Sodicity Research Articles

Mitigation of Soil Salinity using Biochar Derived from Lignocellulosic Biomass

Soil salinisation is recognised as a serious form of soil degradation, affecting crop production and compromising food security. It is crucial to remediate the negative impacts of soil salinisation to improve the associated soil functions. This paper review the various role of biochar, derived through the pyrolysis of fibrous biomass, to improve the physical properties (soil porosity, soil aggregation, water holding capacity, hydraulic conductivity and organic carbon content) and chemical properties (pH, electrical conductivity, exchangeable sodium percentage and sodium adsorption ratio) of saline soil. Physical adsorption and ion exchange are found to be the most common remediation mechanisms of saline soil by biochar.

Salt tolerance potential of halophytic grasses – Phyto-remediation and Physiological perspectives

The experiment was conducted to explore salt tolerance potential of Urochondra setulosa and Sporobolus marginatus (collected from the extreme saline habitat of Rann of Kutch, Gujarat, India) and Leptochloa fusca (from RRS, CSSRI, Lucknow, India). The phytoremediation potential of these halophytes was quantified in terms of reduction in soil EC and pH. It was observed that mean soil pH values reduced from 9.5 to 9.13 and 10.0 to 9.51 whereas mean ECe values decreased from 30 to 19.7, 40 to 28.9 and 50 to 36.47, respectively at the harvest stage. In addition, the tolerance potential of these grasses towards salinity and sodicity was also explored through gas exchange attributes, K+/Na+ and biomass production etc. L. fusca and S. marginatus produced higher biomass under sodic condition while in U. setulosa it increased under salinity stress. Under sodic condition, L. fusca showed less reduction and maintained higher K+/Na+ in their leaf tissues. Based on these various indicators of stress tolerance, the three halophytes could be categorised as salt tolerant or alkaline stress tolerant.

Indicadores de calidad físico-química de las aguas residuales del estado de Oaxaca, México

El estado de Oaxaca posee un sistema hidrológico extenso y complejo, debido a su variación en la disponibilidad regional y temporal. Además, el crecimiento poblacional e industrial han incrementado la descarga de aguas residuales degradando así su calidad. El volumen permitido de aguas residuales que se pueden transferir a los cauces en el estado es de 0.35 m3 s-1; sin embargo, existen descargas ilegales que elevan las concentraciones iónicas; dichas aguas son utilizadas para el riego agrícola desde su origen hasta su desembocadura. Con la finalidad de evaluar cuantitativamente los parámetros sobre las concentraciones iónicas de las aguas residuales para su aplicación en los suelos agrícolas, se establecieron 89 estaciones de muestreo en el verano de 2018 a lo largo del estado. La calidad del agua se clasificó de acuerdo con su conductividad eléctrica (CE), relación de adsorción de sodio (RAS), carbonato de sodio residual (CSR) y concentraciones de boro y fósforo. El coeficiente mg L-1 = af (CE) fue de a = 0.671, este valor a corresponde al tipo de agua de composición SO4‑Cl‑HCO3. El pH fue de 6.98‑7.54‑8.32; la CE fluctuó entre 80-2550 µS cm-1 con un promedio de 475 µS‑cm-1. El contenido de Na2CO3 es de (-0.34)‑0.74‑8.10 mmolc L‑1. El coeficiente de la relación funcional µ (M/L) = af (CE) fue de a = 0.0117. Los valores de la RAS original, ajustado y corregido fueron: RASor 0.27-1.82-11.54, RASaj 0.05-2.76‑23.51 y RAScorr 0.18-1.87-12.66 respectivamente. Para conocer el peligro potencial de sodicidad se calcularon los valores de la relación PSI-RAS y se obtuvo que en RASor = 16.32, RASaj= 28.43, RAScorr = 17.63. De conformidad con los parámetros físico-químicos las aguas residuales de Oaxaca son sulfático-clorhídrico-bicarbonatadas.

English

The gradual decrease of fresh water resources is le ading towards the inevitable use of saline water for irrigation. Using saline waters for irrigation, there is needed to take management practices to prevent the development of excessive soil salinisat ion for crop production. A field experiment was carried out to investigate the effect of saline water irrigation and management practices on uptake of primary and secondary nutrients. At harvest, the si gnificantly highest total N, K, S and Mg uptake was recorded by C 2-FYM, followed by C 3-FYM and C 3/C 4-FYM. Regarding P and Ca total uptake, among water quality levels, the significantly highe st uptake was recorded by C 2 water followed by C 3 water and alternate irrigation with C 3/C 4 water. Among management practices, significantly t he

Rainfall fluctuations and vegetation patterns in alkali grasslands - using self-organizing maps to visualise vegetation dynamics

Knowledge about the drivers of vegetation dynamics in grasslands is fundamental to select appro-priate management for conservation purposes. In this study, we provide a detailed analysis of vegeta-tion dynamics in alkali grasslands, a priority habitat of the Natura 2000 network. We studied vegetation dynamics in five stands of four alkali grassland types in the Hortobagy National Park (eastern Hunga-ry), between 2009 and 2011. We analysed the effect of fluctuations in precipitation on both the overall vegetation composition and on the cover of each species using Self Organizing Map neural networks (SOM). We found that SOM is a promising tool to reveal plant community dynamics. As we analysed species cover and overall vegetation composition separately, we were able to identify the species re-sponsible for particular vegetation changes. Fluctuations in precipitation (a dry season, followed by a wet and an average season) caused quick shifts in plant species composition because of an increasing cover of halophyte forbs, probably because of salinisation. We observed a similar effect of stress from waterlogging in all studied grassland types. The species composition of Puccinellia grasslands was the most stable over the three years with varying precipitation. This was important as this grassland type contained many threatened halophyte species. Self-organising maps revealed small-scale vegetation changes and provided a detailed visualisation of short-term vegetation dynamics, thus we suggest that the application of this method is also promising to reveal community dynamics in more species-rich habitat types or landscapes.

CORRELATIONS BETWEEN SOIL SODICITY AND FOLIAR SYMPTOM OF WOOD DECAY OF KIWIFRUIT

Wood decay of kiwifruit (Actinidia deliciosa) is a relatively new disease of complex etiology. This disease has gained much attention in recent years because it has become widespread in kiwifruit-growing areas. Foliar symptoms of the disease are associated with toxins produced by pathogens and develop presumably in response to certain environmental and physiological factors. Vineyard surveys were conducted over nine years in a main Italian kiwifruit growing- area, to investigate a potential correlation between soil sodicity and the occurrence of leaf symptoms. Greenhouse trials were also carried out to evaluate physiological parameters potentially associated with the symptoms, as transpiration rate, stomatal conductance, net photosynthesis, and water potential of potted vines grown with different levels of soil sodicity. In the vineyard trials, an increase in soil sodicity significantly augmented the incidence of wood decay of kiwifruit. Higher levels of soil sodicity correlated to increased transpiration and decreased water potential in plant tissues, which in turn can increase toxin translocation and accumulation in the leaves.

Water Salinity and Sodicity Effects on Soil Structure and Hydraulic Properties.

Water Salinity and Sodicity Effects on Soil Structure and Hydraulic Properties.

Salinidade, sodicidade e propriedades microbiológicas de Argissolo cultivado com erva-sal e irrigado com rejeito salino

O objetivo deste trabalho foi avaliar o efeito da irrigação com rejeito da dessalinização, oriundo de tanques de produção de tilápia-rosa, sobre as propriedades químicas e microbiológicas de solos cultivados com erva-sal (Atriplex nummularia Lindl.). Quatro áreas foram usadas, das quais duas foram irrigadas com rejeito salino e cultivadas, durante um e cinco anos, com erva-sal. As outras duas áreas foram conduzidas sem irrigação: uma cultivada com vegetação natural e outra com a halófita. Avaliaram-se os parâmetros relativos à salinidade e sodicidade do solo, e também as seguintes características: carbono da biomassa microbiana (Cmic); relação Cmic/carbono orgânico; atividade das enzimas fosfatase ácida, fosfatase alcalina, beta-glucosidase, protease, L-asparaginase, L-glutaminase. A adição de sais afetou as propriedades físicas e químicas dos solos irrigados com rejeito salino, com tendência à salinização e sodificação. A salinidade afetou as propriedades microbiológicas nos solos irrigados, mas o cultivo da halófita favoreceu a produção das enzimas estudadas. O cultivo da erva-sal em áreas que recebem rejeito salino pela irrigação melhora a qualidade biológica dos solos e sua fertilidade, mas não impede a salinização.

Phytoremediation of a sodic forest ecosystem: plant community response to restoration process.

The creation of a new biotope on degraded lands is the focused objective nowadays, on a global level. An attempt was made to rehabilitate sodic waste lands through the establishment of plant cover, with diverse plant communities within Banthra Research Station of the National Botanical Research Institute, Lucknow, India (80degr45min-53degr53min E and 26degr40min- 26degr45min N) for the last three decades. A rehabilitated forest ecosystem developed in this way consists in a number of herbs, shrubs and trees. Derris indica, Dalbergia sissoo, Azadirachta indica, Cassia siamea, Terminalia arjuna, Syzigium cumin were the dominant species in this rehabilitated forest, whereas Sporobolus, Desmostachya and Dactyloctenium were a common genera of grasses /forbs on a barren land. This study showed that species diversity and productivity significantly influenced the soil amelioration process. A comparison of three afforested sites with a varying degree of productivity and diversity indicated that some soil properties were influenced by diversity while others by productivity. Individual effects of diversity and productivity were classified as 42% and respectively 58%, in soil reclamation. A combined effect of both biomass productivity and species diversity contributed about 92% towards amelioration. There was an appreciable reduction in soil pH and ESP (exchangeable sodium percentage) and an increase in organic C and N contents showing that sodicity has receded in the forested soil. This experience can be tried out on similar sites of arid and semiarid regions of the world for the bioreclamation of sodic lands.

Salination and range of arboviruses

Salination and range of arboviruses