ABSTRACT The objectives of this work were to use Sesuvium verrucosum to produce stable and mature compost and vermicompost and to evaluate their influence on the growth and production parameters of the Solanum lycopersicum L. crop. For the preparation of vermicompost, the earthworm Eisenia fetida (Savigny) was used. The proposed treatments were: T1 (negative control) [no organic fertilizer + urea], T2 (positive control) [bovine manure (100%) + urea], T3 (compost) [bovine manure (100%) + urea], T4 (compost) [S. verrucosum (25%) + bovine manure (75%) + urea], T5 (compost) [S. verrucosum (50%) + bovine manure (50%) + urea], T6 (compost) [S. verrucosum (75%) + bovine manure (25%) + urea], T7 (vermicompost) [bovine manure (100%) + urea], and T8 (vermicompost) [S. verrucosum (25%) + bovine manure (75%) + urea]. The results showed that all the treatments were stable, mature and rich in nutrients after 140 days. In general, treatments made from S. verrucosum showed a high pH (7.97–8.45) and electrical conductivity (3.83–8.85 dS m-1). Nonetheless, excluding T7, the treatments made from a proportion of 25% halophyte and 75% bovine manure (T8 and T4) achieved the highest morphological parameters in the different variables that were evaluated, as well as the highest yields compared to controls T1 and T2, followed by T3, T5 and T6, respectively. Therefore, it was concluded that S. verrucosum can serve as a stable and mature organic amendment, rich in nutrients, and that can be used to improve the growth and development of the S. lycopersicum crop.

ABSTRACT Soil degradation and the use of urban biosolid wastes to soil restoration have an economic, social-environmental and health impact. Therefore, there is interest worldwide in the use and comparison of methodologies to establish soil quality indexes (SQIs) based on physical, chemical, and biological indicators of soils. Considering that more than 60% of the territory in the Bajío region of Mexico in the State of Guanajuato is affected by some type of soil degradation, three methodologies for the establishment of SQIs-additive, weighted and unified weighted indexes-were compared in this study to evaluate the short-term effects-30 days-of the addition of biosolids as soil improvers. The methodologies were applied in experiments on carbon (C) and nitrogen (N) mineralization dynamics in a sodic agricultural soil. The ammonium indicator (N-NH4 +) was established as the one that is most related to the quality of the soil. The additive and unified weighted indexes differentiated the level of soil quality with respect to time and treatment. The developed SQIs can be used for short-term assessment of the quality of agricultural soils under amendment addition treatments with biosolids or similar organic products.

RESUMEN La degradación del suelo y el uso de residuos biosólidos urbanos como medio para su restauración tienen un impacto económico, socioambiental y de salud. Por tanto, existe interés a nivel mundial en el uso y comparación de metodologías para establecer índices de calidad del suelo (ICS) basados en los indicadores físicos, químicos y biológicos de los suelos. Considerando que más del 60 % del territorio de la región Bajío de México en el estado de Guanajuato es afectado por algún tipo de degradación del suelo, se compararon en este estudio tres metodologías para el establecimiento de un ICS (índices aditivo, ponderado y ponderado unificado) para evaluar los efectos a corto plazo (30 días) de la adición de biosólidos urbanos como mejoradores del suelo. Las metodologías fueron aplicadas en experimentos de dinámicas de mineralización de carbono (C) y nitrógeno (N) en un suelo agrícola sódico. Se estableció el indicador amonio (N-NH4 +) como el más relacionado con la calidad del suelo. Los índices aditivo y ponderado unificado diferenciaron el nivel de la calidad del suelo respecto al tiempo y a los tratamientos. Los ICS desarrollados pueden ser empleados para evaluar a corto plazo la calidad de suelos agrícolas bajo esquemas de adición de biosólidos urbanos y otros productos orgánicos similares.

Resumen La adición de biosólidos a suelos agrícolas puede ayudar a mejorar la calidad de dichos suelos mediante un mayor almacenamiento de C y N. Se realizó un estudio para analizar el impacto a corto plazo de la adición de biosólidos en la liberación de nutrientes y la actividad microbiana en el suelo. Se evaluó el C de la biomasa microbiana (MB-C), la actividad ureasa (UA) y la mineralización de N y C a diferentes dosis de aplicación de biosólidos (0 mg, 100 mg y 200 mg de N-NH4 + kg-1). Además, se probó un tratamiento solo con biosólidos. Se observó un aumento en la mineralización de C y N, volatilización de NH3 y contenido de MB-C, conforme a la tasa de aplicación. La UA aumentó en promedio 100% en los primeros siete días de incubación para los tratamientos de biosólidos. Estos resultados sugieren una mejora en el contenido de nutrientes y una estimulación positiva de la actividad microbiana.

Abstract Adding biosolids to agricultural soils can improve its quality through increased storage of C and N. A study to analyze the short-term impact of the addition of biosolids on the release of nutrients and the microbial activity in agricultural soil was carried out. The microbial biomass C (MB-C), urease activity (UA), and mineralization of N and C at different application rates of biosolids were evaluated (0 mg, 100mg and 200 mg of N-NH4 + kg-1). In addition, a biosolid-only treatment was tested. It was observed an increase in C and N mineralization, NH3 volatilization, and MB-C content, according to the application rate of biosolids. In biosolid treatments, UA increased 100% on average in the first seven days of incubation. These results suggest that the nutrient content in the soil is improved and microbial activity is positively stimulated.

Abstract: Introduction: Halophiles can be found in hypersaline environments and they can synthesize products of industrial interest. Method: In this work, 37 bacterial strains were isolated from the sediment of a dried-out maar of the “Hoya Rincón de Parangueo” (Mexico) on different culture media with 20% NaCl and pH 9, while potential industrial extracellular enzymes were determined. Results: Eight genera Salsuginibacillus, Alkalibacillus, Bacillus, Staphylococcus, Oceanobacillus, Halomonas and Nesterenkonia besides 15 distinct species belonging to Actinobacteria, Firmicutes and Proteobacteria were identified. The L371, LTA7 and SU3 isolates produced proteases, M20, L5, L7, L8, Y1, Y2, M3, M9 and RA lipases, LTA4 and SU3 amylases, while LTA7, Y2, M5, M9 and RA caseinases with enzymatic activity at pH 9. Production of siderophore was found in 17 isolates. Discussion or Conclusion: It is reported for the first experimental evidence of siderophores production by N. alba, Alkalibacillus and Oceanobacillus at 6% NaCl (w/v). Isolates RE, RG1, RG2, RH1, RA and I11 showed 2.8% to 4.1% genetic distance with Nesterenkonia species and might represent new species.

Resumen: Introducción: Los microorganismos halófilos los podemos encontrar en ambientes hipersalinos y pueden sintetizar productos de interés industrial. Método: En el presente trabajo, 37 aislados se obtuvieron del sedimento del maar desecado de la “Hoya Rincón de Parangueo” (México) en diferentes medios de cultivo que contenían 20% de NaCl y pH de 9, se determinó el potencial de producción de enzimas extracelulares de interés industrial por estos aislados. Resultados: Se identificaron ocho géneros bacterianos Salsuginibacillus, Alkalibacillus, Bacillus, Staphylococcus, Oceanobacillus, Halomonas y Nesterenkonia además de 15 especies diferentes de Actinobacteria, Firmicutes y Proteobacteria. Los aislados L371, LTA7 y SU3 produjeron proteasas, M20, L5, L7, L8, Y1, Y2, M3, M9 y RA lipasas, LTA4 y SU3 amilasas y LTA7, Y2, M5, M9 y RA cacesinasas a pH de 9. La producción de sideróforos se encontró en 17 aislados. Discusión o Conclusión: Se reporta la primera evidencia experimental de la producción de sideróforos por N. alba, Alkalibacillus and Oceanobacillu a una concentración de NaCl al 6% (p/v). Los aislados RE, RG1, RH1, RA e I11 tuvieron una distancia genética de 2.8% a 4.1% con especies de Nesterenkonia por lo que pueden representar nuevas especies.

ABSTRACT The effect of applying sewage sludge to sodic soil on C and N mineralization, microbial biomass, microbial enzymatic activity and biological indicators were evaluated. The sodic soil was agricultural, and the incubation experiment was performed at the laboratory level at 56 days with three treatments: control sodic soil group (T1), sodic soil + sewage sludge at 20 Mg/ha (T2) and at 40 Mg/ha (T3). The results obtained for T2 and T3 were: 56.89 and 33.81 % mineralized C, 3.04 and 1.66 % mineralized N, 0.81 and 0.50 % immobilized carbon by microbial biomass in relation to control (T1). The microbial enzymatic activity increased 2.81 and 3.59 times for T2 and T3 with respect to T1. In the biological indicators qCO2, qFDA and Nmin/Cmic, an increase was observed at the beginning of the mineralization dynamics and gradually decreased over time. The application of sewage sludge to sodic soil had a positive effect on the mineralization of C and N, as well as microbial biomass in the short term. The T2 treatment presented a greater efficiency in the mineralization and immobilization of C, but with respect to N mineralization and microbial enzymatic activity no significant differences were found between T2 and T3. It is recommended to evaluate the application doses of the sewage sludge before its application to sodic soils. It is the first time that the use of biological indicators has been reported to evaluate the application of sewage sludge in a sodic soil of Mexico.

RESUMEN El efecto de la aplicación de lodos residuales a un suelo sódico sobre la mineralización de C y N, biomasa microbiana, actividad enzimática microbiana e indicadores biológicos fueron evaluados. El suelo sódico fue agrícola y el experimento de incubación se realizó a nivel laboratorio a 56 días con tres tratamientos: suelo sódico testigo (T1), suelo sódico más lodos en 20 Mg/ha (T2) y en 40 Mg/ha (T3). Los resultados obtenidos para T2 y T3 fueron: C mineralizado, 56.89 y 33.81 %; N mineralizado, 3.04 y 1.66 %, y C incorporado a la biomasa microbiana en relación con el testigo (T1), 0.81 y 0.50 %. La actividad enzimática microbiana se incrementó 2.81 y 3.59 veces para T2 y T3 con respecto a T1. Los indicadores biológicos qCO2, qFDA y Nmin/Cmic se incrementaron al inicio de la dinámica de mineralización y disminuyeron paulatinamente. La aplicación de lodos residuales al suelo sódico tuvo un efecto positivo sobre la mineralización de C y N, así como en la biomasa microbiana a corto plazo. El tratamiento T2 presentó una mayor eficiencia en la mineralización e incorporación de C, pero respecto a la mineralización de N y actividad enzimática microbiana no se encontraron diferencias significativas entre los tratamientos T2 y T3. Se recomienda evaluar las dosis de aplicación de los lodos residuales antes de su aplicación a suelos sódicos. Es la primera vez que se reporta el uso de indicadores biológicos para evaluar la aplicación de lodos residuales en un suelo sódico mexicano.

Os conhecimentos sobre a dinâmica da matéria orgânica e disponibilidade de nutrientes em solos salinos podem ser úteis para nortear a adoção de estratégias de recuperação e manejo. O objetivo deste trabalho foi avaliar o efeito da condutividade elétrica (EC) e presença de N inorgânico na decomposição da matéria orgânica a dois solos salinos localizados em Guanajuato (México). Nesse sentido, glicose marcada com 14C com ou sem amônio na dose de 200 mg kg-1 de N foi adicionada em dois tipos de solo com valores de condutividade elétrica de 0,94 dS m-1 (baixo EC; LEC) e 6,72 dS m-1 (alta EC; HEC). Amostras de solos foram incubadas durante 21 dias e, ao longo desse tempo, foram avaliadas as concentrações de N inorgânico e a produção de 12CO2 e 14CO2. Após o período de incubação, aproximadamente 60 % da glicose marcada com 14C adicionado ao solo LEC evoluiu como 14CO2, mas somente 20 % no solo HEC a evolução de 14CO2 foi de apenas 20 %. Decorrido um dia de incubação, menos de 200 mg de 14C foram extraídos do solo LEC, ao passo que no solo HEC foram extraídos mais de 500 mg de 14C. Não ocorreu mineralização de N nos dois solos e a adição de glicose reduziu as concentrações de N inorgânico no solo controle e no solo que recebeu N-NH4+. As concentrações de NO2- e NO3- foram, em média, maiores no solo LEC do que no solo HEC, com exceção do teor de NO2-, que foi maior no HEC tratado com NH4+. O aumento da condutividade elétrica promoveu a redução da mineralização de substrato facilmente decomponível e a diminuição do teor de N no solo.

Organic matter dynamics and nutrient availability in saline agricultural soils of the State of Guanajuato might provide information for remediation strategies. 14C labeled glucose with or without 200 mg kg-1 of NH4+-N soil was added to two clayey agricultural soils with different electrolytic conductivity (EC), i.e. 0.94 dS m-1 (low EC; LEC) and 6.72 dS m-1 (high EC; HEC), to investigate the effect of N availability and salt content on organic material decomposition. Inorganic N dynamics and production of CO2 and 14CO2 were monitored. Approximately 60 % of the glucose-14C added to LEC soil evolved as 14CO2, but only 20 % in HEC soil after the incubation period of 21 days. After one day, < 200 mg 14C was extractable from LEC soil, but > 500 mg 14C from HEC soil. No N mineralization occurred in the LEC and HEC soils and glucose addition reduced the concentrations of inorganic N in unamended soil and soil amended with NH4+-N. The NO2- and NO3- concentrations were on average higher in LEC than in HEC soil, with exception of NO2- in HEC amended with NH4+-N. It was concluded that increases in soil EC reduced mineralization of the easily decomposable C substrate and resulted in N-depleted soil.