Nitrogen release from the leaves of some tropical legumes as affected by their lignin and polyphenolic contents
TL;DR: In this article, the chemical composition and N release patterns of legumes being used in tropical agroecosystems were determined in a laboratory experiment and three patterns of net N mineralization emerged during the 8-weeks.
Abstract: Leguminous plant materials used as mulches, green manures and cover crops are generally assumed to provide a readily-available source of N to crops. However, little is known about the chemical composition and N release patterns of the variety of legumes being used in tropical agroecosystems. N release patterns from the leaflets of 10 troplcal legumes and rice straw were determined in a laboratory experiment. Ground leaf material was allowed to decompose in an acid soil (pH 4.5) for 8 weeks and the soil was analyzed periodically for extractable NH4+-N and NO3∼, -N. N release in the soil plus plant material were compared to that of the soil without plant material added and related to the N, lignin and polyphenolic concentrations of the leaflets. Three patterns of net N mineralization emerged during the 8-weeks. One pattern exhibited by the control soil, rice straw and leaves of two of the leguminous plants was a low, positive net mineralization. Another pattern showed much higher rates of mineralization than the control soil and the third pattern showed initial net immobilization followed by low but positive net mineralization rates. The amount of N mineralized during the 8 weeks as compared to the control soil ranged from +46 to −20% of the N added in plant material. Net mineralization was not correlated to % N or % lignin in the leaf material but was found to be negatively correlated to the polyphenolic concentration, r = −0.63, or the polyphenolic-to-N ratio, r = −0.75. Mineralization in excess of the control soil was found only for materials with a polyphenolic-to-N ratio
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TL;DR: In this article, a conceptual model of the processes by which plant leaf and root litter is transformed to soil organic C and CO 2 is presented, which is viewed as resulting from three general sets of characteristics.
1,409 citations
Book•
31 Jul 1993
TL;DR: In this paper, the authors present a classification of Agroforestry systems and practices, including the Multipurpose Trees (MPT) and the Colony Crop Combinations (CCC).
Abstract: Preface. I: Introduction. 1. The History of Agroforestry. 2. Definition and Concepts of Agroforestry. II: Agroforestry Systems and Practices. 3. Classification of Agroforestry Systems. 4. Distribution of Agroforestry Systems in the Tropics. 5. Shifting Cultivation and Improved Fallows. 6. Taungya. 7. Homegardens. 8. Plantation Crop Combinations. 9. Alley Cropping. 10. Other Agroforestry Systems and Practices. III: Agroforestry Species. 11. General Principles of Plant Productivity. 12. Agroforestry Species: the Multipurpose Trees. 13. Component Interactions. IV: Soil Productivity and Protection. 14. Tropical Soils. 15. Effects of Trees on Soils. 16. Nutrient Cycling and Soil Organic Matter. 17. Nitrogen Fixation. 18. Soil Conservation. V: Design and Evaluation of Agroforestry Systems. 19. The Diagnosis and Design (D&D) Methodology. 20. Field Experiments in Agroforestry. 21. On-Farm Research. 22. Economic Considerations. 23. Sociocultural Considerations. 24. Evaluation of Agroforestry Systems. 25. Agroforestry in the Temperate Zone. Glossary. SI Units and Conversion Factors. List of Acronyms and Abbreviations. Subject Index.
1,227 citations
TL;DR: In this article, the authors estimate that 50 to 70% more cereal grain will be required by 2050 to feed 9.3 billion people, which will require increased use of N of similar magnitude if the efficiency with which N is used by the crop is not improved.
Abstract: Presently, 50% of the human population relies on nitrogen (N) fertilizer for food production. The world today uses around 83 million metric tons of N, which is about a 100‐fold increase over the last 100 years. About 60% of global N fertilizer is used for producing the world's three major cereals: rice, wheat, and maize. Projections estimate that 50 to 70% more cereal grain will be required by 2050 to feed 9.3 billion people. This will require increased use of N of similar magnitude if the efficiency with which N is used by the crop is not improved. Fertilizer N‐recovery efficiency by the first crop is 30 to 50%. The remaining N either remains in the soil, the recovery of which in the following crops is very limited (
963 citations
TL;DR: In this paper, an organic resource database (ORD) is introduced that contains information on organic resource quality parameters including macronutrient, lignin and polyphenol contents of fresh leaves, litter, stems and/or roots from almost 300 species found in tropical agroecosystems.
768 citations
Cites background from "Nitrogen release from the leaves of..."
...A variety of multi-variable equations all indicate a hierarchical set of N, lignin and polyphenol content for predicting N release patterns from organic materials (Fox et al., 1990; Palm and Sanchez, 1991; Constantinides and Fownes, 1994a; Tian et al., 1995; Mafongoya et al., 1997; Palm et al., 1997)....
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...…of multi-variable equations all indicate a hierarchical set of N, lignin and polyphenol content for predicting N release patterns from organic materials (Fox et al., 1990; Palm and Sanchez, 1991; Constantinides and Fownes, 1994a; Tian et al., 1995; Mafongoya et al., 1997; Palm et al., 1997)....
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TL;DR: Nutrient dynamics in forest ecosystems in relation to tannins is reviewed to help clarify the role of tannin effects on forest ecosystem processes and nutrient cycling.
Abstract: Tannins make up a significant portion of forest carbon pools and foliage and bark may contain up to 40% tannin. Like many other plant secondary compounds, tannins were believed to function primarily as herbivore deterrents. However, recent evidence casts doubts on their universal effectiveness against herbivory. Alternatively, tannins may play an important role in plant–plant and plant–litter–soil interactions. The convergent evolution of tannin-rich plant communities on highly acidic and infertile soils throughout the world, and the intraspecific variation in tannin concentrations along edaphic gradients suggests that tannins can affect nutrient cycles. This paper reviews nutrient dynamics in forest ecosystems in relation to tannins. Tannins comprise a complex class of organic compounds whose concentration and chemistry differ greatly both among and within plant species. Because the function and reactivity of tannins are strongly controlled by their chemical structure, the effects of tannins on forest ecosystem processes are expected to vary widely. Tannins can affect nutrient cycling by hindering decomposition rates, complexing proteins, inducing toxicity to microbial populations and inhibiting enzyme activities. As a result, tannins may reduce nutrient losses in infertile ecosystems and may alter N cycling to enhance the level of organic versus mineral N forms. The ecological consequences of elevated tannin levels may include allelopathic responses, changes in soil quality and reduced ecosystem productivity. These effects may alter or control successional pathways. While a great deal of research has addressed tannins and their role in nutrient dynamics, there are many facets of tannin biogeochemistry that are not known. This lack of information hinders a complete synthesis of tannin effects on forest ecosystem processes and nutrient cycling. Areas of study that would help clarify the role of tannins in forest ecosystems include improved characterization and quantification techniques, enhanced understanding of structure-activity relationships, investigation of the fate of tannins in soil, further determination of the influence of environmental factors on plant tannin production and decomposition, and additional information on the effects of tannins on soil organisms.
681 citations
References
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Book•
01 Jan 1982
TL;DR: In this paper, the authors present an analysis of organic matter in soil using NMR Spectroscopy and analytical pyrolysis, showing that organic matter is composed of nitrogen and ammonium.
Abstract: Partial table of contents: Organic Matter in Soils: Pools, Distribution, Transformations, and Function. Extraction, Fractionation, and General Chemical Composition of Soil Organic Matter. Organic Forms of Soil Nitrogen. Native Fixed Ammonium and Chemical Reactions of Organic Matter with Ammonia and Nitrite. Organic Phosphorus and Sulfur Compounds. Soil Carbohydrates. Soil Lipids. Biochemistry of the Formation of Humic Substances. Reactive Functional Groups. Structural Components of Humic and Fulvic Acids as Revealed by Degradation Methods. Characterization of Soil Organic Matter by NMR Spectroscopy and Analytical Pyrolysis. Structural Basis of Humic Substances. Spectroscopic Approaches. Colloidal Properties of Humic Substances. Electrochemical and Ion-Exchange Properties of Humic Substances. Organic Matter Reactions Involving Pesticides in Soil. Index.
5,658 citations
TL;DR: In this article, an analysis for the rapid determination of nitrate-N in plant extracts is described. And the complex formed by nitration of salicylic acid under highly acidic conditions absorbs maximally at 410 nm in basic (pH>12) solutions.
Abstract: An analysis is described for the rapid determination of nitrate‐N in plant extracts. The complex formed by nitration of salicylic acid under highly acidic conditions absorbs maximally at 410 nm in basic (pH>12) solutions. Absorbance of the chromophore is directly proportional to the amount of nitrate‐N present. Ammonium, nitrite, and chloride ions do not interfere.
2,870 citations
TL;DR: The effects of initial nitrogen and lignin contents of six species of hardwood leaves on their decomposition dynamics were studied at the Hubbard Brook Experimental Forest by inverse linear relationships between the percentage of original mass remaining and the nitrogen concentration in the residual material.
Abstract: The effects of initial nitrogen and lignin contents of six species of hardwood leaves on their decomposition dynamics were studied at the Hubbard Brook Experimental Forest. Rate con- stants (k) for annual leaf mass loss ranged from -0.08 to -0.47. The rate constants (k) had a negative linear correlation (r2 = .89) with the ratio of initial lignin concentration to initial nitrogen concentra- tion. Decomposition dynamics of the litter materials were described by inverse linear relationships between the percentage of original mass remaining and the nitrogen concentration in the residual material. Initial lignin concentration was highly correlated (r2 = .93) with the slope of the inverse linear relationship for each of the litter types.
2,612 citations