Soil fragmentation and aggregate stability as affected by conventional tillage implements and relations with fractal dimensions

• Published in: Soil & tillage research 2020-03, Vol.197, p.104494, Article 104494
• Main Authors: Tagar, A.A., Adamowski, Jan, Memon, M.S., Do, Minh Cuong, Mashori, A.S., Soomro, A.S., Bhayo, W.A.
• Format: Article
• Language: English
• Subjects: Aggregate size distribution; Aggregate stability; Conventional tillage implements; Fuel consumption
• ISSN: 0167-1987; 1879-3444
• DOI: 10.1016/j.still.2019.104494

•The study evaluated soil structure as affected by conventional tillage implements.•Disk plough followed by two passes of cultivator was found to be the optimal technique for use in a clay loam soil.•Mass fractal dimension and mean weight diameter are strongly inversely correlated.•Higher values of mass fractal dimension and lower values of mean weight diameter may be used to quantify fine seedbeds.•Lower values of mass fractal dimension and higher values of mean weight diameter may be used to quantify coarse seedbeds. Due to a lack of accurate information regarding soil aggregate size distribution and stability, farmers in Sindh, Pakistan often apply excessive tillage, creating an overly fine seedbed that can lead to the depletion of soil organic matter (SOM) and make the soil more vulnerable to wind and water erosion. The current paper investigates the effects of conventional tillage implements on soil fragmentation and aggregate stability, along with how these factors relate to fractal dimensions. The study aims to: (i) achieve a better understanding of soil structure and establish which tillage implement provides the best soil structure and (ii) determine the function that best describes the proportion of small aggregates in the soil. Six tillage treatments were studied, including: moldboard plough + disk harrow two passes (MPDH2), disk plough + cultivator two passes (DPC2), cultivator two passes (C2), cultivator four passes (C4), cultivator six passes (C6), and minimum tillage (disk harrow one pass) (MT) for a clay loam soil. At each of two depths (0-0.15 m and 0.16-0.30 m), four soil samples from randomly selected locations in each plot were collected (3 blocks × 6 tillage × 2 depths × 4 samples, n = 144) with the help of a soil auger. Aggregate size distribution was measured by a dry sieving method, and aggregate stability was determined by a wet sieving method. The correlations between mean weight diameter (MWD), mass fractal dimension (Dm), and soil aggregation were investigated. The greatest proportions of small aggregates and the lowest proportions of intermediate aggregates were found under DPC2 followed by C6, while a greater proportion of intermediate aggregates and a lower proportion of small aggregates was observed under MT. However large aggregates (>25 mm) were negligible across all treatments. The highest values of Dm were found after DPC2, while the highest values of MWD were found after MT. The highest proportion of water stable aggreg