A heritage dataset of soil and water salinity in Bardenas, Spain

Abstract

This article presents the results of soil and water analysis plus the plans —or “maps”— from the Report [1] issued 1974 on salt-affected soils in a new irrigation district located in the semi-arid Bardenas area of Aragón, northern Spain (Fig. 1). The survey was carried out by the now defunct Institute for Agrarian Reform and Development (i.e., IRYDA by its Spanish acronym). Work began in January 1972, with a preliminary reconnaissance survey on 53,000 ha using aerial photographs at a scale of 1:32,000 from the USAF photogrammetric flight of 1956-57 which covered almost the whole of Spain. Photographs from this flight are available on the Spanish aerial photograph viewer (https://fototeca.cnig.es/fototeca/). At that time, levelling for irrigation had not yet begun. This reconnaissance allowed the selection of an area of 32,300 ha (Fig. 1) with relevant salinity symptoms, like irrigated fields with irregular or no crop growth. A more detailed photo interpretation of the area was carried out at 1:12,000 scale from a flight in August 1971. The new irrigation district is fed by high quality water from the Pyrenees, but soon faced salinity problems that were well known to the farmers and echoed by the media [2, 3, 4] in an environment of great social concern about increasing agricultural production [5]. The Report, written in Spanish, is dated July 1974, but the soil profiles were described and sampled between April 1972 and March 1974. The Report [1] consists of two volumes, the first is a Memoria containing data from the surveys, laboratory analyses, pedological descriptions and some photographs of the soils and other land features of agricultural importance, as well as data and calculations for designing the drainage of selected plots. The second volume consists of five folded plans: a) location of the surveyed area at the scale of 1:200,000, and four plans at the scale of 1:25,000, b) soil-geomorphologic units, c) soil units describing their characteristics, d) land use, and e) locations of the described soil profiles and other field observations. Taken together, these data, improved by our orthorectification, gives a picture of the salinity and other soil properties in this area. The reuse of the data for comparisons with the evolution of agriculture in subsequent years —especially soil salinity and sodicity— will help to evaluate the agricultural practices over the last fifty years, particularly after intensive land levelling and irrigation.