Simulating Soil Organic Matter Transformations with the New Implementation of the Daisy Model

Daisy is a well-tested deterministic, dynamic soil-plant-atmosphere model, capable of simulating water balance, nitrogen balance and losses, development in soil organic matter and crop growth and production in crop rotations under alternate management strategies. Originally it was developed as a system of single models describing each process involved, but recently it has been developed into a framework, which can be used for implementation of several different models of each of the different processes. Thus, for example a number of different models for simulating soil water dynamics can be chosen depending on the purpose of the simulation and the availability of data for parameterisation. The sub-model simulating soil organic matter is still a fixed component in the Daisy terminology. This means that there is currently only one model, which can be used to simulate soil organic matter transformations. However this sub-model can be changed considerably. Some examples are given

Application of processed organic municipal solid waste on agricultural land - a scenario analysis

Source separation, composting and anaerobic digestion, with associated land application, are increasingly being considered as alternative waste management strategies to landfilling and incineration of municipal solid waste (MSW). Environmental life cycle assessments are a useful tool in political decision-making about waste management strategies. However, due to the diversity of processed organic MSW and the situations in which it can be applied, the environmental impacts of land application are very hard to determine by experimental means. In the current study, we used the agroecosystem model Daisy to simulate a range of different scenarios representing different geographical areas, farm and soil types under Danish conditions and legislation. Generally, the application of processed organic MSW resulted in increased emissions compared with the corresponding standard scenarios, but with large differences between scenarios. Emission coefficients for nitrogen leaching to the groundwater ranged from 0.03 to 0.87, while those for nitrogen lost to surface waters through tile drains ranged from 0 to 0.30. Emission coefficients for N2O formation ranged from 0.013 to 0.022 and for ammonia volatilization from 0.016 to 0.11. These estimates are within reasonable range of observed values under similar conditions. Furthermore, a sensitivity analysis showed that the estimates were not very sensitive to the mineralization dynamics of the processed organic MSW. The results show that agroecosystem models can be powerful tools to estimate the environmental impacts of land application of processed MSW under different conditions. Despite this, agroecosystem models have only been used to a very limited degree for this purpose

Cellulosic ethanol: interactions between cultivar and enzyme loading in wheat straw processing

<p>Abstract</p> <p>Background</p> <p>Variations in sugar yield due to genotypic qualities of feedstock are largely undescribed for pilot-scale ethanol processing. Our objectives were to compare glucose and xylose yield (conversion and total sugar yield) from straw of five winter wheat cultivars at three enzyme loadings (2.5, 5 and 10 FPU g^-1dm pretreated straw) and to compare particle size distribution of cultivars after pilot-scale hydrothermal pretreatment.</p> <p>Results</p> <p>Significant interactions between enzyme loading and cultivars show that breeding for cultivars with high sugar yields under modest enzyme loading could be warranted. At an enzyme loading of 5 FPU g^-1dm pretreated straw, a significant difference in sugar yields of 17% was found between the highest and lowest yielding cultivars. Sugar yield from separately hydrolyzed particle-size fractions of each cultivar showed that finer particles had 11% to 21% higher yields than coarse particles. The amount of coarse particles from the cultivar with lowest sugar yield was negatively correlated with sugar conversion.</p> <p>Conclusions</p> <p>We conclude that genetic differences in sugar yield and response to enzyme loading exist for wheat straw at pilot scale, depending on differences in removal of hemicellulose, accumulation of ash and particle-size distribution introduced by the pretreatment.</p

Biochar effect on the mineralization of soil organic matter

The objective of this work was to verify whether the addition of biochar to the soil affects the degradation of litter and of soil organic matter (SOM). In order to investigate the effect of biochar on the mineralization of barley straw, soil was incubated with 14C-labelled barley straw with or without unlabelled biochar. To investigate the effect of straw on the mineralization of biochar, soil was incubated with 14C-labelled biochar with or without straw. In addition, to investigate the effect of biochar on old SOM, a soil labelled by applying labelled straw 40 years ago was incubated with different levels of biochar. All experiments had a control treatment, without any soil amendment. The effect of biochar on the straw mineralization was small and nonsignificant. Without biochar, 48±0.2% of the straw carbon was mineralized within the 451 days of the experiment. In comparison, 45±1.6% of C was mineralized after biochar addition of 1.5 g kg-1. In the SOM‑labelled soil, the organic matter mineralized more slowly with the increasing doses of biochar. Biochar addition at 7.7 g kg-1 reduced SOM mineralization from 6.6 to 6.3%, during the experimental period. The addition of 15.5 g kg-1 of biochar reduced the mineralized SOM to 5.7%. There is no evidence of increased degradation of either litter or SOM due to biochar addition; consequently, there is no evidence of decreased stability of SOM.The objective of this work was to verify whether the addition of biochar to the soil affects the degradation of litter and of soil organic matter (SOM). In order to investigate the effect of biochar on the mineralization of barley straw, soil was incubated with 14C-labelled barley straw with or without unlabelled biochar. To investigate the effect of straw on the mineralization of biochar, soil was incubated with 14C-labelled biochar with or without straw. In addition, to investigate the effect of biochar on old SOM, a soil labelled by applying labelled straw 40 years ago was incubated with different levels of biochar. All experiments had a control treatment, without any soil amendment. The effect of biochar on the straw mineralization was small and nonsignificant. Without biochar, 48±0.2% of the straw carbon was mineralized within the 451 days of the experiment. In comparison, 45±1.6% of C was mineralized after biochar addition of 1.5 g kg‑1. In the SOM‑labelled soil, the organic matter mineralized more slowly with the increasing doses of biochar. Biochar addition at 7.7 g kg‑1 reduced SOM mineralization from 6.6 to 6.3%, during the experimental period. The addition of 15.5 g kg‑1 of biochar reduced the mineralized SOM to 5.7%. There is no evidence of increased degradation of either litter or SOM due to biochar addition; consequently, there is no evidence of decreased stability of SOM

On the use of Life Cycle Assessment to improve agronomists&#8217; knowledge and skills toward sustainable agricultural systems

Purpose. In agricultural and forestry sciences higher education, environmental sustainability is most often taught through the discussion of examples of green agricultural practices, such as precision farming, and more rarely by taking a more general point of departure in environmental assessment methods, such as Life Cycle Assessment (LCA). Nevertheless, we think that teaching LCA in the agronomists’ curriculum might significantly contribute to enhance students’ systemic perspective on agricultural sustainability. The purpose of this paper is to highlight which additional knowledge and skills may be given to agronomists thorough the teaching of LCA.Design/Methodology/Approach. We designed two short courses focused on LCA to be followed by students at the Bachelor´s degree in Agronomy (University of Turin, Italy) and at the Master´s degree in Sustainability of Agro-food Networks (UNESCO Chair for Sustainable Development, Turin, Italy). After the courses, students filled in a questionnaire about their opinions on the usefulness and value taken from the short courses. Findings. From students’ answers in the questionnaire and their comments during both teaching sessions, it was possible to point out four key aspects acquired by students during the courses: (I) Complexity of agricultural systems. Application of LCA requires to describe the energy flows and material cycles of the system under study and to decide the allocation of environmental impacts to specific phases of the production. (II) Systemic view of the farms. The need to identify boundaries between technical and natural systems for impact assessment highlights the strong interconnection between the two of them. (III) The problem of efficiency. The application of LCA may highlight that productions that are efficient from an agronomic point of view may not be as efficient from an environmental point of view. (IV) Conceptions about sustainable agriculture. During the group work, students were asked to highlight (if possible) the paradigm of sustainability of the authors of the scientific papers and to discuss it. This way, they were able to reflect on the complexity of the concept on environmental sustainability.Practical Implications. Teaching LCA in an interactive course, agronomists discussed pivotal concepts for environmental sustainability, such as system thinking, the problem of efficiency as well as conceptions about sustainable agriculture. All of these aspects reflect positively on the professional life of the agronomists, even if they will not apply any environmental impact methods in their future careers.Originality/Value. This paper describes a pioneer research in which LCA is used as a pure educational tool for understanding the environmental efficiency of agricultural systems, but also founding concepts of environmental sustainability in the agricultural sector