No abstract

Research was focused on determination of water-stable aggregates (WSA) distribution in soil (cambisol) under different land use (forest, arable land) taking into account also the age of forest stand. Soil samples were collected at three localities separately for arable and forest soil. The localities were selected from map in places where arable land had been afforested in the past. Afterwards 30 samples were dry sieved and then wet sieved to determine the percentage of individual soil fractions of WSA, which allowed comparison of localities. Results showed that from the land use perspective, no prominent differences were evident after dry sieving. However, after the subsequent wet sieving, there was a distinct change. For arable soil, the fraction larger than 2 mm was almost entirely (98.22–98.88%) dissolved into smaller fractions, while the results of forest soil showed much better soil properties, as the largest fractions (>2 mm and 2–1 mm) were still represented in the sample in the range of 34.18% to 69.14%. From the results, it is possible to conclude that aggregation already occurs between 10 and 24 years after the establishment of the forest stand, which should be more investigated during the following research.

<p>Erosion is one of the main soil threats in the Mediterranean region, leading to degradation and desertification of several areas. Water stable aggregates (WSA) is a rate of the extent to which soil aggregates resist falling apart when wetted and hit by rain drops, indicating also the resistence of soil to compaction and soil quality status. This study aims to determine the WSA in differrent soils, characterized by distinct land-uses and soil types. This work is part of Ribeira dos Covões catchment research, in the suburbs of Coimbra, the largest city of central Portugal, where research dealing with soil and hydrological properties has been developed for long time. WSA were investigated for agricultural and forest soils, on both sandstone and limestone. Soil surface samples (0-10cm) were collected in December 2020, and analysed through wet sieving method which quantifies the amount of water-stable soil aggregates fractions. <br><br>Not surprisingly, the results showed that forest soils contain a much higher proportion of water-stable soil aggregates of larger fractions than agricultural soil, where the smaller fractions prevailed. Similar results have been also reported in previous studies and found during our previous research at Praha-Suchdol locality (Housle), in Czech Republic. The fraction distribution of WSA in sandstone and limestone was comparable for forest soils. In case of agricultural soils, distribution of WSA was slightly different. WSA are a relevant part of soil surface layer, with important impacts on other soil properties (e.g. soil moisture, hydrophobicity, infiltration), thus affecting the rainfall-runoff-erosion processes, previously investigated in the study area. Further research will be developed to better assess WSA differences between distinct forest types, given the relevance of vegetation species for example on hydrophobicity and WSA dynamics. A better understanding of WSA in different soil types will be useful to support improved soil management and mitigate land degradation.</p>