic preparations (CMBD) and inorganic fertilizers (IN); means of three application rates and four replicates; bars indicate significant differences (p<0.05) (Scheller & Raupp, 2005)

Amino acids in soil organic matter are essential components for the synthesis of humic substances in agricultural soils. The total contents of hydrolysable amino acids (THAA) in the soil was highest for the treatment with farmyard manure plus biodynamic perparations, remarkably lower for the treatment with farmyard manure alone, but lowest for the mineral fertilizer treatment.

One reason for the higher THAA contents in the organic treatments may be the supply of amino acids by farmyard manure, but not by mineal fertilizer. However, the amount of applied amino acids (and thus the fertilisation rate) did not influence THAA contents. It thus seems that fertilizer treatments rather change amino acid metabolism. As shown by the THAA contents of manure treatments with and without biodynamic preparations, amino acid metabolism was positively influenced by the perparations.

Reference:
SCHELLER, E.; RAUPP, J. (2005): Amino acid and soil organic matter content of topsoil in a long term trial with farmyard manure and mineral fertilizers. Biol. Agric. Hortic. 22, 379-397
 

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Diversity of soil microorganisms (Shannon index with standard error; p<0.05) in topsoil after 23 years of farmyard manure without (CM) and with biodynamic preparations (CMBD) and inorganic fertilizers (IN), each at three rates (1-3); 70 hours after starting the test ( Raupp et al., 2004)

The Shannon index is a measure for the diversity of soil microflora. Among the manure fertilized plots, the fertilizer rate did not influence microbial diversity. However, on minerally fertilized plots, diversity decreased with increasing fertilizer application. This effect was found to be significant during several measurements. At the highest rate of mineral fertilizer (140 kg N ha^-1), microbial diversity was lowest. Only for the low and medium mineral fertilizer rates, the Shannon index was simliar to that of manure treatments. These results support earlier findings in this experiment, showing a lower organic carbon content, lower microbial biomass and decreased enzyme activities in mineral treatments compared to manure treatments [Bachinger, 1996; more].

 

Reference:
BACHINGER, J. (1996): Der Einfluß unterschiedlicher Düngungsarten (mineralisch, organisch, biologisch-dynamisch) auf die zeitliche Dynamik und die räumliche Verteilung von bodenchemischen und -mikrobiologischen Parametern der C- und N-Dynamik sowie auf das Pflanzen- und Wurzelwachstum von Winterroggen. Diss. Univ. Gießen. Schriftenreihe Bd. 7, Inst. f. biol.-dyn. Forschung, Darmstadt

RAUPP, J.; NIEHUS, A.; OLTMANNS, M. (2004): Die Diversität der Boden-Mikroflora ist bei Rottemistdüngung höher als bei Mineraldüngung. Mitt. Ges. Pflanzenbauwiss. 16, 149-150  Download the PDF file

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Micronutrients in topsoil

Although organic fertilizers always contain micronutrients, on the long term it should be observed if the fertilizer can maintain the total contents in soil and ensure the supply of plants.

In our long-term trials, organically fertilized soils have higher organic carbon contents and a higher microbial activity than minerally fertilized soils. The higher organic carbon contents increases the soil's sorption capacity. Consequently, a higher complexation of micronutrients might result, which could decrease micronutrient availability in the soil (e.g. for Cu).

We investigated whether long-term organic and mineral fertilization influences the total contents of manganese (Mn), copper (Cu) and zinc (Zn) in the soil as well as their plant-available fractions. The treatment with manure plus biodynamic preparations displayed the significantly highest total zinc contents in soil, the minerally fertilized treatment the lowest and the manure treatment without preparations intermediate zinc contents.


Total contents of micronutrients in topsoil (mg kg^-1 dry matter) in the year 2004 with fertilisation treatments; results with different letters are statistically different (p<0.05); Fischer et al. (2005)

The inputs of zinc and copper are increased by farmyard manure application. Both elements are components of feedstuffs and are thus partly excreted by animals.
 

	Extractable micronutrient contents (mg kg-1 dry matter) and pH in topsoil, 2004; results with different letters are statistically different (p<0.05); Fischer et al. (2005)

The plant available Mn and Cu did not differ among the fertilizer treatments. The lower pH of 6.5 for the mineral treatment (as against 6.7 for organic fertilization) may have caused Mn mobilisation. Potentially positive effects of the higher Mn supply by organic fertilizers might thus have been reduced. The amount of available Zn was distinctly lower in the mineral treatment than in the organic treatments, although the lower pH in MIN might have caused a better zinc availability.

Reference:
FISCHER, M.; RAUPP, J.; MÄDER, P.; DUBOIS, D.; RÖMHELD, V. (2005): Micronutrient status in two long-term trials with fertilisation treatments and different cropping systems. Köpke, U. et al. (eds.), Researching Sustainable Systems. Proc. 1st Sci. Conf. of ISOFAR, 21-23 Sep 2005, Adelaide, South Australia, 522-525  Download the PDF file

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Micronutrient contents in potato leaves

Micronutrient contents (mg kg-1 dry matter) youngest fully developed potato leaves, results with different letters are statistically different (p<0.05); Fischer et al. (2005)

The manganese and zinc contents in organically manured potatoes were clearly lower than in minerally fertilized potatoes. However, plants under all treatments did not grow at deficient conditions.

The amounts of extractable micronutrients in the soil displayed a different distribution, and no correlation with the contents in plants was found (see above). Possibly, at this site also non-plant available micronutrients were detected by the extraction method. The plants' nutrient uptake was obviously influenced by further parameters, e.g. rhizosphere conditions (pH, microflora).


Reference:
FISCHER, M.; RAUPP, J.; OLTMANNS, M.; RÖMHELD, V. (2005): Mikronährstoffversorgung in einem Langzeitversuch mit Stallmist- und mineralischer Düngung; pflanzenbauliche Konsequenzen für den Ökologischen Landbau. Mitt. Ges. Pflanzenbauwiss. 17, 385-386  Download the PDF file

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The symbiosis with arbuscular mycorrhizal fungi (AMF)

Root length of potatoes infected with AMF in percent after farmyard manure without (CM) and with biodynamic preparations (CMBD) and mineral fertilizers (MIN), each at three rates (1-3) in 2004; bars show standard error (Scharfy et al., 2005)

The symbiosis of potato roots with arbuscular mycorrhizal fungi (AMF) was enhanced by manure fertilization.

In the manure treatments, a higher percentage of root colonization than in the mineral treatment was observed. This finding was statistically significant for the high fertilization rates. It is often assumed that the higher phosphorus contents in minerally fertilized soils cause these differences. However, this option can be ruled out in this study as the contents of available phosphorus were similar for all treatments. Obviously, in this study manure fertilisation specifically enhanced AMF development.

The AM fungal colonized root length in percent of the total root length estimated in two different soil depths

The establishment of AMF symbiosis with spring wheat was rather influenced by fertilization rate than by fertilizer type.

The AM fungal colonized root length of spring wheat was generally decreased in response to increasing amounts of fertilizer application. However, the decrease was smaller for organic fertilizer.

The concentration of phosphorus in straw of both fertilizer treatments increased with increasing fertilizer application (data not shown, see RAUPP et al., 2009). It is therefore assumed that the plants' P status was a major determinant of the external AM fungal root colonization.

The number of AM fungal spores per g dry soil Soil depth CMBD  Low   High MIN Low   High Means 0-5 cm 203 223 133 157 179 y   213 c  145 ab   5-10 cm 154 166 121 137 145 x   160 b   129 a

Clearly higher numbers of AM spores were found in organically fertilized than in minerally fertilized soils.

This result was found at both soil depths. The organic fertilizer seems to have stimulated AMF sporulation. A stimulation of AM sporulation by organic substances like humic acids or chitin has been described previously (Gryndler et al. 2003, 2004), and it is possible that such effects played a role in this study as well.

Since spores are the major reproductive organs of AM fungi, our results suggest that (i) AM fungal fitness in terms of reproductive success was higher in organically compared with minerally fertilized soil, and that (ii) organic fertilization may increase the AM infefective potential over that of minerally fertilized soils.

Literature cited:
GRYNDLER, M.; HRŠELOVÁ, H.; SUDOVÁ, R.; GRYNDLEROV, H.; REZÁČOVÁ, V.; MERHAUTOVÁ, Á. (2004): Hyphal growth and mycorrhiza formation by the arbuscular mycorrhizal fungus Glomus claroideum BEG 23 is stimulated by humic substances. Mycorrhiza 15:483-488.

GRYNDLER, M.; JANSA, J.; HRŠELOVÁ, H.; CHVÁTALOVÁ, I.; VOSÁTKA, M. (2003): Chitin stimulates development and sporulation of arbuscular mycorrhizal fungi. Applied Soil Ecology 22:283-287.

References:

SCHARFY, D.; RAUPP, J.; NEUMANN, E.; RÖMHELD, V. (2005): Der Einfluss organischer Düngung im Langzeitdüngungsversuch auf das Ausmaß der Wurzelinfektion mit Arbuskulärer Mykorrhiza sowie die Entwicklung des Wurzelexternen Myzels bei Kartoffel (Solanum tuberosum). Beiträge zur 8. Wissenschaftstagung Ökologischer Landbau, Kassel, 1.-4. März 2005; 229-232 Download the PDF file

RAUPP, J.; OLTMANNS, M.; JAROSCH, A.-M.; NEUMANN, E. (2009): Ertrag und Wurzelkolonisation mit arbuskulären Mykorrhiza-Pilzen von organisch oder mineralisch gedüngten Weizen auf trockenem, sandigen Boden. Beiträge zur 10. Wissenschaftstagung zum Ökologischen Landbau, ETH Zürich, 11.-13. Februar 2009. Verlag Dr. Köster, Berlin. S.34-37 organic eprints