Saline Sodic Soil Amendments

El objetivo del trabajo fue evaluar el efecto de un vermicompost sobre las propiedades de un suelo salino-sódico del Cebollal de Coro. Se realizó un experimento de incubación para comparar tres dosis de vermicompost. Se implementaron cuatro tratamientos: un tratamiento sin vermicompost (T1); T2: 1% vermicompost; T3: 5% vermicompost y T4: 10% vermicompost, durante un período de incubación de 28 días, con mediciones a los 7, 14, 21, y 28 días. En cada una de estas fechas fueron evaluadas las variables pH del suelo, conductividad eléctrica (CE), porcentaje de sodio intercambiable (PSI), carbono orgánico del suelo (COS), carbono de biomasa microbiana (CBM) y actividad ureásica (AU). El pH, la CE y el PSI disminuyeron durante el ensayo. La CE para T4 mostró una reducción del 62% con respecto a los valores iniciales (3,48 dS/m). La aplicación de los diferentes tratamientos logró reducir los valores iniciales del pH del suelo (8,30); el tratamiento más efectivo fue T4, ya que los suelos pasaron de la condición de alcalinos a suelos neutros (pH ≤ 7,5). Con la aplicación de 10% de vermicompost se logró reducir el PSI en un 50%. El COS aumento en todos los tratamientos evaluados, siendo los valores más altos para T4 el cual fue de 6,7 g/kg en comparación al valor inicial de 2,5 g/kg. Así mismo, el C-BM resultó con incrementos significativo en todos los tratamientos, encontrándose los valores más altos en T4 (612,5 µg g-1) con respecto a los valores iniciales (36,4 µg g-1). La AU aumentó significativamente con la adición del vermicompost. Al cabo de 28 días de incubación se encontraron valores de  67,8 µg NH4+g-1 para T4, lo cual representa un incremento de seis veces con respecto al tratamiento control (T1). La adición de vermicompost demostró ser una buena estrategia para la recuperación integral de suelos salino-sódicos.

Descriptores: Salinidad; Enmiendas Orgánicas; Recuperación de suelo

The contamination of groundwater by heavy metal, originating either from natural soil sources or from anthropogenic sources is a matter of utmost concern to the public health. Remediation of contaminated groundwater is of highest priority since billions of people all over the world use it for drinking purpose. In this paper, thirty five approaches for groundwater treatment have been reviewed and classified under three large categories viz chemical, biochemical/biological/biosorption and physico-chemical treatment processes. Comparison tables have been provided at the end of each process for a better understanding of each category. Selection of a suitable technology for contamination remediation at a particular site is one of the most challenging job due to extremely complex soil chemistry and aquifer characteristics and no thumb-rule can be suggested regarding this issue. In the past decade, iron based technologies, microbial remediation, biological sulphate reduction and various adsorbents played versatile and efficient remediation roles. Keeping the sustainability issues and environmental ethics in mind, the technologies encompassing natural chemistry, bioremediation and biosorption are recommended to be adopted in appropriate cases. In many places, two or more techniques can work synergistically for better results. Processes such as chelate extraction and chemical soil washings are advisable only for recovery of valuable metals in highly contaminated industrial sites depending on economical feasibility.► A number of groundwater treatment technologies for heavy metal remediation have been reviewed. ► Iron based techniques, Biological Sulphate Reduction and Permeable Reactive Barriers were most successful in the past decade. ► Biosorption is the emerging field mostly experimented in laboratories. ► More than one techniques can be coupled for site specific problems for better performance.

To evaluate the effect of organic and biopolymers conditioners on chemical and biological properties a soil sodium-salt from Cebollal of Coro, six treatments were considered: without application of conditioner (T1), cactus data (Stenocereus griseus (Haworth) Buxb) extract (T2), Spain Tuna (Opuntia ficus-indica) extract (T3), vermicompost (T4), biopolymers biosol (T5) and desalt (T6). Conditioners were applied to the soil in liquid form at a concentration of 20 g L-1, and the soil was incubated for 45 days with measurements of basal respiration, pH, electrical conductivity, exchangeable cations and exchangeable sodium percentage at 7, 15, 30 and 45 days. The results showed a decrease in the values of electrical conductivity and exchangeable sodium in relation to baseline values on the ground. Also, it found that basal respirationincreased significantly, indicating a comprehensive reclamation of the soil. The most efficient treatments in reducing the electrical conductivity were T3 and T5 with values of 1.47 and 1.44 dS m-1, respectively; meanwhile higher values of organic carbon were recorded for T2, T3 and T4 treatments, which showed values of 22.40, 17.89 and 15.55 g kg-1, respectively. A negative correlation (P <0.05) was observed between electrical conductivity and organic matter content (r = -0.46); Likewise, a negative association between organic matter content and exchangeable sodium (r = -0.65), and positive between the organic matter and the rate of removal of sodium, indicating that the increase of organic matter contributes to the reduction of salts and sodium contents in the soil.
Key words: conditioners, salinity, biological activity.

The removal of sodium salts from saline soils by salt tolerant crops, as alternative for costly chemical amendments, has emerged as an efficient low cost technology. Lysimeter experiments were carried out on a highly saline sodic soil (ECe = 65.3 dS m −1 , ESP = 27.4, CEC = 47.9 cmole (+) kg −1 , and pH = 7.7) and irrigated with canal water (EC = 2.2 dSm −1 , SAR = 4.8) to investigate reclamation efficiency under four different treatments: control (no crop and no gypsum application) (C), gypsum application equivalent to 100% gypsum requirement (G 100), planting sea orach (Atriplex halimus) as phytoremediation crop (Cr), planting sea orach with gypsum application equivalent to 50% gypsum requirement (CrG 50). Soil salinity (ECe) and exchangeable sodium percentage (ESP) were significantly reduced compared to the control. Average ESP and ECe (dS m −1) in the top layer were 9.1, 5.8 (control), 4.8, 3.7 (Cr), 3.3, 3.9 (CrG 50), and 3.8, 3.1 (G 100), respectively. Atriplex halimus can be recommended as phytoremediation crop to reclaim highly saline sodic clay loam soils.

The contamination of groundwater by heavy metal, originating either from natural soil sources or from anthropogenic sources is a matter of utmost concern to the public health. Remediation of contaminated groundwater is of highest priority since billions of people all over the world use it for drinking purpose. In this paper, thirty five approaches for groundwater treatment have been reviewed and classified under three large categories viz chemical, biochemical/biological/biosorption and physico-chemical treatment processes. Comparison tables have been provided at the end of each process for a better understanding of each category. Selection of a suitable technology for contamination remediation at a particular site is one of the most challenging job due to extremely complex soil chemistry and aquifer characteristics and no thumb-rule can be suggested regarding this issue. In the past decade, iron based technologies, microbial remediation, biological sulphate reduction and various adsorbents played versatile and efficient remediation roles. Keeping the sustainability issues and environmental ethics in mind, the technologies encompassing natural chemistry, bioremediation and biosorption are recommended to be adopted in appropriate cases. In many places, two or more techniques can work synergistically for better results. Processes such as chelate extraction and chemical soil washings are advisable only for recovery of valuable metals in highly contaminated industrial sites depending on economical feasibility. Various technologies for remediating heavy metal contaminated groundwater has been reviewed. © 2011 Elsevier Ltd.

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The removal of sodium salts from saline soils by salt tolerant crops, as alternative for costly chemical amendments, has emerged as an efficient low cost technology. Lysimeter experiments were carried out on a highly saline sodic soil (ECe = 65.3 dS m(-1), ESP = 27.4, CEC = 47.9 cmole+ kg(-1), and pH = 7.7) and irrigated with canal water (EC = 2.2 dSm(-1), SAR = 4.8) to investigate reclamation efficiency under four different treatments: control (no crop and no gypsum application) (C), gypsum application equivalent to 100% gypsum requirement (G100), planting sea orach (Atriplex halimus) as phytoremediation crop (Cr), planting sea orach with gypsum application equivalent to 50% gypsum requirement (CrG50). Soil salinity (ECe) and exchangeable sodium percentage (ESP) were significantly reduced compared to the control. Average ESP and ECe (dS m(-1)) in the top layer were 9.1, 5.8 (control), 4.8, 3.7 (Cr), 3.3, 3.9 (CrG50), and 3.8, 3.1 (G100), respectively. Atriplex halimus can be recommended as phytoremediation crop to reclaim highly saline sodic clay loam soils.