| 1. |
- Adler, Karl, et al.
(författare)
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Digital soil mapping of copper in Sweden: Using the prediction and uncertainty as decision support in crop micronutrient management
- 2022
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Ingår i: Geoderma Regional. - : Elsevier BV. - 2352-0094. ; 30
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Tidskriftsartikel (refereegranskat)abstract
- Digital soil mapping (DSM) of topsoil copper (Cu) concentrations and prediction intervals covering 90% of agricultural land in Sweden was performed, in order to identify areas at risk of Cu deficiency. A total of 12,527 soil samples were used to calibrate the DSM model, using airborne gamma radiation data, climate data, topographical data and soil texture class data. Among the samples included, 11,093 had no laboratory-analysed Cu concentrations, so their Cu concentrations were predicted using portable X-ray fluorescence (PXRF) measurements. Cross-validation of the PXRF model resulted in Nash-Sutcliffe model efficiency coefficient (E) of 0.66 and mean absolute error (MAE) of 3.3 mg kg−1. Cross-validation of the DSM model showed somewhat lower performance (E = 0.57, MAE = 4.1 mg kg−1). Based on the lower bound of the prediction interval (5th percentile), 48% of agricultural soils in Sweden are most likely not at risk of Cu deficiency (>7 mg kg−1). The Cu map was also validated against concentrations in soil samples from five fields (25–47 ha in size; four samples per ha). The field means were predicted with a MAE of 1.0 mg kg−1 and within-field variation was reproduced with a field-wise squared Pearson correlation coefficient (r2) of 0–0.36. The classification metric ‘recall’ showed that the map of soil Cu concentrations might not predict all possible areas at risk of being Cu deficient, as observational data indicates that about 22% of soils in the mapped area should have Cu concentrations below the risk limit. However, the metric ‘precision’ showed that when the soil map predicted a concentration at or below 7 mg kg−1, it was generally correct. Increasing the limit resulted in the recall and precision increasing rapidly. The remaining 52% of agricultural soils at risk of being below the Cu concentration limit can be targeted by laboratory analysis or monitoring.
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| 2. |
- Adler, Karl, et al.
(författare)
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Predictions of Cu, Zn, and Cd Concentrations in Soil Using Portable X-Ray Fluorescence Measurements
- 2020
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Ingår i: Sensors (Basel, Switzerland). - : MDPI AG. - 1424-8220. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- Portable X-ray fluorescence (PXRF) measurements on 1520 soil samples were used to create national prediction models for copper (Cu), zinc (Zn), and cadmium (Cd) concentrations in agricultural soil. The models were validated at both national and farm scales. Multiple linear regression (MLR), random forest (RF), and multivariate adaptive regression spline (MARS) models were created and compared. National scale cross-validation of the models gave the following R-2 values for predictions of Cu (R-2 = 0.63), Zn (R-2 = 0.92), and Cd (R-2 = 0.70) concentrations. Independent validation at the farm scale revealed that Zn predictions were relatively successful regardless of the model used (R-2 > 0.90), showing that a simple MLR model can be sufficient for certain predictions. However, predictions at the farm scale revealed that the non-linear models, especially MARS, were more accurate than MLR for Cu (R-2 = 0.94) and Cd (R-2 = 0.80). These results show that multivariate modelling can compensate for some of the shortcomings of the PXRF device (e.g., high limits of detection for certain elements and some elements not being directly measurable), making PXRF sensors capable of predicting elemental concentrations in soil at comparable levels of accuracy to conventional laboratory analyses.
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| 3. |
- Alshihabi, Omran, et al.
(författare)
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CropSAT – A decision support system for practical use of satellite images in precision agriculture
- 2020
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Ingår i: Lecture Notes in Electrical Engineering. - Cham : Springer International Publishing. - 1876-1100. ; 684, s. 415-421
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Konferensbidrag (refereegranskat)abstract
- CropSAT is an interactive decision support system (DSS) that provides vegetation index (VI) maps from Sentinel-2 data all across the globe and lets users delineate fields, design variable-rate application of user specified inputs (mainly nitrogen, but also e.g. fungicides or growth regulators) based on the VI maps. The CropSAT DSS was initially developed in a research project at the Swedish University of Agricultural Sciences (SLU), and has since its launch in 2015 been continuously developed in a private-public-partnership between SLU, private companies and the Swedish Board of Agriculture. Now it has global coverage, is continuously updated with new satellite images, and is provided free-of-charge in multiple languages (including Arabic and French). The present study aims at describing the CropSAT systems, summarizing research results from the ongoing developmental process and pointing to opportunities for applications in precision agriculture, e.g. in Morocco and other countries in North Africa.
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| 4. |
- Alshihabi, Omran, et al.
(författare)
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CropSAT – opportunities for applications in precision agriculture in Africa
- 2020
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The present paper aims at describing the CropSAT system, a Sentinel-2-based interactive decision support system (DSS) that provides vegetation index (VI) maps free-of-charge all across the globe for different applications in precision agriculture. We summarize research results from the ongoing developmental process and pointing to opportunities for development and application in precision agriculture in Africa. The DSS was initially developed in a research project at the Swedish University of Agricultural Sciences (SLU), and has since its launch in 2015 been continuously developed in a private-public-partnership between SLU, private companies and the Swedish Board of Agriculture. One of the main applications of CropSAT is providing spatial variation maps of several VIs to be used in variable rate application (VRA) of any input in agriculture (fertilizers, pesticides or growth regulators). These maps could be either downloaded in different formats compatible with a wide range of spreaders/sprayers available in the machinery market, or printed out to be used manually or with the help of smart phones localization apps, for example to support discussion in advisory situations. Such a DSS is an appropriate platform for developing other application using the satellite images like nitrogen uptake estimation, protein content/yield prediction and water stress assessment. Ongoing research is now running to develop and integrate models in CropSAT for new applications and the tool is subject of research and development projects in other countries worldwide. An initial study was carried out to test the DSS in Tunisia in collaboration between SLU, the National Agronomic Institute of Tunisia (INAT) and the National Institute of Field Crops (INGC) to assess the feasibility for application under arid and semi-arid climate where different crops varieties are used. Further development in Tunisia will focus on integrating crops water status indices in order to use the tool for irrigation water management. Now CropSAT has continuously updated global coverage with new satellite images (about every three days in North Africa), and is provided in multiple languages including English, Arabic and French.
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| 5. |
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| 6. |
- Karlsson, Per Erik, 1957, et al.
(författare)
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Evidence for Impacts of Near-ambient Ozone Concentrations on Vegetation in Southern Sweden
- 2009
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Ingår i: Ambio. - : Royal Swedish Academy of Sciences. ; 38:8, s. 425-431
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Tidskriftsartikel (refereegranskat)abstract
- Substantial impacts of near-ambient ozone concentrations on agricultural crops, trees, and seminatural vegetation are demonstrated for southern Sweden. Impacts of ambient ozone levels (2–15 μL L-¹ hr annual accumulated ozone exposure over a threshold of 40 nL L-¹ [AOT40]) range from a 2%–10% reduction for trees (e.g., leaf chlorophyll, tree growth) up to a 15% reduction for crops (e.g., yield, wheat/potato). Visible leaf injury on bioindicator plants caused by ambient ozone levels has been clearly demonstrated. The humid climatic conditions in Sweden promote high rates of leaf ozone uptake at a certain ozone concentration. This likely explains the comparatively large ozone impacts found for vegetation in southern Sweden at relatively low ozone concentrations in the air. It is important that the future methods used for the representation of ozone impacts on vegetation across Europe are based on the leaf ozone uptake concept and not on concentration-based exposure indices, such as AOT40.
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| 7. |
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| 8. |
- Marzec-Schmidt, Katarzyna, et al.
(författare)
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Modelling the Effects of Weather Conditions on Cereal Grain Contamination with Deoxynivalenol in the Baltic Sea Region
- 2021
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Ingår i: Toxins. - : MDPI AG. - 2072-6651. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Fusarium head blight (FHB) is one of the most serious diseases of small-grain cereals worldwide, resulting in yield reduction and an accumulation of the mycotoxin deoxynivalenol (DON) in grain. Weather conditions are known to have a significant effect on the ability of fusaria to infect cereals and produce toxins. In the past 10 years, severe outbreaks of FHB, and grain DON contamination exceeding the EU health safety limits, have occurred in countries in the Baltic Sea region. In this study, extensive data from field trials in Sweden, Poland and Lithuania were analysed to identify the most crucial weather variables for the ability of Fusarium to produce DON. Models were developed for the prediction of DON contamination levels in harvested grain exceeding 200 µg kg−1 for oats, spring barley and spring wheat in Sweden and winter wheat in Poland, and 1250 µg kg−1 for spring wheat in Lithuania. These models were able to predict high DON levels with an accuracy of 70–81%. Relative humidity (RH) and precipitation (PREC) were identified as the weather factors with the greatest influence on DON accumulation in grain, with high RH and PREC around flowering and later in grain development and ripening correlated with high DON levels. High temperatures during grain development and senescence reduced the risk of DON accumulation. The performance of the models, based only on weather variables, was relatively accurate. In future studies, it might be of interest to determine whether inclusion of variables such as pre-crop, agronomic factors and crop resistance to FHB could further improve the performance of the models.
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| 9. |
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| 10. |
- Namirembe, Sara, et al.
(författare)
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Soil organic carbon in agricultural systems of six countries in East Africa – a literature review of status and carbon sequestration potential
- 2020
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Ingår i: South African Journal of Plant and Soil. - : Informa UK Limited. - 0257-1862 .- 2167-034X. ; 37, s. 35-49
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Forskningsöversikt (refereegranskat)abstract
- Cropland soils are considered to have the potential to sequester atmospheric CO2 through agronomic best management practices (BMPs). To estimate this potential in East Africa, the authors reviewed 69 published studies from Ethiopia, Kenya, Rwanda, Tanzania, Uganda, and Burundi assessing the effect of land use conversion from native vegetation to cropland on soil organic carbon (SOC) and the extent to which carbon sequestration is feasible through BMPs. Reported losses of SOC in the top 30 cm of the soil profile in short (<10 years), medium (10-25 years), and long (>25 years) term were 6.7 +/- 6.0, 13.0 +/- 9.2, and 2.8 +/- 1.0 t C ha(-1) year(-1), respectively, for forest-to-cropland; and 16.0, 2.1 +/- 2.2 and 0.3 +/- 0.8 t C ha(-1) year(-1) respectively, for woodland-to-cropland conversion. Duration to steady-state SOC was 21-38 years for forest-to-cropland conversion. Short-term SOC sequestration (t C ha(-1) year(-1)) in the 0-30 cm layer as a result of BMPs was 19.7 +/- 3.9 from crop residues, 14.8 +/- 8.7 from farmyard manure, 3.5 +/- 4.5 from inorganic fertilizers, 2.7 from agroforestry, and 2.5 from improved fallow. However, the studies reviewed were mostly short-term and concentrated to a few locations. Future research should address these gaps.
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