Irrigation has a critical role for crop production worldwide. In particular, irrigation is a major issue due to the growing food demand and climate change. Irrigation affects yields and the emission ...of greenhouse gases such as CO₂ and N₂O by soils. Here, we review the effect of irrigation on soil organic carbon and N₂O emissions. We analysed 22 investigations in various regions of the world. Interactions between irrigation, soil and management factors are described. The main points are: (1) The influence of irrigation is strongly dependent on climate and initial soil organic carbon content. For instance, irrigation of cultivated desert soils led to an average increase of 90 % to over 500 % of soil organic carbon. (2) Irrigation of semiarid regions increases soil organic carbon by 11 % to 35 %. (3) No consistent effects of irrigation were observed in humid regions. In many cases, N₂O emissions increase after precipitation or irrigation. (4) Comparison of N₂O emissions from irrigated and non-irrigated fields shows that availability of reactive nitrogen compounds controls increased N₂O emissions under irrigation, in most cases. Here, increases of about 50 % to 140 % in N₂O emissions were reported.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Carbon sequestration has been proposed as a way to mitigate the impact of CO2 on the climate. At the COP21, the ‘4 per 1000 Soils for Food Security and Climate’ initiative was launched with the goal ...to increase global soil organic carbon (SOC) stocks by 4‰ per year. The Thyrow long-term field experiment DIV.2 was chosen to determine the feasibility of this 4 per 1000 goal under the dry and sandy conditions in Eastern Germany. The effects of different fertilizing regimes on SOC contents and winter rye yields were investigated. Winter rye is a representative crop for the region and grown as a monoculture in the experiment. The 4 per 1000 goal was achieved in all treatments including the unfertilized control, although ploughing takes place and straw is removed every year. The highest carbon sequestration of up to 0.5 t ha−1 a−1 was provided by a combination of mineral and manure fertilization. In three out of four years, no yield difference was observed between mineral-only fertilization (120 kg ha−1 N) and a combination of mineral and organic N (97.4 kg ha−1 plant available N) fertilization. Yields increased over the years in the treatment with pure organic N and decreased in all other treatments.
Digestates are commonly used as organic inputs in agriculture. This study aimed to answer four questions: (1) What are the immediate and longer-term impacts of digestates on soil microbial activity?; ...(2) How much of the digestates’ carbon is mineralized within the first months? (3) How do the nitrogen, lignin, cellulose, and hemicellulose contents of digestates influence microbial activity and carbon mineralization? (4) How does the soil type influence mineralization? To investigate this, dehydrogenase activity (DHA) was measured in a field trial and in laboratory experiments with five digestates (DGs), cattle slurry, and cattle manure. DHA measurements were supplemented with soil respiration experiments using two different soils. DHA was significantly increased by all organic inputs, but decreased back to the control level within seven months under field conditions. Twenty percent to 44% of the organic carbon (Corg) in the digestates was converted to CO2 after 178 days. Soil respiration was significantly negatively correlated to lignin content (r = −0.82, p < 0.01) and not correlated to nitrogen, cellulose, or hemicellulose content. On the basis of equal carbon application, slurry promoted soil respiration and DHA more strongly than digestates in the short term.
Assembled results from 20 European long-term experiments (LTE), mainly from the first decade of the twenty-first century, are presented. The included LTEs from 17 sites are the responsibility of ...institutional members of the International Working Group of Long-term Experiments in the IUSS. Between the sites, average annual temperatures differ between 8.1 and 15.3°C, annual precipitation between 450 and 1400 mm, and soil clay contents between 3 and 31%. On average of 350 yield comparisons, combined mineral and organic fertilization resulted in a 6% yield benefit compared with mineral fertilization alone; in the case of winter wheat, the smallest effect was 3%, the largest effect, seen with potatoes, was 9%. All unfertilized treatments are depleted in soil organic carbon (SOC), varying between 0.36 and 2.06% SOC. The differences in SOC in unfertilized plots compared with the respective plots with combined mineral (NPK) and organic (10 t ha⁻¹ farmyard manure) fertilization range between 0.11 and 0.72%, with an average of 0.3% (corresponding to ∼15 t ha⁻¹). Consequently, the use of arable soils for carbon sequestration is limited and of low relevance and merely depleted soils can temporarily accumulate carbon up to their optimum C content.
Full text
Available for:
BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
We studied the effects of long-term organic and mineral fertilization on soil microarthropods and soil chemical parameters in a field experiment under semi-arid conditions in Central Spain. Two ...different regimes of organic manuring, i.e. farmyard manure applied once in 3 years versus annual manuring with crop residues were compared. Soil carbon and nitrogen contents were increased markedly by farmyard manure, whereas straw and green manure had no significant effect. In contrast, the abundance of soil microarthropods was increased by annual application of straw and green manure, but not by farmyard manure last applied 2.5 years before sampling. We conclude that in the field experiment under study the abundance of soil microarthropods was influenced by the immediate food supply rather than by soil chemical parameters, such as carbon and nitrogen content or the pH. Biodiversity of soil microarthropods, as estimated by the Shannon index, was not affected significantly by straw and green manure. Obviously, other management practices, especially tillage, are limiting the species composition of soil microarthropods and thereby overshadow possible effects of fertilization on diversity.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The aim of this study was to determine the effect of drought stress on four sunflower genotypes (Tarsan, Sanbro, TR-3080 and DKF-2525) and the relationship between some physiological and phenological ...characters at 30% (drought stress) and 60% (well-watered) irrigation from soil water capacity. Stress treatment was started from the emergence until R1 stage (bud visible) under the controlled conditions of greenhouse. The results showed that plants responses in some parameters such as leaf, stem and total dry weight, total leaf area, young fully developed leaf area, plant height, WUE (water use efficiency), RWC (relative water content), SLW (specific leaf weight) and Delta13C isotope (carbon isotope discrimination) are gradually declined under drought stress condition. On the other hand, some responses such as to proline content and chlorophyll of leaves are increased at the same drought condition. The highly significant relationships were found between both WUE and Delta13C isotope and proline, especially under drought condition. Generally, sunflower genotypes with lower SLW (leaf thickness) showed higher water content than those with higher SLW mainly due to highly negative relationship with RWC, under drought stress condition. However, the Sanbro cultivar can be used as a parental genotype in sunflower breeding programs due to its high RWC, WUE, total dry weight, high proline accumulation and low Delta13C isotope under drought stress conditions. Our study suggested that selection for WUE using indirect Delta13C isotope can presumably be of great value in sunflower breeding programs aimed at developing drought tolerant genotypes. It can also be confirmed that measuring young fully developed leaf area can be enough to determine the leaf area because there is a close correlation between total leaf area and the young fully developed leaves on a plant in both normal and drought conditions.
Depending on the quality of the input substrates, process parameters, and postfermentation treatments, digestates may contain a broad spectrum of potentially toxic elements. We suspected that these ...contents may vary on a broad scale even under seemingly stable process conditions at the biogas plant. Digestates from four biogas plants were therefore continuously analyzed for their contents of phosphorus, nitrogen, cadmium, copper, lead, and zinc over a period of six years. The input substrates varied between the plants (e.g., cattle and pig slurry and rye and maize silage), but were the same for each plant over the whole period. The N : P ratio of the digestates ranged from 2 to 24, with the digestate coming from cofermentation of pig slurry and energy crops (“DG Pig”) having the widest range of N : P ratio over the years. Heavy metal loads of all digestates and during all evaluations did not exceed the limits set by European or German legislation, but as previously expected, showed a large variability especially if cattle or pig manure were used as substrates. Copper content of Cattle slurry before digestion was 897.7 mg kg−1 DM in one case, and zinc content of DG Pig reached 590.2 mg kg−1 DM also once during the investigation. As a result, we strongly recommend to monitor especially phosphorus, copper, and zinc contents in digestates very closely and in short intervals.
Full text
Available for:
FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Im Mittelpunkt der Untersuchung von Winterweizensorten unter Standortbedingungen Brandenburgs stand die Fragestellung: Welche Sortenunterschiede bestehen hinsichtlich der Ökostabilität, der ...Leistungsfähigkeit und der Reaktion auf trockenere Witterungsbedingungen? Dazu wurden auf Basis von mehrortigen und mehrjährigen Ergebnissen aus Sortenversuchen in Brandenburg und unter Nutzung biostatistischer Parameter verschiedene Weizensorten beurteilt. Die Bewertung zur Ökostabilität und Leistungsfähigkeit umfasste neben der deskriptiven Statistik die Parameter Ökovalenz, lineare Regressionsanalyse und Floating Checks. Weiterhin wurden verschiedene Einflussgrößen auf die Ertragsvariabilität im Rahmen einer Varianzkomponentenanalyse berechnet und die Sortenreaktion auf unterschiedliche Witterungsbedingungen anhand der klimatischen Wasserbilanz geprüft. Die Auswertung der Sortenversuche zeigte, dass die Umwelt (Ort × Jahr) den stärksten Einfluss auf die Ertragsvariabilität hatte. Im Vergleich dazu war der Sorteneinfluss deutlich geringer. Dennoch wiesen die Sorten deutliche Unterschiede hinsichtlich der Leistungsfähigkeit, Ökostabilität und der Reaktion unter differenzierten Umweltbedingungen auf. Die Ergebnisse sind für die Sortenprüfung und -bewertung, die Züchtung und die landwirtschaftliche Praxis gleichermaßen bedeutsam. Sie liefern Informationen zu den umweltabhängig variierenden Eigenschaften der Sorten und bieten Unterstützung für die standortgerechte Sortenempfehlung sowie bestmögliche Sortenwahl durch die Entwicklung eines Bewertungsschemas.
While current variety recommendations are based on replicated small-plot trials in a specific region for which the trial is thought to be representative, genotype × environment interactions, ...genotype × management interactions, and increasing weather fluctuations make it increasingly difficult to predict which variety will be best in a given environment. An additional approach is therefore to decentralize variety trials and place them on working farms. However, although on-farm trials offer potentially more relevance for direct variety selection on site, they are also likely to be subject to more noise and trial entries can often not be fully replicated. To evaluate the relative merit of on-farm trials vs. fully replicated trials conducted at experimental stations, we tested 6 maize varieties at four farms and at two stations in a region dominated by sandy soils. The variance of variety rankings over the years within each site was used as proxy to evaluate the consistency of variety information gained at each location. For dry matter yield, on-farm trials showed both the highest and the lowest consistency of variety ranking, with the consistency being intermediate at the experimental stations. For some quality parameters, namely non-fibre carbohydrate and starch content, the majority of on-farm trials showed more consistent variety ranking over the years than the more consistent of the two replicated trials. This suggests that in terms of year-on-year reliability of maize yield and quality, on-farm trials may have the potential to complement replicated variety trials. For both types of trials, however, there is also scope for decreasing technical sources of variation. DOI: 10.5073/JfK.2014.11.03, https://doi.org/10.5073/JfK.2014.11.03
•Irrigation does not impact yield-related total GHG emissions.•GHG emissions due to irrigation are compensated by higher yields and C-sequestration.•GHG emissions from pre-chains were the main source ...of the total GHG emissions.
Irrigation induces processes that may either decrease or increase greenhouse gas emissions from cropping systems. To estimate the net effect of irrigation on the greenhouse gas emissions, it is necessary to consider changes in the crop yields, the content of soil organic carbon and nitrous oxide emissions, as well as in emissions from the use and production of machinery and auxiliary materials. In this study the net greenhouse gas emissions of a cropping system on a sandy soil in northeast Germany were calculated based on a long-term field experiment coupled with two-year N2O flux measurements on selected plots. The cropping system comprised a rotation of potato, winter wheat, winter oil seed rape, winter rye and cocksfoot each under three nitrogen (N) fertilization intensities with and without irrigation. Total greenhouse gas emissions ranged from 452 to 3503kg CO2-eqha−1 and 0.09 to 1.81kg CO2-eqkg−1 yield. Application of an adequate amount of N fertilizer led to a decrease in greenhouse gas emissions compared to zero N fertilization whereas excessive N fertilization did not result in a further decrease. Under N fertilization there were no significant differences between irrigation and non-irrigation. Increases in greenhouse gas emissions from the operation, production and maintenance of irrigation equipment were mainly offset by increases in crop yield and soil organic carbon contents. Thus, on a sandy soil under climatic conditions of north-east Germany it is possible to produce higher yields under irrigation without an increase in the yield-related greenhouse gas emissions.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
PDF
