Effects of the amendment with almond shell, bio-waste and almond shell-based biochar on the quality of saline-alkali soils.

This study aimed to evaluate the effect of the amendment with almond shell bio-waste (AS) and almond shell-based biochar (ASB), in different mass ratios (5, 10, and 15%), on the physicochemical properties of three different saline soils, using the growth of arugula seedlings as a bioindicator of the enhancement achieved. Data were analyzed based on a completely randomized design in a factorial arrangement with four replications. The results showed that the low-salinity soil (T1) presented the best physicochemical characteristics and growth parameters. The addition of AS and ASB in low proportions to the saline soils reduced the pH and electrical conductivity values. An increase in the amendment proportion led to an increase in these variables. Moisture, organic matter, and organic carbon increased, and the cation exchange capacity decreased, generating positive effects on soil quality. The values of exchangeable sodium percentage (ESP) showed that T3 presented the highest sodicity, followed by T2 and T1. The treatment with 5% ASB produced better results regarding total plant length, fresh and dry weights, leaf area, and leaf chlorophyll content. Finally, linear regression models were applied to describe the dependence of the agronomic variables on the ratio of biochar added.

Living in extreme environments: distribution of Lyciumhumile (Solanaceae), an endemic halophyte from the Altiplano-Puna region, South America.

Very few Solanaceae species are able to grow in saline soils; one of them is Lyciumhumile. This species is endemic to the Altiplano-Puna region (Central Andes, South America) where there are multiple extreme environmental conditions such as hypersaline soils. Here we present an updated description and distribution of L.humile including its new record for Bolivia at the edges of "Salar de Uyuni", the largest salt flat in the world; we discuss its ecological role in saline environments by analyzing soil salinity and cover-abundance values ​​of the studied sites. According to IUCN criteria, we recommend a category of Least Concern for L.humile, but the growing development of lithium mining in saline environments of the Altiplano-Puna region may potentially threaten exclusive communities.

The oil spill and the use of chemical surfactant reduce microbial corrosion on API 5L steel buried in saline soil.

In order to evaluate the biocorrosion of API 5L metal buried in saline soils, three different conditions in microcosms were evaluated. The control microcosm contained only saline soil, the second had the addition of petroleum, and the third contained the addition of both petroleum and surfactant. The corrosion rate of the metals was measured by loss of mass after 30 days, and the microbial communities were delineated using 16S rRNA gene sequencing techniques. The species were dominated by halophiles in all samples analyzed. Among the bacteria, the predominant group was Proteobacteria, with emphasis on the Alphaproteobacteria and Gammaproteobacteria. Betaproteobacteria and Deltaproteobacteria members were also identified in a smaller number in all conditions. Firmicutes were especially abundant in the control system, although it was persistently present in other conditions evaluated. Bacteroidetes and Actinobacteria were also present in a considerable number of OTUs in the three microcosms. Halobacteria were predominant among archaea and were present in all conditions. The analysis pointed to a conclusion that in the control microcosm, the corrosion rate was higher, while the microcosm containing only oil had the lowest corrosion rate. These results suggest that, under these conditions, the entry of other carbon sources favors the presence of petroleum degraders, rather than samples involved in the corrosion of metals.

Salinidade do solo em ambiente protegido / Soil salinity in protected environment

Por muito tempo, a exploração dos sistemas agrícolas em sua totalidade vem associado ao manejo inadequado dos agroecossistemas. Um dos problemas que afetam o processo de produção agrícola é a salinização do solo, pois elevados níveis de salinidade dificultam a absorção de água e nutrientes pelos vegetais convertendo-se em problemas de ordem nutricional, toxicológico, físico, químico, biológico e, em casos mais extremos, a salinidade do solo pode desencadear outro processo conhecido como desertificação, tornando o solo inapropriado para o cultivo. No ambiente protegido, o principal meio de adubação é a fertirrigação, cujas causas da salinidade são evidenciadas pelo uso excessivo de fertilizantes e pela má qualidade da água de irrigação que provém em sua maioria de poços com alto teor de cloreto de sódio (NaCl). Diferentemente do que ocorre em cultivos a campo, que há entrada de água, por meio da precipitação natural, a água que entra no ambiente protegido provém unicamente da irrigação, precipitação artificial, onde o método da irrigação localizada é utilizado pela maioria dos produtores. A salinização em ambiente protegido é independente das condições climáticas ou do tipo de solo empregado no cultivo, uma vez que ocorre um aumento da condutividade elétrica da solução do solo aliada a altas doses de adubos que proporcionam o acúmulo de sais na superfície. O presente trabalho teve como objetivo abordar por meio de uma revisão de literatura, os principais fatores que promovem o processo de salinização do solo em ambiente protegido.(AU)

For a long time, the exploration of agricultural systems in their entirety comes associated with the inadequate management of agroecosystems. One of the problems that affect the process of agricultural production is the soil salinization, because high levels of salinity hinder the water and nutrients absorption by vegetables, becoming nutritional, toxicological, physical, chemical, biological problems and in more extreme cases, soil salinity can trigger another process known as desertification, making the soil unsuitable for cultivation. In the protected environment the main means of fertilization is the fertigation, whose salinity causes are evidenced by the excessive use of fertilizers and by the poor quality of irrigation water that comes mostly from wells with high sodium chloride (NaCl) content. Contrary to what happens in field crops, where there is input of water through natural precipitation, water entering the protected environment comes solely from irrigation, artificial precipitation, where the irrigation method is located and used by most producers. The salinization in protected environment is independent of the climatic conditions or the type of soil used in the cultivation, once there is an increase in the electrical conductivity of the soil solution with high doses of fertilizers that provide the accumulation of salts on the surface. The present study had as objective to approach through a literature review, the main factors that promote the process of soil salinization in a protected environment.(AU)

Water potential in soil and Atriplex nummularia (phytoremediator halophyte) under drought and salt stresses.

Atriplex nummularia is a halophyte widely employed to recover saline soils and was used as a model to evaluate the water potentials in the soil-plant system under drought and salt stresses. Potted plants grown under 70 and 37% of field capacity irrigated with solutions of NaCl and of a mixture of NaCl, KCl, MgCl2 and CaCl2 reproducing six electrical conductivity (EC): 0, 5, 10, 20, 30, and 40 dS m-1. After 100 days, total water (Ψw, plant) and osmotic (Ψo, plant) potentials at predawn and midday and Ψo, soil, matric potential (Ψm, soil) and Ψw, soil were determined. The type of ion in the irrigation water did not influence the soil potential, but was altered by EC. The soil Ψo component was the largest contributor to Ψw, soil. Atriplex is surviving ECs close to 40 dS m-1 due to the decrease in the Ψw. The plants reached a Ψw of approximately -8 MPa. The water potentials determined for different moisture levels, EC levels and salt types showed huge importance for the management of this species in semiarid regions and can be used to recover salt affected soils.

Salinidade do solo em ambiente protegido / Soil salinity in protected environment

Por muito tempo, a exploração dos sistemas agrícolas em sua totalidade vem associado ao manejo inadequado dos agroecossistemas. Um dos problemas que afetam o processo de produção agrícola é a salinização do solo, pois elevados níveis de salinidade dificultam a absorção de água e nutrientes pelos vegetais convertendo-se em problemas de ordem nutricional, toxicológico, físico, químico, biológico e, em casos mais extremos, a salinidade do solo pode desencadear outro processo conhecido como desertificação, tornando o solo inapropriado para o cultivo. No ambiente protegido, o principal meio de adubação é a fertirrigação, cujas causas da salinidade são evidenciadas pelo uso excessivo de fertilizantes e pela má qualidade da água de irrigação que provém em sua maioria de poços com alto teor de cloreto de sódio (NaCl). Diferentemente do que ocorre em cultivos a campo, que há entrada de água, por meio da precipitação natural, a água que entra no ambiente protegido provém unicamente da irrigação, precipitação artificial, onde o método da irrigação localizada é utilizado pela maioria dos produtores. A salinização em ambiente protegido é independente das condições climáticas ou do tipo de solo empregado no cultivo, uma vez que ocorre um aumento da condutividade elétrica da solução do solo aliada a altas doses de adubos que proporcionam o acúmulo de sais na superfície. O presente trabalho teve como objetivo abordar por meio de uma revisão de literatura, os principais fatores que promovem o processo de salinização do solo em ambiente protegido.(AU)

For a long time, the exploration of agricultural systems in their entirety comes associated with the inadequate management of agroecosystems. One of the problems that affect the process of agricultural production is the soil salinization, because high levels of salinity hinder the water and nutrients absorption by vegetables, becoming nutritional, toxicological, physical, chemical, biological problems and in more extreme cases, soil salinity can trigger another process known as desertification, making the soil unsuitable for cultivation. In the protected environment the main means of fertilization is the fertigation, whose salinity causes are evidenced by the excessive use of fertilizers and by the poor quality of irrigation water that comes mostly from wells with high sodium chloride (NaCl) content. Contrary to what happens in field crops, where there is input of water through natural precipitation, water entering the protected environment comes solely from irrigation, artificial precipitation, where the irrigation method is located and used by most producers. The salinization in protected environment is independent of the climatic conditions or the type of soil used in the cultivation, once there is an increase in the electrical conductivity of the soil solution with high doses of fertilizers that provide the accumulation of salts on the surface. The present study had as objective to approach through a literature review, the main factors that promote the process of soil salinization in a protected environment.(AU)

Spectral indices for the detection of salinity effects in melon plants

Water scarcity and soil salinization affect large semiarid agricultural areas throughout the world. The maintenance of agricultural productivity implies better agricultural practices and a careful selection of resistant crops. A proper monitoring of the physiological status of plants can lead to better knowledge of plant nutritional requirements. Visible and near-infrared (VNIR) radiometry provides a non-destructive and quantitative method to monitor vegetation status by quantifying chemical properties using spectroscopic techniques. In this study, the capability of VNIR spectral measurements to detect salinity effects on melon (Cucumis melo L.) plants was tested. Melon plants were cultivated under multiple soil salinity conditions (electrical conductivity, (EC)1:5: 0.5, 1.0 and 2.5 dS m-1). Spectral data of leaves were transformed into vegetation indices indicative of the physiological status of the plants. The results showed differences for N (p 0.05), K and Na content (p 0.01) due to salinity suggesting different degrees of salt stress on the plants. Specific leaf area increased with salinity levels (p 0.001). The capabilities of VNIR radiometry to assess the influence of soil salinity on melon physiology using a non-destructive method were demonstrated. A normalized difference vegetation index (NDVI750-705), and the ratio between water index (WI) and normalized difference vegetation index (WI/NDVI750-705) showed significant relationships (p 0.01) with the salinity. Therefore, this method could be used for in-situ early detection of salinity stress effects.(AU)

Spectral indices for the detection of salinity effects in melon plants

Water scarcity and soil salinization affect large semiarid agricultural areas throughout the world. The maintenance of agricultural productivity implies better agricultural practices and a careful selection of resistant crops. A proper monitoring of the physiological status of plants can lead to better knowledge of plant nutritional requirements. Visible and near-infrared (VNIR) radiometry provides a non-destructive and quantitative method to monitor vegetation status by quantifying chemical properties using spectroscopic techniques. In this study, the capability of VNIR spectral measurements to detect salinity effects on melon (Cucumis melo L.) plants was tested. Melon plants were cultivated under multiple soil salinity conditions (electrical conductivity, (EC)1:5: 0.5, 1.0 and 2.5 dS m-1). Spectral data of leaves were transformed into vegetation indices indicative of the physiological status of the plants. The results showed differences for N (p 0.05), K and Na content (p 0.01) due to salinity suggesting different degrees of salt stress on the plants. Specific leaf area increased with salinity levels (p 0.001). The capabilities of VNIR radiometry to assess the influence of soil salinity on melon physiology using a non-destructive method were demonstrated. A normalized difference vegetation index (NDVI750-705), and the ratio between water index (WI) and normalized difference vegetation index (WI/NDVI750-705) showed significant relationships (p 0.01) with the salinity. Therefore, this method could be used for in-situ early detection of salinity stress effects.