Using 137Cs Resampling Method to Estimate Mean Soil Erosion Rates for Selected Time Windows

This book provides guidelines for using a new approach of resampling the Cs-137 radionuclide tracer which is used to estimate soil erosion rates. The Cs-137 resampling approach will improve significantly the use of the Cs-137 method for assessment of soil erosion, because resampling the radionuclide repeatedly (at least two times, but more sampling campaigns are possible) allows to avoid several methodological difficulties associated with Cs-137 method, namely the problems with small-scale spatial heterogeneity, the question of representativeness of reference site, reference samples, and inappropriate time extent of evaluated period. All these methodological problems are very important for reliability and accuracy of erosion rates estimated by Cs-137 method. If using single sampling approach, the small-scale spatial heterogeneity can be overcome by high number of sampling points, but this is time and labour demanding solution increasing the expenses of the erosion research. The representativeness of reference site is evaluated usually on the basis of expert judgement and knowledge of land use history of studied area, but this approach is often uncertain because the expert judgement can be subjective and the data on land use history is often not sufficient. Further, in many areas an appropriate reference site is not available, what limits the territorial extent of using Cs-137 method. The resampling approach offers its second sampling to be done in a proximate vicinity of the same points sampled during the first sampling campaign. A great advantage is the possibility to decide how long time windows should be investigated. Choosing the time schedule of first and second sampling allows to shorten the time window and adjust it to the study objectives. This is a great improvement of the Cs-137 method, because the time period since the Cs-137 fallout is still growing and thus if using the single sampling approach the results refer to still longer and longer time window(since the Cs-137 fallout until the sampling time), and this period (recently ca 60 years assuming the maximum Cs-137 fallout in 1963) is too long to represent stable land use, because land uses are changing over the time and having the same land use over six decades is rather rare. The improvement of Cs-137 method achieved by resampling approach is significantly contributing to understanding the erosion dynamics and estimating its rates under changing environmental conditions (such as land uses, weather), and it will bring a significant benefit to soil conservation programmes, because Cs-137 method is indispensable for assessing the medium and long term soil erosion rates, and this information is among the basic inputs needed for planning and designing soil conservation measures.

Paolo Porto is currently Associate Professor in Agricultural Hydraulics and Torrent control, at the University Mediterranea of Reggio Calabria (Italy), and Professor in the field of Physical Geography and Geomorphology at the Kazimierz Wielki University of Bydgoszcz (Poland). He obtained in 1989 his Master degree in Forest Sciences at the University Mediterranea, and he completed his PhD in 1995 in Catchment hydrology and torrent control at the University of Bari (Italy). His research activity was developed with the support of several fellowships spent at the Dept of Civil Engineering of the Colorado State University, USA (6 months), at the Department of Engineering and Agro-Forest Technologies of the University of Palermo, Italy (2 years), at the National Research Council of Cosenza, Italy (4 years), and at the Dept of Geography of the University of Exeter, UK (3 years) where he was appointed as 'Honorary Member' from February 2014 to January 2017. His research activity (Scopus H-index=28) in soil erosion, radionuclides, hydrology, and torrent control is well documented in over 100 papers published in international and national journals. Paolo Porto covers also the role of President (2021-2025) of the International Commission on Continental Erosion (IAHS/ICCE), and Vice-President (2022-2025) of the International Association of Sediment and Water Sciences (IASWS).

Emil Fulajtar: Soil scientist working recently at National Agriculture and Food Centre, Soil Science and Conservation Institute in Bratislava, Slovakia, graduated in Geography and Cartography at Comenius University, Bratislava, Slovakia (1987), MSc in Soil Science at University of Ghent, Belgium (1993), PhD in Pedology at Comenius University, Bratislava, Slovakia (2003), was working originally in general pedology, soil genesis, soil classification and soil mapping. Since 1994 he specialised in soil erosion research (measuring, modelling, and mapping of soil erosion) andfurther he specialised in nuclear techniques used in soil science, mainly using fallout radionuclides (FRN) in soil erosion assessment, compound specific stable isotope (CSSI) technique used for identification of sediment sources and cosmic ray neutron sensor (CRNS) using for soil moisture assessment. His major achievements are contributions to study of soil genesis of Chernozems on loess, identification of new vertisol soil type in Slovakia, contributions to modelling of soil erosion using Universal soil loss equation (USLE), developing methods for erosion mapping using remote sensing and extensive measurements of soil erosion rates at erosion plots, elementary watersheds, and with Cs-137 method. These results are summarised in book soil erosion and conservation, two book chapters on soil erosion and a number of research papers. He is also an author of methodological handbook for using Cs-137 method for soil erosion assessment and coauthor of methodological chapter on soil sampling and two editions of Slovak soil classification. Apart of conducting own research he was working many years also in soil research management as scientific secretary at European Commission, COST (Cooperation in Science and Technology) Office (2001-2003), science officer at European Science Foundation, COST Office (2004-2005) and project officer at International Atomic Energy Agency (2006-2007 and 2016-2023) and he is coauthor of a number of research papers presenting the results of erosion research projects conducted in various countries.

Lee Kheng Heng has a PhD in soil science from Massey University, New Zeeland, and has more than 30 years' experience in soil-plant-water interaction research, agricultural water management, water use efficiency, integrated nutrient-water interactions and diffuse pollution control for sustainable agricultural production systems.

Over nearly 24 years, Dr Heng worked at the Soil and Water Management & CropNutrition (SWMCN) Subprogramme, in the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture, in Vienna, Austria. Since 2014, she was the Head of SWMCN Section, developing the overall strategy of the Soil Subprogramme. Dr Heng recently (October 2023) retired from the IAEA. During her working period at IAEA she coordinated a number of research project on various aspects of soil water management, developing new techniques of soil moisture measurement such as the cosmic ray neutron sensor (CRNS); using stable isotopes for identification of water pollution from agriculture; using fallout radionuclides (FRN) for assessment of soil erosion, etc. Further she was involved in a great number of technical cooperation projects transferring the nuclear techniques to developing countries, as well as giving lectures at IAEA training activities on new nuclear techniques. The work assists scientists in IAEA Member States to develop, validate and disseminate a range of soil, water and crop management technology packages through the use of nuclear and nuclear-related techniques.

Her work span over all continents with special focus on tropical areas of Asia, Africa and Americas. She is the author and co-author of a huge number of research papers and several monographies, especially the methodological books on various aspects of nuclear techniques published by Springer and IAEA TecDoc series.

She was also working at FAO, Rome, Italy, on AquaCrop model, a crop water productivity model, simulating yield response to water of herbaceous crops, and the effects of environment and management on crop production and food security.

Dr Heng won several awards for her professional achievements including the IAEA Superior Achievement Award, IAEA Merit Awards, IAEA Merit Promotion and the USDA-Agricultural Research Service (ARS) Outstanding Sustained Effort Technology Transfer Award for Outstanding Work in Technology Transfer to Users.

Before joining the IAEA, Dr Heng worked as a research associate at the University of Melbourne, Australia. Prior to that she worked as a Soil and Environmental Scientist at Landcare Crown Research Institute in New Zealand.