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Soil erosion reduces the sustainability of agricultural sector by loss of productive soil and through negative impacts on surface waters. In Finland, considerable efforts have been made to reduce soil erosion, but the suspended sediment loads to surface waters have not markedly reduced. A major limitation has been the lack of high-resolution data on erosion risk for efficient targeting of the erosion management efforts. In this study, by using the Revised Universal Soil Loss Equation (RUSLE) a two-meter resolution erosion risk data was developed and consequently the spatial distribution of the erosion risk of Finnish agricultural land was analysed. With agricultural management practices of 2019, the average erosion of agricultural land was estimated to be 430 kg ha-1 yr-1, and it varied at the municipality scale from 100 to 1290 kg ha-1 yr-1. At more local scales the erosion risk had even greater variability, and areas with high erosion risk were differently located in terms distances to water bodies. The results also suggest that the past erosion management efforts have not been well-targeted according to the actual erosion risk. Altogether, the results indicate that erosion mitigation measures can be improved by inclusion of high-resolution data in the planning and implementation of the measures, by considering the spatial variability of the erosion risk over multiple spatial scales, and by implementation of location specific erosion reduction measures. [ABSTRACT FROM AUTHOR]

To achieve appropriate yield levels, inherent nitrogen (N) supply and biological N fixation are often complemented by fertilization. To avoid economic losses and negative environmental impacts due to over‐application of N fertilizer, estimation of the inherent N supply is critical. We aimed to identify the roles of soil texture and organic matter in N mineralization and yield levels attained in cereal cultivation with or without N fertilization in boreal mineral soils. First, the net N mineralization and soil respiration were measured by laboratory incubation with soil samples varying in clay and organic carbon (C) contents. Secondly, to estimate the inherent soil N supply under field conditions, both unfertilized and fertilized cereal yields were measured in fields on clay soils (clay 30–78%) and coarse‐textured soils (clay 0–28%). In clay soils (C 2.5–9.0%), both the net N mineralization and the cereal yields (without and with fertilization) decreased with increasing clay/C ratio. Moreover, in soils with high clay/C ratio, the agronomic N use efficiency (additional yield per kg of fertilizer N) varied considerably, indicating the presence of growth limitations other than N. In coarse‐textured soils, the yield increase attained by fertilization increased with increasing organic C. Our results indicate that for clay soils in a cool and humid climate, the higher the clay content, the more organic C is needed to produce reasonable yields and to ensure efficient use of added nutrients without high N losses to the environment. For coarse soils having a rather high mean organic C of 2.3%, the organic C appeared to improve agronomic N use efficiency. For farmers, simple indicators such as the clay/C ratio or the use of non‐N‐fertilized control plots may be useful for site‐specific adjustment of the rates of N fertilization. Highlights: We aimed to identify simple indicators of inherent soil N supply applicable at the farm level.In clay soils, the net N mineralization was found to correlate negatively with the clay/C ratio.In coarse‐textured soils, agronomic N use efficiency improved with increasing soil organic C.Clay soils with high clay/C ratio are at risk of low yield levels. [ABSTRACT FROM AUTHOR]

Nitrogen (N) and phosphorus (P) are both essential plant nutrients. However, their joint response to plant growth is seldom described by models. This study provides an approach for modeling the joint impact of inorganic N and P fertilization on crop production, considering the P supplied by the soil, which was approximated using the soil test P (STP). We developed yield response models for Finnish spring barley crops (Hordeum vulgare L.) for clay and coarse-textured soils by using existing extensive experimental datasets and nonlinear estimation techniques. Model selection was based on iterative elimination from a wide diversity of plausible model formulations. The Cobb-Douglas type model specification, consisting of multiplicative elements, performed well against independent validation data, suggesting that the key relationships that determine crop responses are captured by the models. The estimated models were extended to dynamic economic optimization of fertilization inputs. According to the results, a fair STP level should be maintained on both coarse-textured soils (9.9 mg L-1 a-1) and clay soils (3.9 mg L-1 a-1). For coarse soils, a higher steady-state P fertilization rate is required (21.7 kg ha-1 a-1) compared with clay soils (6.75 kg ha-1 a-1). The steady-state N fertilization rate was slightly higher for clay soils (102.4 kg ha-1 a-1) than for coarse soils (95.8 kg ha-1 a-1). This study shows that the iterative elimination of plausible functional forms is a suitable method for reducing the effects of structural uncertainty on model output and optimal fertilization decisions. [ABSTRACT FROM AUTHOR]

The lattice Boltzmann method is increasingly utilized in the simulation of flow-induced wall shear stress needed in various applications. In image-based flow simulations, the simulation geometry is usually based on a three-dimensional reconstruction of the true structure of the pore space obtained, for example, by X-ray tomography. The geometry is then given in a voxel-based representation, which complicates an accurate determination of the surface-normal vectors that are necessary in the computation of the wall shear stress. To avoid this problem, we introduce here a method for the determination of surface-normal vectors directly from a greyscale image instead of its segmented binary image version. The proposed method is fast and automatic, and it can be used for an arbitrary pore space geometry provided in a greyscale form by any imaging modality. We show that this method can produce accurate surface-normal vectors even for binary images and that their accuracy is further increased when the original greyscale images are used instead. We compute wall shear stresses for generated benchmark geometries and then demonstrate the utility of the method for soil samples with ‘random’ pores imaged by X-ray tomography. [ABSTRACT FROM AUTHOR]

Changes in land use alter the natural cycling of phosphorus (P) in soil. Understanding the chemical nature of these changes is important when developing sustainable management practices for cultivated soils. In this study, we evaluated the ability of commonly used laboratory methods to characterize land use-induced changes in various P pools. Also, the characteristics of soil P revealed by different methods are discussed. Soil samples were taken from three differently managed field plots of the same clay soil: uncultivated grassland and organic and conventional crop rotations. Soil P reserves were characterized using Chang and Jackson and Hedley sequential fractionation procedures and by sodium hydroxide (NaOH)-ethylenediaminetetraacetic acid (EDTA) extraction followed by 31P NMR spectroscopy. Both of the tested fractionation methods identified differences in the P pools and provided evidence regarding land use-induced changes. However, the 31P NMR analysis suggests that the quality of organic P in this soil was not affected by the change in land use. [ABSTRACT FROM AUTHOR]

Fertilizer applications should be based on relevant yield response models and be economically justified. In this study, we defined the yield response models of cereals to phosphorus (P) fertilization on the major Finnish soil types by the means of a research synthesis and meta-analysis. We also calculated economically optimum P rates under different price combinations of P fertilizer (1-3 € kg) and cereal yields (100-300 € tn), for 1-year decision interval of P applications. Our material consisted of data on P fertilizer experiments conducted in Finland during the last 60 years on clay, coarse-textured mineral and organic soils, with variable soil test P (STP) status at the start of the experiments. The cereals cultivated were spring barley, oats, spring and winter wheat, and winter rye. The applied P rates ranged between 6 and 100 kg ha. For low STP classes, Mitscherlich-type exponential models were appropriate for all soil groups, predicting 17-27% higher maximum yields when compared to the controls without added P. In contrast, for medium and high STP classes, the yield responses to increasing P rates were scattered around zero in most soils. Phosphorus fertilization had also negligible effect on 1,000-seed and test weights. On Finnish cereal farms, when P fertilizer is purchased, the present P rates allowed by the Agri-Environmental Programme are uneconomically high. It appears that P fertilization can be substantially reduced on majority of Finnish fields, or even omitted for years, without economic loss under current (2 € kg) or higher P fertilizer prices. [ABSTRACT FROM AUTHOR]

Glyphosate [(N-(phosphonomethyl)glycine)] is a widely used herbicide and it is known to compete for the same sorption sites in soil as phosphorus. Persistence and losses of glyphosate were monitored in a field with low phosphorus status and possible correlation between glyphosate and phosphorus leaching losses was studied. Glyphosate and its metabolite AMPA (aminomethyl phosphonic acid) residues in soil samples were analysed after a single application in autumn. Twenty months after the application the residues of glyphosate and AMPA in the topsoil (0–25 cm) corresponded to 19% and 48%, respectively, of the applied amount of glyphosate, and traces of glyphosate and AMPA residues were detected in deeper soil layers (below 35 cm). These results indicate rather long persistence for glyphosate in boreal soils. Surface runoff and subsurface drainflow were collected continuously all year round for 20 months and analysed for glyphosate, AMPA, dissolved phosphate, total phosphorus and total suspended solids. The glyphosate concentrations in the surface runoff water were highest, with 99% of the total leaching losses obtained, during the periods of snow melting and soil thawing in the first winter following the autumn application. The total leaching of glyphosate was 5.12 g ha−1 and that of AMPA 0.48 g ha−1, corresponding to about 0.51% and 0.07%, respectively, of the applied amount of glyphosate. No residues of glyphosate and AMPA were detected in the subsurface drainflow. The correlations between concentrations of glyphosate and dissolved orthophosphate as well as glyphosate and total phosphorus in surface runoff were significant ( p < 0.01). [ABSTRACT FROM AUTHOR]

Increased nutrient loading causes deterioration of receiving surface waters in areas of intensive agriculture. While nitrate and particulate phosphorus load can be efficiently controlled by reducing tillage frequency and increasing vegetation cover, many field studies have shown simultaneously increased loading of bioavailable phosphorus. In the latest phase of the Rural Programme of EU agri-environmental measures, the highest potential to reduce the nutrient loading to receiving waters were the maximum limits for fertilization of arable crops and retaining plant cover on fields with, e.g., no-till methods and uncultivated nature management fields. Due to the latter two measures, the area of vegetation cover has increased since 1995, suggesting clear effects on nutrient loading in the catchment scale as well. We modeled the effectiveness of agri-environmental measures to reduce phosphorus and nitrogen loads to waters and additionally tested the performance of the dynamic, process-based INCA-P (Integrated Nutrients in Catchments—Phosphorus) model to simulate P dynamics in an agricultural catchment. We concluded that INCA-P was able to simulate both fast (immediate) and slow (non-immediate) processes that influence P loading from catchments. Based on our model simulations, it was also evident that no-till methods had increased bioavailable P load to receiving waters, even though total P and total N loading were reduced. [ABSTRACT FROM AUTHOR]

In the European Union, various crop diversification systems such as crop rotation, intercropping and multiple cropping, as well as low-input management practices, have been promoted to sustain crop productivity while maintaining environmental quality and ecosystem services. We conducted a data analysis to identify the benefits of crop associations, alternative agricultural practices and strategies in four selected regions of Europe (Atlantic, Boreal, Mediterranean North and Mediterranean South) in terms of crop production (CP). The dataset was derived from 54 references with a total of 750 comparisons and included site characteristics, crop information (diversification system, crop production, tillage and fertilization management) and soil parameters. We analyzed each effect separately, comparing CP under tillage management (e.g., conventional tillage vs. no tillage), crop diversification (e.g., monoculture vs. rotation), and fertilization management (e.g., mineral fertilization vs. organic fertilization). Compared with conventional tillage (CT), CP was higher by 12% in no tillage (NT), in fine- and medium-textured soils (8–9%) and in arid and semiarid sites located in the Mediterranean Region (24%). Compared to monoculture, diversified cropping systems with longer crop rotations increased CP by 12%, and by 12% in soils with coarse and medium textures. In relation to fertilization, CP was increased with the use of slurry (40%), and when crop residues were incorporated (39%) or mulched (74%). Results showed that conversion to alternative diversified systems through the use of crop rotations, with NT and organic fertilization, results in a better crop performance. However, regional differences related to climate and soil-texture-specific responses should be considered to target local measures to improve soil management. [ABSTRACT FROM AUTHOR]

In the last few decades, various crop diversification strategies and management practices have been promoted to improve or at least maintain environmental quality and agroecosystem services. We conducted a data-analysis to evaluate the effectiveness of alternatives for crop diversification and environmentally friendly farming management for arable crops in four selected European pedoclimatic regions and typical cropping systems in the Atlantic, Boreal, Mediterranean North, and Mediterranean South regions. The dataset was retrieved from 38 references and included data on site-specific environmental conditions, soil tillage, crop rotation, fertilization, and final soil organic carbon content (SOC). No tillage (NT) was more effective (7%) in increasing SOC content than minimum tillage (MT) across the studied depths (from 5 to 40 cm). Conservation tillage as whole, including NT, MT, and rotational tillage (RT) positively affected SOC content in the top 10 cm (28%) in comparison with conventional tillage (CT). Compared to monoculture, longer crop rotations (3–5 years) and the introduction of legumes resulted in higher increases in SOC contents (18%), that were higher in semiarid conditions (11%) than under humid and sub-humid climates (3.2%). The effect of fertilization on SOC contents was higher in the Mediterranean North region (28%), and organic fertilization showed the highest increases (25%) compared to the control with mineral fertilization. Higher increases in SOC contents with tillage and fertilization management were found in sites with lower SOC contents in the control treatment (conventional tillage and mineral fertilization respectively). The data analysis indicated that various European arable agroecosystems benefit both from diversified cropping systems and the adoption of environmentally friendly farming management and are thereby capable to increase SOC contents. [ABSTRACT FROM AUTHOR]