Costs, Environmental Gains, and Potential for National Self-Sufficiency with Ecological Recycling Agriculture in Sweden—Calculations Based on Case Studies of 30 Farms

A necessary reduction in climate impact and raised interest in the self-sufficiency of food in Sweden serve as the major background for the study. The purpose was to examine whether conversion of Swedish agriculture following principles of Ecological Recycling Agriculture (ERA) could be a realistic alternative. Case studies of 22 ERA farms were performed, and results were presented for five production groups in kg production, carbon sequestration, and nutrient balance per hectare. The farms show climate impact substantially lower than Swedish average agriculture, through 85% lower commodity purchases and 2.3 times larger carbon sequestration due to more ley cropping. Target diets with varying amounts of meat and dairy products were defined and matched with the production and presented in scenarios where the farms’ staple food production is upscaled for a Swedish population of 11 million inhabitants. Results are presented in kg of food category produced, hectares of arable land, CO2 equivalents, and kg of N surplus per capita. The scenario results show that it is possible to achieve at least a 90% decrease in climate impact. It is concluded that it is within range for Sweden to be self-sufficient in staple foods based on the available acreage of arable land by adopting Ecological Recycling Agricultural principles in a similar manner as the studied farms.

Carbon Cost of Applying Nitrogen Fertilizer

Carbon Sequestration in Soils of Latin America

The production, transport, and application of N fertilizer incur COemissions to the atmosphere, which must be subtracted from any apparent increases in soil organic matter before calculating the net carbon sequestration in agricultural soils. Similarly, net carbon sequestration in arid-land soils is reduced by COis emissions when fossil fuels are used to pump irrigation water and when pedogenic carbonate precipitates in soils. Application of manure, important to maintaining agricultural tilth, does not offer a mechanism for the net sequestration of carbon in soils that is relevant to the Kyoto Protocol.

Aggregate-associated carbon compositions explain the variation of carbon sequestration in soils after long-term planting of different tea varieties

Residue management, conservation tillage and soil restoration for mitigating greenhouse effect by CO 2-enrichment

The application of innovative practices of soil organic matter (SOM) management, based on either soil amendment with hydropohobic mature compost or with a water-soluble biomimetic catalyst, has shown to enhance organic carbon sequestration in agricultural soils. In three different agricultural sites in Italy, field plots under maize were treated with traditional deep tillage, minimum tillage, green manuring and mature compost, whereas field plots under wheat were added with the iron–porphyrin catalyst. In terms of soil physical quality, mature compost additions improved soil aggregate stability by favoring the increase of water-stable macroaggregates. After 3 years of field experiments, both minimum tillage and green manuring treatments confirmed short-term and even negative effects on organic carbon (OC) accumulation, as compared to traditional tillage. Conversely, the hydrophobic protection exerted by compost amendments on SOM successfully fixed OC in soil from 3 to 22 ton ha−1 more than for traditional tillage, depending on the experimental site. Solid-state CPMAS-NMR spectra of humic substances (HS) extracted from treated soils allowed the molecular characterization of the stable organic matter pool. NMR data combined with chemometric methods revealed that compost-added soils progressively incorporated aliphatic and aromatic hydrophobic components into soil humic fractions over the experimental period. Though more variable among experimental sites, the treatment with biomimetic catalyst positively affected both total soil organic carbon (SOC) content and molecular characteristics of humic extracts. An increased aromaticity and hydrophobicity was shown in the spectra of HS from soils treated with the biomimetic catalyst, thus suggesting an effective photo-polymerization of soil aromatic components and their progressive inclusion into the humic pool. In the first and second year of treaments with the water-soluble iron–porphyrin catalyst, the in situ catalyzed photo-polymerization of SOM effectively occurred since soils were found to have sequestered from 4 to 24 ton ha−1 more than the control.

Summary The Kyoto Protocol explicitly allows the storage of carbon (C) in ecosystems resulting from afforestation to be offset against a nation's carbon emissions and paves the way for carbon storage in soils to be eligible as carbon offsets in the future. More information is required about how afforestation affects carbon storage, especially in the soil. We report a study in which soil carbon storage in first‐rotation Mediterranean Pinus radiata plantations, established on former cereal fields and vineyards, was measured and modelled. Measurements were made on plantations of several ages, as well as repeat measurements at the same site after 5 years. We tested the ability of two widely used soil organic matter models (RothC and Century) to predict carbon sequestration in Mediterranean forest soils. Increases in the top 5 cm of soil of about 10 g C m −2 year −1 were observed after afforestation of former vineyards, but nitrogen (N) either remained the same or decreased slightly. During afforestation, most organic matter accumulated in the ectorganic layers at a rate of 19 g C m −2 year −1 in former vineyards and 41 g C m −2 year −1 in former cereal fields. The RothC and Century models were sensitive to previous land use and estimated a carbon sequestration potential over 20 years of 950 and 700 g C m −2 , respectively. The accurate simulation of the dynamics of soil organic matter by RothC, together with measured above‐ground inputs, allowed us to calculate below‐ground inputs during afforestation. The Century model simulated total C and N, including the ectorganic horizons, well. Simulations showed a depletion of N in the below‐ground fractions during afforestation, with N limitation in the former vineyard but not on former cereal land. The approach demonstrates the potential of models to enhance our understanding of the processes leading to carbon sequestration in soils.

This study was conducted to determine the effect of tillage systems and soil organic amendments on rice growth, yield and carbon sequestration on paddy soil. The experiment was conducted by using 2x4 factorials in complete randomized design. The first factor was tillage systems (conventional tillage; to and minimum tillage; t1) and the second factor was soil organic amendments (mungbean; p0, sesbania; p1, sunhemp; p2 and rice straw; p3). The results demonstrated that adding organic matter derived from mungbean to the soil was the highest and significantly different of plant height and carbon stock in rice (P?0.01). The tillage system and organic matter amendment was not significantly different of rice yield. However, tillage systems with a mungbean amendment tent to increased the rice yield. Soil organic matter was the highest in sumhep amendment in soil as following by sesbania, mungbean and rice straw, respectively. In addition, minimum tillage system can increase carbon sequestration in soil at 15 cm soil depth (P?0.01).

A disconnect between O horizon and mineral soil carbon – Implications for soil C sequestration

There is limited knowledge of the contribution of afforested arable land to mitigation of greenhouse effects. In the AFFOREST project we evaluated the rate and magnitude of carbon (C) sequestration in biomass and soils following afforestation of cropland. Two oak (Quercus robur) and four Norway spruce (Picea abies) afforestation chronosequences (age range 1 to 90 years) were studied with respect to C sequestration in Denmark, Sweden and the Netherlands.

Managing carbon sequestration in soils: concepts and terminology

Carbon sequestration in soil amended with anaerobic digested matter

One of the main options for carbon mitigation identified by the IPCC is the sequestration of carbon in soils. In this paper we use statistical relationships derived from European long‐term experiments to explore the potential for carbon sequestration in soils in the European Union. We examine five scenarios, namely (a) the amendment of arable soils with animal manure, (b) the amendment of arable soils with sewage sludge, (c) the incorporation of cereal straw into the soils in which it was grown, (d) the afforestation of surplus arable land through natural woodland regeneration, and (e) extensification of agriculture through ley‐arable farming. Our calculations suggest only limited potential to increase soil carbon stocks over the next century by addition of animal manure, sewage sludge or straw ( 15 Tg C y–1), but greater potential through extensification of agriculture (≈ 40 Tg C y–1) or through the afforestation of surplus arable land (≈ 50 Tg C y–1). We estimate that extensification could increase the total soil carbon stock of the European Union by 17%. Afforestation of 30% of present arable land would increase soil carbon stocks by about 8% over a century and would substitute up to 30 Tg C y–1 of fossil fuel carbon if the wood were used as biofuel. However, even the afforestation scenario, with the greatest potential for carbon mitigation, can sequester only 0.8% of annual global anthropogenic CO2‐carbon. Our figures suggest that, although efforts in temperate agriculture can contribute to global carbon mitigation, the potential is small compared to that available through reducing anthropogenic CO2 emissions by halting tropical and sub‐tropical deforestation or by reducing fossil fuel burning.

Soil organic carbon (SOC) sequestration in arable soils is a challenging goal. We focused on the effect of crop rotation and previous land use for future carbon sequestration on two experimental fields on Retisols with four contrasting fertilization treatments each. We analyzed the SOC dynamics and used the RothC model to forecast the SOC. We found a consistent increase in SOC stocks and stable fractions of the soil organic matter (SOM) with C accumulation in the next 70 years compared to the 90-year experimental period, more evident under the Representative Concentration Pathway 4.5 (RCP4.5) compared with the RCP8.5 scenario. The expected increase in SOC will be higher in the crop rotation with a grass field than in the experiment with an alternation of row crops and cereals. The efficiency depended on stable SOM fractions, and fields with more extended cultivation history showed higher SOM stability. Proper crop rotations are more important for SOC stability than the uncertainty associated with the climate change scenarios that allows timely adaptation. The goal of a 4‰ annual increase of SOC stocks may be reached under rotation with grasses in 2020–40 and 2080–90 when applying a mineral or organic fertilizer system for scenario RCP4.5 and a mineral fertilizer system in 2080–2090 for scenario RCP8.5.