The Bajío—Mexico’s central lowlands—is a region of economic importance because of its agricultural industry. Over time, agricultural practices have led to soil deterioration, loss of fertility, and abandonment. In this study, six agricultural soils were analyzed: AGQ, CTH, CTJ, JRM, CRC, and CYI, and used to develop a soil quality index (SQI) that includes the use of physicochemical, biological, and ecophysiological indicators to differentiate soil quality. Principal component analysis (PCA) was used, reducing the indicators from 46 to 4, which represents 80.4% of data variability. It was implemented the equation of additive weights using the variance of the principal components as a weight factor for the SQI. The developed SQI was according to the indicators WHC, SLT, N-NO3−, and qCO2, differentiating the quality of soils from the agricultural management in low quality (JRM < CYI < AGQ) and moderate quality (CTJ < CRC < CTH). The use of biological and ecophysiological indicators added to the PCA and the equation of additive weights allowed establishing an SQI with a minimum of indicators, sensitive to agricultural management, facilitating its interpretation and implementation for the Mexican Bajío region and soils in similar conditions around the world.
El uso de semilla de calidad para la producción de maíz (Zea mays L.) constituye una de las inversiones más rentables para el agricultor y justifica ampliamente la investigación en técnicas adecuadas para generarla. La elección del patrón de siembra (PS) de los progenitores en la producción de semilla híbrida de maíz es importante para lograr un equilibrio entre rendimiento y calidad de semilla. El objetivo del presente estudio fue determinar el efecto del PS sobre la calidad física y fisiológica de la semilla del híbrido de maíz H-135. Se evaluaron cinco PS en cuanto a relación hembra-macho, cuatro compactos (PSC) 4:1, 6:1, 8:1, 10:1 y el testigo convencional (6:2); además, se estudió el efecto de tres tamaños (grande, mediana y chica) y dos formas (plana y redonda) de semilla. El experimento se realizó bajo un diseño completamente al azar con arreglo factorial. Los resultados mostraron diferencias significativas (P ≤ 0.05) entre PS en la expresión del peso volumétrico (PV), germinación total (GT) y vigor (VS). El mayor VS se obtuvo con el PSC 8:1 (P ≤ 0.05). Entre formas de semilla se encontraron diferencias en VS, GT y peso de mil semillas (PMS). La semilla redonda superó a la plana en 13 % (P ≤ 0.05) en PMS; sin embargo, la semilla plana fue superior a la redonda en 6 % en VS. El tamaño de la semilla afectó significativamente el PMS, PV y GT. En PV, la semilla mediana presentó la media más alta (76.1 kg hL-1). La semilla grande fue superior (94.4 %) en GT, mientras que las medianas y chicas presentaron germinación de 93.7 y 91.8 %, respectivamente. Los mejores resultados se obtuvieron con los PSC 4:1 y 8:1, y con la semilla de forma plana y tamaño grande.
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.
La adaptación del cultivo de maíz a siembras tempranas requiere de mejorar su tolerancia a bajas temperaturas, en términos de capacidad de las semillas para germinar y generar plántulas que prosperen a tales temperaturas. El objetivo del presente trabajo fue identificar las variables que a nivel de semilla y plántula están involucrados en la tolerancia a bajas temperaturas de líneas e híbridos de maíz adaptados a los Valles Altos de México. Se evaluaron en condiciones de laboratorio e invernadero 17 materiales genéticos, incluidos un híbrido del trópico y una variedad sintética de condiciones templadas. Los genotipos se evaluaron en laboratorio en temperaturas de: 4, 8, 12 y 25 °C. Los materiales genéticos originarios de la zona de mayor altitud presentaron mejor tolerancia, altos porcentajes de germinación, peso seco de plúmula y radícula; además de mayor velocidad de emergencia. El peso seco de la radícula fue proporcionalmente menos afectada que la plúmula por bajas temperaturas. La respuesta de tolerancia a bajas temperaturas se indujo en los genotipos susceptibles al reducir de 8 a 4° C la temperatura. Los resultados sugieren que la prueba fría con 8° C durante 7 días previo a la inducción de la germinación puede considerarse como una prueba rápida para detectar tolerancia a bajas temperaturas.
As the global population grows, the demand for food increases and puts a strain on food production systems and agricultural productivity, causing soil degradation. Soil Quality Indexes (SQIs) have been developed to maintain and improve soil quality. However, due to the variety of soils and SQIs, analyzing and comparing results has been historically difficult. Therefore, in this study, we carried out a systematic review with meta-analysis focused on soil quality studies of agricultural soils under intensive agriculture using the unified weighted additive SQI methodology (SQIU). We analyzed 65 quality observations obtained from 22 studies. Chemical indicators were the most prevalent in the SQIUs, followed by physical and biological indicators. Conventional soil management had negative effects on soil quality (–7.55%). From the factors analyzed, the minimum database had a significant effect on the soil quality results, but not the number of indicators that made up the SQIU. The SQIU made up of chemical-biological indicators (CB) presented negatively overestimated measurements of soil quality (–32.53%), exaggerating the damage to the analyzed soils. The indicators that correlated most strongly with the size of the effect on agricultural soil quality were the cation exchange capacity (CEC), carbon to nitrogen ratio (C/N), and microbial biomass carbon (MBC). The SQIU is a feasible tool to interpret the quality of agricultural soils around the world, as it makes it possible to obtain a simple and generalized view of soil conditions.
The increasing production of biosolids (BS) as a result of urban wastewater treatment generates pollution problems in their management and final disposal, and a better management is needed for their disposal. The composting of BS is an alternative process for obtaining a product with potential application as an organic amendment in the recovery of agricultural soils. As a biotechnological contribution, this study analyzed a composting process with BS, bovine manure (BM) and rice husks using four treatments T1 (C/N = 24); T2 (C/N = 34); T3 (C/N = 44); T4 (C/N = 54) for 120 days, in order to develop compost quality indexes (CQIs) through the analysis of 18 physicochemical, biological and ecophysiological indicators. Subsequently, three methodologies—successfully used on soils—were implemented for the development of the CQIs called “unified”, “additive” and “nemoro”. The indicators that comprised the CQIs were nitrification index (NI) and synthetic enzymatic index (SEI). The CQIs made it possible to differentiate the quality of the compost according to the treatments applied. The treatments used resulted in composts considered phytonutritious whose average quality value depending on the CQI developed was considered high (CQIw = 0.62), moderate (CQIa = 0.56) and low (CQIn = 0.30). The developed CQIs can be applied to determine the quality of BS composting systems reducing the cost of monitoring.
Campeche es unos de los principales estados productores de soya (Glycine max L. Merr.) en México, con un rendimiento promedio de 2.6 t ha-1; sin embargo, en éste se tiene una variación significativa en los rendimientos anuales. Algunos autores han asociado estas variaciones a los genotipos, a las fechas de siembra y a su interacción. Por considerar que en este tema existe poca información se realizó este trabajo con el objetivo de estudiar los efectos de cuatro fechas de siembra (19 junio, 10 julio, 2 de agosto y 20 de agosto) durante 2017 y 2018 en el rendimiento de nueve variedades de soya (H100, H200, H300, H400, H600, Tamesí, Vernal, Luziania y Mariana). El experimento se estableció con un arreglo de parcelas divididas en un diseño experimental de bloques completos al azar. Los análisis estadísticos fueron análisis de varianza, pruebas de medias, análisis de componentes principales y de regresión en los sitios (SREG) para las para las interacciones genotipo x ambiente. Las fechas del 19 de junio y 10 de julio tuvieron el rendimiento más alto (3 t ha-1), el cual estuvo asociado con el peso de grano, el número de ramas por planta y el número de semillas por planta. Al retrasar la fecha de siembra se redujo el rendimiento por planta entre 5.7 y 10 g día-1, asociado a una disminución en el peso de grano, número de vainas, semillas y ramas por planta. En las siembras del 19 de junio sobresalió en rendimiento H100 y en la del 10 de julio destacó H200. Las variedades con menores rendimientos fueron Mariana (2.3 t ha-1) y Luziania (2.4 t ha-1). Los resultados de este estudio sugieren que no es recomendable sembrar soya en fechas tardías de agosto en Campeche.
Urban biosolids present a considerable concentration of nutrients, which are currently wasted and deposited in landfills causing environmental contamination. In the present study, a dimensionality reduction technique is used to select indicators with a higher relationship in their variability. Subsequently, a multivariate nonlinear regression process is used to establish an equation that allows predicting the behavior of the soluble organic carbon indicator. The indicators with the greatest relationship with the variability of the data analyzed were N-NO3-, N-NH4+/N-NO3- and IES. The resulting model presented a correlation of 30% with the soluble organic carbon indicator in the composting systems.
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