| 1. |
- Bergström, Lars, et al.
(författare)
-
Turnover and Losses of Phosphorus in Swedish Agricultural Soils: Long-Term Changes, Leaching Trends, and Mitigation Measures
- 2015
-
Ingår i: Journal of Environmental Quality. - : Wiley. - 0047-2425 .- 1537-2537. ; 44, s. 512-523
-
Tidskriftsartikel (refereegranskat)abstract
- Transport of phosphorus (P) from agricultural fields to water bodies deteriorates water quality and causes eutrophication. To reduce P losses and optimize P use efficiency by crops, better knowledge is needed of P turnover in soil and the efficiency of best management practices (BMPs). In this review, we examined these issues using results from 10 Swedish long-term soil fertility trials and various studies on subsurface losses of P. The fertility trials are more than 50 years old and consist of two cropping systems with farmyard manure and mineral fertilizer. One major finding was that replacement of P removed by crops with fertilizer P was not sufficient to maintain soil P concentrations, determined with acid ammonium lactate extraction. The BMPs for reducing P leaching losses reviewed here included catch crops, constructed wetlands, structure liming of clay soils, and various manure application strategies. None of the eight catch crops tested reduced P leaching significantly, whereas total P loads were reduced by 36% by wetland installation, by 39 to 55% by structure liming (tested at two sites), and by 50% by incorporation of pig slurry into a clay soil instead of surface application. Trend analysis of P monitoring data since the 1980s for a number of small Swedish catchments in which various BMPs have been implemented showed no clear pattern, and both upward and downward trends were observed. However, other factors, such as weather conditions and soil type, have profound effects on P losses, which can mask the effects of BMPs.
|
|
| 2. |
- Djodjic, Faruk, et al.
(författare)
-
Distributed, high-resolution modelling of critical source areas for erosion and phosphorus losses
- 2015
-
Ingår i: AMBIO: A Journal of the Human Environment. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 44, s. S241-S251
-
Tidskriftsartikel (refereegranskat)abstract
- Phosphorus losses from arable land need to be reduced to prevent eutrophication of surrounding waters. Owing to the high spatial variability of P losses, cost-effective countermeasures need to target parts of the catchment that are most susceptible to P losses. Field surveys identified critical source areas for overland flow and erosion amounting to only 0.4-2.6 % of total arable land in four different catchments in southern Sweden. Distributed modelling using high-resolution digital elevation data identified 72-96 % of these observed erosion and overland flow features. The modelling results were also successfully used to predict occurrence of overland flow and rill and gully erosion in a catchment in central Sweden. Such exact high-resolution modelling allows for accurate placement of planned countermeasures. However, current legislative and environmental subsidy programmes need to change their approach from income-loss compensation to rewarding high cost effectiveness of implemented countermeasures.
|
|
| 3. |
- Eckersten, Henrik, et al.
(författare)
-
Management and spatial resolution effects on yield and water balance at regional scale in crop models
- 2019
-
Ingår i: Agricultural and Forest Meteorology. - : Elsevier BV. - 0168-1923 .- 1873-2240. ; 275, s. 184-195
-
Tidskriftsartikel (refereegranskat)abstract
- Due to the more frequent use of crop models at regional and national scale, the effects of spatial data input resolution have gained increased attention. However, little is known about the influence of variability in crop management on model outputs. A constant and uniform crop management is often considered over the simulated area and period. This study determines the influence of crop management adapted to climatic conditions and input data resolution on regional-scale outputs of crop models. For this purpose, winter wheat and maize were simulated over 30 years with spatially and temporally uniform management or adaptive management for North Rhine-Westphalia ((similar to)34 083 km(2)), Germany. Adaptive management to local climatic conditions was used for 1) sowing date, 2) N fertilization dates, 3) N amounts, and 4) crop cycle length. Therefore, the models were applied with four different management sets for each crop. Input data for climate, soil and management were selected at five resolutions, from 1 x 1 km to 100 x 100 km grid size. Overall, 11 crop models were used to predict regional mean crop yield, actual evapotranspiration, and drainage. Adaptive management had little effect (< 10% difference) on the 30-year mean of the three output variables for most models and did not depend on soil, climate, and management resolution. Nevertheless, the effect was substantial for certain models, up to 31% on yield, 27% on evapotranspiration, and 12% on drainage compared to the uniform management reference. In general, effects were stronger on yield than on evapotranspiration and drainage, which had little sensitivity to changes in management. Scaling effects were generally lower than management effects on yield and evapotranspiration as opposed to drainage. Despite this trend, sensitivity to management and scaling varied greatly among the models. At the annual scale, effects were stronger in certain years, particularly the management effect on yield. These results imply that depending on the model, the representation of management should be carefully chosen, particularly when simulating yields and for predictions on annual scale.
|
|
| 4. |
|
|
| 5. |
- Villa Solis, Ana, et al.
(författare)
-
Aggregation of soil and climate input data can underestimate simulated biomass loss and nitrate leaching under climate change
- 2022
-
Ingår i: European Journal of Agronomy. - : Elsevier BV. - 1161-0301 .- 1873-7331. ; 141
-
Tidskriftsartikel (refereegranskat)abstract
- Predicting areas of severe biomass loss and increased N leaching risk under climate change is critical for applying appropriate adaptation measures to support more sustainable agricultural systems. The frequency of annual severe biomass loss for winter wheat and its coincidence with an increase in N leaching in a temperate region in Germany was estimated including the error from using soil and climate input data at coarser spatial scales, using the soil-crop model CoupModel. We ran the model for a reference period (1980-2010) and used climate data predicted by four climate model(s) for the Representative Concentration Pathways (RCP) 2.6, 4.5 and 8.5. The annual median biomass estimations showed that for the period 2070-2100, under the RCP8.5 scenario, the entire region would suffer from severe biomass loss almost every year. Annual incidence of severe biomass loss and increased N leaching was predicted to increase from RCP4.5 to the 8.5 scenario. During 2070-2100 for RCP8.5, in more than half of the years an area of 95% of the region was projected to suffer from both severe biomass loss and increased N leaching. The SPEI3 predicted a range of 32 (P3 RCP4.5) to 55% (P3 RCP8.5) of the severe biomass loss episodes simulated in the climate change scenarios. The simulations predicted more severe biomass losses than by the SPEI index which indicates that soil water deficits are important in determining crop losses in future climate scenarios. There was a risk of overestimating the area where "no severe biomass loss + increased N leaching" occurred when using coarser aggregated input data. In contrast, underestimation of situations where "severe biomass loss + increased N leaching" occurred when using coarser aggregated input data. Larger annual differences in biomass estimations compared to the finest resolution of input data occurred when aggregating climate input data rather than soil data. The differences were even larger when aggregating both soil and climate input data. In half of the region, biomass could be erroneously estimated in a single year by more than 40% if using soil and climate coarser input data. The results suggest that a higher spatial resolution of especially climate input data would be needed to predict reliably annual estimates of severe biomass loss and N leaching under climate change scenarios.
|
|
| 6. |
- Villa Solis, Ana, et al.
(författare)
-
Assessing soil erodibility and mobilization of phosphorus from Swedish clay soils - Comparison of two simple soil dispersion methods
- 2012
-
Ingår i: Acta Agriculturae Scandinavica, Section B - Soil and Plant Science. - : Informa UK Limited. - 0906-4710 .- 1651-1913. ; 62, s. 260-269
-
Tidskriftsartikel (refereegranskat)abstract
- Erodibility of Swedish clay soils estimated according to the existing methods is usually low, but high levels of suspended solids and attached unreactive phosphorus have been recorded in drainage water from fields and catchments dominated by clay soils. Inherent susceptibility to soil erosion is usually assessed through aggregate stability studies or dispersion tests. The latter are simple to perform and produce good results when compared against runoff lysimeter experiments. The environmental soil test to determine the potential for sediment and phosphorus transfer in runoff from agricultural land (DESPRAL) and soil suspension turbidity (SST) dispersion tests, which differ in soil-liquid ratio and shaking and settling times, were compared here for their ability to indicate the erodibility of 10 Swedish clay soils. The tests proved to be significantly correlated (r = 0.78), but DESPRAL showed higher repeatability (r(i) = 0.995) than SST (r(i) = 0.824). Variation in soil dispersion was explained by clay, sand and organic matter content in DESPRAL and by clay and sand content in SST. An additional study on the effect of soil storage duration on dispersion (DESPRAL test) in 15 soil samples showed that storage had no effect on some soils, but significantly decreased dispersion in others after only 8 weeks. Therefore, soil dispersion tests should be performed as soon as possible after sample drying. The DESPRAL and SST tests proved to be a good option for estimating the erodibility factor K in the Revised Universal Soil Loss equation under Swedish conditions and were able to differentiate the susceptibility to sediment losses for different clay soils. They provided an indirect measure of the amounts of sediment and P mobilized, but further work is needed to calibrate them against measured values at field and catchment scale.
|
|
| 7. |
- Villa Solis, Ana, et al.
(författare)
-
Determining suspended solids and total phosphorus from turbidity: comparison of high-frequency sampling with conventional monitoring methods
- 2019
-
Ingår i: Environmental Monitoring and Assessment. - : Springer Science and Business Media LLC. - 0167-6369 .- 1573-2959. ; 191
-
Tidskriftsartikel (refereegranskat)abstract
- Suspended solids (SS) are important carriers of pollutants such as phosphorus (P) in streams, but the sampling frequency in monitoring programs is usually insufficiently frequent to capture episodic SS and total P (TP) peaks. The suitability of turbidity and conductivity as a surrogate for SS and TP was studied using 108 monitoring stations located in catchments of different sizes, land uses, and pollution levels. The use of high-frequency turbidity measurements to estimate SS and TP loads was compared with the use of two sampling methods (grab, flow-proportional sampling) in a case study. When all samples were considered, turbidity was a good predictor of SS (r(2) = 0.76) and TP (r(2) = 0.75). For single sites, there was a large range in how well turbidity could predict the two variables. The site-specific turbidity-SS relationship was significant at 87% of sites (mean r(2) = 0.72). The site turbidity and conductivity-TP relationship was significant at 78% of sites (mean r(2) = 0.62). A stronger turbidity-SS relationship was found in catchments with a higher percentage of agricultural land. The turbidity and conductivity-TP relationship was stronger when the TP concentration was high. In the case study, TP loads were smallest when estimated with grab sampling, which missed several discharge peaks. Loads estimated with high-frequency turbidity measurements were 19-51% smaller than with flow-proportional sampling, probably due to differences in sampling points. High-frequency turbidity measurements can be a viable alternative to conventional sampling methods in studies on concentration dynamics and load estimates.
|
|
| 8. |
- Villa Solis, Ana, et al.
(författare)
-
DRAFT Synthesis report on soil science in European Higher Education
- 2021
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The European Joint Partnership “Towards climate smart sustainable management of agricultural soils” (EJP SOIL, https://projects.au.dk/ejpsoil/) is a European 5-year effort to strengthen research capacity and new knowledge on climate adaptation and mitigation for agricultural soils. This survey is supporting by providing a baseline on the current state of soil science in European Higher Education institutions (HEI). This was done through a survey to 274 HEIs in Europe. A total of 86 complete answers were received where every EJP SOIL country was represented with at least one response. Preliminary results showed that only 10% of the HEIs had a dedicated soil science department. The majority of soil science is embedded in a department where environmental sciences, agricultural sciences and earth sciences are the main academic topics. Respondents reported an increased enrolment at BSc, and no change for MSc and PhD. Mixed trends could be seen for specific countries and universities, with both increases and decreases in student enrolment. Traditional lecture based teaching dominated soil science teaching and learning activities, both at BSc and MSc levels. However, results suggested that study programs are evolving to include more generic competences as well as active learning methods (e.g. problem-based learning, case studies). Still, at BSc level the proportion of courses that did not have any computer/modelling component was about 1/3. Top 3 priorities for internationalisation were to i) attract students from abroad, ii) provide more opportunities to send students abroad and iii) develop strategic research partnerships. Finally, respondents’ perception was that job opportunities for soil science students have mainly increased in the past ten years.
|
|
| 9. |
- Villa Solis, Ana, et al.
(författare)
-
Effects of input data aggregation on simulated crop yields in temperate and Mediterranean climates
- 2019
-
Ingår i: European Journal of Agronomy. - : Elsevier BV. - 1161-0301 .- 1873-7331. ; 103, s. 32-46
-
Tidskriftsartikel (refereegranskat)abstract
- Soil-crop models are used to simulate ecological processes from the field to the regional scale. Main inputs are soil and climate data in order to simulate model response variables such as crop yield. We investigate the effect of changing the resolution of input data on simulated crop yields at a regional scale using up to ten dynamic crop models. For these models we compared the effects of spatial input data aggregation for wheat and maize yield of two regions with contrasting climate conditions (1) Tuscany (Italy, Mediterranean climate) and (2) North Rhine Westphalia (NRW, Germany, temperate climate). Soil and climate data of 1 km resolution were aggregated to resolutions of 10, 25, 50, and 100 km by selecting the dominant soil class (and corresponding soil properties) and by arithmetic averaging, respectively. Differences in yield simulated at coarser resolutions from the yields simulated at 1 km resolution were calculated to quantify the effect of the aggregation of the input data (soil and climate data) on simulation results.The mean yield difference (bias) at the regional level was positive due to the upscaling of productive dominant soil(s) to coarser resolution. In both regions and for both crops, aggregation effects (i.e. errors in simulation of crop yields at coarser spatial resolution) due to the combined aggregation of soil and climate input data increased with decreasing resolution, whereby the aggregation error for Tuscany was larger than for North Rhine Westphalia (NRW). The average absolute percentage yield differences between grid cell yields at the coarsest resolution (100 km) compared to the finest resolution (1 km) were by about 20-30% for Tuscany and less than 15 and 20% for NRW for winter wheat and silage maize, respectively.In the Mediterranean area, the prediction errors of the simulated yields could reach up to 60% when looking at individual crop model simulations. Additionally, aggregating soil data caused larger aggregation errors in both regions than aggregating climate data.Those results suggest that a higher spatial resolution of climate and especially of soil input data are necessary in Mediterranean areas than in temperate humid regions of central Europe in order to predict reliable regional yield estimations with crop models. For generalization of these outcomes, further investigations in other sub humid or semi-arid regions will be necessary.
|
|
| 10. |
|
|
