08147 - Agricultural Chemistry

Learning outcomes

After teaching, students acquire the basic knowledge of chemistry and biochemistry of the soil-plant system, and is able to understand at the molecular mechanisms that regulate the activity of the soil surface, of agroecosystem function, the processes that underpin energy conversion in biological systems in a more complete view of the complex organization and functionality of the plant.

Course contents

A) Prerequisites

Students attending this course should have a good knowledge of the basics of mathematics, physics, chemistry and plant biology. Such skills are provided by the basic courses of the first year.

B) Didactic units

The course is divided into three didactic units

Unit 1 – Plant Biochemistry (18 hours)

1 . Living being components

Structure, classification and functions- Carbohydrates, lipids, aminoacids, proteins.

Enzymes – Structure, properties and classification. Enzymatic reactions kynetics. Enzymatic inhibition. Co-factors and co-enzymes of redox reactions.

2. Chlorophyll Photosynthesis

Light reactions – Chlorophylls and other pigments, photosystem structure, Z scheme, electron transport chain, photo-phosphorilation, cyclic electron transport.

Dark reactions –Calvin cycle, RUBISCO structure and functions, RUBISCO regulation systems, photo-respiration

Photosynthesis in C4 e CAM plants

3. Respiration and lipid metabolism

Glycolysis. Alcoholic and lactic fermentations. Krebs cycle. Cytochrome ossidative system and ossidative phosphorilation. Pentose-phosphate metabolic pathway. Energy aspects of respiration.

Knowledge gained in Didactic Unit 1:

• Main life components (bio-molecules) structure
• Main mechanisms of photosynthesis.
• Main metabolic pathways related to energy production in plants.

Unit 2 – Soil Chemistry (18 hours)

1. Soil components

Mineral components – Minerals, crystals, ionic beams and coordination numbers, silicates, phyllosilicate structure, allophanes, oxides and hydroxides, carbonates.

Organic components – Classification and main transformation processes. Non-humic compounds: carbohydrates, nitrogen compounds, phosphorous compounds, sulphur compounds, lipids. Humic compounds: extraction, fractioning, classification, composition, physico-chemical properties.

2. Soil chemical and physical properties

Surface properties – Soil particles specific surface, charge source.

Adsorption and cationic exchange – Models, double layer thickness and potential, exchange bases, exchange features, cation exchange capacity (CEC), affinity, lyotropic series, exchange equations, dilution effects.

Adsorption and anionic exchange – Soil anions, specific adsorption. Phosphate adsorption, isotherms and equations, dissolution-precipitation mechanisms.

Soil reaction – Soil pH definition, soil pH measurement, active and exchangeable acidity, pH-based soil classification, pH and nutrients, pH and soil biological activities, main buffer systems and soil pH regulation systems.

3. Soil Biochemistry

Soil organisms – Functional classification, bacteria and residue chain, microbial activity and soil properties

Soil enzymes – Enzyme location. Extra-cellular enzymes classification, stabilization mechanisms, heterogeneous enzymatic catalysis, enzyme properties and functions

Carbon cycle – C sources, degradation, humification and mineralization.

Humification – Theories, enzyme role, carbon mean residence time, carbon balance.

Agronomical function of the organic matter – Effect on soil physical properties, nutritional effects, effects on extra-cellular enzyme activities, pseudo-hormonal activities.

4. Anomalous soils

Acidic soils – Formation, chemical and physical characteristics, correction.

Salt soils – Formation, chemical and physical characteristics, correction.

Sodium soils - Formation, chemical and physical characteristics, correction.

Knowledge gained in Didactic Unit 2:

• Structure of main soil components
• Chemical, physical and biological processes linked to soil functioning
• Characteristics and correction methods of anomalous soils

Unit 3 - Exercises (24 hours)

After a preliminary discussion on the importance of performing, in modern agriculture, accurate chemical and physical soil analyses, the exercises take place in the didactic laboratory. Lab activities focus on the determination of some of the main soil properties: texture, reaction, total carbonates, organic matter, cation exchange capacity, salinity and so on. Lab exercises continue with the discussion of the obtained analytical results. Such discussion, related to the themes developed in class lessons, aims at establishing a relationship between the measured physico-chemical parameters and their meaning in terms of soil functionality. The exercises are carried out in strict collaboration with the ones related to the Elements of Geopedology module.

Readings/Bibliography

The use of teacher didactic material, provided in the class lectures and online available, besides lessons notes, will be of fundamental importance.

The consultation of the following books related to the themes developed in the lectures is recommended

Fondamenti di Biochimica Agraria - Patron Ed. Bologna

Fondamenti di Chimica del Suolo - Patron Ed. Bologna

Teaching methods

The course is subdivided into two parts:

1) Class lectures: Students should gain the knowledge on the chemical and biochemical processes at the basis of soil/plant system, through class lectures. Knowledge acquisition and comprehension skills will be constantly monitored, during class lectures, through a continue interaction between the students and the teacher. Such interaction consists in requests by the teacher of discussing some topics of the course, for their impact on current issues linked to the subject of the course, and will aim at developing judgement autonomy and improving communication skills

2) Exercises: Students should attend laboratory experiments, aiming at providing analytical results for the investigation of chemical and biological processes related to a certain soil. Such part of the course will also aim at verifying the ability of applying the theoretical knowledge about the managing of soils.

Assessment methods

The learning test for the Agricultural Chemistry course is made through a final oral examination, carried out together with the exam of the second module (Elements of Geopedology) of the integrated course (Agricultural Chemistry with Elements of Geopedology). The oral exam deals with the topics developed in the lessons; there will be 3 basic questions, one for each thematic area of the course (soil chemistry, plant biochemistry, geopedology). Starting from this scheme, appropriate investigations related to the discussed topics will take place. The exam must be completely passed and the candidate must reach at least a score of 18/30 in each of the learning subjects of the integrated course. The academic board will express the final evaluation by calculating the arithmetic mean of the scores of each learning subject. The length of the oral exam should be about 45 minutes.

Teaching tools

Overhead projector, personal computer and projector will be used for class lectures.

Laboratory exercises will take place in the laboratories placed in the building of the course.

Office hours

See the website of Claudio Marzadori