Peter Sørensen

Peter Sørensen
Aarhus University | AU · Department of Agroecology

PhD

About

154
Publications
27,894
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4,999
Citations
Additional affiliations
June 1993 - March 1996
Risø National Laboratory
Position
  • Researcher
March 1990 - April 1993
Risø National Laboratory
Position
  • PhD Student

Publications

Publications (154)
Article
Full-text available
Background There is an increasing interest in using lignocellulosic feedstocks for biogas production. Treatment of these feedstocks prior to anaerobic digestion (AD) can enhance their accessibility to microorganisms involved in the process. To improve the digestion of recalcitrant feedstocks and boost biogas yields, many biogas plants now employ tw...
Article
Full-text available
Cover crops offer a potential biogas feedstock, and to enable continuous operation of the biogas plant, ensiling can be used for biomass preservation. The aim of the present study was to assess the environmental impacts of biogas production at an organic dairy farm for two modelled scenarios: (1) harvesting and ensiling of cover crops and cereal st...
Article
Full-text available
Cover crops are important in organic arable cropping systems because they improve soil fertility and suppress annual weeds in the post-harvest period (the period between cash crops), but their effectiveness against perennial weeds is less clear. This study analyzed outbreaks of perennial weeds in two long-term organic crop rotations with and withou...
Article
Full-text available
Introduction Cattle slurry used as fertilizer in crop production is a mix of feces, urine, water, and bedding material from the housing system. Previous studies have shown that slurry nitrogen (N) availability to crops is dependent on C/N ratio. As the bedding material can contribute a significant part of total slurry carbon (C), its characteristic...
Chapter
Service crops (SCs) are widely used in low input systems as a source for nitrogen (N), and in intensive cropping systems for reducing N leaching by taking up residual soil N after the harvest of the main crop. This chapter discusses benefits of SCs, which are defined here as crops grown for providing ecosystem services and not grown for harvest, an...
Article
Full-text available
Engineered wetland systems (EWS) are globally recognized as efficient wastewater treatment solutions with the potential for sustainable biomass production. The need arises to understand hydrothermal carbonization's (HTC) potential in nutrient and resource recovery from this biomass. While willows are well-studied in bioenergy, their utility in HTC...
Chapter
This chapter discusses optimizing slurry management in agricultural practices. It begins by first highlighting current decision tools for optimizing manure management, then goes on to review modifying animal slurry pH to enhance its value as a biobased fertilizer through methods such as bio acidification and alkalinization. A section on improving m...
Article
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Biogas operation parameters are usually optimised to enhance biogas yields while ignoring digestate quality. This study evaluated the effects of varying operation parameters and input feedstocks used in co-digestion with manure on digestate properties and N turnover in soil for 80 days. Net inorganic N release (% of N input) from digestates varied...
Article
Full-text available
Cattle slurry is an important nitrogen source for maize on dairy farms. Slurry injection is an effective measure to reduce ammonia emissions after field application, but with higher risk of nitrous oxide emission than surface application. This study compared soil mineral nitrogen dynamics and nitrous oxide emissions with two ways of application. Fi...
Article
Full-text available
Background A high use‐efficiency of fertilizer N remains essential to sustain high crop productivity with low environmental impact. However, little is known on the long‐term lability of mineral fertilizer N. Aims To quantify crop uptake and leaching of ¹⁵ N‐labelled mineral fertilizer that has been retained in an agricultural soil for 25–30 years...
Article
Increasing the production of grain legumes in Europe will contribute to protein self-sufficiency and provide direct and indirect environmental benefits, e.g., delivering ecosystem services such as N input via biological N2 fixation (BNF). Faba bean (Vicia faba L.) is the main grain legume cultivated in Europe with increasing interest from the organ...
Article
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Manure treatment such as anaerobic digestion and solid-liquid separation has shown a potential to abate greenhouse gas (GHG) emissions, but few studies have considered GHG emissions from both storage and field application regarding crop yield. In this study, four different organic fertilizers were studied: untreated cattle manure (CA); digestate of...
Article
Full-text available
Biogas production from anaerobic digestion (AD) of biowastes is restricted by the recalcitrant nature of many substrates, and this may also reduce the fertiliser value of the produced digestate. The degradability of substrates can potentially be enhanced by physico-chemical pre-treatments before AD, and/or the degradation can be increased by a long...
Article
Full-text available
Ammonia (NH3) emissions resulting from the field application of livestock slurry has both negative human health and environmental impacts. However, decreasing the exposed surface area (ESA) of slurry upon application can reduce NH3 volatilization by limiting its atmospheric exposure. In the present study, three strategies for depositing slurry with...
Article
Full-text available
Anaerobic digestion (AD) is an important tool for reducing greenhouse gas emissions from agricultural production. A prolonged retention time by adding an extra anaerobic digestion step can be utilized to further degrade the digestates, contributing to increased nitrogen mineralisation and reducing decomposable organic matter. These modifications co...
Preprint
Full-text available
Purpose: The crop uptake and leaching of labelled fertilizer N applied 25-30 years ago was measured in different agricultural cropping systems to improve the understanding and quantification of the long-term fate of fertilizer N. Methods: ¹⁵N-labelled mineral fertilizers were added to a field plot with different crops over 5 years. After 12 years a...
Article
Nitrate leaching from agricultural soils is a considerable environmental concern related to nitrogen (N) application, and in some countries N fertilizer application is regulated by legislation to reach environmental goals. Information about the change in nitrate leaching with changes in mineral N fertilizer rates is important under such conditions....
Article
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NLES5 is the fifth version of an empirical model for predicting annual nitrate leaching from the root zone (1-meter depth), accounting for effects of nitrogen (N) inputs, crop sequences, autumn and winter crop cover, soil types, and weather conditions. It was developed and calibrated based on a comprehensive nitrate leaching dataset, primarily from...
Article
Full-text available
Livestock manure is a major source of the greenhouse gases (GHGs) methane (CH4) and nitrous oxide (N2O). The emissions can be mitigated by production of biogas through anaerobic digestion (AD) of manure, mostly together with other biowastes, which can substitute fossil energy and thereby reduce CO2 emissions and postdigestion GHG emissions. This pa...
Article
There is an urgent need to replace mineral phosphorus (P) fertilizers placed near the maize seed at sowing with other management strategies to ensure a more environmentally friendly silage maize production and to avoid depletion of the phosphate rock reserve. The main objective of this study was to test and investigate effects of different tine geo...
Article
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Worldwide dairy processing plants produce high volumes of dairy processing sludge (DPS), which can be converted into secondary derivatives such as struvite, biochar and ash (collectively termed STRUBIAS). All of these products have high fertilizer equivalent values (FEV), but future certification as phosphorus (P)-fertilizers in the European Union...
Article
Background Placed cattle slurry (CS) provides essential nutrients such as nitrogen (N) and phosphorus (P) to young maize (Zea Mays L.) plants and may substitute the use of mineral starter fertilizers. However, placement depth and distribution of slurry may influence the plant growth response. Aims The objective was to evaluate the effects of slurr...
Article
Full-text available
Elemental sulfur (ES) is commonly used as a fertilizer S source but needs to be oxidized to sulfate to become plant‐available. We assessed how placement (surface applied or incorporated) affects the oxidation of ES fertilizers. The fertilizers included an ES powder, a suspension of biogenic ES particles, and three granular fertilizers: two ES–bento...
Article
Digested, undigested and green organic amendments were used to improve soil fertility and minimize any harmful effects. To understand the events in soil, we evaluated the nitrogen (N) and sulfur (S) mineralization in soil after adding with cattle manure and green manure. Eleven organic amendments were fresh dairy cattle manure, digested cattle manu...
Article
On farms with intensive animal production, manure represents a significant source of nitrogen (N) in crop production. Cattle deep litter is a common manure type in Denmark due to concerns regarding animal welfare. With a low ammonium to total N ratio, large quantities of deep litter are needed to meet crop N requirements. However, documentation reg...
Article
Cover crop (CC) mixtures including both legume and non-legume species have the potential to reduce nitrate leaching and increase N availability in the system through biological N 2 fixation (BNF). However, the provision of multiple services depends on the biomass expression of functionally diverse species. Cover crop growth can be manipulated throu...
Article
The plant availability of manure nitrogen (N) is influenced by manure composition in the year of application whereas some studies indicate that the legacy effect in following years is independent of the composition. The plant availability of N in pig and cattle slurries with variable contents of particulate matter was determined in a 3-year field s...
Article
Silage maize (Zea mays L.) is an important crop for forage on northwestern European dairy cattle farms. We examined the effect of readily available soil phosphorus (P) on early maize growth and linked in‐season height growth to final harvest yield using field plots with contrasting P supply in a one‐year study embedded in a long‐term experiment. Wa...
Article
The yields of crops in organic farming are typically lower than in conventional farming, although this depend greatly on local climatic conditions and on crop and soil management. A long-term study over three consecutive 4-year cropping cycles at three locations in Denmark compared organic arable cropping systems varying in fertilization management...
Article
Full-text available
Inputs of nitrogen to agricultural production systems are necessary to produce food, feed and fibre, but nitrogen (N) losses from those systems represent a waste of a resource and a threat to both the environment and human health. The nitrogen use efficiency (NUE) of an agricultural production system can be seen as an indicator of the balance betwe...
Article
Residues from hydrogen sulfide (H2S) removal in biogas filters contain sulfur (S) in various forms (sulfate, sulfide, elemental S) that, if properly stored, is potentially valuable as crop fertilizer. We investigated 1) the turnover of the S compounds from filter materials during storage in untreated and digested cattle manure (CM), and 2) the S fe...
Article
Cover crops (CC) may play an essential role in the recycling of nutrients in organic farming systems with cereals. Harvest time of cereals and management of straw in the field can affect the growth of CC and subsequent nitrogen (N) fertiliser replacement value (NFRV) in the following crop. This study investigates 1) the effect of harvest time, 2) c...
Article
Background: The fertilizer value of phosphorus (P) in waste products relies heavily on its availability to the subsequent crop. Aim: We studied the link between extractable P in waste products and apparent P recovery (APR, i.e., difference in plant P uptake between P amended and un‐amended soils divided by the amount of P added) using spring barley...
Article
Accumulation of phosphorus (P) in soil can be a problem on intensive livestock farms with maize cropping, when mineral P starter fertilisers are applied in combination with evenly injected liquid manure before sowing. We examined the possibilities of replacing mineral P starter fertiliser with placement of cattle slurry close to the maize row befor...
Article
Full-text available
This article displays a dataset obtained in two field trials conducted in 2016 in Denmark. Leaf phosphorus (P) and nitrogen (N) concentrations at leaf-stage five (V5) and silage maize dry matter (DM) yield were determined in response to seven treatments with different slurry row-injection methods and combinations of slurry acidification and additio...
Article
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Placement of cattle slurry below the row could potentially replace mineral phosphorus (P) starter fertilizer in corn (Zea mays) production, but a concentrated slurry layer near the seed may also restrict root growth. This study was designed to assess how the distance between seed and layer‐banded slurry affected initial growth of corn. In a pot exp...
Article
Full-text available
Legume-based cover crops (CC) provide a wide range of ecosystem services, including nitrate leaching reduction, nitrogen (N) fertilization and soil carbon (C) sequestration. However, the scarcity of information on belowground C and N increases the uncertainty on the magnitude of these effects. We quantified C and N input in soil (hereafter plant-de...
Article
Full-text available
Aims Cover crops (CC) have been widely used to improve soil quality and sustain agricultural productivity. However, the turnover of carbon (C) and nitrogen (N) from different species and parts of CCs incorporated into the soil under Northern European conditions remains unclear. Methods In this study, we examined mineralization of C and N from isol...
Article
Full-text available
Efficiently recovered, sulfur (S) from the (bio)-gas desulfurization process may be reused as on-farm S fertilizer. Despite some reduction of sulfate and elemental S to sulfide during a storage in untreated and digested manure, the filter products were a valuable source of plant available S. Sulfur deficiency in crop production has become a recurri...
Article
Anaerobic digestion (AD) has the potential to enhance the availability of nitrogen (N) from green manures; however, part of the sulfur (S) is lost with the biogas. In this study, the N and S availabilities from untreated and digested cover crop (CC) and straw mixtures were measured after application to soil in the laboratory. In addition, a micropl...
Article
The concept of soil health emphasizes the role of soil organisms in sustainable agriculture and relies on bioindicators to assess the impact of management options. This study employed Collembola, a key group of microarthropods with intimate links to soil microbial activity, as bioindicators to reveal the sustainability of using acidified cattle slu...
Article
We investigated the interacting effects of inorganic nitrogen and the main inorganic phosphorus form in dairy manure (dicalcium phosphate, CaHPO4) on growth, nutrient uptake, and rhizosphere pH of young maize plants. In a pot experiment, three levels of CaHPO4 (0, 167, and 500 mg P pot⁻¹) were combined with nitrogen (637 mg N pot⁻¹) applied at five...
Article
Legume-based cover crop (CC) mixtures can increase nitrogen (N) availability in arable systems, reducing the need for external N inputs, as they retain soil N and fix atmospheric N 2. However, they need sufficient biomass accumulation to influence soil N availability. Early establishment through undersowing can improve CC growth and plant N accumul...
Article
A better appraisal of the plant availability of soil phosphorus (P) added with animal manure is crucial to alleviate environmental impacts from over‐application of P. This study compares the availability of P to maize in the Askov long‐term experiments using unmanured plots and plots receiving corresponding rates of N, P and K in mineral fertilizer...
Article
Full-text available
Green manure mixtures including legumes and forbs can help to increase N availability in organic arable systems. Anaerobic digestion of green manures may provide ammonium rich digestate, which can be redistributed as fertilizer. The aim of this study was to investigate the effect of plant species composition, cutting strategy and anaerobic digestio...
Chapter
Animal manure is the most important source of nutrients applied in most organic farming systems. Nitrogen (N) is often the most yield-limiting factor in non-leguminous crops, and thus lack of N may cause reduced yield and low protein content in many crops. In addition, N is the nutrient that is most easily lost, and these losses may have serious en...
Article
Converting arable land to permanent grassland remains an efficient option for increased carbon (C) storage in agricultural land. We quantified changes in C and nitrogen (N) in topsoil from the Sandmarken experiment (initiated 1894 in Denmark) before and after its conversion to semi‐natural grassland in 1998. Because of different fertilizer applicat...
Conference Paper
Full-text available
A good cover crop (CC) growth is essential to reach their potential effect on nitrate leaching reduction and N supply to the following crop. The present study investigated the effect of main crop manure application and row space, and CC sowing time on N accumulation in undersown CC biomass and their N fertilizer value for the subsequent crop. Early...
Article
Plant roots are generally considered to decompose slower than shoots and contribute more to accumulation of soil organic matter, and management history is expected to shape the structure and function of decomposer communities in soil. Here we study the effect of chemical characteristics of shoots and roots from fodder radish (Raphanus sativus oleif...
Thesis
Soil is one of the most important terrestrial carbon (C) stores. In agroecosystems, the amount of soil C in topsoil is variable under different environments and managements. Thus, to increase C input and enhance the soil organic C (SOC) content in cropping systems it is necessary to explore the managements practices that may achieve this, such as u...
Article
For corn grown on two light-textured soils, leaf P and N concentrations at the six-leaf stage represented their respective concentrations in shoots. At the seven/eight-leaf stage, the P concentration was higher in leaves than in shoots. Biomass at the seven/eight-leaf stage is linked to the N to P ratio in leaves and shoots at the six-leaf stage.
Article
Full-text available
The article Cattle slurry acidification and application method can improve initial phosphorus availability for maize, written by Ingeborg F. Pedersen, Gitte H. Rubæk and Peter Sørensen, was originally published Online First without open access.
Article
Components of the field nitrogen (N) balance (input and surplus) are often used to predict nitrate leaching from agricultural lands. However, management factors, such as use of catch crops, greatly affect the actual loss and are a key to reduce N leaching. The present study is based on the 4th cycle of a long-term crop rotation experiment in Denmar...
Article
The effects of organic versus conventional farming systems on changes in soil organic carbon (SOC) has long been debated. The effects of such comparisons may depend considerably on the design of the respective systems and climate and soil conditions under which they are performed. Here, we compare a range of arable organic and conventional crop sys...
Article
Full-text available
Reliable information on belowground plant biomass is essential to estimate belowground carbon inputs to soils. Estimations of belowground plant biomass are often based on a fixed allometric relationship of plant biomass between aboveground and belowground parts. However, environmental and management factors may affect this allometric relationship m...
Article
Full-text available
The innovation and expansion in the bioenergy sector produce increased amounts of solid residues, e.g. ashes and biochars, which may derive from more diverse origins of biomass. Recycling of nutrients like phosphorus (P) in such residues to agricultural soils contributes to sustainability in both energy and agriculture systems. In this study the P...
Article
The expansion of the bioenergy sector and adoption of novel thermal conversion technologies produce increasingly large amounts of biomass ashes and biochars. Before returning such products to agricultural soil, the plant availability of nutrients when mixing with soil should be assessed. The objective of this study was to evaluate the potassium (K)...
Poster
Full-text available
Slurry from livestock and biogas digestate are valuable fertilizers used in large amounts all over Europe. However significant amounts of nitrogen (N) are lost during and after fertilization with a negative impact on the environment. Depending on environmental and soil conditions, the ammonium (NH4+) applied with the slurry or biogas digestate is r...
Article
Full-text available
A simple empirical model was developed for estimation of net mineralisation of pig and cattle slurry nitrogen (N) in arable soils under cool and moist climate conditions during the initia