Designing crop rotations in organic and low-input agriculture: Evaluation of pre-crop effects

In this overview, the preceding effects of crop pairs are classified by establishing schematic diagrams for use in crop rotation planning in low external input or organic agricultural systems. Results from previous crop rotation trials and earlier diagrams cited in the literature were evaluated in order to classify the succession effects for more than 25 main crop species. Additional information about several cultivation remarks were annotated in small letters for every crop sequence. In a tabular overview, the crop species were arranged into three main categories according to the different duration of their pre-crop effects: I. N fixing, soil fertility increasing legumes and legume-grass mixtures; II. N depleting, intense soil fertility reducing non-legumes; III. modest soil fertility reducing non-legumes

Effects of increasing fertilization in organic farming fodder cultivation and market crop systems

In 1992, on experimental stations of the Saxony State Institute of Agriculture, two organic field trials were set up on loamy sand and a loess loam in western Saxony, eastern Germany. In these long-term field trials questions of fodder cultivation and market crop systems, crop rotations with legume-grass, wheat and maize, different organic fertilizer regimes and nutrient cycling were analyzed regarding their effects on soil fertility, yield and quality of the plant products. The main results and conclusions of the first nine years of these organic field trials are introduced and summarized here

Grain legume nitrogen fixation and balance model for use in practical (organic) agriculture

In extensive agricultural systems, i.g. organic farming, nutrient balance calculations are of high importance. Common calculation models for nitrogen fixation of grain legumes are either of far too much complexity especially for use in agricultural practice or of too low accuracy. Measurements in the literature of grain yield, harvest index, N2 fixation, N content, N surplus, Nmin content of the soil, etc., were compiled. Correlation analyses were then carried out with Vicia faba L. and Pisum sativum L. data sets from conventional and organic field trials per-formed in Central European. Grain yield or N output, Nmin content before sowing, and the N harvest index proved to be the most effective driving variables for developing a calculation model for plant nitrogen fixation and the surplus amount. All the variables mentioned are listed in farmers’ plot card indices, with the exception of the N harvest index, an essential variable which is not detectible by the farmer. Therefore, the N harvest index was indirectly determined through the effects of grain yield and Nmin content using non-linear multiple re-gression analyses. Comparing calculations between common and the improved forms of mod-els showed significantly better conformity between measured and calculated datasets of grain legumes

Laser-controlled adaptive optic for beam quality enhancement in a multipass thin disk amplifier

We devise a laser-controlled adaptive optical element which operates intracavity under high intensity radiation. This element substitutes a conventional mechanically deformable mirror and is free of critical heat-sensitive components and electronics. The deformation mechanism is based on the projection of a CW control laser onto a specially designed mirror. Mounted to a water-cooled heat sink, the mirror can handle laser radiation beyond 3 MW/cm^2. The properties of the adaptive optical element including the maximum correctable wavefront pitch of 800 nm are discussed. The successful implementation in a multipass thin disk amplifier is presented. An improvement of the beam quality by a factor of three is achieved. We identify measures to enhance the performance of the adaptive optic towards efficient operation in a high-power laser system

Effects of conventional and organic land use types on water protection criteria in Germany

The mean values and ranges of several water protection criteria were calculated for arable land, grassland and forests in Germany on the basis of research work and the literature. By additional evaluation steps, relationships and efficiency coefficients were calculated for the different types of land use. Methods of balance calculations are proposed as preventive strategies for efficient water protection

Isotopic tiling theory for hyperbolic surfaces

In this paper, we develop the mathematical tools needed to explore isotopy classes of tilings on hyperbolic surfaces of finite genus, possibly nonorientable, with boundary, and punctured. More specifically, we generalize results on Delaney-Dress combinatorial tiling theory using an extension of mapping class groups to orbifolds, in turn using this to study tilings of covering spaces of orbifolds. Moreover, we study finite subgroups of these mapping class groups. Our results can be used to extend the Delaney-Dress combinatorial encoding of a tiling to yield a finite symbol encoding the complexity of an isotopy class of tilings. The results of this paper provide the basis for a complete and unambiguous enumeration of isotopically distinct tilings of hyperbolic surfaces

Site adjusted organic matter balance method for use in arable farming systems

Common humus balance methods give distinct inexact results and do not meet nowadays requirements in Germany. Outgoing from the method of KOERSCHENS et al. (2004) an improved, site adjusted, semi-quantitative method was developed for manual use in agricultural practice and consultation. In the validation and optimization process over 300 variants from 39 long-term field trials were used, which represent the most important site conditions of Central Europe (Germany). The optimization work was done in four steps. Identification of site specific groups with homogenous humification levels. Distinct different humification characteristics were recognized for the organic matter of different German site conditions (soil, climate). Six site specific groups could be identified when comparing the results of the humus balancing with the field trial organic matter content changes of the soils. Humification coefficients of the crop species. The effects of the crop species cultivation, and the climate and soil conditions on the humification process were combined and expressed in the crop species humification coefficients. Optimal values were obtained when the results of the humus balancing were in accordance with the organic matter content chance of the trials (objective function: 0 kg Corg ha-1 ≈ 0 % Corg content change). Equal assessments of the site specific groups were reached by systematic adjustments of the humification coefficients of the crop species until the objective function was observed. Humification coefficients of the organic materials. Additional analyses of multiple long-term field trial results have shown, that the organic material coefficients of the common balance method were fixed at somewhat too high values. Over this, the humification values were negatively related to increasing supply of organic materials. Therefore, these coefficients were corrected according to the field trial results. Classification system for the humus balance results. The nitrogen surface balance of the field trials was suitable for to evaluate the soil fertility and environmental tolerance of the humus balance results. Under a specific N surplus constraint (e.g. 50 kg N ha-1), arable cultivation systems without mineral nitrogen fertilization (e.g. organic farming) can tolerate much higher humus surplus values than systems with increasing nitrogen fertilization. For use in different arable farming systems, therefore, the common classification scheme (A to E system of VDLUFA) was corrected. Through installation of humification coefficients in site-specific groups adjusted to the Corg content change in the soil, and adaptation of the humification coefficients of the organic materials, the optimization process resulted in a large improvement of the method accuracy (s2=0,034 to s2=0,011). For practical use, only a little information about site specific characteristics, the crop species in the crop rotation and the amounts of added organic materials are necessary in the calculations

Estimates of weak and electromagnetic nuclear decay signatures for neutrino reactions in Super-Kamiokande

We estimate possible delayed β decay signatures of the neutrino induced reactions on 16O in a two-step model: the primary neutrino (ν,l) process, where l is the lepton in the final state, is described within the random phase approximation, while the subsequent decay of the excited nuclear state in the final channel is treated within the statistical model. We calculate partial reaction cross sections leading to β unstable nuclei. We consider neutrino energies up to 500 MeV, relevant for atmospheric neutrino detection in Super-Kamiokande, and supernova neutrino spectra

Weak reactions on 12C within the Continuum Random Phase Approximation with partial occupancies

We extend our previous studies of the neutrino-induced reactions on 12C and muon capture to include partial occupation of nuclear subshells in the framework of the continuum random phase approximation. We find, in contrast to the work by Auerbach et al., that a partial occupation of the p1/2 subshell reduces the inclusive cross sections only slightly. The extended model describes the muon capture rate and the 12C(nu_e,e-)12N cross section very well. The recently updated flux and the improved model bring the calculated 12C(nu_mu,mu^-)12N cross section (~ 17.5 10^{-40} cm^2) and the data (12.4 +/- 0.3(stat.) +/- 1.8(syst.) 10^{-40} cm^2) closer together, but does not remove the discrepancy fully.Comment: 12 pages, 2 figure