Introducción: El agua subterránea del acuífero del Valle de Tecamachalco (AVT) es la principal fuente de abastecimiento para las actividades productivas en la zona, condición que ha generado su sobreexplotación.
Objetivo: Analizar la variación temporal de los niveles estáticos del AVT de 1997 a 2016 para determinar el nivel de abatimiento del agua subterránea del acuífero.
Metodología: Se utilizaron datos históricos de la red de monitoreo del Comité Técnico de Aguas Subterráneas de Tecamachalco, y se registraron niveles estáticos de 89 pozos. Se aplicó la prueba 30 Mann-Kendall a los datos piezométricos y se incorporó el análisis espacial con el método de 31 interpolación de Kriging.
Resultados: El nivel del agua en el periodo evaluado presentó una tendencia decreciente. Los 33 niveles estáticos del acuífero presentaron un abatimiento promedio de 14 m; por ello, el proceso de agotamiento es insostenible de continuar con la misma tendencia.
Limitaciones del estudio: No hay estadísticas de la extracción de agua subterránea; los datos existentes son inconsistentes, por lo que se optó por una prueba estadística no paramétrica que refleja el comportamiento (abatimiento y recuperación) de los pozos monitoreados.
Originalidad: Existen pocos estudios sobre la dinámica de abatimiento de agua subterránea del AVT. La combinación de un método estadístico y uno geográfico es una herramienta útil para mostrar el comportamiento de los niveles de agua.
Conclusiones: El AVT presenta una situación crítica que condiciona la disponibilidad y el aprovechamiento del agua subterránea, lo que afecta directamente a la actividad agrícola de la zona.
Introduction: The groundwater of the Tecamachalco Valley aquifer (TVA) is the main source of supply for productive activities in the area, a condition that has generated its overexploitation.
Objective: To analyze the temporal variation in the static levels of the TVA from 1997 to 2016 in order to determine the level of groundwater depletion in the aquifer.
Methodology: Historical data from the monitoring network of the Tecamachalco Groundwater Technical Committee was used, and static levels of 89 wells were recorded. The Mann-Kendall test was applied to the piezometric data and spatial analysis was incorporated with the Kriging interpolation method.
Results: The water level in the evaluated period showed a downward trend. The static levels of the aquifer showed an average drop of 14 m; therefore, the depletion process is unsustainable if the same trend continues.
Study limitations: There are no statistics on groundwater extraction; the existing data are inconsistent, so a non-parametric statistical test was chosen to reflect the behavior (depletion and recovery) of the monitored wells.
Originality: There are few studies on the dynamics of TVA groundwater depletion. The combination of a statistical and a geographical method is a useful tool to show the behavior of water levels.
Conclusions: The TVA presents a critical situation that conditions the availability and use of groundwater, which directly affects agricultural activity in the area.

Introduction: Planting bean and corn in multi-row beds, complemented with rainwater harvesting, has increased grain and dry matter yields.
Objective: To design and evaluate a planter to distribute seeds in four-row beds.
Methodology: The planter was created based on the design phases of mechanical engineering. Once built, the seed metering and fertilizer system was evaluated on a test bench. The first one was conducted under three conditions and ten operating speeds with bean and corn. The second one was performed under an operating condition with granulated urea. Subsequently, the planter was evaluated in agricultural soil with both species of seed and four forward speeds, and the horizontal distribution of the plants, planting depth and volume of the dikes formed in the soil were determined.
Results: On the test bench, it was found that the number of seeds per linear meter of bean and corn was reduced in all three test conditions. In the field, it was observed that the variables evaluated were affected by the operating speed.
Study limitations: The planter was only evaluated with corn grains and bean at a maximum speed of 7.5 km∙h^-1 on a test bench and at 7 km∙h^-1 in the field.
Originality: The planter allows seeding four-row beds and, at the same time, forming dikes in the soil to store rainwater.
Conclusions: The planter is a viable option to mechanize the corn and bean planting system in four-row beds, for irrigation and rainfed conditions.

Introduction: The management of irrigation areas aims to achieve an efficient use of resources for full user satisfaction.
Objectives: To propose a methodology for hydrosystemic management in which crop demand, irrigation planning in the allocation and distribution of water, as well as conduction capacity concur.
Methodology: A hydrosystemic management function was developed in which the variables of interest, consisting of six stages, concur and the “Santa Rosa” irrigation module of irrigation district 075, Sinaloa, Mexico, was evaluated. A maximum ten-day water demand requirement was estimated, with an established area of 22 518 ha and a maximum irrigation demand area of 13 548 ha.
Results: Irrigation distribution planning in the evaluated module requires a maximum flow of 27.18 m³∙s^-1, being satisfied with the canal capacity (27.87 m³∙s^-1), and a maximum ten-day volume of 11 million m³.
Study limitations: Only the controlled demand distribution method was used, since it is employed in irrigation districts in Mexico.
Originality: The variables of an irrigation area are analyzed and implemented together, which will facilitate the integrated operation of large agricultural hydrosystems.
Conclusions: The application of the proposed management instrument will facilitate water delivery according to the controlled demand distribution method in Mexico’s irrigation districts.

Introduction: Due to the hypotheses set out in the equations for the design of hydraulic structures, the flow does not follow a real behavior; therefore, it is necessary to build physical and numerical models to obtain adequate results.
Objective: To obtain the characteristic curve of the real behavior of the transition zone of a culvert with inlet control, as well as the mathematical models of the hydraulic operation.
Methodology: The experiment was carried out in a physical model built and instrumented with two sensors: an HC-SR04 for measuring the water level and an FS400a for the discharge. The inlet discharge was varied with a gate valve to obtain the characteristic curve. By means of least-squares fitting, the mathematical models for the weir, transition, orifice and overall operation zones were obtained.
Results: The characteristic curve of the system was fitted to a third degree polynomial. The global model Q = f(H) ranged from 0.066 to 0.286 m, where 25 % of the water surface heights (0.066 < H ≤ 0.117 m) behaved as a weir, 23.53 % (0.117 < H ≤ 0.165 m) as a transition zone and 51.47 % (0.165 < H ≤ 0.286 m) as an orifice, obtaining in all cases an R² > 0.98.
Study limitations: The models obtained can only be scaled in culverts with geometry similar to the physical model studied.
Originality: We worked with experimental data and the weir-orifice transition model.
Conclusions: The transition zone presented a curved trend, although the linear model, found in the literature, only loses 0.2 % accuracy.

Introduction: The productivity of current agricultural practices depends largely on the use of fertilizers. A major limitation of conventional fertilizers is their low crop yields, so the development and application of new types of fertilizers using nanotechnology are potentially effective options for increasing agricultural production.
Objective: To synthesize and characterize calcium-loaded gelatin nanoparticles, and evaluate their behavior as controlled-release systems.
Methodology:The nanoparticles were obtained by spray drying. The physicochemical characteristics of the particles were analyzed by scanning electron microscopy and FTIR spectroscopy, while their behavior as controlled release systems was evaluated by in vitro tests.
Results: Calcium-loaded gelatin nanoparticles with average sizes below 700 nm, mainly spherical morphology and smooth microstructure were obtained. FTIR spectra showed the formation of electrostatic interactions between the charge and the gelatin. In vitro tests allowed to assume that the biopolymer matrix acted adequately in the controlled release of calcium ions.
Limitations of the study: The physicochemical characteristics of nanomaterials only apply to the processing conditions used.
Originality: There are no reports on calcium-loaded biopolymer nanomaterials with potential application in agriculture.
Conclusions: Gelatin nanoparticles, with adequate morphology and sizes, which act as controlled calcium release systems were obtained.

Introduction: The use of energy requires collection systems to improve heat transfer capacity.
Objective: To evaluate the effect of the incorporation of microparticles in the process fluid of a compound parabolic collector (CPC) on its ability to operate.
Methodology: A CPC incorporated with activated carbon (102.2 nm), Chinese ink (198.4 nm) and copper particles (160.1 nm) was evaluated for operation at four angles of inclination (30, 35, 40 and 45°).
Results: The energy collection was based on a natural convection mechanism, with a film coefficient that varied between 10.6 and 15.8 W∙m^-2∙°C^-1. The operation with 30° inclination showed the best characteristics of radiant energy collection, where the energy efficiency was 44.6 % for the system based on pure water, 61.0 % with copper particles, 63.2 % with activated carbon and 68.4 % with Chinese ink.
Limitations of the study: The study provides values of thermal convection coefficients that correspond to the particular conditions evaluated. In order to evaluate the performance of the system under different conditions, it is necessary to build models based on dimensional analysis that allow the evaluation of heat transfer coefficients in situations of use of diverse operating variables.
Originality: The incorporation of microparticles in the process fluid increases the potential for collecting radiant energy from a CPC.
Conclusions: The use of microparticles has the potential to improve the operation of a CPC.