Application of Fractal Theory to quantify Soil Aggregate Stability as influenced by Tillage Treatments

Abstract

Soil structure is critical for the seed germination, growth of plants, and water and contaminants transport. Soil structure is modified by tillage treatments. A scale is needed to quantify the tillage-induced changes in soil structure. The present study investigated the ability of fractal dimension to quantify soil aggregate stability in a calcareous soil in an arid region as influenced by tillage treatments. Furthermore, the non-linear fractal dimension D nl was compared with mean-weight diameter D mw and geometric mean diameter D gm of aggregates. Results indicated that fractal dimension D nl was more appropriate than D mw and D gm to quantify soil aggregate stability induced by tillage treatments. The mouldboard plough plus disc (MD) and twice chisel plough, orthogonal to each other plus disc (2CD) treatments, due to higher soil aggregate fragmentation, are not recommended. On the other hand, the no-till (NT) and till-planting (TP) treatments resulted in the best soil aggregate stability, but low yield may be obtained in the NT treatment. Furthermore, the chisel plough plus disc (CD), and Khishchi tined implement plus disc (KD) treatments were not significantly different from the NT and TP treatments. However, temporal analysis of the non-linear fractal dimension indicated that the values of D nl were increased during the experiment years, particularly, in the MD, CD, CR, and 2CD treatments, while the fractal dimension in the TP and NT treatments started to increase late in the 4th year. Therefore, the tillage-planting and the NT treatments may be the most appropriate tillage treatment in the conservation of soil aggregate stability.