Effect of the Organic Residues of Miscanthus × giganteus on the Soil Organic Matter Level of Arable Soils

During a complex investigation programme on the evaluation of the long-term ecological impact of cropping Miscanthus , the substrate composition of residues in 4–8-year-old stands of Miscanthus × giganteus and the contribution of Miscanthus residues to soil organic matter (SOM) were investigated. Only about 50 % of the above-ground biomass produced yearly was suitable for harvest because of pre-harvest losses and harvesting residues. The potential supply to SOM was therefore 3.1 t ha⁻¹ carbon annually accumulated by the litter, and 9.1 t ha⁻¹ carbon accumulated by rhizomes and roots in the long term. These organic residues mineralized differently in laboratory experiments at generally high rates of decomposition. Analysis of soluble portions of the organic substance of these biomass components by hydrolysis with hot water, 2 % HCl and 80 % H₂SO₄ confirmed the results. Setting the SOM effect of an equivalent farmyard-manure (FYM) supply to 100 %, Miscanthus residues reached 60 % (stubble, rhizomes), 80–90 % (pre-harvest losses) and 100 % (roots). Established Miscanthus stands are able to produce about 8.2 t ha⁻¹ organic substance, which is comparable with FYM in terms of SOM impact. This kind of calculation showed higher values for Miscanthus than for the agricultural crops investigated to date. An SOM increase of about 0.5 % on sandy soils and 0.2 % on silt soil was determined after 6–8 years of cropping Miscanthus × giganteus .     

On the Importance of Soil Homogeneity when Evaluating Field Trials

The existence of strong heterogeneity of soils on a scale of plots for field trials is demonstrated by a trial for fodder crops on a Lithic Rendoll in Upper Bavaria, Germany. Initial basic (pH, C_org, C_carb texture) as well as physical (saturated hydraulic conductivity, bulk density, pore size distribution) soil properties vary strongly across a single plot. Due to the great extent of these variations, the effects of preceding and succeeding crops on soil structural properties within a subplot or subsubplot can only be evaluated with high uncertainty. The effect of weather on soil structural properties during the 18 month trial period must also be considered. Therefore, (i) no sampling of the soil at the end of the trial was done, and (ii) surveying the soil before designing field trials is recommended.     

Conversion of SO2−4-S and Changes in Glucosinolate Content in Leaves of Rape Seedlings Transplanted

The conversion of SO^2-₄ -S and changes in content of S in various constituents in leaves of rape seedlings transplanted were investigated by using (NH₄)₂³⁵SO₄ as a tracer to exploit formation and accumulation of glucosinolates in oilseed rape. Seedlings grown under sandy culture absorbed ³⁵SO^2-₄ which was added to the cultural solution and incorporated into amino acids, glucosinolates and proteins rapidly. Distribution of extractable ³⁵S with 70 % methanol in glucosinolates in leaves declined with time from labelling, while those in amino acids rised correspondingly. Per cents of ³⁵S incorporated into bound form in total ³⁵S increased linearly and those of ³⁵S into glucosinolates and amino acids decreased with time within five days from labelling. After that the relative amounts of ^3SS in three constituents was basically constant. Content on dry weight basis of labelled glucosinolates and amino acids expressed as μmol S/g.d.w. increased linearly with time from labelling with absorption of ³⁵SO^2-₄from soil by the seedlings under soil culture. Compared with seedlings grown under sandy culture, more ³⁵S was incorporated into glucosinolates in leaves of seedlings grown under soil culture.     

Physiological Responses of Wheat (Triticum Aestivum L.) –Aegilops Sharonensis Introgression Lines to Excess Copper

Two wheat lines (TL3 and TL5) derived from selection for Cu tolerance among wheat – Aegilops sharonensis hybrids were compared when grown as hydroponics at zero (control), 10⁻⁶ and 10⁻⁵  m CuSO₄. The morphometric measurements showed that the line TL5 with a more inhibited root system under 10⁻⁶  m CuSO₄ had a less inhibited shoot growth under 10⁻⁵  m CuSO₄ as compared to TL3. The decreased maximum efficiency of photosystem II and the more pronounced trend towards increased catalase activity suggested that despite the better shoot growth, the leaves of TL5 were more functionally injured. The increased content of carotenoids at excess Cu and the higher peroxidase and catalase activities of TL3 in control plants might contribute to its better stress tolerance. While no significant changes in enzyme activities were found at 10⁻⁶  m Cu, at 10⁻⁵  m the activities tended to increase. Although the close values of free phenolics concentrations in control plants, at Cu excess their content was higher in TL5 compared to TL3. The free phenolics content in roots at 10⁻⁶  m Cu decreased, and although higher at 10⁻⁵  m Cu, it remained below the control in TL3, and above the control in TL5. From the obtained results TL3 emerged to be more tolerant to excess Cu than TL5.     

Irrigation Water Management for Efficient Water Use in Mulched Onion

Caused by the necessarily imperfect seed placement accuracy of sowing machines and, additionally, caused by many other biotic and abiotic factors, the resulting plant stands exhibit nonregular spatial distributions of its plants. Based on several simplifying assumptions, a stochastic approach is developed which allows an estimation of the effects of nonregular spatial patterns on yield per area. In this approach, two random variables are attached to each plant: single plant yield E and individual space A . The latter is estimated by the area of Thiessen polygons. Yield per area, calculated by the expectation of the ratio E/A , can be approximately expressed dependent on the means ( Ē and Ā ) and coefficients of variation ( v _E and v _A ) of E and A and their correlation ( r _EA ). In relation to the commonly used estimate Ē/Ā for yield per area, one obtains yield decreases if v _A / v _E  <  r _EA . This inequality, however, will be usually valid in the field of applications. The theoretical approaches and results were applied to three experimental data sets for drilled seeds of winter oilseed rape ( Brassica napus L.) (plant density: 60 plants m⁻², row distance: 10 cm). These data sets are characterized by different accuracies of longitudinal distributions within rows (58 %, 101 %, 150 %): yield depression increases with an increasing variability of plant distances within rows.     

Seed Composition, Seedling Emergence and Early Seedling Vigour of Red Kidney Bean Seed Produced at Elevated Temperature and Carbon Dioxide

Understanding the influence of growth temperature and carbon dioxide (CO₂) on seed quality in terms of seed composition, subsequent seedling emergence and early seedling vigour is important under present and future climates. The objective of this study was to determine the combined effects of elevated temperature and CO₂ during seed-filling of parent plants on seed composition, subsequent seedling emergence and seedling vigour of red kidney bean ( Phaseolus vulgaris ). Plants of cultivar 'Montcalm', were grown at daytime maximum/nighttime minimum sinusoidal temperature regimes of 28/18 and 34/24 °C at ambient CO₂ (350 μmol mol⁻¹) and at elevated CO₂ (700 μmol mol⁻¹) from emergence to maturity. Seed size and seed composition at maturity and subsequent per cent emergence, early seedling vigour (rate of development) and seedling dry matter production were measured. Elevated CO₂ did not influence seed composition, emergence, or seedling vigour of seeds produced either at 28/18 or 34/24 °C. Seed produced at 34/24 °C had smaller seed size, decreased glucose concentration, but significantly increased concentrations of sucrose and raffinose compared to 28/18 °C. Elevated growth temperatures during seed production decreased the subsequent per cent emergence and seedling vigour of the seeds and seedling dry matter production of seed produced either at ambient or elevated CO₂.     

Organic Recycling for Soil Quality Conservation in a Sub-tropical Plateau Region

The long-term effect of organic recycling on some aspects of quality in a lowland rice soil of an Indian plateau region was studied. The experiment was set up at the agricultural experimental farm of the Indian Statistical Institute, Giridih, Bihar, India. Two rice cultivars, and treatments with four organic supplements (cowdung manure, Leuceana leaves, decomposed farm residue and Sesbania ), chemical fertilizers (urea, superphosphate and muriate of potash) and no input were arranged in a factorial randomized block design. Organic supplements improved soil quality parameters such as water holding capacity, total organic C, microbial biomass C, urease and acid phosphatase activities of soils in comparison to chemical fertilizers and no input. Among the organic supplements, cowdung manure gave significantly higher organic C (1.39%), microbial biomass C (276.46 μg g⁻¹ dry soil), urease activity (32.79 and 21.22 μg urea hydrolized g⁻¹ dry soil h⁻¹ at 37 °C by the buffer and non-buffer method, respectively) and acid phosphatase activity (1.99 μmol p-nitrophenol released g⁻¹ dry soil h⁻¹ at 37 °C) than the others. The conversion of organic C into biomass C (2.46%) was highest in Leuceana -treated soil.     

Stickstoffaufnahme und Stickstoffrückstände von Hauptfrucht-und Ausfallrapsbeständen

Nitrogen Uptake and Nitrogen Residuals of Winter Oil-Seed Rape and Fallout Rape
The objective of the investigation was a study of the relationship between seed dry-matter production and vegetative dry-matter production in oil-seed rape crops and their dependence on the production conditions. In addition to the relationship between the N-uptake during the vegetation period and the N-residue after harvest was of major interest. Furthermore the potential for N-uptake in fallout rape was measured. Over two vegetation periods factorial field experiments with winter oil-seed rape, cv. Lirabon, different drilling techniques and different nitrogen fertilization levels were tested. Measured traits were: the dry-matter accumulation including root mass and fall-off leaf-material mass, the N-uptake of both the oil-seed crops and the fallout rape stands, and, simultaneously, the soil NO₃-N content. Finally the harvest indices and the N-harvest indices were calculated.
Combined with a N-uptake of up to 330 kg N/ha, oil-seed rape crops produced up to 200 dt dry matter/ ha. At seed yield levels of 33dt/ha (d.m.), harvest indices varied from 0.14—0.23 and N-harvest indices varied from 0.30–0.50. As a result of the residue of vegetative plant material at harvest, leaf losses before harvest and the soil NO₃-N-contents at harvest up to 275 kg N/ha remained in the field. After the harvest of oil-seed rape, the soil NO₃-N-contents were quickly reduced by emerging and growing fallout rape stands. However, following soil-preparation measures in the autumn, a continuous rise in the soil NO₃-N-content was observed.     

Water Relations, Abscisic Acid and Yield of Wheat Plants in Relation to the Interactive Effect of Seawater and Growth Bioregulators

Irrigation of wheat plants with seawater (10 and 25 %) led to significant increases in free and bound abscisic acid (ABA) in leaves, especially at 25 %. The relative water content (RWC) and water use efficiency (calculated from grain yield, WUE_G, or from biomass yield, WUE_B) of the seawater-irrigated plants were lower than those of the control. Grain pre-soaking in gibberellic acid (GA₃), indole-3-acetic acid (IAA) or ABA reduced the levels of accumulated ABA (free and bound) produced by seawater irrigation. The stress imposed by seawater generally reduced yield and yield components of wheat plants and the effect was more pronounced at the higher level of seawater irrigation (25 %). Furthermore, seawater treatments decreased the carbohydrate content and increased the protein content of the developing grains. The effect of seawater treatments on ion concentrations in the developing grains was not consistent. The application of growth bioregulators appeared to mitigate the effect of seawater salinity stress on wheat productivity. GA₃ was the most effective hormone in this regard. The economic yield (grain yield) had a strong positive correlation with RWC, WUE_G, WUE_B, plant height, shoot fresh and dry weight, grain number/main spike, kernel weight and harvest index.     

青海东部地膜覆盖对土壤固碳能力和肥力水平的影响

为探究青海东部地区地膜覆盖条件下单施化肥对土壤固碳能力和土壤肥力的影响,为实现该地区地膜覆盖种植方式生产的可持续发展提供理论依据。通过对青海东部地区旱地玉米农田连续3年田间覆膜试验,研究地膜覆盖条件下单施化肥栽培模式对耕层(0~20 cm)土壤有机碳(SOC)、活性有机碳(LOC)、碳库管理指数(CMI)、可提取腐殖质碳(C_HE)、胡敏酸碳(C_HA)和富里酸碳(C_FA)的影响。结果表明：覆膜条件下单施化肥栽培模式的SOC、LOC和CMI均小于露地对照;C_HE、C_HA和C_FA均随着种植年限的增加而有所增加,但其增加程度总体上均小于露地对照。随着种植年限的增加,至2020年地膜覆盖土壤LOC/SOC值比试验开始前降低了4.97%,而露地对照则升高了1.11%;同时地膜覆盖有机碳氧化稳定系数(KOS)均高于露地对照;土壤C_HA/C_FA值和PQ值均大于露地对照。单施化肥条件下连续地膜覆盖栽培模式使土壤固碳能力有所下降,土壤有机碳趋于稳定而不利于被生物利用;使土壤肥力下降,土壤质量向不良方向发展,长期以往可能会对该地区作物产量的稳定性和持续生产产生不利的影响。     

Seasonal Changes in the Photosynthetic Capacity of Winter Rape Plants under Different Nitrogen Regimes Measured in the Field

Winter rape (cv.'Falcon') grown under different nitrogen regimes (N₀, N₁₂₀; 0 and 120 kg.ha⁻¹, respectively) in northern Germany was investigated over the 1996 spring–summer season. Using a CO₂, H₂O diffusion porometer, diurnal courses or net photosynthesis and respiration were measured in situ and were related to microclimatic conditions and leaf water relations. Photosynthesis was modelled and daily CO₂ gain was calculated. In contrast to the N₁₂₀ plants, plants of the low nitrogen plot (N₀) grew less densely and their leaves behaved more like sun leaves. Increased nitrogen supply had little influence on photosynthetic capacity but it increased productivity through higher leaf area index and an extended period of photosynthetic activity. N₁₂₀ plants also appeared to be better acclimated to hot, summer conditions. Higher nitrogen supply substantially increased seed production with the yield of the N₁₂₀ plants being 16% of the N₀ plants.     

Nitrogen Fixation by Hybrids of White Clover (Trifolium repens L.) and Trifolium nigrescens

Development of hybrids between white clover ( Trifolium repens L.) and Trifolium nigrescens provides a novel route for genetically improving the reproductive capacity of white clover, provided the hybrids are agronomically viable, particularly with respect to N₂ fixation. A comparative study of growth and rates of N₂ fixation over 21 days was conducted with the parental species, F ₁ hybrids and backcross hybrids, in flowing solution culture, without a supply of mineral N to the plants. T. nigrescens was unable to fix N₂ in association with the strains of Rhizobium leguminosarum biovar. trifolii selected for inoculation. Rates of N₂ fixation per plant increased in the order T. nigrescens < F ₁ hybrid < T. repens < backcross 1. Specific rates of N₂ fixation (days 0–21) increased in the order T. nigrescens < F ₁ hybrid < backcross 1 <  T. repens . Dry matter production and nodule biomass per plant increased at a higher rate in backcross 1 hybrids than in T. repens. The results suggest that the potential for N₂ fixation by backcross 1 hybrids is at least as great as that by T. repens .     

A Rapid Method for Measuring Freezing Resistance in Crop Plants

The objective of this study was to develop a technique based on chlorophyll fluorescence to assess freezing injury and resistance of leaves. Optimization was done with faba bean leaves and applicability to other crops was examined at winter and spring with types of barley, oats, rape and faba beans. Selected leaves from young hardened beans were subjected to standardized freezing tests with different minimum temperatures ( T _min) and fluorescence was monitored. After a dark period basic fluorescence ( F _O was induced by 0.2 μmol m⁻² s⁻¹ pulsed red light and maximum fluorescence ( F _m) was assayed at different light intensities. 1500 μmol m⁻² s⁻¹ rendered to give the maximum possible output of Fm and best differentiation of differently damaged leaves by F _n= F _m - F _O. Leaf temperature during measurement and during a short storage (± 2 h) should be kept at about 0°C to avoid biases between differently damaged leaves. The measuring spot on the leaf must be standardized since fluorescence response differed at the tip and base of a leaflet, but not between the two leaflets of a faba bean leaf. The applicability of F _rr (ratio of F _r of stressed to unstressed leaves) as a measure of resistance was demonstrated by comparison of winter hardiness of cultivars with freezing resistance calculated from the relationship of F _vr and the T _min used in freezing tests.     

Die Blattanatomie eines schnell und eines langsam wachsenden Grases in Abhängigkeit von der Stickstoffversorgung

Leaf anatomy of a fast- and a slow-growing grass as dependent on nitrogen supply
The grass species Lolium perenne and Festuca rubra , originating from habitats with differing N-availability, differ in their relative growth rate. This is mainly caused by the higher specific leaf area of L. perenne compared to F. rubra . The leaf anatomy of both species was further investigated. The species were raised in growth chambers under high and low N-supply. The higher specific leaf area of L. perenne (27 mm² mg^–1) in relation to F. rubra (14 mm² mg^–1) was mainly caused by a lower leaf density (0.23 vs. 0.33 mg mm^–3). The level of N-supply influenced both leaf density and leaf thickness. The leaf volume of L. perenne comprised higher fractions of epidermis and lower fractions of mesophyll and intercellular space compared to F. rubra . However, the discrepancy in leaf density between the species could not be explained by anatomical differences. Under low N-supply, the leaves of both species had higher amounts of vascular bundles and fibre cells and lower amounts of intercellular space, which partly explained the higher density of the leaves. It is concluded, that thinner cell walls and higher amounts of cytoplasm cause the higher specific leaf area of L. perenne .     

Ecophysiology of the Plant–Rhizosphere System

The rhizosphere is the site of organic deposition and the generator of habitat and resource heterogeneity for soil organisms. Plants can modify their rhizosphere through nutrient, moisture and O₂ uptake from the rhizosphere, rhizo-deposition and production of root exudates. As a result, rhizosphere chemical (pH, nutrient solubility, O₂, CO₂ and other chemicals), physical (moisture and aeration), and biological (soil pathogens, beneficial microorganisms and allelopathy) characteristics will be changed or modified. Rhizosphere microorganisms have positive or negative effects on plant growth and morphology by affecting the plant hormone balance, plant enzymatic activity, nutrient availability and toxicity, and competition with other plants. Plants modify the rhizosphere and as a result will modify the community.     

Cytogenetic analysis of F1, F2 and BC1 plants from intergeneric sexual hybridization between Sinapis alba and Brassica oleracea by genomic in situ hybridization

By intergeneric sexual hybridization between Sinapis alba and Brassica oleracea , F₁, F₂ and BC₁ progeny plants were produced. S. alba plants (genome SS, 2n = 24) were pollinated with B. oleracea (genome CC, 2n = 18), and the fertile F₁ plants were pollinated with B. oleracea to obtain BC₁ plants. GISH analysis showed that 10 out of 12 F₁ plants had 12 S. alba chromosomes (one full S chromosome set) and nine B. oleracea chromosomes (one C chromosome sets), representing the expected hybrids. However, two F₁ plants had 12 S chromosomes and 18 C chromosomes (two C chromosome sets), indicating unexpected hybrids. A maximum of three trivalents between C and S chromosomes were identified at metaphase I of semi-fertile F₁ pollen mother cells (PMCs), which indicates homology and chromosome pairing between these two genomes. The C genome had obviously been doubled in two F₂ plants from selfed semi-fertile F₁ plants. BC₁ plants consisted of 18 C chromosomes and different numbers of one, five and six additional S chromosomes, respectively. Monosomic alien addition lines developed in the present study can be used for B. oleracea breeding and Sinapis alba gene mapping.     

Inheritance of very high glucosinolate content in Ethiopian mustard seeds

Seed meal amendments rich in glucosinolates are of interest for soil pest and disease control. The Ethiopian mustard ( Brassica carinata A. Braun) line N2-6215, with very high levels of seed glucosinolates (160 μmol/g), was developed from the line C-101 (116 μmol / g) following mutagenesis. The objective of this research was to study the inheritance of very high seed glucosinolate content. Plants of N2-6215 were reciprocally crossed with plants of the line C-101. The F₁, F₂, and BC₁F₁ plant generations were evaluated in two environments and seeds from individual plants were analysed for total glucosinolate content. The very high glucosinolate content in N2-6215 seeds was largely subject to maternal control. No cytoplasmic effects were detected. The trait was found to be oligogenic and determined by at least two or three genes. The estimates of broad-sense heritability were 0.45 and 0.58 in both environments, whereas the estimates of narrow-sense heritability were 0.35 and 0.50. The moderate heritability and oligogenic control of the trait suggest the feasibility of breeding for increased seed glucosinolate content in Ethiopian mustard.     

The effect of delays in establishment of a static or dynamic controlled atmosphere on the quality of ‘Hass’ avocado fruit

The effect of delays of 1, 5, 10 or 15 d after harvest in establishing a static controlled atmosphere (SCA) or dynamic controlled atmosphere (DCA) on the quality of ‘Hass’ avocados (Persea americana Mill.) was investigated. Fruit were stored at 5 °C in SCA (5% O₂/5% CO₂) or DCA (<3% O₂/0.5% CO₂) for 6 weeks and compared with fruit stored in air. In addition, to determine whether increasing the CO₂ in the DCA would affect the fruit quality, DCA-stored fruit were compared with fruit held in a DCA with 5% CO₂ (DCA + CO₂) established 1 d after harvest. The quality of fruit was assessed at the end of storage and after ripening at 20 °C. DCA-stored fruit ripened in 4.6 d compared with 7.2 d for SCA-stored fruit, or 4.8 d for air-stored fruit. In addition, the incidences of stem end rot (SER), body rot (BR) and vascular browning (VB) were lower in DCA-stored fruit (35%, 29% and 29%, respectively) than in SCA-stored fruit (57%, 52% and 49%, respectively), or air-stored fruit (76%, 88% and 95%, respectively). Delaying the establishment of both SCA and DCA for 15 d resulted in significantly more advanced skin colour at the end of storage (average rating score 11.9) compared with other delay periods (4.6–5.1). There was no significant effect of delay on the time to ripen, skin colour when ripe or any ripe fruit disorder incidence. The incidence of diffuse flesh discolouration (DFD) was not only <1% when averaged over all delays but only occurred at >0.5% incidence in the 15 d delay treatment in DCA (4.8%) and not in SCA. The incidence of diffuse flesh discolouration was 62% in air-stored fruit. Inclusion of 5% CO₂ in DCA retarded fruit ripening from 4.7 to 6.9 d and increased the incidence of rots at the end of storage from 5% to 14%, and increased the incidence in ripe fruit of SER from 30% to 56% and of BR from 27% to 55%. It is concluded that fruit quality was better after CA storage than after air storage, and that DCA storage was better than SCA. The effect of DCA is to independently reduce the time to ripen after storage and the incidence of rots when ripe. Delaying the application of SCA or DCA did not affect the expression of rots, but may increase the incidence of DFD. Inclusion of CO₂ at 5% in CA retarded fruit ripening but stimulated rot expression and should not be used for CA storage of New Zealand grown ‘Hass’ avocados.     

Vorkommen von Regenwürmern in landwirtschaftlich rekultivierten Flächen in der Niederrheinischen Bucht

Nitrogen dynamics under a pasture on marchy soil
The nitrogen dynamics were studied on the drainage experimental field of the former grassland research and march experimentation station of Lower Saxony. Four variants applying different nitrogen festilization regimes, from 0 up to 380 kg N/ha/a, were investigated. Nitrogen concentrations were measured by analysing soil samples from different depths for NH₄ und NO₃ contents. Balancing the nitrogen flows the N-output in the forage, the drainage outflow, the netimmobilization, and the N-input by fertilization, biological N-fixation, balk deposition and animal excrements were realized. Nitrogen replacements through the soil profile and nitrate losses in the drainage outflow were relatively low. High watercarrying capacity of the soil and high water consumption by the pasture allow only small rates of displacement of nitrogen. No relevant amounts of mineral nitrogen were found in the soil during the vegetation period because of high nitrogen takeup by the plantbiomass. A certain accumulation of nitrate was observed in late autumn. The concentration however remained unrelevant with respect to goundwater polution. In the drainage water maximal 8 kg of nitrate were leached under the highest fertilized variant. The saldo of the nitrogen balance indicates considerable amounts of nitrogen being lossed by denitrification and ammonia volatilization.     

Einfluß der N-Düngung auf Ertragsentwicklung landwirtschaftlicher Kulturen und Veränderung des mineralischen N-Gehaltes im Boden bei achtjährigen Dauerversuchen

Influence of long-time Nitrogen-fertilizing on yield response of agricultural crops and mineralized Nitrogen in soil
In the years 1979–1986 a fertilizer trial with increasing Nitrogen amount was performed in order to prove the N_min-method according to S charpf and W ehrmann . The N_min-method regards the mineralized N in soil (N_min) for optimizing the N-fertilizer amount at the begin of vegetation, could be confirmed. The optimal N-rate (including N_min) was for winter wheat and winter barley 120 kg/ha, winter rye 100 kg/ha and sugar beet 200 kg/ha. For cereals additional N-rates were given at the end of tillering 20 kg/ha N and at ear emergency 60 kg/ha N. For the optimal N-fertilizing system we found a positive N-balance (input-output) in a range of 10–25 kg/ha. The influence of N-fertilizing on the mineralized N-amount in soil was very small comparing to influence of weather, soil type or crops. Only at one location a little increase of N_min (10–15 kg/ha) could be observed after a positive N-balance (50 kg/ha).