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Técnicas adaptadas da etnociência clássica foram utilizadas para descrever e avaliar os conhecimentos de um grupo de artesãos camponeses do Agreste Paraibano sobre alguns solos que eles usam como recurso cerâmico. Cinco perfis de solo foram descritos por agrônomos-pesquisadores (abordagem eticista) e por camponeses (abordagem emicista), em locais onde a população local extrai material para cerâmica. Amostras coletadas em ambas as abordagens foram usadas para caracterização morfológica e analítica desses solos. Os camponeses pesquisados foram capazes de distinguir, identificar e nomear diversos materiais de solo, arranjados em estratos ao longo dos perfis de solo, de modo comparável ao arranjo dos horizontes pedogenéticos. A visão, o tato e o paladar foram empregados pelos artesãos na avaliação da qualidade do solo para cerâmica. Quatro perfis descritos junto às fontes de material cerâmico foram classificados como Planossolo Nátrico e um como Planossolo Háplico. A realização de pesquisas etnopedológicas em diferentes contextos sociais e pedológicos pode contribuir para o avanço da ciência do solo, sendo também uma oportunidade para melhor compreender as formas camponesas de conhecimento e manejo de solos.Classic ethnoscientific techniques were adapted to describe and analyze the knowledge of peasant potters about soils they use for making pottery in a rural village in the Agreste region, State of Paraiba, northeastern Brazil. Five soil profiles from pits where local people obtain pottery clay were formally described by researchers (etic approach) and by peasant artisans (emic approach). Samples collected during both the emic and etic approaches were used for the morphological and analytical soil characterization. The peasant potters were able to distinguish, identify, and name soil materials arranged in layers along the soil profiles, somehow comparable to the arrangement of the pedogenetic horizons. Vision, touch and taste are used by local potters to evaluate the quality of pottery clay. Among the soil profiles described near clay pits, four were classified as Haplic Solonetz, and one as Eutric Planosol, according to the FAO/UNESCO legend. Ethnopedological studies in different social and pedological environments could contribute to the advancement of soil science and are an opportunity for an improvement in the understanding and appreciation of soil knowledge and management by peasant potters.

Subsurface-tile drainage is designed to remove gravitational water and soluble salts from the soil-root zone. However, soil swelling, as influenced by soil Na and electrical conductivity (EC), will reduce saturated hydraulic conductivity. The objective of the experiments reported in this paper was to determine the influence of Na and EC on the amount of water retained at field capacity (− 33 kPa) in northern Great Plains Na-affected soils. Field capacity water (gravimetric water content) for all soils increased with increasing sodium adsorption ratio (SAR) and decreasing EC, respectively. For example, at an EC of 4 dS m − 1 , the amount of water retained at field capacity increased from 0.23 to 0.31 g g − 1 as SAR in the treatment solution increased from 7 to 28. For the Exline soil at 30–60 cm depth, field capacity water decreased from 0.31 to 0.18 g g − 1 when EC increased from 0.5 to 15 dS m − 1 at SAR 24. In general, across all SAR values, an EC greater than 4 dS m − 1 was required to prevent swelling. However, for soils with high natural salinity, no significant difference was observed for field capacity water using the above methods; high salt content and the presence of calcite in these soils may have reduced the potential for water retention and may have lower field capacity. Therefore, to maintain drainage performance in sodium-affected soils one should regularly monitor Na and EC within the soil profile so that EC values do not fall below critical threshold values. [ABSTRACT FROM AUTHOR]