The International Atomic Energy Agency (IAEA), through the Joint Division with the Food and Agriculture Organization (FAO) of the United Nations, assists its Member States in applying nuclear techniques to alleviate challenges in food safety, food security and sustainable agricultural development. The Soil and Water Management & Crop Nutrition (SWMCN) Subprogramme, within the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, has made significant contributions to the development of isotopic techniques for the assessment of soil degradation and the development of efficient soil and land conservation approaches. These techniques include fallout radionuclides such as 137 Cs, 210 Pb ex , 7 Be, and 239+240 Pu as well as 13 C stable isotope and compound-specific stable isotope analyses. These methodologies were developed and/or refined through the work of researchers from developed and developing countries who were selected to work within the frame of IAEA's Coordinated Research Projects (CRPs). Internal research activities implemented in the Joint FAO/IAEA's SWMCN Laboratory in Seibersdorf supported the work accomplished in the CRPs. The methodologies thus developed have been subsequently disseminated to developing countries by IAEA's Technical Cooperation Programme to assist Member States to adopt climate-smart agriculture and reduce soil degradation that poses a threat to food security and the environment. This review paper provides an overview of the activities conducted in the frame of CRPs for combating soil erosion over the last 20 years and highlights the major achievements. Examples of the success and the impact obtained in Morocco, Madagascar, and Vietnam in using these isotopic techniques are presented.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Abstract. Cosmic-ray neutron sensing (CRNS) has emerged as a reliable method for soil moisture and snow estimation. However, the applicability of this method beyond research has been limited due to, among others, the use of relatively large and expensive sensors. This paper presents the tests conducted to a new scintillator-based sensor especially designed to jointly measure neutron counts, total gamma-rays, and muons. The neutron signal is firstly compared against two conventional gas-tube-based CRNS sensors at two locations (Austria and Germany). The estimated soil moisture is further assessed at four agricultural sites in Italy based on gravimetric soil moisture collected within the sensor footprint. The results show that the signal detected by the new scintillator-based CRNS sensor is well in agreement with the conventional CRNS sensors and with the gravimetric soil moisture measurements. In addition, the muons and the total gamma-rays simultaneously detected by the sensor show promising features for a better correction of the incoming variability and for discriminating irrigation and precipitation events, respectively. Further experiments and analyses should be conducted, however, to better understand the added value of these additional data for soil moisture estimation. Overall, the new scintillator design shows to be a valid and compact alternative to conventional CRNS sensors for non-invasive soil moisture monitoring that can open the path to a wide range of applications.
The presented study uses the recent colour aerial photographs, historical black and white aerial photographs, and detailed digital elevation model to assess the spatial distribution and long-term temporal dynamics of soil loss in agriculturally intensively exploited loess hilly land with a subcontinental temperate climate. The strongly eroded soils appear in the studied area as bright patterns, surrounded by darker soils, and they are well visible on aerial photos. Three approaches of interpretation of aerial photographs were tested: visual interpretation, pixel-based image classification, and object-based image classification. All three methods provided detailed maps of soil redistribution patterns. The bright areas as the areas of soil degradation characterized by erosion increased from 1949 until 2011 by 76%. A detailed map of areal erosion patterns was used for the validation of water erosion models. LS-factor of USLE and ED’ index of USPED were selected for expressing the relation of real erosion to the terrain. The relationship between surface morphology and real erosion is very complex, and the tested water erosion models do not express it sufficiently. Therefore, the first and second-order directional derivative of the surface elevations with respect to the tillage direction has been tested. The absolute value of the first-order directional derivative showed better results and better corresponded with the real erosion pattern than the other morphometric characteristics. The findings suggest that tillage is the dominant erosion factor in the area.
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