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Nylinder J.,Gothenburg University | Stenberg M.,Rural economics and Agricultural Society of Skaraborg | Stenberg M.,Swedish University of Agricultural Sciences | Jansson P.-E.,KTH Royal Institute of Technology | And 3 more authors.
Agriculture, Ecosystems and Environment

High uncertainties are common in detailed quantification of the N budget of agricultural cropping systems. The process-based CoupModel, integrated with the parameter calibration method known as Generalized likelihood uncertainty estimation (GLUE), was used here to define parameter values and estimate an N budget based on experimental data from an organic farming experiment in south-west Sweden. Data on nitrate (NO 3 -) leaching and nitrous oxide (N 2O) emissions were used as a basis for quantifying N budget pools. A complete N budget with uncertainties associated with the different components of the N cycle compartments for two different fields (B2 and B4) is presented. Simulated N 2O emissions contributed 1-2% of total N output, which corresponded to 7% and 8.7% of total N leaching for B2 and B4, respectively. Measured N 2O emissions contributed 3.5% and 10.3% of total N leaching from B2 and B4, respectively. Simulated N inputs (deposition, plant N fixation and fertilisation) and outputs (emissions, leaching and harvest) showed a relatively small range of uncertainty, while the differences in N storage in the soil exhibited a larger range of uncertainty. One-fifth of the GLUE-calibrated parameters had a significant impact on simulated NO 3 - leaching and/or N 2O emissions data. Emissions of N 2O were strongly associated with the nitrification process. The high degree of equifinality indicated that a simpler model could be calibrated to the same field data. © 2011 Elsevier B.V. Source

Soderstrom M.,Swedish University of Agricultural Sciences | Borjesson T.,Lantmannen Lantbruk | Roland B.,Rural economics and Agricultural Society of Skaraborg | Stadig H.,Rural economics and Agricultural Society of Skaraborg
Precision Agriculture

Within-field variations in the mycotoxin deoxynivalenol (DON) in oat grain were investigated at two farms in south-west Sweden. At Sarestad farm (sampled 2012), where one of two fields studied was ploughed annually and the other was under no-till cultivation, the DON concentration varied between 28 and 1 755 ppb. The level was higher (270–5 000 ppb) at Entorp farm (sampled 2013). Within-field prediction models for DON were constructed using a data mining method (multi-variate adaptive regression splines) with satellite data, an ECa sensor and airborne laser scanning. At Sarestad, the no-till field had higher DON content, with the highest values in silty patches in the otherwise clayey soil. Sensor data related to soil and crop conditions had the potential to describe the DON variability within fields. The covariance between DON content and auxiliary data differed at Entorp farm, where high DON values (>2 000 ppb) were found in clayey parts of the field. This pattern was attributed to poor drainage with recurring waterlogging. Within these clayey parts, the highest DON contents coincided with the highest biomass density. South-west Sweden received much less rainfall in 2013 than in 2012, which may have resulted in different DON patterns in relation to soil types. In 2012, more permeable silty soils apparently promoted growth, biomass production and DON production, whereas in 2013 a poorly drained clayey soil with high water-holding capacity favoured development of high DON concentrations. © 2014, Springer Science+Business Media New York. Source

Stenberg M.,Swedish University of Agricultural Sciences | Ulen B.,Swedish University of Agricultural Sciences | Soderstrom M.,Swedish University of Agricultural Sciences | Roland B.,Rural economics and Agricultural Society of Skaraborg | And 2 more authors.
Science of the Total Environment

In order to explore the influence of site-specific soil properties on nitrogen (N) and phosphorus (P) losses between individual fields and crop sequences, 16 drained fields with clay soils were investigated in a four-year study. Mean total N (TN) loss was 6.6-11.1 from a conventional, 14.3-21.5 from an organic and 13.1-23.9kgha-1year-1 from an integrated cropping system across a 4year period, with 75% in nitrate form (NO3-N). Mean total P (TP) loss was 0.96-3.03, 0.99-4.63 and 0.76-2.67kgha-1year-1, from the three systems respectively during the same period, with 25% in dissolved reactive form (DRP). Median N efficiency was calculated to be 70% including gains from estimated N fixation. According to principal component factor (PCA) analysis, field characteristics and cropping system were generally more important for losses of N and P than year. Accumulation of soil mineral N in the autumn and (estimated) N fixation was important for N leaching. No P fertilisers were used at the site in either cropping system. Total P concentration in drainage water from each of the fields was marginally significantly (p<0.05) correlated to TP concentration in the topsoil (r=0.52), measured in hydrochloric acid extract (P-HCl). Mean DRP concentrations were significantly (p<0.01) correlated to degree of P saturation (DPS-AL) and soil carbon (C) content in the topsoil (r=0.63). Good establishment of a crop with efficient nutrient uptake and good soil structure was general preconditions for low nutrient leaching. Incorporation of ley by tillage operations in the summer before autumn crop establishment and repeated operations in autumn as well, increased N leaching. Crop management in sequences with leguminous crops needs to be considered carefully when designing cropping systems high efficiency in N utilisation and low environmental impact. © 2011 Elsevier B.V. Source

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