CLIMATE - SOIL - BALTIC SEA - BIODIVERSITY

Peer-reviewed studies from the Carbon Action platform

PLANT BIODIVERSITY PROMOTES SOIL MICROBIAL COMMUNITIES AND SUSTAINABLE AGRICULTURE

CAPPELLI, SERAINA ET AL. 2022. PLANT BIODIVERSITY PROMOTES SUSTAINABLE AGRICULTURE DIRECTLY AND VIA BELOWGROUND EFFECTS. TRENDS IN PLANT SCIENCE. |

Plant diversity is known to have positive effects on ecosystem functioning. The extent to which this is mediated via soil microbiota remains unclear. This article gives an overview of the current state of knowledge about the relationships between plant diversity, soil microbiota, and ecosystem functioning. The authors state that plant diversity increases microbial diversity – and that both above- and belowground biodiversity can help to enhance and maintain the sustainability of agricultural ecosystems. There are still knowledge gaps regarding to the interactions between plants and soil microbes in different environments, and the effects of agricultural practices on the link between biodiversity and ecosystem functioning.

CLIMATE CHANGE INDUCES CARBON LOSS FROM ARABLE MINERAL SOILS

HEIKKINEN, JAAKKO ET AL. 2022. CLIMATE CHANGE INDUCES CARBON LOSS OF ARABLE MINERAL SOILS IN BOREAL CONDITIONS. GLOBAL CHANGE BIOLOGY. |

One-fourth of the global soil organic carbon (SOC) is stored in the boreal region, where climate is warming fast. In this study, SOC content of topsoil in arable lands decreased on average at the rate of 0.35 % per year between 2009–2018. The most important drivers of the soil carbon loss were the increase in summertime (May–Sep) temperature and increased precipitation. Former organic soils were particularly prone to high SOC losses. It seems that although SOC content can be increased by management practices, such as diversifying crop rotations and cultivating perennial grasses, it is unlikely that these management practices are sufficient to counterbalance all the climate-change-induced SOC losses. Thus, it is important to reduce greenhouse gas emissions, too.

CALIBRATING SOIL CARBON MODEL WITH MULTIPLE DATASETS IMPROVES THE MODEL’S PERFORMANCE

VISKARI, TONI ET AL. 2022. CALIBRATING THE SOIL ORGANIC CARBON MODEL YASSO20 WITH MULTIPLE DATASETS. GEOSCIENTIFIC MODEL DEVELOPMENT. |

Soil carbon models can be used for assessing global soil carbon distributions and changes in carbon stocks. The models’ performances are affected by the data and methods used to calibrate them. In soil carbon modelling, the calibration refers to comparing the values produced by the model to the values of soil carbon measurement datasets. In this study, the performance of an updated version of soil carbon model Yasso, named Yasso20, was assessed when calibrated with one or with multiple datasets. Yasso20 was also compared to the previous version of the Yasso model. The results demonstrated that the model showed a better global performance, when calibrated with data from multiple different ecosystems. Yasso20 model performed better with the validation data than the previous version of the model.

FIELD OBSERVATORY – AGRICULTURAL SOIL CARBON MONITORING, REPORTING AND VERIFICATION

Nevalainen, Olli et al. 2022. Towards agricultural soil carbon monitoring, reporting and verification through Field Observatory Network (FiON). GEOSCIENTIFIC INSTRUMENTATION, METHODS AND DATA SYSTEMS |

Better monitoring of sequestered soil carbon in different soils and climate conditions is necessary for improving carbon farming practices and understanding their impacts. Field Observatory Network (FiON) has established a methodology towards monitoring and forecasting agricultural carbon sequestration by combining offline and near-real-time field measurements, weather data, satellite imagery and modelling. An open, web-based dashboard called Field Observatory (fieldobservatory.org) has been built to disseminate the work and the results.

A COMMON AGRICULTURAL SOIL TEST MEASURES LEGACY PHOSPHORUS ACCUMULATED IN DRAINAGE DITCHES

MATTILA, TUOMAS & EZZATI, GOLNAZ. 2022. A COMMON AGRICULTURAL SOIL TEST CAN IDENTIFY LEGACY P HOTSPOTS IN A DRAINAGE DITCH NETWORK. JOURNAL OF ENVIRONMENTAL MANAGEMENT |

Legacy phosphorus refers to the accumulated phosphorus in excess to soil phosphorus storage capacity. When there is more phosphorus than the soil can store, phosphorus is prone to leaching. Commonly used Mehlich-3 soil test can identify phosphorus saturation and legacy phosphorus. In this study, previously published data based on samples taken from sediments of drainage ditch bankside soils, was re-analysed. According to the results, the cost effective Mehlich-3 soil test is an appropriate tool for locating the hotspots with most susceptible soil phosphorus to losses in the ditch network.

ESTIMATING CATION EXCHANGE CAPACITY FROM AGRONOMIC SOIL TESTS

MATTILA, TUOMAS & RAJALA, JUKKA. 2021. ESTIMATING CATION EXCHANGE CAPACITY FROM AGRONOMIC SOIL TESTS: COMPARING MEHLICH-3 AND AMMONIUM ACETATE SUM OF CATIONS SOIL SCIENCE SOCIETY OF AMERICA JOURNAL |

Soil cation exchange capacity (CEC) measures the soil’s ability to hold and release nutrients. Because measuring CEC is laborious, faster methods to estimate CEC from soil samples have been developed. In this study, the results from two common estimation methods were compared with a dataset of 48 soil samples. The compared estimation methods differ in their extraction: Mehlich-3:a is commonly used in the USA, AAc in Europe. Based on the results, these traditional methods underestimate measured cation exchange capacity by 36% for Mehlich-3 and 24% for AAc. Thus, the CEC estimation methods should be updated. The estimation can be improved by including aluminium content (leads to 12 % overestimate) or by developing the mathematical model used (3 % overestimate). Offering land managers accurate information allows them to understand their soils’ potential to store and release nutrients and to make better decisions on liming and soil amendment.

HOW DO FARMERS CHOOSE THE CARBON FARMING PRACTICES?

MATTILA, TUOMAS ET AL. 2021. HOW FARMERS APPROACH SOIL SEQUESTRATION? LESSONS LEARNED FROM 105 CARBON-FARMING PLANS. SOIL AND TILLAGE RESEARCH |

In this study, 105 Finnish farmers were trained for the basics of carbon farming and instructed to make a Carbon Farming Plan for one of their fields. The Carbon Farming Plans were evaluated by a team of experts and through soil carbon balance calculations. In addition, potential nutrient limitations and the existing carbon stock were identified from soil tests. The assessment of the plans indicated high potential for additional soil carbon storage. The quality of most plans was good. The largest carbon storage potential was estimated for measures with large additions of nutrient-poor amendments, such as biochar and paper mill sludge, or in grazing. The farmers favoured measures with relatively low carbon storage benefits but high potential benefits for soil structure and productivity. The magnitude of planned carbon storage over 5 years on most farms was so small, that it is challenging to measure it through soil sampling. This finding supports the earlier conclusions that a combination of modelling and soil sampling is needed to verify the carbon storage.

DIFFERENCES OF AGRONOMIC SOIL TESTS IN IDENTIFYING NUTRIENT DEFICIENCIES

MATTILA, TUOMAS & RAJALA, JUKKA. 2021. DO DIFFERENT AGRONOMIC SOILT TESTS IDENTIFY SIMILAR NUTRIENT DEFICIENCIES? SOIL USE AND MANAGEMENT |

In this study, five commercially available soil tests, which evaluate soil nutrient levels, were compared using soil samples collected from 24 fields during a short-term (4 years) soil quality experiment. The different tests resulted in different magnitudes of nutrients, but the results were correlated. However, the tests identified different nutrient deficiencies. Local calibration is needed for interpretation of the tests’ results for the nutrient deficiencies. The findings indicated that soil testing should be used as a complementary tool and not a replacement for plant tissue testing.

SMARTPHONE-BASED ESTIMATION OF GREEN COVER DEPENDS ON THE CAMERA USED

MATTILA, TUOMAS & HEINONEN, REIJA. 2021. SMARTPHONE-BASED ESTIMATION OF GREEN COVER DEPENDS ON THE CAMERA USED. AGRONOMY JOURNAL |

Smartphone-based visual assessment of vegetation cover is a promising, fast, and repeatable approach that allows land managers to compare measurements on their farm with other farms. This study determined the influence of the smartphone device on green cover measurements on several crops. Forty fields in Finland were sampled between 10 and 28 July 2020. The results were compared also with Sentinel-2 remote sensing of normalized difference vegetation index (NDVI) and biomass quadrants. The findings suggest that smartphone-based monitoring can be used at least to classify vegetation to low, medium, and high density but that results from different cameras should not be compared.

EFFECTS OF TILLAGE MANAGEMENT ON CLAY SOIL PROPERTIES AND EROSION

HONKANEN, HENRI ET AL. 2021. Response of boreal clay soil properties and erosion to ten years of no-till management. SOIL & TILLAGE. |

This study compared the effects of conventional tillage and no-till management on soil properties and soil carbon at a clay soil site sown with spring cereal in southwestern Finland. Total soil erosion was 56 % less in no-till than in conventional tillage, although the surface water discharge from the no-tilled fields was higher. In no-till, the topsoil had higher proportion of large macroaggregates and more organic carbon bound to them. Moreover, the earthworm density and their species number were higher. No-tillage is an effective method to reduce soil erosion and to increase the carbon content of topsoil, but also other means to increase carbon input especially below the topsoil layer of clay soils are necessary.

AN AGRICULTURAL GRASSLAND IN SOUTHERN FINLAND WAS A CARBON SINK IN A 2-YEAR STUDY

HEIMSCH, LAURA ET AL. 2020. Carbon dioxide fluxes and carbon balance of an agricultural grassland in southern Finland. BIOGEOSCIENCES DISCUSS |

This study was conducted in an agricultural grassland site conversing from intensive towards regenerative agricultural management. Carbon dioxide fluxes between the field and the atmosphere were measured for two years from 2018 to 2020. The first summer studied was particularly dry, which reduced the field’s carbon dioxide fluxes. However, the field acted as a carbon sink during both measurement years.

A ROADMAP TO ECOLOGICAL DATA-MODEL INTEGRATION

FER, ISTEM ET AL. 2020. BEYOND ECOSYSTEM MODELING: A ROADMAP TO COMMUNITY CYBERINFRASTRUCTURE FOR ECOLOGICAL DATA‐MODEL INTEGRATION. GLOBAL CHANGE BIOLOGY |

Integrating different measurement efforts and observations into ecosystem models is a bottleneck for fully exploiting the available data. This study takes a look at the information infrastructure that connects ecosystem modelling and measurements, and proposes a roadmap to reduce the divisions between empirical research and modelling. The authors conclude that the use of accessible, scalable, and transparent research tools which utilize the expertise of the whole scientific community, is a key to data-model integration. Based on this, Carbon Action is developing a verification system for soil carbon sequestration.

CLIMATE CHANGE MITIGATION IN AGRICULTURE: MEASURES, COSTS AND POLICIES

OLLIKAINEN, M. ET AL. 2020. CLIMATE CHANGE MITIGATION AND AGRICULTURE: MEASURES, COSTS AND POLICIES – A LITERATURE REVIEW. AGRICULTURAL AND FOOD SCIENCE |

This literature review focused on the use of policy instruments to incentivise the adoption of greenhouse gas mitigation measures on farms. Carbon taxes and emissions trading were assessed to perform best, although they involve challenges in measuring and verifying changes in the emissions. Estimation of carbon sequestration in arable soils faces problems of the heterogeneity in sequestration capacity and the permanence of sequestration. Different models and measurements also produce highly variable estimates of the emissions reductions and the costs. More consistent information is needed for policy designs.

SOIL ORGANIC CARBON AND CLAY CONTENT ARE DECIDING FACTORS FOR CEREAL YIELDS

SOINNE, HELENA ET AL. 2020. Soil organic carbon and clay content as deciding factors for net nitrogen mineralization and cereal yields in boreal mineral soils. EUROPEAN JOURNAL OF SOIL SCIENCE |

Soil organic carbon and clay contents affect nitrogen mineralisation, nitrogen fertilizer needs of crops, and yields in boreal mineral soils. To achieve appropriate yield levels, farmers often complement soil nitrogen supply by fertilization. Estimation of the inherent soil nitrogen supply is vital for avoiding the economic losses and negative environmental impacts caused by overapplication of nitrogen fertilizers. This study aimed to identify simple indicators of soil nitrogen supply applicable at the farm level.

Clay soils with high clay/carbon ration were found to be at risk of low yield levels. Nitrogen mineralization reduced with the increasing clay/carbon ratio. Thus, according to this study, higher clay content of a field requires more organic carbon for achieving the adequate yields. In coarse-textured mineral soils, nitrogen use efficiency increased with increasing soil organic carbon.

Estimation of carbon stocks in boreal cropland soils

Hekkinen, Jaakko et al. 2020. Estimation of carbon stocks in boreal cropland soils ‐ methodological considerations. European Journal of Soil Science |

Harnessing agricultural soils as carbon sinks requires methods for verifying changes in soil organic carbon stocks. More precise estimates of the effects of different land-use and management types on soil organic carbon are also needed. In this study, a sample set included in the Finnish national soil monitoring network was used to determine the soil organic carbon stock and the vertical distribution of it in Finnish agricultural mineral soils. The results showed that the boreal agricultural mineral soils have high carbon contents. Crop rotations with perennial crops enriched carbon in the soil surface. Detecting the change of soil carbon stocks via soil sampling requires a high number of samples. Thus, verification requires modelling combined with field-level data, which can be collected using for instance remote sensing.

STATE DATA ASSIMILATION AS A TOOL FOR FORECASTING SOIL CARBON STOCKS

Viskari, Toni et al. 2020. Improving Yasso15 soil carbon model estimates with ensemble adjustment Kalman filter state data assimilation. Geoscientific Model Development |

Model-based forecasts of soil organic carbon (SOC) are important for assessing the soil carbon pools and their changes. However, the reliability and applicability of these forecasts is limited due to the lack of detailed observations. This study aimed to figure out whether the SOC model and forecast based on available measurement data can be updated by using state data assimilation (SDA). In this method, which is used for example in weather forecasting, the information from several sources is combined to create more precise estimations. The results of this study showed that SDA is a beneficial tool for forecasting changes in soil organic carbon stocks.

COMBINING SEVERAL MODELS TO IMPROVE THE PREDICTIONS OF SOIL ORGANIC CARBON

Farina, Roberta et al. 2020. Ensemble modelling, uncertainty and robust predictions of organic carbon in long‐term bare‐fallow soils. Global Change Biology |

Simulation models are used for creating predictions for soil organic carbon (SOC) dynamics in global carbon cycle. In this study, SOC results simulated from different models were assessed by comparing the simulations to field data conducted across Europe. The decay of carbon in these long-term bare-fallow plots has been monitored for decades after the last application of plant material. This provides the opportunity to study decomposition without continuous input of organic material. According to this study, an ensemble of different models can improve the reliability of the long-time predictions of SOC dynamics by reducing the uncertainty of the model estimates.

EARLY ARRIVING PARASITE STRAINS ALTER THE PARASITE ASSEMBLAGE OF PLANT HOST

Halliday, Fletcher et al. 2020. Facilitative priority effects drive parasite assembly under coinfection. Nature Ecology &Evolution |

Plant host individuals are often coinfected with diverse parasite assemblages, resulting in complex interactions among parasites within hosts. However, the role of the host’s immunity in the coinfection process remains poorly understood. In this study, researchers tested how the host’s response to the first parasite infection affect its susceptibility to subsequent infections. The results showed that the prior infection by one parasite strain increased susceptibility to other strains and altered the parasite assemblages. The diversity of the parasite strains also distributes spatially and temporally during epidemics.