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Nitrogen (N) budgets at the farm gate level account for all N inputs and outputs in a particular farm. Indicators derived from the N budgets are crucial for characterising farm performance, due to the important role of N in food production and environmental sustainability. However, comparisons among farm N indicators from different farms, farm types and regions require conducting systematic monitoring of N budgets following a standardised and solid approach. Because of this, the EU N Expert Panel (EUNEP) developed a guidance document to estimate N inputs and outputs at the farm gate and calculate the N indicators. In this study, the EUNEP approach was applied to 1,240 farms from various case studies in Europe, with the aim of increasing understanding of the factors that contribute to differences in N indicators at the farm level, and to derive possible target values. Farm level data were collected from six countries located in five different environmental zones in Europe: Atlantic Central (France, Ireland, The Netherlands), Atlantic North (Denmark, Germany), Continental (Germany), Mediterranean North (Spain) and Mediterranean South (Spain). The N budgets were calculated for each farm, and the data were analysed to calculate three related indicators: Nitrogen use efficiency (NUE), N output and N surplus. The results show remarkable variations in N indicators across Europe. Arable farms had the lowest mean N input and N surplus and the highest mean N output and NUE, whereas livestock farms had the highest mean N input and N surplus, and the lowest mean N output and NUE. Median NUE was 61% for arable farms, 28% for dairy and 43% for pig farms. Externalisation had a large effect on animal farm N indicators, and the results highlight the need to introduce correction factors when calculating and interpreting the farm balance. After accounting for externalisation, median NUE decreased to 19% for dairy farms and 23% for pig farms. Therefore, several options were proposed to better consider feed production and manure management in N indicators calculations. Overall, the differences in NUE between farms were mainly related to differences in farm type, management (production intensity and practices) and probably also soil and climate conditions. Nitrogen indicator targets for specific farm types and linkages with agricultural or environmental policy may contribute to optimise NUE and reduce N surplus at the farm level.

Agricultural Nitrogen (N) management remains a key environmental challenge. Improving N management is a matter of urgency to reduce the serious ecological consequences of the reactive N. Nitrate (NO3 --N) leaching was measured under suckler beef production systems stocked at two intensities: 1. Intensive, 210 kg organic N ha-1 with two cut silage harvests; and 2. Rural Environmental Protection Scheme (REPS), 170 kg organic N ha-1 with one cut silage harvest. Three replicate plots of each treatment were instrumented with ceramic cups (8 per plot), randomly placed within each plot at a depth of 1 m to collect soil solution for NO3 --N at 50 kPa suction to collecting vessels one week prior to sampling. Samples were taken on a total of 53 sampling dates over 3 winter drainage periods (2002/03, 2003/04 and 2004/05). Over the course of the experiment the mean annual soil solution NO3 --N concentration exceeded the MAC twice out of 15 means (5 treatments over 3 years). The REPS grazing and silage sub treatments had significantly lower mean annual soil solution total oxidized N (TON) concentrations than the respective intensive treatments in years 2 and 3. Annual total NO3 --N losses over the three years in Intensive and REPS systems ranged from 55 to 71 and 15 to 20 kg N ha-1, respectively. Mean N surpluses in Intensive and REPS systems were 210 and 95 kg ha-1, respectively with the corresponding mean N inputs of 272 and 124 kg N ha-1. The reduction in N inputs under the REPS system results in lower N leaching losses and contributed to a significant reduction in pressures on water quality.

The application of agricultural biosolids to land is likely to increase on farms as pressures intensify to manage nutrients and carbon, especially with regard to slurry. Although much work has been carried out in this area, it has tended to focus on specific aspects of the application-use cycle, without a coherent framework and notably the role of soil biology has been little studied in this context, or considered appropriately in the development and application of slurry management systems. In this review article we present a hypothesis that the configuration of the soil microbial community is determined by the history of long-term inputs to which the community has been subjected and that the resultant configuration determines the instantaneous responses of the associated soil to the presence of slurries, and posit a set of critical questions which would effectively test this.

Animal manures and plant-based manures are used for biogas production by anaerobic digestion (AD). After AD the concentration of ammonium-N in manure is increased and the concentration of decomposable C is decreased. Thus, the potential first year fertilizer value of the manure can be increased by the treatment. However, pH is also increased by AD thereby increasing the risk of ammonia losses. The objective of this paper was to compare N turnover in soil after application of digested and corresponding undigested manures, and to compare N fertilizer values of digested manures after direct injection or surface-banding in cereals. After AD of pig and cattle slurry the increase in potential plant availability was equivalent to 10-25% of total manure N. AD of cattle faeces and a mixed cattle diet increased the net mineral N release in soil even more to about 60 and 80% of total N, respectively. The present results indicate that the plant availability of N of digested plant materials is similar to that of digested cattle slurry. After surface-banding of digested manures rich in fibers, such as cattle and plant-based manures, significant ammonia loss can be expected resulting in relatively poor utilization of manure N.