Application of fractal theory in assessing soil aggregates in Indian tropical ecosystems

• Published in: Journal of forestry research 2012, Vol.23 (3), p.355-364
• Main Authors: Tripathi, S. K, Kushwaha, C. P, Basu, S. K
• Format: Article
• Language: English
• Subjects: aggregate stability; agroecosystems; arid lands; Biomedical and Life Sciences; crop production; Forestry; forests; fractal dimensions; land use change; Life Sciences; minimum tillage; Original Paper; savannas; soil aggregates; soil aggregation; 农业生态系统; 分形理论; 印度; 土地利用变化; 土壤团粒结构; 土壤团聚体; 热带稀树草原; 生态系统评估
• ISSN: 1007-662X; 1993-0607
• DOI: 10.1007/s11676-012-0271-3

Soil aggregation varies according to climatic and manage- ment factors, and is difficult to measure because of irregular shapes and sizes of soil aggregates. We applied fractal theory to assess soil aggrega- tion as affected by （1） land use change from forest to savanna, （2） nutri- ent additions in forest, ecotone, and savanna ecosystems, and （3） tillage practice and residue treatments in an agro-ecosystem. We used fractal dimensions nonlinear （D,o,-lin） and linear （Dlin） based on number of ag- gregates （N） and mass of aggregates （M） （the range of values were 2.6-2.89 and 2.694.41, respectively） to capture the variations in the sizes of soil aggregates due to land use and treatments/management in these ecosystems. The variation in the values of non-linear fractal dimension based on mass （DMnon-lin） was smaller in forest and savanna ecosystems with and without nutrient additions, while the variation was wider in agro-ecosystems with different management practices. Linear fractal dimensions based on number （Dr~i,） and mass （DMlin） of aggregates var- ied marginally in these ecosystems and did not capture the variations in soil aggregates well. The variations in non-linear fractal dimension indi- cate that continued nitrogen loading in forest accelerates the formation of macro-aggregates, whereas in savanna the situation was reversed. The values of non-linear fractal dimensions did not show significant change after 6 years of nutrient additions in the ecotone; reflecting a buffering mechanism of this system in soil aggregate formation. On the basis of non-linear fractal dimension values, we conclude that residue retention and minimum tillage are appropriate for proper maintenance of soil ag- gregate stability for sustained crop production in the Indian dry land agro-ecosystems