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In this paper, we estimate the cost-effectiveness of tillage methods as a measure to reduce phosphorus loss. The study was based on real-world information on costs. Data on phosphorus loss for different soil tillage methods were modelled. The cost-effectiveness of various soil tillage methods were related to autumn ploughing. The results showed large variation in cost-effectiveness related to erosion risk. Furthermore, spring harrowing was the most cost-effective method to reduce phosphorus loss, followed by autumn harrowing and spring ploughing in spring cereals. Implementation of changed tillage methods showed lower costs for spring cereals compared to winter wheat. The differences in costs between areas were most evident for spring tillage due to differences in yields and agronomic management. Cost-effectiveness is an important criterion in selecting mitigation methods, but due to large variations in the effect of changed tillage, these should be locally adapted to the high risk areas of erosion. [ABSTRACT FROM PUBLISHER]

This paper in a uniform manner examines temporal trends in phosphorus (P) concentrations and losses from small and well-monitored agricultural catchments in the Nordic and Baltic countries. Thirty-four catchments (range 0.1–33 km2) in Norway (8), Denmark (5), Sweden (8), Finland (4), Estonia (3), Latvia (3) and Lithuania (3) were selected for the study. The time series ranged from 10 (2002–2011) to 21 years (1989–2009). The monthly P concentration and loss time series were tested for significant monotone trends (p< 0.05; two-sided test) using the partial Mann–Kendall test with stream discharge as an explanatory variable. The results show a large variation in concentrations and losses of total phosphorus (TP) among the 34 studied catchments, where the long-term mean annual losses varied from 0.09 to 7.5 kg TP ha−1. In addition, a large interannual variability in losses within catchments was found with up to a factor of 23 between years within the same catchment. Six catchments showed downward temporal trends in the TP loss time series. One upward trend in TP losses was detected in a catchment in south-west Sweden. Eight downward trends were detected in the TP concentration time series. Overall, our results show (1) a huge variability in mean P losses and concentrations among catchments, (2) a huge temporal variability in losses within catchments and (3) few detectable changes in P losses and concentrations over the study period. The results showcase the need for implementation of mitigation strategies towards reduced P losses from agricultural landscapes in the Nordic/Baltic Sea region in order to improve P water quality and ecology in surface waters. [ABSTRACT FROM PUBLISHER]

Elevated nutrient concentrations in streams in the Norwegian agricultural landscape may occur due to faecal contamination.Escherichia coli(E. coli) has been used conventionally as an indicator of this contamination; however, it does not indicate the source of faecal origin. This work describes a study undertaken for the first time in Norway on an application of specific host-associated markers for faecal source tracking of water contamination. Real-time quantitative polymerase chain reaction (qPCR) onBacteroidaleshost-specific markers was employed for microbial source tracking (MST) to determine the origin(s) of faecal water contamination. Four genetic markers were used: the universal AllBac (Bacteroidales) and the individual specific markers BacH (humans), BacR (ruminants) and Hor-Bac (horses). In addition, a pathogenicity test was carried out to detect the top seven Shiga toxin-producingE. coli(STEC) serogroups. The ratio between each individual marker and the universal one was used to: (1) normalise the markers to the level of AllBac in faeces, (2) determine the relative abundance of each specific marker, (3) develop a contribution profile for faecal water contamination and (4) elucidate the sources of contamination by highlighting the dominant origin(s). The results of the qPCR MST analyses indicated the actual contributions of humans and animals to faecal water contamination. The pathogenicity test revealed that water samples were STEC positive at a low level, which was in proportion to the concentration of the ruminant marker. The outcomes were verified statistically by coupling the findings of major contamination sources with observations in the field regarding local land use (residential or agricultural). Furthermore, clear correlations between the human marker andE. colicounts as well as the ruminant marker and STEC quantity in faecally contaminated water were observed. The results of this study have the potential to help identify sources of pollution for targeted mitigation of nutrient losses. [ABSTRACT FROM PUBLISHER]

Elevated phosphorus (P) use is a worldwide problem for the sustainability of agricultural production with consequences for both food production and water quality. The objective of this paper was to investigate the effect of P application and P balance on stream P concentrations in different production systems of Norwegian agriculture. The average application of P in the studied catchments ranged from 21 to 53 kg P ha−1yr−1, including the P application in both mineral fertiliser and manure for the monitoring periods (16–20 years). The highest P application was found in a catchment with high livestock density, and potato and vegetable production. This catchment also showed the highest P balance (applied P minus P removed with yields) of 26 kg P ha−1yr−1on average, and also a very high soil P status (P-AL). The P balance for all other catchments ranged from 3 to 13 kg P ha−1yr−1. For all catchments, the average application of mineral P fertiliser decreased during the monitoring period, especially during the last 2–3 years. However, total P application increased in three catchments due to increased livestock density and manure P application. Average concentrations of total P in the streams varied from 65 to 392 µg L−1. The highest concentration was measured in the stream from the catchment with highest P balance and soil P status. The concentrations of dissolved reactive P varied from 27 to 63 µg L−1with the highest concentration measured from an area with intensive livestock production. Reducing P application and soil P status to the minimum level for crop growth is important for the environmental quality of surface waters. [ABSTRACT FROM AUTHOR]

With the increase in planting area of spring maize and nitrogen (N) application in Heilongjiang province, the high potential of N pollution to the environment and resource waste should be given urgent attention. In this study, N use efficiency (NUE), grain harvest index and partial factor productivity of nitrogen were calculated to evaluate the balance between N application, grain yield and soil N content based on a 3-year plot experiment with different N application. The results showed that high N application did not result in high NUE, rather it decreased, and that low N application with high NUE led to soil N deficit. Considering N surplus and NUE in spring maize production, the primary conclusion could be drawn that 180 kg N ha−1are acceptable both for grain yield and N risk to environment for spring maize in Harbin area. [ABSTRACT FROM AUTHOR]

Erosion and loss of soil is a large problem for water quality all over the world. Mitigation measures need to target the main sources of erosion at the right scale. For many areas there is still great uncertainty at the catchment level as to what are the main sources of erosion and how they can be managed. The objective of this article was to investigate the effect of tillage on soil losses at the field and catchment scale. Long-term monitoring data (20 years) from a catchment and a nested field site in the south eastern Norway were used. Results from the Vandsemb field showed that soil losses were on average 940 kg ha−1 yr−1 for years (n=5) when the field was autumn ploughed and 174 kg ha−1 yr−1 for years (n=8) when the field was not tilled in autumn. For the total monitoring period, surface soil losses were 330 kg ha−1 yr−1, whereas sub-surface soil losses were 130 kg ha−1 yr−1. Total phosphorus and dissolved reactive phosphorus (DRP) losses in surface runoff were 460 g ha−1 yr−1 and 150 g ha−1 yr−1, respectively and in sub-surface runoff they were 530 g ha−1 yr−1 and 270 g ha−1 yr−1, respectively. At the catchment scale, no relationship was found between the soil tillage on agricultural fields and the variation in losses of suspended sediments (SS) at the catchment scale. The average losses at Mørdre were for suspended sediments 2140 kg ha−1yr−1, for total phosphorus 2320 g ha−1 yr−1, and for DRP 240 g ha−1 yr−1. Weather conditions, especially during winter, were important for the temporal variation in losses of SS at both sites. Soil losses from the Mørdre catchment were approximately five times higher than from the Vandsemb field. The study findings suggest that changes in soil tillage were not the dominating cause of variations in loss of SS from the catchment, although these changes were important at the field scale. [ABSTRACT FROM PUBLISHER]

Soil erosion is considered a serious environmental problem in parts of Norway. The effect on water quality is the most important concern, and the improvement of water quality is the major aim for mitigation techniques and regulations on tillage. Documentation of effects of tillage practices therefore has a high priority. In this paper, results from five plot experiments are presented. They are all located in the grain-growing district in southeastern Norway on clay and loam soils. Tillage treatments for spring cereals and winter cereals are compared. The effect of tillage is pronounced on erodible soils. The results showed that annual average soil losses in surface runoff for autumn-tilled and spring-tilled plots were 7 and 0.8 t ha−1yr−1 at Bjørnebekk; 4.3 and 0.4 t ha−1yr−1 at Askim; 2.6 and 0.2 t ha−1yr−1 at Hellerud; 1.1 and 0.2 t ha−1yr−1 at Øsaker; and 0.18 and 0.1 t ha−1yr−1 at Syverud, respectively. The corresponding total phosphorus losses were 8.4 and 1.5 kg ha−1yr−1 at Bjørnebekk; 4.5 and 0.8 kg ha−1yr−1 at Askim; 3.0 and 0.8 kg ha−1yr−1 at Hellerud; 1.30 and 0.44 kg ha−1yr−1 at Øsaker; and 0.43 and 0.45 kg ha−1yr−1 at Syverud for autumn and spring tillage, respectively. The effects were less pronounced on soils with a lower erodibility, but reduced autumn tillage is the most effective way to mitigate soil erosion as well as total phosphorus losses. The study also showed that the total phosphorus losses are closely correlated with soil losses. The results show the importance of soil tillage for soil and phosphorus losses and suggest that farmers avoid autumn tillage on areas with high erosion risk. [ABSTRACT FROM PUBLISHER]

The phosphorus (P) Index, a risk assessment tool, is a simple approach used to rank the potential for P loss from agricultural fields. The P Index identifies areas where sources of P coincide with high risk of P transfer. Factors included in the P Index, developed for Pennsylvania, USA were justified in relation to Norwegian conditions and relevant changes were made. Phosphorus application rate was modified by crop P removal. Additional factors for: 1) P release by freezing of plant residues, 2) flooding frequency, 3) risk of leaching, and 4) annual precipitation were included. Management practices in the Index were adjusted to reflect the effect of time and method of P application on P loss, as well as erosion control measures relevant to agricultural management in Norway rather than Pennsylvania. Testing of the suggested P Index showed that it ranks the potential for P loss from several agricultural catchments in the south-eastern part of Norway relatively well ( R 2 =0.79). Continuous development of the Index to include new knowledge about processes for P loss as well as regional differences is of great importance for future use of the P Index. [ABSTRACT FROM AUTHOR]