Evaluating Non-Market Values of Agroecological and Socio-Cultural Benefits of Diversified Cropping Systems.

We explored how consumers value the ecological and socio-cultural benefits of diversified food production systems in Finland. We used a stated preference method and contingent valuation to quantify consumers' willingness to pay (WTP) for the benefits of increased farm and regional scale diversity of cultivation practices and crop rotations. Three valuation scenarios were presented to a representative sample of consumers: the first one focused on agroecosystem services on cropland, the second on wider socio-cultural effects and the third was a combination of them. The results suggest that consumers are willing to pay on the average €228 per household annually for the suggested diversification. This is equal to €245 per hectare of cultivated cropland. The results also indicate that 21% of consumers were not willing to pay anything to support more diverse cropping systems. The relatively high WTP for both agroecological and socio-cultural benefits provide important messages for actors in the food chain and for policy makers on future targeting of economic resources within agri-environmental schemes.

Modelling CO2 and CH4 emissions from drained peatlands with grass cultivation by the BASGRA-BGC model.

Cultivated peatlands under drainage practices contribute significant carbon losses from agricultural sector in the Nordic countries. In this research, we developed the BASGRA-BGC model coupled with hydrological, soil carbon decomposition and methane modules to simulate the dynamic of water table level (WTL), carbon dioxide (CO2) and methane (CH4) emissions for cultivated peatlands. The field measurements from four experimental sites in Finland, Denmark and Norway were used to validate the predictive skills of this novel model under different WTL management practices, climatic conditions and soil properties. Compared with daily observations, the model performed well in terms of RMSE (Root Mean Square Error; 0.06-0.11 m, 1.22-2.43 gC/m2/day, and 0.002-0.330 kgC/ha/day for WTL, CO2 and CH4, respectively), NRMSE (Normalized Root Mean Square Error; 10.3-18.3%, 13.0-18.6%, 15.3-21.9%) and Pearson's r (Pearson correlation coefficient; 0.60-0.91, 0.76-0.88, 0.33-0.80). The daily/seasonal variabilities were therefore captured and the aggregated results corresponded well with annual estimations. We further provided an example on the model's potential use in improving the WTL management to mitigate CO2 and CH4 emissions while maintaining grass production. At all study sites, the simulated WTLs and carbon decomposition rates showed a significant negative correlation. Therefore, controlling WTL could effectively reduce carbon losses. However, given the highly diverse carbon decomposition rates within individual WTLs, adding indicators (e.g. soil moisture and peat quality) would improve our capacity to assess the effectiveness of specific mitigation practices such as WTL control and rewetting.

Nitrogen stocks and flows in an acid sulfate soil.

Besides causing acidification, acid sulfate (AS) soils contain large nitrogen (N) stocks and are a potential source of N loading to waters and nitrous oxide (N2O) emissions. We quantified the stocks and flows of N, including crop yields, N leaching, and N2O emissions, in a cultivated AS soil in western Finland. We also investigated whether controlled drainage (CD) and sub-irrigation (CDI) to keep the sulfidic horizons inundated can alleviate N losses. Total N stock at 0-100 cm (19.5 Mg ha-1) was smaller than at 100-200 cm (26.6 Mg ha-1), and the mineral N stock was largest below 170 cm. Annual N leaching (31-91 kg N ha-1) plus N in harvested grain (74-122 kg N ha-1) was 148% (range 118-189%) of N applied in fertilizers (90-125 kg N ha-1) in 2011-2017, suggesting substantial N supply from soil reserves. Annual emissions of N2O measured during 2 years were 8-28 kg N ha-1. The most probable reasons for high N2O emission rates in AS soils are concomitant large mineral N pools with fluctuating redox conditions and low pH in the oxidized subsoil, all favoring formation of N2O in nitrification and denitrification. Although the groundwater level was higher in CD and CDI than in conventional drainage, N load and crop offtake did not differ between the drainage methods, but there were differences in emissions. Nitrogen flows to the atmosphere and drainage water were clearly larger than those in non-AS mineral soils indicating that AS soils are potential hotspots of environmental impacts.

Climate and Soil Characteristics Determine Where No-Till Management Can Store Carbon in Soils and Mitigate Greenhouse Gas Emissions.

Adoption of no-till management on croplands has become a controversial approach for storing carbon in soil due to conflicting findings. Yet, no-till is still promoted as a management practice to stabilize the global climate system from additional change due to anthropogenic greenhouse gas emissions, including the 4 per mille initiative promoted through the UN Framework Convention on Climate Change. We evaluated the body of literature surrounding this practice, and found that SOC storage can be higher under no-till management in some soil types and climatic conditions even with redistribution of SOC, and contribute to reducing net greenhouse gas emissions. However, uncertainties tend to be large, which may make this approach less attractive as a contributor to stabilize the climate system compared to other options. Consequently, no-till may be better viewed as a method for reducing soil erosion, adapting to climate change, and ensuring food security, while any increase in SOC storage is a co-benefit for society in terms of reducing greenhouse gas emissions.

Tillage and crop residue management methods had minor effects on the stock and stabilization of topsoil carbon in a 30-year field experiment.

We studied the effects of tillage and straw management on soil aggregation and soil carbon sequestration in a 30-year split-plot experiment on clay soil in southern Finland. The experimental plots were under conventional or reduced tillage with straw retained, removed or burnt. Wet sieving was done to study organic carbon and soil composition divided in four fractions: 1) large macroaggregates, 2) small macroaggregates, 3) microaggregates and 4) silt and clay. To further estimate the stability of carbon in the soil, coarse particulate organic matter, microaggregates and silt and clay were isolated from the macroaggregates. Total carbon stock in the topsoil (equivalent to 200 kg m(-2)) was slightly lower under reduced tillage (5.0 kg m(-2)) than under conventional tillage (5.2 kg m(-2)). Reduced tillage changed the soil composition by increasing the percentage of macroaggregates and decreasing the percentage of microaggregates. There was no evidence of differences in the composition of the macroaggregates or carbon content in the macroaggregate-occluded fractions. However, due to the higher total amount of macroaggregates in the soil, more carbon was bound to the macroaggregate-occluded microaggregates in reduced tillage. Compared with plowed soil, the density of deep burrowing earthworms (Lumbricus terrestris) was considerably higher under reduced tillage and positively associated with the percentage of large macroaggregates. The total amount of microbial biomass carbon did not differ between the treatments. Straw management did not have discernible effects either on soil aggregation or soil carbon stock. We conclude that although reduced tillage can improve clay soil structure, generally the chances to increase topsoil carbon sequestration by reduced tillage or straw management practices appear limited in cereal monoculture systems of the boreal region. This may be related to the already high C content of soils, the precipitation level favoring decomposition and aggregate turnover in the winter with topsoil frost.

Declining trend of carbon in Finnish cropland soils in 1974-2009.

Soil organic matter not only affects soil properties and productivity but also has an essential role in global carbon (C) cycle. We studied changes in the topsoil C content of Finnish croplands using a dataset produced in nationwide soil monitoring. The monitoring network consisting of fields on both mineral and organic soils was established in 1974 and resampled in 1987, 1998, and 2009. Over the monitoring period from 1974 to 2009, cultivated soils showed a continuous decline in C concentration (g kg(-1) ). In organic soils, C concentration decreased at a mean rate of 0.2-0.3% yr(-1) relative to the existing C concentration. In mineral soils, the relative decrease was 0.4% yr(-1) corresponding to a C stock (kg m(-2) ) loss of 220 kg ha(-1)  yr(-1) . The change in management practices in last decades toward increasing cultivation of annual crops has contributed to soil C losses noted in this study. The results, however, suggest that the C losses result partly from other processes affecting cultivated soils such as climatic change or the continuing long-term effect of forest clearance. We estimated that Finnish cropland soils store 161 Tg carbon nationwide in the topmost 15 cm of which 117 Tg is in mineral soils. C losses from mineral soils can therefore total up to 0.5 Tg yearly.

Fluxes of N2O, CH4 and CO2 in a meadow ecosystem exposed to elevated ozone and carbon dioxide for three years.

Open-top chambers (OTCs) were used to evaluate the effects of moderately elevated O3 (40-50 ppb) and CO2 (+100 ppm) and their combination on N2O, CH4 and CO2 fluxes from ground-planted meadow mesocosms. Bimonthly measurements in 2002-2004 showed that the daily fluxes of N2O, CH4 and CO2 reacted mainly to elevated O3, while the fluxes of CO2 also responded to elevated CO2. However, the fluxes did not show any marked response when elevated O3 and CO2 were combined. N2O and CO2 emissions were best explained by soil water content and air and soil temperatures, and they were not clearly associated with potential nitrification and denitrification. Our results suggest that the increasing O3 and/or CO2 concentrations may affect the N2O, CH4 and CO2 fluxes from the soil, but longer study periods are needed to verify the actual consequences of climate change for greenhouse gas emissions.

Carbon sequestration potential in European croplands has been overestimated.

Yearly, per-area carbon sequestration rates are used to estimate mitigation potentials by comparing types and areas of land management in 1990 and 2000 and projected to 2010, for the European Union (EU)-15 and for four country-level case studies for which data are available: UK, Sweden, Belgium and Finland. Because cropland area is decreasing in these countries (except for Belgium), and in most European countries there are no incentives in place to encourage soil carbon sequestration, carbon sequestration between 1990 and 2000 was small or negative in the EU-15 and all case study countries. Belgium has a slightly higher estimate for carbon sequestration than the other countries examined. This is at odds with previous reports of decreasing soil organic carbon stocks in Flanders. For all countries except Belgium, carbon sequestration is predicted to be negligible or negative by 2010, based on extrapolated trends, and is small even in Belgium. The only trend in agriculture that may be enhancing carbon stocks on croplands at present is organic farming, and the magnitude of this effect is highly uncertain. Previous studies have focused on the potential for carbon sequestration and have shown quite significant potential. This study, which examines the sequestration likely to occur by 2010, suggests that the potential will not be realized. Without incentives for carbon sequestration in the future, cropland carbon sequestration under Article 3.4 of the Kyoto Protocol will not be an option in EU-15.