Estimation of N2O emission factors for soils depending on environmental conditions and crop management

Nitrous oxide (N2O) contributes 8% to anthropogenic global warming, of which about one third are direct emissions of agricultural soils. These N2O emissions are often estimated using the default IPCC 2006 emission factor of 1% of the amount of N applied for mineral fertilizer, manure and crop residues. However, a large variation in emission factors exists due to differences in environment (e.g. weather and soil conditions), crops (grassland, arable land, crop residues) and management (e.g. type of manure and fertilizer, application rates, time of application). We developed a simple approach to determine N2O emission factors that depend on environmental, crop and management factors. The main factors controlling N2O emission are nitrate content, oxygen content, available C content, temperature and pH. The starting point of the method was a two-year monitoring study of Velthof et al. (1996), who found an emission factor of exactly 1% for grassland on a sandy soil fertilized with calcium ammonium nitrate. The conditions of this experiment were set as the reference from which the effects of other environmental conditions and management on the N2O emission factor were estimated. Based on literature and expert knowledge we determined for 19 sources of N input, three soil types, two land use types, three precipitation classes, two pH classes and three temperature classes the effect on the default emission factor. The calculated N2O emission factors ranged from 0 to 10%. The approach was applied to a European scale, using the INTEGRATOR model. The results were also produced with the standard IPCC approach and the empirical approach by Stehfest and Bouwman (2006). Differences in the overall results at EU27 scale and at regional scale are discussed. The emission factors derived from this inference scheme can improve predictions of N2O emissions with integrated large-scale model

Comparison of indices for the prediction of nitrogen mineralization after destruction of managed grassland

Intensively managed grasslands are occasionally chemically killed with herbicide and ploughed in order to grow an arable crop. After this management, large N mineralization rates with large losses to the environment are commonly observed. However, it remains to be determined to what extent the chemical killing contribute to increased N mineralization. In this study the potential nitrogen (N) mineralization from grasslands, that were killed with herbicides but otherwise undisturbed, was investigated in a laboratory experiment with undisturbed soil columns. Subsequently we assessed the predictive value of several laboratory indices for N mineralization after chemically killing of the grass. Mineralization rates varied from 0.5 to 3.0 g N m-2 wk-1. The contents of total N, total C, dissolved organic carbon (DOC) and hot-KCl extractable NH4 + were best related to N mineralization rates (R2=50, 48, 38 and 47%, respectively). In combination with information on the N content of the roots and stubble and the age of grassland at destruction, up to 62% of the variation in N mineralization rates could be explained. Although previous studies suggested that dissolved organic nitrogen (DON) is a good indicator for mineralization rates, this was not the case after chemically killing grass in the current study

Kunstmestvervangers onderzocht; een tussenstand

Informatieblad over kunstmestvervanger

Synthesis of the research within the framework of the Mineral Concentrates Pilot

The agronomic, economic and environmental impacts of the production of mineral concentrate and its use as mineral fertilizer were examined in a pilot in 2009 and 2010. In this pilot, the mineral concentrates were applied as fertilizer above the application standard for manure, but within the nitrogen application standard of the Nitrates Directive. The study consisted of i) monitoring of products from slurry treatment, ii) research on agricultural and environmental impacts of application of mineral concentrate as fertilizer, iii) research on user experience and an economic analysis and iv) Life Cycle Assessment (LCA). This report is a synthesis of the results of the various studies. The research data will serve for consultation with the European Commission on a possible permanent permission to use of mineral concentrates as replacement of mineral fertilizers

Regionaal nutriëntenmanagement; een verkenning van perspectieven en beperkingen

De van oudsher monofunctionele landbouw verandert steeds meer in een multifunctionele landbouw, waarin meerdere functies van het landelijke gebied worden verweven. Met behulp van regionaal nutriëntenbeheer kan worden ingespeeld op regiospecifieke landbouwkundige, milieukundige en economische randvoorwaarden die aan landbouw worden gesteld. In deze studie zijn perspectieven en beperkingen van regionaal nutriëntenbeheer verkend. Voor veel landbouwbedrijven is een forse inspanning nodig om aan de normenvan het voorgenomen uniforme mestbeleid te voldoen. In sommige regio's zijn wellicht stringentere normen nodig en in andere regio's wellicht minder stringente. Regionaal nutriëntenbeheer speelt hierop in. Perspectieven voor regionaal nutriëntenbeheer liggen vooral in het beheer van nutriëntenstromen tussen verschillende (landbouw)sectoren in een regio, de aanpak van specifieke milieuproblemen, regionale bemestingsadviezen, landbouwvoorlichting en waterbeheer

Nitrous oxide emissions from multiple combined applications of fertiliser and cattle slurry to grassland

Fertiliser and manure application are important sources of nitrous oxide (N2O) emissions from agricultural soils. The current default IPCC emission factor of 1.0% is independent of the type of fertiliser and manure, and application time, method and rate. However, in the IPCC Tiered system it is possible to use more specific emission factors that better reflect the actual fertiliser and manure management in a given country or region. The first and primary aim of this study was to determine whether the combination of cattle slurry injection with fertiliser application, which is common practice in intensively managed grasslands in the Netherlands and neighbouring countries, warrants an adjusted emission factor. A second aim was to evaluate whether alternative emission factors, based on N uptake and N surplus, respectively, give more insight in the N2O emission rates of various fertilisation strategies. In a 2-year field experiment on sandy soil in the Netherlands we measured the annual N2O emission from grasslands receiving repeated simultaneous applications of fertiliser and cattle slurry. The N2O fluxes and N uptake by grass were measured from plots receiving calcium ammonium nitrate (CAN) at four application rates, either with or without additional application of liquid cattle slurry, applied through shallow soil injection. The average emission factor for fertiliser-only treatments was 0.15%. The annual N2O emissions were similar for treatments receiving only fertiliser or only cattle slurry. In the first experimental year, application of cattle slurry increased the emission factor for fertiliser to 0.35%, but the second year showed no effect of cattle slurry on the emission from fertiliser. With regard to the first objective, we conclude that these results do not conclusively justify an adjusted emission factor for combined application of fertiliser and cattle slurry. To minimise risks however, it is sensible to avoid simultaneous application of fertiliser and cattle slurry. The N2O emission factor expressed as percentage of kg N uptake by grass was consistently higher after combined application of fertiliser and cattle slurry (0.29%), compared to fertiliser-only (0.17%). With regard to the second objective we conclude that an emission factor based on N uptake expresses the relatively inefficient N supply of cattle slurry to crop growth better than the traditional emission factor based on N application

Effects of ageing and cultivation of grassland on soil nitrogen

Nitrogen losses from agriculture in the Netherlands have to be strongly decreased because of national and international policy (e.g. Nitrate Directive). The cultivation of grassland when grassland is renewed or converted into arable land may enhance net nitrogen mineralization and, thereby, nitrogen losses via leaching and denitrification. These nitrogen losses can be decreased by adjustment of management, but a good insight into the soil processes during ageing and after cultivation of grassland is required. A literature study was carried out to quantify the effects of ageing and cultivation of grassland on nitrogen losses from the soil. The study shows that the risk on losses increases when grassland age increases, the period between cultivation and reseeding increases and the nitrogen uptake capacity of the next crop decreases. In the Netherlands, only a few studies have been carried out and, especially, a quantification of the effects of cultivation on nitrogen losses under Dutch conditions is lacking. It is recommended to set up integral field studies in which both the agricultural and environmental effects of grassland cultivation are quantified. The results must be used to develop measures and tools to achieve environmentally and agriculturally sound systems of permanent and temporal grasslands

Kunstmestvervangers onderzocht; Ammoniak- en lachgasemissies

Onderzoek naar praktijkervaringen met kunstmestvervangers. In dit informatieblad staan de emissies van ammoniak (NH3) en lachgas (N2O) centraal. Bij toediening van mineralenconcentraten aan de bodem kunnen emissies van ammoniak (NH3) en lachgas (N2O) optreden. Het mineralenconcentraat bestaat uit een ammoniumoplossing met een laag gehalte aan organische stikstof en een hoge pH. De combinatie van de aanwezigheid van ammonium en een hoge pH leidt tot een risico op ammoniakemissie. Dit risico kan beperkt worden door het concentraat emissie-arm toe te dienen

Some environmental aspects of grassland cultivation; the effects of ploughing depth, grassland age, and nitrogen demand of subsequent crops

The Netherlands has submitted a derogation under the Nitrate Directives to the European Union (EU) in 2000. In the final opinion by a group of experts about the Dutch derogation, recommendations on ploughing of grasslands were included dealing with i) the depth of ploughing of permanent grassland, ii) the age of temporary grassland and iii) the nitrogen demand of the subsequent crop of temporary grassland. A literature study was carried out in order to provide scientific information on these three issues. No studies were found in literature in which the effects of cultivation depth on nitrogen mineralisation and losses in reseeded grassland were assessed. The results of transformation of grassland into arable land show no clear effects of ploughing depth on N mineralisation. Differences in nitrogen mineralisation after 5 and 3 years temporary grassland are small. Italian and perennial ryegrass, potato, silage maize, winter wheat, and several vegetables have a high nitrogen demand (i.e. >250 kg N ha-1)