• Authors:
    • Haneklaus, S.
    • Schrader, S.
    • Jeromin, K.
    • Hotker, H.
    • Paulsen, H.
    • Rahmann, G.
    • Schnug, E.
  • Source: Aspects of Applied Biology
  • Issue: 79
  • Year: 2006
  • Summary: Although it is the aim of organic farming to increase biodiversity, there is little information about the impact of organic farming on birds. From 2001 to 2003, the number of breeding birds was recorded annually on the organic experimental farm of the Institute of Organic Farming (600 ha), and on adjacent conventional and organic farms (60 ha and 40 ha) in Northern Germany. The number of skylark ( Alauda arvensis) territories increased considerably after the conversion from conventional to organic farming on the premises of the Institute. Their number remained unvaried on the conventional farm. The highest density of skylark territories was found on the farm which has been under organic management for many years. The number of yellowhammer ( Emberiza citronella) territories fluctuated largely in relation to the availability of field margin strips, both on conventional and organic land. During the breeding season aerial hunters (swallows and swifts) and raptors significantly preferred organic fields. Outside the breeding season, densities of raptors (in autumn and in winter), seed-eating birds (in autumn) and insect-eating birds (in autumn) were significantly higher on organic than on conventional fields.
  • Authors:
    • Schulte, M.
  • Source: Gesunde Pflanzen
  • Volume: 57
  • Issue: 2/3
  • Year: 2005
  • Summary: Herbicide-resistant varieties currently play a key role among the genetically modified arable crops soyabean, cotton, oilseed rape, and maize grown worldwide. Reasons for the quick increase in areas cultivated by herbicide-resistant crops are, among others, shortcomings of existing chemical weed control solutions in these crops and an increase in cultivation methods using minimum tillage techniques. As a countermove, the minimum or no-till cropping area increased significantly, due to the introduction of herbicide-resistance technology, particularly in soybeans. Decision criteria during the past 8 years for choosing adequate weed control systems using herbicide-resistant or conventional varieties were: varietal performance, superior crop tolerance and application timing flexibility, efficacy of post-emergent weed control measures in dry areas, controlled weed spectrum, and duration of activity including control of resistant weed biotypes. Due to restrictive labelling instructions and lack of authorization in main overseas export markets, including European liability and coexistence rules, sales restrictions are essential decision parameters for individual farms. The technical progress of herbicide-resistance technology is achieved in the short and medium term by further development of spraying sequences and tank mixtures towards ready-formulated mixtures of complementary herbicides with conventional residual mixture partners. To control and prevent the spread of new herbicide-resistant weed biotypes, complementary herbicides are combined with other modes of action. Further developments are combinations of various other transgenic traits with transgenic herbicide resistance and herbicide-resistant varieties of (worldwide) less important minor crops without satisfying conventional chemical weed control solutions. For long-term developments, plastid transformation techniques to prevent the unwanted dissemination of transgenic features could gain importance.
  • Authors:
    • Kreye, H.
  • Source: Bulletin OILB/SROP
  • Volume: 27
  • Issue: 10
  • Year: 2004
  • Summary: In a long-term field trial, the effects of three different tillage systems on harmful organisms and yield were investigated. The focus was on fungal diseases, weeds and slugs. With the ploughing system as the standard, a non-inversion/conservation tillage and a direct drilling/no till system were compared with one another. The crop rotation oilseed rape-wheat-barley, which was established in 1995, was reconverted into a crop rotation oilseed rape-wheat-wheat in 1998 due to problems with volunteer wheat in the following barley in the two ploughless tillage systems. The occurrence of Phoma root-collar and stem disease, the most important in Germany, was not affected in comparison over the years by the intensity of the cultivation. For Sclerotinia stem rot, a correlation could only be determined with the tillage systems in one year of the trial series. The infection became more severe with decreasing intensity of soil cultivation. Whether this result can be reproduced in future growing seasons remains to be seen. Effects on the incidence of Verticillium longisporum could not be determined. Other diseases arose only sporadically at very low levels. However, in comparison, the occurrence of weeds was affected significantly. The amount of grass weed species ( Alopecurus myosuroides, Apera spica-venti, volunteer barley) increased in the systems without ploughing. The effect on dicotyledonous weed species was dependent on the particular species. In individual years, heavy slug damage could be correlated with direct drilling system.
  • Authors:
    • Wiemken, A.
    • Boller, T.
    • Mader, P.
    • Ineichen, K.
    • Sieverding, E.
    • Oehl, F.
  • Source: Applied and Environmental Microbiology
  • Volume: 69
  • Issue: 5
  • Year: 2003
  • Summary: The impact of land use intensity on the diversity of arbuscular mycorrhizal fungi (AMF) was investigated at eight sites in the "three-country corner" of France, Germany, and Switzerland. Three sites were low-input, species-rich grasslands. Two sites represented low- to moderate-input farming with a 7-year crop rotation, and three sites represented high-input continuous maize monocropping. Representative soil samples were taken, and the AMF spores present were morphologically identified and counted. The same soil samples also served as inocula for "AMF trap cultures" with Plantago lanceolata, Trifolium pratense, and Lolium perenne. These trap cultures were established in pots in a greenhouse, and AMF root colonization and spore formation were monitored over 8 months. For the field samples, the numbers of AMF spores and species were highest in the grasslands, lower in the low- and moderate-input arable lands, and lowest in the lands with intensive continuous maize monocropping. Some AMF species occurred at all sites ("generalists"); most of them were prevalent in the intensively managed arable lands. Many other species, particularly those forming sporocarps, appeared to be specialists for grasslands. Only a few species were specialized on the arable lands with crop rotation, and only one species was restricted to the high-input maize sites. In the trap culture experiment, the rate of root colonization by AMF was highest with inocula from the permanent grasslands and lowest with those from the high-input monocropping sites. In contrast, AMF spore formation was slowest with the former inocula and fastest with the latter inocula. In conclusion, the increased land use intensity was correlated with a decrease in AMF species richness and with a preferential selection of species that colonized roots slowly but formed spores rapidly.
  • Authors:
    • Searchinger,Timothy D.
    • Sehy,Ulrike
    • Ruser,Reiner
    • Munch,Jean Charles
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 99
  • Issue: 1
  • Year: 2003
  • Summary: Nitrous oxide emissions and selected soil properties in a high and a low yielding area of a maize field were monitored weekly over a 1-year period. In both the high and the low yielding area, N2O emissions from a treatment subject to site-specific N-fertilization were compared to a conventionally fertilized control. Emission peaks were measured following N fertilization, rainfall, harvest, tillage and freeze-thaw cycles from all treatments in conditions favorable for denitrification. Between 80 and 90% of annual emissions were released between April and September. A value of 60% WFPS was identified as a threshold for the induction of elevated N2O emissions (>50 mug N2O-N m(-2) h(-1)). A significant relationship (r(2) = 0.41) between N2O flux rates and WFPS was found when neither soil nitrate contents nor temperature were limiting for microbial denitrification. Mean cumulative N2O emissions from the control treatments in the high yielding area, located in a footslope position and thus receiving lateral water and nutrient supply, more than doubled those from the control treatments in the low yielding area in a shoulder position (8.7 and 3.9 kg N2O-N ha(-1), respectively). Higher average WFPS in the high yielding area was identified as responsible for this difference. The site-specific fertilized treatments in the low yielding area were supplied with 125 kg N fertilizer ha-1 as compared to 150 kg N fertilizer ha(-1) (control treatments). This reduction resulted in 34% less N2O released in roughly 10 months following differentiated fertilization while crop yield remained the same. In the high yielding area, N fertilizer supply in the site-specific fertilized treatment was 175 kg N ha(-1) as compared to 150 kg N ha(-1) in the control. Neither crop yield nor N2O emissions were significantly affected by the different fertilizer rates. (C) 2003 Elsevier Science B.V. All rights reserved.
  • Authors:
    • Post, W. M.
    • West, T. O.
  • Source: Soil Science Society of America Journal
  • Volume: 66
  • Issue: 6
  • Year: 2002
  • Summary: Changes agricultural management can potentially increase the accumulation rate of soil organic C (SOC), thereby sequestering CO2 from the atmosphere. This study was conducted to quantify potential soil C sequestration rates for different crops in response to decreasing tillage intensity or enhancing rotation complexity, and to estimate the duration of time over which sequestration may occur. Analyses of C sequestration rates were completed using a global database of 67 long-term agricultural experiments, consisting of 276 paired treatments. Results indicate, on average, that a change from conventional tillage (CT) to no-till (NT) can sequester 57 +/- 14 g C m(-2) yr(-1), excluding wheat (Triticum aestivum L.)-fallow systems which may not result in SOC accumulation with a change from CT to NT. Enhancing rotation complexity can sequester an average 20 +/- 12 g C m(-2) yr(-1), excluding a change from continuous corn (Zea mays L.) to corn-soybean (Glycine mar L.) which may not result in a significant accumulation of SOC. Carbon sequestration rates, with a change from CT to NT, can be expected to peak in 5 to 10 yr with SOC reaching a new equilibrium in 15 to 20 yr. Following initiation of an enhancement in rotation complexity, SOC may reach a new equilibrium in approximately 40 to 60 yr. Carbon sequestration rates, estimated for a number of individual crops and crop rotations in this study, can be used in spatial modeling analyses to more accurately predict regional, national, and global C sequestration potentials.
  • Authors:
    • Bakken ,L. R.
    • Dörsch,P.
    • Holtan-Hartwig, L.
  • Source: Soil Biology and Biochemistry
  • Volume: 34
  • Issue: 11
  • Year: 2002
  • Summary: Abstract: To explore the reason for reported high field fluxes of nitrous oxide (N2O) from temperate soils in winter and early spring, we investigated the temperature response of denitrifier N2O production and reduction in soil from three arable field sites along a temperature transect reaching from Finland over Sweden to Germany. Process rates were determined in anaerobic slurries with or without added NO3-, N2O and C2H2 at 0, 5, 10, 15, and 20C (and 30C in one experiment). The experiments were conducted immediately after the soils had become anaerobic, and after a long (48 h) anaerobic pre-incubation with excess of carbon and electron acceptors. All denitrifying enzymes were found to be active in the soil at onset of anaerobiosis. Significant levels of N2O production and reduction occurred at 0 8C, both at onset of anaerobiosis and after the 2 days anaerobic pre-incubation. Temperature response of N2O production and reduction could be fitted to an Arrhenius function in the range 5-20 °C, yielding apparent activation energies between 28 and 76 kJ mol -1. The estimated activation energy of the N2O reduction was found to be similar or lower than that for N2O production. High field N2O fluxes in winter and early spring could thus not be explained by the temperature sensitivity of the two processes. However, major deviations from the regular Arrhenius response were found for two soils at near freezing temperature. The rates measured at 0 °C were much lower than those predicted by the Arrhenius function based on data in the temperature range 5-20 °C. Low temperature may thus exert a particular challenge to denitrifying communities for some reason, and the effect was found to be most severe for the N2O reduction process. When such a breakdown affects N2O reductase to a greater extent than the N2O producing enzymes (NO3-, NO2-, and NO reductase), as was found in our soils, it will result in high N2O fluxes at low temperature. The temperature response of the estimated net N2O emission potential (based on measured N2O production and reduction rates) differed significantly between the three sites, indicating inherent differences between their microbial communities.
  • Authors:
    • Ottow, J. C. G.
    • Benckiser, G.
    • Weiske, A.
  • Source: Nutrient Cycling in Agroecosystems
  • Volume: 60
  • Issue: 1-3
  • Year: 2001
  • Summary: In a 3-year field experiment the effect of the new nitrification inhibitor DMPP (3,4-dimethyl pyrazole phosphate, trade name ENTEC) on the release of N2O and on methane oxidation was examined in comparison to dicyandiamide (DCD). Soil samples were analysed for the concentrations of ammonium, nitrite, nitrate and for the degradation kinetics of DMPP as well as DCD. DMPP decreased the release of N2O by 41% (1997), 47% (1998) and 53%(1999) (with an average of 49%) while DCD reducedN2O emissions by 30%(1997), 22%(1998) and 29% (1999) (with an average of 26%), respectively. Both nitrification inhibitors (NI) failed to affect methane oxidation negatively. The plots that received DCD or DMPP, respectively, even seem to function as enhanced sinks for atmospheric methane. DMPP apparently stimulated methane oxidation by ca. 28% in comparison to the control. The concentrations of ammonium remained unaffected by nitrification inhibitors whereas the amounts of nitrite diminished in the plots treated with DCD by 25% and with DMPP by 20%, respectively. Nitrate concentrations in soil were in both NI treatments 23% lower than in the control. DMPP and DCD did not affect the yields of summer barley, maize and winter wheat significantly. Dicyandiamide was mineralized more rapidly than DMPP (data for the cropping season in 1997 as an example).
  • Authors:
    • Roggenstein, V.
    • Fischbeck, G.
    • Dennert, J.
  • Source: Getreide Magazin
  • Issue: 3
  • Year: 2001
  • Summary: A study was initiated in 1980 in Germany on a soil with 4% humus and 18.2 mg P 20 5/100 g soil and 35.7 mg K 20/100 g soil. Crops included winter wheat, barley, rye, oats, rape, and maize. Annual soil analyses showed an unexpectedly large variation following inputs of up to 60 kg P/ha and 80 kg K/ha. The difference in P and K supply between fertilized and unfertilized plots was around 20%. However, the effect on yields was less than might have been expected. Non-application of P did not influence yield, while non-application of K resulted in 5% decrease (despite high K availability). No direct relationship was found between soil analysis and yields.
  • Authors:
    • Düring, R. A.
    • Tebrügge, F.
  • Source: Soil & Tillage Research
  • Volume: 53
  • Issue: 1
  • Year: 1999
  • Summary: This paper reviews research performed at the Justus-Liebig-University of Giessen, Germany into the impact of different tillage systems on soil properties and quality. The impact of intensive soil tillage treatments on several soil properties was described by means of selected data obtained through long-term interdisciplinary research. The experiments were based on comparative application (long-term, up to 18 years investigations) of the respective tillage options on different soils (e.g. Eutric Cambisol, Eutric Fluvisol) ranging in texture from sand to a silt loam. These soils are located at five field sites with different crop rotations in the central German state of Hesse. Tillage intensity of the systems was considered to decrease in the following sequence: Conventional plough tillage (CT), reduced tillage (RT), and no-tillage (NT). For elucidating the impact of tillage intensity, the tillage extremes CT and NT were compared. Physical conditions of soil as influenced by the application of RT were considered to be intermediate between CT and NT. In general, bulk density in the upper layer of NT soils was increased, resulting in a decrease in the amount of coarse pores, and a lower saturated hydraulic conductivity when compared with the CT and RT soils. Surface cover by crop residues and higher aggregate stability under NT protected soil fertility by avoiding surface sealing and erosion. Lateral losses of herbicides were also reduced under NT conditions, whereas the susceptibility for preferential vertical transport of herbicides needs further evaluation. Accumulation of organic matter and nutrients near the soil surface under NT and RT were favorable consequences of not inverting the soil and by maintaining a mulch layer on the surface. Those improvements were associated with enhanced biological activities in NT and RT topsoils. Increased earthworm activity in NT treatments was associated with a system of continuous macropores which improved water infiltration rates. Earthworms support decomposition and incorporation of straw. Soils which have not been tilled for many years were more resistant to vehicle passage; consequently, the compaction by traffic was lower. Penetration resistance curves indicate that a uniformly stable structure had developed over the years in NT soils. Overall, the results show that RT and NT were beneficial to the investigated soil properties. If crop rotation, machinery, and plant protection are well adapted for the introduction of conservation tillage, these systems may replace conventional ploughing systems in many cases in German agriculture. (C) 1999 Elsevier Science B.V. All rights reserved.