Manure Application Techniques Research Articles

Impact of interannual weather variation on ammonia emissions and concentrations in Germany

Ammonia is one of the most impactful pollutants emitted from agricultural activities, harming human health and contributing to biodiversity loss. In ammonia emission inventories, the spatial distribution of annual emissions is mostly approximated by constant empirical emission fractions, which do not account for spatial variability, nor for temporal variability within a year or between years caused by weather variations. Besides, factors like manure properties, soil properties, and manure application techniques also lead to differences in the amount of ammonia emitted into the atmosphere. By not or only partly accounting for these factors, significant uncertainties are introduced into ammonia emission estimates at regional and national scales. In this study, we applied the empirical ALFAM2 model to derive spatially explicit slurry application emission fractions from cropland for use in the large-scale INTEGRATOR model, using the information on slurry properties (dry matter content and pH), manure application rate, application technique, incorporation time, air temperature, wind speed, and rainfall rate. In addition, the impact of weather on the ammonia emissions from animal housing and manure storage systems was included through a temperature-dependent scaling. We applied the method to investigate the year-to-year spatio-temporal variabilities of ammonia emissions and modeled concentrations across Germany from 2015 to 2018. Through the comparison with in situ measurements and satellite-derived observations, we studied how surface concentrations and total columns relate to local meteorology. We found that the spatio-temporal variability in emission fractions improves the ability to reproduce the interannual variability observed in ammonia concentration and total column measurements. This study shows that the developed approach to derive spatially explicit emission fractions can significantly improve ammonia emission modeling and is of great importance for studying the temporal variability between years.

Influence of manure application method on veterinary medicine losses to water

Veterinary medicines are routinely used within modern animal husbandry, which results in frequent detections within animal manures and slurries. The application of manures to land as a form of organic fertiliser presents a pathway by which these bioactive chemicals can enter the environment. However, to date, there is limited understanding regarding the influence of commonly used manure application methods on veterinary medicine fate in soil systems. To bridge this knowledge gap, a semi-field study was conducted to assess the influence of commonly used application methods such as, broadcast, chisel sweep, and incorporation on veterinary medicine losses to waters. A range of veterinary medicines were selected and applied as a mixture; these were enrofloxacin, florfenicol, lincomycin, meloxicam, oxytetracycline, sulfadiazine, trimethoprim and tylosin. All the assessed veterinary medicines were detected within surface runoff and leachates, and the concentrations generally decreased throughout the irrigation period. The surface runoff concentrations ranged from 0.49 to 183.47 μg/L and 2.26–236.83 μg/L for the bare soil and grass assessments respectively. The leachate concentrations ranged from 0.04 to 309.66 μg/L and 0.33–37.79 μg/L for the bare soil and grass assessments respectively. More advanced application methods (chisel sweep) were found to significantly reduce the mass loads of veterinary medicines transported to surface runoff and leachate by 13–56% and 49–88% over that of broadcast. Incorporating pig slurries reduced the losses further with surface runoff and leachate losses being 13–56% and 49–88% lower than broadcast. Our results show that manure application techniques have a significant effect on veterinary medicine fate in the environment and as such these effects should be considered in the decision-making processes for the management of manures as well as from a risk mitigation perspective for aquatic compartments.

Effects of Liquid Manure Application Techniques on Ammonia Emission and Winter Wheat Yield

Ammonia emissions following liquid manure application impair human health and threaten natural ecosystems. In growing arable crops, where immediate soil incorporation of the applied liquid manure is not possible, best-available application techniques are required in order to decrease ammonia losses. We determined ammonia emission, crop yield and nitrogen uptake of winter wheat in eight experimental sites across Germany. Each individual experiment consisted of an unfertilized control (N0), broadcast calcium ammonium nitrate (CAN) application as well as four different techniques to apply cattle slurry (CS) and biogas digestate (BD). Fertilizer was applied to growing winter wheat at a total rate of 170 kg N ha−1 split into two equal dressings. The following application techniques were tested for both liquid manure types: (i) trailing hose (TH) application using untreated and (ii) acidified (~pH 6) liquid manure (+A), as well as (iii) a combination of open slot injection (SI) for the first dressing and trailing shoe (TS) application for the second dressing without and (iv) with the addition of a nitrification inhibitor (NI) for the first dressing. The highest ammonia emissions (on average 30 kg N ha−1) occurred following TH application of BD. TH application of CS led to significantly lower emissions (on average 19 kg N ha−1). Overall, acidification reduced ammonia emissions by 64% compared to TH application without acidification for both types of liquid manures. On average, the combination of SI and TS application resulted in 23% lower NH3 emissions in comparison to TH application (25% for the first application by SI and 20% for the second application by TS). Supplementing an NI did not affect ammonia emissions. However, decreasing ammonia emissions by acidification or SI did not increase winter wheat yield and nitrogen uptake. All organically fertilized treatments led to similar crop yield (approx. 7 t ha−1 grain dry matter yield) and above-ground biomass nitrogen uptake (approx. 150 kg ha−1). Yield (8 t ha−1) and nitrogen uptake (approx. 190 kg ha−1) were significantly higher for the CAN treatment; while for the control, yield (approx. 4.5 t ha−1) and above-ground biomass nitrogen uptake (approx. 90 kg ha−1) were significantly lower. Overall, our results show that reducing NH3 emissions following liquid manure application to growing crops is possible by using different mitigation techniques. For our field trial series, acidification was the technique with the greatest NH3 mitigation potential.

Ammonia emission measurement with an online wind tunnel system for evaluation of manure application techniques

Abstract Field application of liquid manure contributes substantially to atmospheric ammonia. Low emission application methods are commonly used to reduce ammonia transfer to the atmosphere. To document which application method results in lower ammonia volatilization there is a need for high precision measurements to ensure that small differences in total emission and emission patterns can be quantified. This paper presents the evaluation and application of a new system of dynamic chambers (wind tunnels) with online cavity ring down spectroscopy measurements of ammonia. The system allows for high time resolution of 104 min throughout the measuring period (≥90 h) when testing two treatments and one reference in triplicates. Measurement variability is low with a coefficient of variation of 13 ± 8% within triplicates. The system was used to investigate the effect of trailing shoes compared to trailing hoses on different soil and crop types, where the expected differences in ammonia volatilization are low. The results show that when applying pig slurry on coarse sand a significant reduction of 47 ± 20% was obtained, whereas the reduction when applied on loamy sand and sandy loam was lower and occasionally insignificant. During ten experiments on three different soil types, an overall average reduction of ammonia volatilization from using trailing shoes compared to trailing hoses was found to be 19 ± 12%. Furthermore, the importance of correct use of trailing hoses was examined by comparing with application above the crop canopy. Application at the ground surface gave an ammonia emission reduction of 40 ± 13% compared to application 20 cm above the canopy.

Coupling crop and bio-economic farm modelling to evaluate the revised fertilization regulations in Germany

The German Fertilization Ordinance, implementing mainly the EU Nitrates Directive, was revised in 2017. We couple the bio-economic farm model FarmDyn and the crop system modelling framework SIMPLACE to assess the environmental and economic impact of the revised ordinance. The analysis focuses on specialized pig fattening and arable farms in the federal state of North Rhine-Westphalia. Most dominant farm types are derived from a farm typology based on the German Farm Structure Survey 2016. Following the revised ordinance, a farm type representing pig farms with a high stocking density lowers its emissions from 50 to 38 kg nitrate (NO3−) nitrogen ha−1 and 18 to 8 kg ammonia (NH3) nitrogen ha−1 from manure application. Compliance costs are 2.32 Euro (€) pig−1 and are mainly caused by the need to export manure to meet the stricter nutrient surplus thresholds. A pig farm type with lower stocking density mainly adapts to the compulsory use of low-emission manure application techniques, resulting in almost constant NO3− leaching, a NH3 reduction from manure application of 13 to 9 kg NH3- nitrogen ha−1, and compliance costs of 0.42 € pig−1. The two assessed arable farm types, which start to import manure under the revised ordinance, can lower costs by 109 and 118 € ha−1. However, manure import increases NO3− leaching and NH3 volatilization. Our results show that intensive pig farms realize a high emission reduction and lose a relevant share of their standard gross margin when complying with the revised ordinance. However, farm types with low stocking density, representing a high share of the pig farms in the study area, show little or no changes in costs and emissions. These findings are relevant for efficient enforcement and targeted support measures. Furthermore, the import of manure on arable farms comprises the danger of regional pollution swapping, which policymakers should address by complementary measures. Future research should focus on improving the data base for crop modelling and on scaling-up the farm model to the regional scale to directly link emission changes and environmental targets.

The Response of CO2 Flux to Soil Warming, Manure Application and Soil Salinity

In this research effect of different soil types (normal and saline), farmyard manure norms (2 ton/ha - 4 ton/ha), manure application techniques (surface and subsurface) and soil temperature levels (20-25°C, 25-30°C, 30-35°C, 35-40°C, 40-45°C and 45-50°C) were examined of the soil CO2 flux on the pots at the laboratory conditions. According to obtained results, soil type (ST), manure norm (MN), manure application technique (MAT) and soil temperature (T) values changed CO2 flux. CO2 flux value of saline soil condition smaller than the normal soil condition. As an expected result, increased the manure amount increased the CO2 flux from soil to atmosphere. However, CO2 flux on the condition that subsurface manure application was less than surface manure application. CO2 flux values at the high soil temperatures were more than low soil temperature conditions. According to the interaction (T*ST, T*MN and T*MAT) results were not statistically significant. Soil CO2 flux were affected by gradually increasing of temperature.

On-farm compliance costs with the EU-Nitrates Directive: A modelling approach for specialized livestock production in northwest Germany

In the EU, several environmental regulations aim at protecting the environment from agricultural nitrogen and phosphorus losses. The German regulation on farmers' nutrient management, especially implementing the EU Nitrates Directive, was revised in 2017. It comprises considerable tightening of numerous measures and costs for farmers to comply with. We provide the first systematic farm-level analysis of compliance costs of the recent revision in a case study for the federal state of North Rhine-Westphalia. To do so, we apply a bio-economic optimisation model at farm level to a representative sample of specialized dairy and pig farms. The sample is derived by Latin Hypercube sampling based on the observed distribution of farm characteristics from official agricultural statistics. Modelling results are evaluated by grouping of farms and a statistical meta-model. Results show highly heterogeneous compliance costs reaching from 0 to 2.66 Euro per pig and 0 to 0.83 cent per kg milk. 47.3% of pig and 38.4% of dairy farms do not face any costs. Pig farms with high compliance costs are characterized by high stocking density, the absence of low-emission manure application techniques and phosphorus-enriched soils. Dairy farms with high compliance costs have no low-emission manure application techniques and a high share of grassland. For dairy farms, stricter thresholds for nutrient application do not cause any compliance costs. The meta-model reveals the large effect of prices and assumptions regarding the fertilizer management on compliance costs. Results are of relevance beyond the case study area as other regions in the EU have a similar agricultural structure and need to fulfill the same EU directives. Policymakers need to be aware that high compliance costs increase the incentive of non-compliance and also consider heterogeneous impacts when designing complementary policies. Future research should focus on long-term adaption of farmers and include transaction costs as well as technical progress.

Accounting for uncertainties in ammonia emission from manure applied to grassland

A recent study has raised doubts about the ammonia emission reduction achieved in the Netherlands when applying manure to grassland by means of low-emission techniques such as narrow band and shallow injection. The critics claim that percentages of ammonia released to the atmosphere associated with low-emission techniques might even overlap with that from surface broadcast spreading given the large alleged experimental uncertainties in measurements. Consequently, the rationale behind the regulations to which farmers are exposed is questioned. In this study, it is shown that the alleged large uncertainties were obtained by means of an erroneous statistical method and that the real uncertainties are much smaller. It is also shown that, even when there is a large uncertainty in individual measurements, previous conclusions about differences in emission between different manure application techniques are still valid. It is further argued in this study that uncertainty in the percentage of applied ammonia emitted is implicitly taken into account in any comparative statistical analysis conducted in the past.

Assessing ammonia emission abatement measures in agriculture: Farmers' costs and society's benefits – A case study for Lower Saxony, Germany

Ammonia (NH3) emissions have adverse impacts on the environment and, being a precursor for fine particulate matter, also on human health. About 95% of NH3 emissions in Germany originate from agriculture, mainly from livestock husbandry. This case study is aimed at presenting an approach that evaluates NH3 emission abatement measures in agriculture regarding their abatement costs for farmers and their benefits for the society in terms of avoided external costs of health damages and loss of terrestrial biodiversity. Following the impact-pathway chain, an economic-ecological farm model for estimating NH3 emission reductions and abatement costs was combined with an environmental impact assessment model for estimating the benefits for human health and biodiversity. The case study analysed a variety of manure storage cover and application techniques in Lower Saxony, a region in the north-west of Germany with the highest livestock density in Germany and high NH3 emissions. In the reference situation, the damage costs of NH3 emissions were EUR 2.7 billion. The implementation of concrete storage covers and slurry injection, the most effective measures, reduced NH3 emissions by 25% and achieved net benefits of EUR 505 million. Farmers' abatement costs averaged over all farms ranged from EUR 3.6 to 6.8 per kilogramme NH3 reduced. The abatement costs per farm type ranged from EUR 2.4 to 16.6 for floating plastic covers and from EUR 2.2 to 11.4 for concrete covers. The abatement costs for floating plastic covers were lower for grazing livestock specialists, while the abatement costs for concrete covers were lower for pig specialists, poultry specialists and mixed farms. Farm type specific abatement costs for manure application techniques ranged from EUR 4.5 to 9.6 per kilogramme NH3 reduced with little variation between trailing shoe and cultivator/injector techniques. Abatement costs for trailing shoe application were lower than for cultivator/injector application for grazing livestock specialists, poultry specialists and mixed farms. The average benefits per kilogramme NH3 reduced were EUR 14.1 for health and EUR 10.4 for biodiversity, totalling EUR 24.5. As the benefits exceed the abatement costs for all measures analysed in this study, principally, they can be recommended for implementation. However, the variation in abatement potentials and costs per farm type indicate differences in suitability. While manure covers should above all be implemented by pig specialists because of their high abatement potential, manure application techniques should be implemented by grazing livestock specialists. Among manure storage covers, floating plastic covers are more favourable for grazing livestock specialists, whereas concrete covers are more suitable for all other farm types. The analysis with the farm model was considered more appropriate than recent analyses at technical or macroeconomic level, because the abatement costs reflect differences in farm types, detailed production processes and farmers' profit-maximising behaviour. Overall, it can be concluded that an assessment of NH3 emission abatement measures should be carried out for farm types and should consider impacts of NH3 emission abatement both on human health and biodiversity. The presented modelling approach enables to estimate abatement costs for farm types and benefits for human health and biodiversity. Cost-efficient NH3 emission abatement measures tailored to farm types can be identified and farm type specific regional abatement strategies can be developed.

Production and management of cattle manure in the UK and implications for land application practice

AbstractA review of livestock and manure management across the UK was undertaken as part of a wider study of important factors impacting on greenhouse and other gaseous emissions from agriculture. All major livestock sectors were covered by the review, but only data on cattle manure are reported in this study. Cattle manure comprises 67 Mt (80%) of the total 83 Mt of UK annual livestock manure production during the housing period. Overall, about 47% of total UK cattle manure production was estimated to be as undiluted slurry and 53% as solid, mainly straw‐based farmyard manure (FYM). Survey data suggested important regional differences in cattle manure management across the UK; examples include the predominance of slurry in SW Scotland, N Ireland and to a lesser extent, in Wales, compared to the continued importance of straw‐based FYM systems in England. Survey data on land application of manures from the British Survey of Fertiliser Practice (BSFP) generally showed the expected distribution of cattle manure application timings, dominated by crop sowing/establishment or growth patterns. However, in recent years, an apparent increase in land spreading in February–April, with less application in November–January is encouraging, the trend towards spring/early summer spreading of cattle slurry suggesting greater appreciation of its value as a nutrient source. BSFP returns on manure application techniques have also shown increasing uptake of shallow injection of cattle slurry, from <1% (2004) to 10% (2013) and for increasing rapid (<6 h) incorporation of FYM, from 3% (2007) to 14% (2013).

Combined analysis of climate, technological and price changes on future arable farming systems in Europe

In this study, we compare the relative importance of climate change to technological, management, price and policy changes on European arable farming systems. This required linking four models: the SIMPLACE crop growth modelling framework to calculate future yields under climate change for arable crops; the CAPRI model to estimate impacts on global agricultural markets, specifically product prices; the bio-economic farm model FSSIM to calculate the future changes in cropping patterns and farm net income at the farm and regional level; and the environmental model INTEGRATOR to calculate nitrogen (N) uptake and losses to air and water. First, the four linked models were applied to analyse the effect of climate change only or a most likely baseline (i.e. B1) scenario for 2050 as well as for two alternative scenarios with, respectively, strong (i.e. A1-b1) and weak economic growth (B2) for five regions/countries across Europe (i.e. Denmark, Flevoland, Midi Pyrenées, Zachodniopomorski and Andalucia). These analyses were repeated but assuming in addition to climate change impacts, also the effects of changes in technology and management on crop yields, the effects of changes in prices and policies in 2050, and the effects of all factors together. The outcomes show that the effects of climate change to 2050 result in higher farm net incomes in the Northern and Northern–Central EU regions, in practically unchanged farm net incomes in the Central and Central–Southern EU regions, and in much lower farm net incomes in Southern EU regions compared to those in the base year. Climate change in combination with improved technology and farm management and/or with price changes towards 2050 results in a higher to much higher farm net incomes. Increases in farm net income for the B1 and A1-b1 scenarios are moderately stronger than those for the B2 scenario, due to the smaller increases in product prices and/or yields for the B2 scenario. Farm labour demand slightly to moderately increases towards 2050 as related to changes in cropping patterns. Changes in N2O emissions and N leaching compared to the base year are mainly caused by changes in total N inputs from the applied fertilizers and animal manure, which in turn are influenced by changes in crop yields and cropping patterns, whereas NH3 emissions are mainly determined by assumed improvements in manure application techniques. N emissions and N leaching strongly increase in Denmark and Zachodniopomorski, slightly decrease to moderately increase in Flevoland and Midi-Pyrenées, and strongly decrease in Andalucia, except for NH3 emissions which zero to moderately decrease in Flevoland and Denmark.

SPECIAL TOPICS — Mitigation of methane and nitrous oxide emissions from animal operations: II. A review of manure management mitigation options1

This review analyzes published data on manure management practices used to mitigate methane (CH4) and nitrous oxide (N2O) emissions from animal operations. Reducing excreted nitrogen (N) and degradable organic carbon (C) by diet manipulation to improve the balance of nutrient inputs with production is an effective practice to reduce CH4 and N2O emissions. Most CH4 is produced during manure storage; therefore, reducing storage time, lowering manure temperature by storing it outside during colder seasons, and capturing and combusting the CH4 produced during storage are effective practices to reduce CH4 emission. Anaerobic digestion with combustion of the gas produced is effective in reducing CH4 emission and organic C content of manure; this increases readily available C and N for microbial processes creating little CH4 and increased N2O emissions following land application. Nitrous oxide emission occurs following land application as a byproduct of nitrification and dentrification processes in the soil, but these processes may also occur in compost, biofilter materials, and permeable storage covers. These microbial processes depend on temperature, moisture content, availability of easily degradable organic C, and oxidation status of the environment, which make N2O emissions and mitigation results highly variable. Managing the fate of ammoniacal N is essential to the success of N2O and CH4 mitigation because ammonia is an important component in the cycling of N through manure, soil, crops, and animal feeds. Manure application techniques such as subsurface injection reduce ammonia and CH4 emissions but can result in increased N2O emissions. Injection works well when combined with anaerobic digestion and solids separation by improving infiltration. Additives such as urease and nitrification inhibitors that inhibit microbial processes have mixed results but are generally effective in controlling N2O emission from intensive grazing systems. Matching plant nutrient requirements with manure fertilization, managing grazing intensity, and using cover crops are effective practices to increase plant N uptake and reduce N2O emissions. Due to system interactions, mitigation practices that reduce emissions in one stage of the manure management process may increase emissions elsewhere, so mitigation practices must be evaluated at the whole farm level.

Assessment of nitrogen content in buffalo manure and land application costs

Buffalo (<em>Bubalus bubalis</em>) livestock for mozzarella cheese production plays a fundamental role in the economy of southern Italy. European and Italian regulations consider nitrogen content in buffalo manure to be the same as that of cattle manure. This study aimed to assess whether this assumption is true. The first aim of the study was to assess nitrogen content in buffalo manure. Samples were taken from 35 farms to analyse nitrogen and phosphorous concentration in the manure. Analysis confirmed a lower nitrogen concentration (2%) in buffalo manure. A secondary aim of the study was to evaluate whether manure application techniques that are apparently less suitable,<em> e.g.</em> splash plate spreader, could be feasible. The cost of different methods of land application of manure and their characteristics were evaluated on the basis of one operational cycle. Considering losses for volatilisation, and taking into account cost assessment, the immediate incorporation of buffalo manure (nitrogen content 2%) is a suitable method of ammonia volatilisation. However, it is expensive and involves high fuel consumption in relation to the environmental benefit.

A model for inventory of ammonia emissions from agriculture in the Netherlands

Agriculture is the major source of ammonia (NH3). Methodologies are needed to quantify national NH3 emissions and to identify the most effective options to mitigate NH3 emissions. Generally, NH3 emissions from agriculture are quantified using a nitrogen (N) flow approach, in which the NH3 emission is calculated from the N flows and NH3 emission factors. Because of the direct dependency between NH3 volatilization and Total Ammoniacal N (TAN; ammonium–N + N compounds readily broken down to ammonium) an approach based on TAN is preferred to calculate NH3 emission instead of an approach based on total N. A TAN-based NH3-inventory model was developed, called NEMA (National Emission Model for Ammonia). The total N excretion and the fraction of TAN in the excreted N are calculated from the feed composition and N digestibility of the components. TAN-based emission factors were derived or updated for housing systems, manure storage outside housing, manure application techniques, N fertilizer types, and grazing. The NEMA results show that the total NH3 emission from agriculture in the Netherlands in 2009 was 88.8 Gg NH3–N, of which 50% from housing, 37% from manure application, 9% from mineral N fertilizer, 3% from outside manure storage, and 1% from grazing. Cattle farming was the dominant source of NH3 in the Netherlands (about 50% of the total NH3 emission). The NH3 emission expressed as percentage of the excreted N was 22% of the excreted N for poultry, 20% for pigs, 15% for cattle, and 12% for other livestock, which is mainly related to differences in emissions from housing systems. The calculated ammonia emission was most sensitive to changes in the fraction of TAN in the excreted manure and to the emission factor of manure application. From 2011, NEMA will be used as official methodology to calculate the national NH3 emission from agriculture in the Netherlands

Optimising manure management for GHG outcomes

This paper focuses on improvements to livestock manure management to reduce environmental pollution and emission of greenhouse gases (GHG). Livestock manures contain large amounts of plant nutrients and organic matter (OM). Structural changes to livestock production and ample supply of cheap chemical fertilisers have decreased the interest and possibilities of farmers in using manure for the fertilisation of crops and grasslands and maintenance of soil fertility. As a result, many livestock producers dispose of manure as cheaply as possible causing serious pollution of soil, water and atmosphere. In addition, livestock production systems contribute to climate change by emission of the GHG carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Careful recycling of livestock manures to fertilise crops and grasslands and improve soil fertility is considered the most suitable and cost-effective option for environmentally friendly disposal. Manure management legislation in The Netherlands is described to explain the principles. These include complete collection of faeces and urine of confined livestock, adaptation of the period and rate of manure application to the N and P requirements of crops, and use of manure collection, storage and application techniques aiming at low ammonia (NH3) losses. Effects of sustainable manure management on GHG emissions are described. Optimising the period, rate and technique of manure application to crops and grassland causes effective utilisation of manure N and reduces direct and indirect losses of N2O. In addition, effective recycling of manure nutrients and OM allows a reduction in the use of chemical fertilisers and fossil energy and contributes to the maintenance or improvement of the carbon content of agricultural ecosystems. The relatively high costs of sustainable manure management stimulate farmers to optimise feed conversion and minimise manure production per unit of product by good livestock feeding and management practices. High feed conversion efficiency reduces CH4 emission by enteric fermentation and may reduce feed imports and related GHG emissions. In addition, it is shown that livestock categories differ widely in feed conversion efficiency and N and P excretion per unit of product. Finally, anaerobic digestion of livestock slurries provides a valuable energy source and reduces CH4 emission of stored slurry and, possibly, N2O emission after field application of the slurry.

Interpretation of results from on-farm experiments: manure-nitrogen recovery on grassland as affected by manure quality and application technique. 1. An agronomic analysis

In a 5-year field experiment, a comparison was made between the manure application practices of two adjacent dairy farms in the north of the Netherlands. Grassland management systems at Drogeham and Harkema contrasted in manure application technique (surface application versus shallow injection, respectively), quality of applied manure (slurry + MX: slurry with Euromestmix® clay mineral additive versus regular slurry), and some relevant site characteristics (high versus low soil organic matter content and soil moisture supply). Effects of manure types and application techniques, and treatment of the soil with a micro-organism supplement, were tested in a factorial experiment at the two sites, two blocks per site, one with and one without additional application of 157 kg N ha −1 year −1 inorganic fertilizer. Apparent N recovery was higher after shallow injection than after surface application. For plots receiving no additional inorganic fertilizer, this difference was largest for slurry + MX applied at site Harkema, since this slurry-site combination resulted in the highest observed average apparent N recovery following shallow injection (47%) and the lowest N recovery following surface application (20%). For plots receiving additional inorganic fertilizer N the contrasts between treatments were less pronounced. Year effects on N uptake and dry matter production could be related to cumulative temperature and precipitation surplus over the growing season. A simple comparison between the grassland management systems was carried out based on the response curves derived from the experiment. This demonstrated that the grassland system where slurry was applied by shallow injection is not necessarily the lowest in actual amount of N not accounted for (i.e., potentially lost). The efficiency of the Harkema system strongly depended on high N recovery, but showed high potential losses in some years and a high herbage crude protein content in other years, due to the low DM production capacity. On the other hand, the Drogeham system was tuned to high DM production and was characterized by higher system stability, as reflected by more stable relationships between DM production and N not accounted for and herbage crude protein content. These differences between the systems were probably to a large extent caused by differences in water balance and soil organic matter content.

Nutrient flows for poultry production in The Netherlands

Government targets for ammonia emission and for N and P loss per hectare (ha) of agricultural land were used to assess carrying capacity for poultry production in The Netherlands with data from 1990. In addition, the effect of alternative management strategies on carrying capacity was determined. Ammonia emission from poultry production in 1990 [20.5 gigagrams (Gg) N] exceeded the target for 2000 (i.e., 6.9 Gg N). Targets defined for 2000 and 2010 (i.e., 4.6 Gg N) can be achieved, however, without reducing poultry numbers, assuming national introduction of measurements studied. Measures that reduced ammonia emission directly, i.e., introduction of low-emission housing or manure application techniques, were most effective. In 1990, N and P losses equalled 215 kg/ha for N and 31 kg/ha for P. The N loss was slightly lower than the target for 2000 (219 kg N/ha) but exceeded the target for 2010 (144 kg N/ha). Reduction of application of artificial N fertilizer, however, reduced N loss effectively from 215 to 22 kg/ha. National P loss in 1990 exceeded the target for 2000 (15.3 kg P/ha). Reduction of application of artificial P fertilizer reduced P loss most effectively from 31 to 14 kg/ha. To achieve the target for 2010 (8.7 kg P/ha), additional reduction in P excretion by poultry is required. This reduction can be achieved by use of phytase in layer and broiler feed and by use of a coarse Ca source in layer feed. Unlike pig production, carrying capacity for poultry production in The Netherlands is not limited by governmental targets for acidification, eutrophication, or drinking water contamination.

Nutrient flows in agriculture in The Netherlands with special emphasis on pig production.

Annual nitrogen (N), phosphorus (P), and potassium (K) flows in agriculture in The Netherlands were identified and quantified in 1990, with special emphasis on pig production. Also, the effects that various management strategies in pig production have on NPK emission in 1990 were compared using a static deterministic simulation model. Ammonia emission from pig production in 1990 (60.9 Gg N) exceeded the defined target for the year 2000 (12.7 Gg N). Measures that affect volatilization of ammonia directly (i.e., introduction of low-emission stables, manure storage facilities, or manure application techniques) reduced ammonia emission most effectively. These measures, however, should be combined with a reduction in application of artificial N fertilizer to avoid an increase in N losses through leaching, run-off, or denitrification. Targets for ammonia emission in the year 2010 require a reduction in the pig population of 24 to 62%, in addition to implications of measures described in this article. National NPK losses in 1990 through leaching, run-off, or denitrification, predicted at 223.5 kg/ha for N, 32.7 kg/ha for P, and 67 kg/ha for K, exceeded government targets for the year 2010 (185 kg N/ha; 8.7 kg P/ha; norm not set for K). Reducing application of artificial NPK fertilizer reduced national NPK losses most effectively. For P, use of phytase and feeding pigs in accordance with their P requirements is required, in addition to limited use of artificial P fertilizer to meet targets for the year 2010. Hence, from an environmental point of view, pig production in The Netherlands is limited primarily by ammonia emission targets for the year 2010.