ReviewThe effects of organic inputs over time on soil aggregate stability – A literature analysis
Introduction
Aggregate stability is a keystone factor in questions of soil fertility and environmental problems. Resistance of the aggregate to physical stresses determines soil sensitivity to crusting and erosion (Le Bissonnais, 1996a), germination and rooting of cultivated plants (Lynch and Bragg, 1985, Angers and Caron, 1998) and the ability of a soil to store carbon through the physical protection of organic molecules (Jastrow and Miller, 1997). Factors that influence aggregate stability have been frequently reviewed (Le Bissonnais, 1996b, Kay, 1998, Bronick and Lal, 2005, Amezketa, 1999). Texture, clay mineralogy, cation content, aluminium and iron oxides, and soil organic matter are the major soil properties influencing aggregate stability. Organic matter (OM) is a major factor affecting aggregate stability because its abundance and characteristics can be modified by agricultural practices. In many cultivation systems, fresh OM is periodically returned to the soil as litter or crop residues but the amounts and quality of the organic input are variable. This agricultural practice would appear to be an interesting solution for maintaining soil fertility and for soil rehabilitation in degraded situations.
Over years or even over seasons, aggregate stability in the field increases or decreases due to climatic conditions, agricultural practices (tillage or no tillage) and the decomposition of fresh organic input. In several conceptual models the increase of aggregate stability after organic additions to the soil is related to the decomposition dynamics of the inputs. In 1965, Monnier proposed a conceptual scheme (Fig. 1) that describes the effect of different reference products on soil aggregate stability across time scales varying from weeks, months to years after the incorporation. Some products, such as green manure had intense effects within a month on aggregate stability, while less readily decomposable materials, such as decomposed manure, had small initial effects but relatively large effects at the annual scale. Monnier proposed that the short-term effects of organic matter on aggregate stability were due to the turnover of microbial products and cells while the long-term effects were due to humified compounds.
Other authors proposed conceptual models that support this scheme (Guckert et al., 1975, Golchin et al., 1994, Chenu et al., 1998, Six et al., 2000). Formation and stabilization of aggregates by organic matter (Six et al., 2004) and interactions between aggregative factors and aggregate structures (Lynch and Bragg, 1985) have been reviewed already.
However, Monnier's scheme is the only one that simultaneously takes into account the effects of different products and the effect of aggregating factors on aggregate stability following organic inputs.
This review is aimed at identifying the well described although still unclear relationships between the decomposition of organic inputs to soil and aggregate stability. A specific objective was to discuss the validity of the conceptual model proposed by Monnier (1965). For this, we collected literature data about the effects of different organic inputs on soil aggregate stability and compared them with Monnier's scheme. We compared the relationships between binding agents and aggregate stability after organic additions. Then, we examined different points that are not explicitly taken into account in this scheme: the quality (intrinsic characteristics) and the quantity (rate of addition) of the organic product, the direct physico-chemical effect of the product immediately after the input and the effect of soil type in response to an organic product.
Section snippets
Material and methods
We based this literature analysis on the scheme proposed by Monnier in 1965 (Fig. 1). Monnier proposed a conceptual model where the effects of aggregate stability in terms of intensity, time and persistence of the measured effect depend on the organic products. In his model, Monnier presented aggregate stability in three phases identified as zones A, B and C. Zone A corresponds to the initial weeks after the input. During this phase, a maximal intensity effect of organic products on aggregate
Evidence of organic input effects on aggregate stability
Studies focusing on the impacts of organic inputs on aggregate stability are summarized in Table 1. Several studies used model molecules such as monosaccharides (e.g. Martin, 1945a), casein, lignin (e.g. Martin and Waksman, 1942, Martin, 1945b) or humic compounds (Fortun et al., 1989). A large range of complex organic products were also investigated, from different crop residues (e.g. Martens, 2000) to manures (e.g Gerzabek et al., 1995, Paré et al., 1999), composts (e.g. Martin, 1942,
The relationships between soil aggregate stability and binding agents during the decomposition of organic products
Several biological binding agents have been recognised as responsible for aggregation and aggregate stability. Monnier's model emphasises that the peak in aggregate stability is related to microbial decomposing agents. Here we recorded relationships between aggregate stability and binding agents over time after the addition of organic matter to the soil (Table 2). Good correlations were observed, in some cases, with microbial biomass over time (Kushwaha et al., 2001, Sonnleitner et al., 2003,
Underlying questions of Monnier's conceptual model
Several points are not clearly explained or predicted by Monnier's model, but should be taken into account to estimate the effects of an organic product on aggregate stability.
Conclusion
Poor soil structural stability is a serious and increasing problem in several areas of the world. An appropriate management of organic matter additions to soils may increase aggregate stability and thus reduce crusting and erosion problems. With this in mind it is necessary to select the quality, quantity and timing of organic matter additions to achieve the expected increases in aggregate stability over time. The conceptual scheme proposed by Monnier (1965) provides a framework for classifying
Acknowledgements
This study was funded by the French agency for environment and energy (ADEME). The authors would like to thank Sandhya Chennu, Ivan Woodhatch and Michael Corson for their judicious comments and decisive help in smoothing the text. We would also like to acknowledge the useful comments of the anonymous reviewers. Samuel Abiven was funded by the University of Zurich and the Swiss national foundation for Science while writing the manuscript.
References (86)
- et al.
Structural stability and carbohydrate contents of an ultisol under different management systems
Soil & Tillage Research
(2001) - et al.
Organic matter components and aggregate stability after the application of different amendments to a horticultural soil
Bioresource Technology
(2001) - et al.
Soil structure and management: a review
Geoderma
(2005) - et al.
Effects of compost, mycorrhiza, manure and fertiliser on some physical properties of a chromoxerert soil
Soil and Tillage Research
(2004) Influence of a fungal polysaccharide, scleroglucan, on clay microstructures
Soil Biology & Biochemistry
(1989)- et al.
Aggregate stability and microbial community dynamics under drying-wetting cycles in a silt loam soil
Soil Biology & Biochemistry
(2006) - et al.
A quantification of short-term macro aggregate dynamics: influences of wheat residue input and texture
Soil Biology & Biochemistry
(2005) - et al.
Changes in aggregation do not correspond with changes in labile organic C fractions in soil amended with 14C-glucose
Soil Biology & Biochemistry
(1996) - et al.
Formation of stable aggregates in degraded soil by amendment with urban refuse and peat
Geoderma
(1994) - et al.
Stabilization of aggregates by microbial biomass as affected by soil texture and type
Applied Soil Ecology
(1997)
Soil organic matter and water-stable aggregates under different tillage and residue conditions in a tropical dryland agroecosystem
Applied Soil Ecology
Plant residue biochemistry regulates soil carbon cycling and carbon sequestration
Soil Biology & Biochemistry
An improved sieving machine for estimation of soil aggregate stability
Geoderma
Organic matter quality and structural stability of a Black Chernozemic soil under different manure and tillage practices
Geoderma
An incubation experiment to determine factors involving aggregation changes in an arid soil receiving urban refuse
Soil Biology & Biochemistry
Changes in composition of soil polysaccharides and aggregate stability after carbon amendments to different textured soils
Applied Soil Ecology
Soil macroaggregate turnover and microaggregate formation: a mechanism for C sequestration under no-tillage agriculture
Soil Biology & Biochemistry
A history of research on he link between (micro)aggregates, soil biota, and soil organic matter dynamics
Soil & Tillage Research
Effect of straw, vegetable oil and whey on physical and microbiological properties of a chernozem
Applied Soil Ecology
Carbohydrates and aggregation in lowlands soils of Nigeria as influenced by organic inputs
Soil & Tillage Research
Biochemical composition and mineralization kinetics of organic inputs in a sandy soil
Soil Biology & Biochemistry
Changes in soil microbial biomass and aggregate stability following burning and soil rehabilitation
Geoderma
Dynamics of aggregate stability and biological binding agents during the decomposition of organic material
European Journal of Soil Science
Soil aggregate stability: a review
Journal of Sustainable Agriculture
Soil aggregate stability improvement with urban composts of different maturities
Soil Science Society of America Journal
Plant-induced changes in soil structure: processes and feedbacks
Biogeochemistry
Aggregate stability to water
Particular and mineral-associated organic matter in water-stable aggregates as affected by mineral fertilizer and manure applications
Canadian Journal of Soil Science
Descripcion de un simulador de lluvia para estudios de erosibilidad del suelo y estabilidad de los agregados al agua
Anales de Edafologia y Agrobiologia
Effect of different types of organic materials and lime on soil aggregation
Soil Science
Aggregation and organic matter decompostion in soils amended with de-inking paper sludge
Soil Science Society of America Journal
Clay-organic matter associations in soils: microstructure and contribution to soil physical stability
The contribution from hyphae, roots and organic-carbon constituents to the aggregation of a sandy loam under long-term clover-based and grass pastures
European Journal of Soil Science
Short-term effects of biological and physical forces on aggregate formation in soils with different clay mineralogy
Plant and Soil
Aggregate structure and carbon, nitrogen, and phosphorus in native and cultivated soils
Soil Science Society of America Journal
Effect of farmyard manure and its humic fractions on the aggregate stability of a sandy-loam soil
Journal of Soil Science
Effect of bituminous materials on soil aggregation
Arid Soil Research and Rehabilitation
Response of soil aggregate stability to manure amendments in the Ultuna long-term soil organic matter experiment
Zeitschrift für Pflanzenernährung und Bodenkunde
Soil structure and carbon cycling
Australian Journal of Soil Research
Microflore et stabilité structurale des sols
Revue de l'Ecologie et de la Biologie du Sol
Changes in microbial biomass C, soil carbohydrate composition and aggregate stability induced by growth of selected crop and forage species under field conditions
Journal of Soil Science
Cited by (552)
Soil aggregate stability governs field greenhouse gas fluxes in agricultural soils
2024, Soil Biology and Biochemistry