The Role of Organic Matter in Modern Agriculture

1. Organic residues in modern agriculture.- 1.1 Introduction.- 1.2 Supply of nutrients by organic additives.- 1.3 Effects of organic additives on the physical properties of the — soil.- 1.4 Effects of organic amendments on yield.- 1.5 Conclusions.- 1.6 References.- Section 1: Nitrogen and phosphorus supply to plants by organic matter and their transformations.- 2. Effects of organic matter on nitrogen and phosphorus supply to plants.- 2.1 Introduction.- 2.2 Nitrogen.- 2.2.1 Forms of organic N in soil.- 2.2.2 N mineralization.- 2.2.2.1 Organic soils.- 2.2.2.2 Mineral soils.- 2.2.3 Available nitrogen.- 2.2.3.1 Chemical extractants.- 2.2.3.2 Incubation procedures.- 2.2.3.3 Field estimates of N availability.- 2.2.3.4 Crop uptake of soil N.- 2.2.4 Environmental influences.- 2.2.5 Forest soils.- 2.3 Phosphorus.- 2.3.1 Nature of soil organic P.- 2.3.2 P mineralization.- 2.3.2.1 Phosphatases.- 2.3.2.2 Effect of liming.- 2.3.3 Soil organisms in relation to P availability.- 2.4 Organic amendments.- 2.4.1 Animal manures.- 2.4.2 Other organic amendments.- 2.5 Conclusions.- 2.6 References.- 3. The role of organic matter and ammonium in producing high corn yields.- 3.1 Introduction.- 3.2 Review of literature.- 3.2.1 Beneficial effect on yields of organic manures.- 3.2.2 Ammonium and nitrate as a nitrogen source.- 3.2.3 Energy requirements for NH+4 -grown and NO?3 -grown — plants and for the combined sources.- 3.3 Results.- 3.4 Discussion.- 3.5 References.- 4. Nitrogen transformations in Histosols.- 4.1 Introduction.- 4.2 Histosol subsidence.- 4.3 Nitrogen mineralization.- 4.4 Nitrification.- 4.5 Nitrogen in drainage water of organic soils.- 4.6 Denitrification.- 4.7 Conclusions.- 4.8 References.- Section II: Effects of soil organic matter and redox on micronutrients availability to plants.- 5. Soil organic matter interactions with trace elements.- 5.1 Introduction.- 5.2 Importance of complexes of Fe, Mn, Zn and Cu with humic — substances to agriculture.- 5.2.1 Physiological and biochemical functions.- 5.2.2 Transport of micronutrients to plant roots.- 5.2.3 Supply of micronutrients to higher plants.- 5.3 Nature of organic complexing agents in soil.- 5.3.1 Defined biochemical compounds.- 5.3.2 Humic substances.- 5.3.2.1 Extraction and fractionation.- 5.3.2.2 Mechanisms of metal ion binding by humic and fulvic acids.- 5.3.2.3 Solubility characteristics.- 5.3.2.4 Metal ion binding capacity.- 5.3.2.5 Reduction properties.- 5.4 Use of micronutrient-enriched organic wastes and naturally — occuring metal organic complexes as soil amendments.- 5.4.1 Iron-organo complexes.- 5.4.1.1 Polyflavenoids and lignosulfonates.- 5.4.1.2 Manure and composts.- 5.4.1.3 Sewage sludge.- 5.4.1.4 Coal, lignite and peat.- 5.4.2 Zinc-, copper- and manganese- organo complexes.- 5.5 Stability constants of metal complexes with humic and fulvic — acids.- 5.5.1 General considerations.- 5.5.2 Modeling approaches.- 5.5.2.1 Macromolecule as the central group.- 5.5.2.2 Metal ion as the central group.- 5.5.2.3 Polynuclear complexes.- 5.6 Summary and conclusions.- 5.7 References.- 6. Effect of soil redox conditions on microbial oxidation of organic matter.- 6.1 Introduction.- 6.2 Sources and types of organic matter.- 6.2.1 Soil organic matter.- 6.2.2 Root exudates.- 6.2.3 Added substrates.- 6.3 Role of inorganic redox couples on microbial respiration.- 6.3.1 Aerobic respiration.- 6.3.2 Facultative anaerobic respiration.- 6.3.3 Nitrate respiration.- 6.3.4 Manganese respiration.- 6.3.5 Iron respiration.- 6.3.6 Anaerobic respiration.- 6.3.7 Sulfate respiration.- 6.3.7.1 Fermentation.- 6.4 Kinetics of microbial organic matter oxidation.- 6.4.1 Rate of reaction.- 6.4.2 Soil and environmental factors.- 6.4.2.1 Soil moisture.- 6.4.2.2 Oxidant supply.- 6.4.2.3 Temperature.- 6.4.3 Substrate factors.- 6.5 Influence of aerobic/anaerobic respiration of organic matter — on soil biochemical processes.- 6.5.1 Nitrogen.- 6.5.2 Phosphorus.- 6.5.3 Potassium, calcium and magnesium.- 6.5.4 Sulfur.- 6.5.5 Micronutrients and heavy metals.- 6.6 Agronomic and environmental significance.- 6.7 References.- Section III: Soil microorganisms, biofertilizers and biocontrol agents: their interactions with soil organic matter and effects on soil fertility.- 7. Soil microorganisms, soil organic matter and soil fertility.- 7.1 Introduction.- 7.2 The living fraction (plants, animals, microorganisms).- 7.3 The dead fraction: Fresh organic matter.- 7.4 The natural soil organic matter: Humus.- 7.5 The role of soil microorganisms in phosphorus availability — to higher plants.- 7.6 Subsoil, humus and fertility.- 7.7 Biological transformation of microbial residues in soil.- 7.8 Nitrogen fixation and soil organic matter.- 7.9 Rhizosphere microflora, organic matter and soil fertility.- 7.10 Soil organic matter and plant diseases.- 7.11 Conclusions.- 7.12 References.- 8. The role of organic matter in the introduction of biofertilizers and biocontrol agents to soils.- 8.1 Introduction.- 8.2 Rhizobium.- 8.3 Azotobacter and other free living bacteria.- 8.4 Vesicular-arbuscular mycorrhizae.- 8.5 Ectomycorrhiza.- 8.6 Systems for biological control of soilborne plant pathogens.- 8.7 Conclusions.- 8.8 References.- Section IV: Effects of soil organic matter and applied sewage sludge on soil structure and fertility.- 9. Soil organic matter extraction, fractionation, structure and effects on soil structure.- 9.1 Introduction.- 9.2 Structure of humus materials.- 9.3 Extraction of humic substances.- 9.4 Extraction of soil polysaccharides.- 9.5 Fractionation of humic substances.- 9.6 Fractionation of soil polysaccharides.- 9.7 Primary structures of humic substances.- 9.8 Secondary and terrtiary structures of humic substances.- 9.9 General conclusions from studies of humic structures.- 9.10 Structures of soil polysaccarides.- 9.11 Interactions of humus materials with soil inorganic — components.- 9.12 Humic substances — clay interactions.- 9.13 Soil polysaccharide — clay interactions.- 9.14 Humus — oxyhydroxide interactions.- 9.15 Humus and soil aggregates.- 9.16 References.- 10. Sewage sludge organic matter and soil properties.- 10.1 Introduction.- 10.2 Effect of sewage sludge organic matter on soil physical — properties.- 10.2.1 Bulk density.- 10.2.2 Aggregation and aggregate stability.- 10.2.3 Porosity and pore size distribution.- 10.3 Hydraulic conductivity.- 10.3.1 Moisture retention.- 10.3.2 Effect of sewage sludge organic matter on soil chemical — properties.- 10.3.3 Carbon.- 10.3.4 Nitrogen.- 10.3.5 pH.- 10.3.6 Cation exchange capacity.- 10.3.7 Electrical conductivity.- 10.3.8 Phosphorus.- 10.3.9 Metals.- 10.3.10 Redox potential.- 10.4 Effect of sewage sludge organic matter on soil biological — properties.- 10.4.1 Microorganisms.- 10.4.2 Macrofauna.- 10.4.3 Plants.- 10.5 References.- Section V: The use of peat and composts as container media.- 11. Peat and peat subsitutes as growth media for container-grown plants.- 11.1 Historical review.- 11.2 General introduction.- 11.2.1 Physical properties.- 11.2.2 Chemical properties.- 11.2.3 Other properties.- 11.3 Physical characteristics.- 11.3.1 Bulk and particle density.- 11.3.1.1 Particle and pore size distribution.- 11.3.2 Porosity and aeration.- 11.3.3 Water holding capacity (water retention curve).- 11.4 Chemical characteristics.- 11.4.1 Carbon/Nitrogen (C/N) ratio.- 11.4.2 Cation exchange capacity.- 11.4.3 Substrate pH.- 11.4.4 Nutrients availability in organic substrates.- 11.5 Biological characteristics.- 11.5.1 Decomposition rate.- 11.5.2 Effects of decomposition products.- 11.5.2.1 Enzymatic activity.- 11.5.2.2 Growth regulating activity.- 11.6 Organic materials used as growth media.- 11.6.1 Peat.- 11.6.2 Peat substitutes.- 11.6.2.1 Bark.- 11.6.2.2 Sawdust and woodchips.- 11.6.2.3 Sewage sludge and municipal composts.- 11.6.2.4 Treated animal excreta.- 11.6.2.5 Other organic materials.- 11.7 References.- 12. Effects of composts in growth media on soilborne pathogens.- 12.1 Introduction.- 12.2 The composting process.- 12.3 Maturity of composts.- 12.4 Chemical properties.- 12.5 Physical properties.- 12.6 Biological properties.- 12.7 References.