Cation dynamics in soils with different salinity levels growing irrigated rice

Abstract

SUMMARYSalinity levels in soils of the Outer Coastal Plain of Rio Grande do Sul, Brazil, can be high, due to excess of Na in the irrigation water, evapotranspiration and soil development from marine sediments. The cultivation of irrigated rice could be an alternative, since ion uptake as well as leaching by the establishment of a water layer could mitigate the effects of soil salinity. This study aimed to evaluate the dynamics of basic cations in the solution of Albaqualf soils with different salinity levels growing irrigated rice. The plow layer contained exchangeable Na percentages (ESP) of 5.6, 9.0, 21.2 and 32.7 %. The plant stand, dry matter, Na, K and Ca + Mg uptake at full flowering and grain yield were evaluated. The levels of Na, K, Ca + Mg and electrical conductivity (EC) in the soil solution were also measured weekly during the rice cycle at four soil depths, in the water layer and irrigation water. The Na, K and Ca + Mg uptake by rice at full flowering was used to estimate ion depletion from the layer under root influence. Soil salinity induced a reduction in the rice stand, especially in the soil with ESP of 32.7 %, resulting in lower cation uptake and very low yield at that site. As observed in the water layer and irrigation water, the Na, K, Ca + Mg and EC levels in the soil solution decreased with time at depths of 5, 10 and 20 cm, regardless of the original soil salinity, showing that cation dynamics in the plow layer was determined by leaching and root uptake, rather than by the effect of evapoconcentration of basic cations in the soil surface layer.Index terms: exchangeable sodium percentage, potassium, calcium, magnesium, electrical conductivity.(

Assessment of agricultural land salinization via soil analysis and remote sensing data: Case study in Pavlodar region, Kazakhstan

“…The variable EC is used to monitor soil salinity due to the practicality of measurement and high correlation with total dissolved solids, as it represents the phenomenon of transfer of electric cur-rent developed by charged particles, ionic solutes (cations and anions) and colloids to the force acting on the electric field (Campos Carmona et al 2010). As a result, soil samples from all agricultural plots had an electrical conductivity below 0.06 dS/m.…”

Crescimento inicial e acúmulo de sódio em plantas de arroz submetidas à salinidade

“…A intensidade com que a salinidade afeta o crescimento e a produtividade do arroz é determinada por fatores associados à própria planta, ao solo e à água, às práticas de manejo e às condições ambientais (Carmona et al, 2010). Levando-se em consideração a interação entre tais fatores, uma cultivar pode manifestar tolerância à salinidade, sobrevivendo e, às vezes, até crescendo, mesmo que em taxas menores, ou pode mostrarse suscetível, apresentando redução severa no crescimento ou morte, dependendo da intensidade do estresse (Cambraia, 2005).…”

Adubação potássica em arroz irrigado conforme a capacidade de troca catiônica do solo

“…Fraga et al (2009), em estudo com os mesmos solos do presente trabalho, concluíram que a maior capacidade do Neossolo Litólico eutrófico vertissólico, em comparação ao Gleissolo Háplico e ao Planossolo Háplico, ambos eutróficos arênicos, está relacionada à maior presença de feldspatos de potássio e de esmectitas, e que a contribuição de formas não trocáveis de K para o conteúdo disponível do nutriente no solo sempre ocorre. Da mesma forma, Carmona et al (2010) relataram importante contribuição dessas formas não trocáveis na nutrição do arroz, mesmo em Planossolos Háplicos, da Planície Costeira Externa do Rio Grande do Sul.…”