Spatio-temporal variation of reference evapotranspiration from empirical methods in Chihuahua, Mexico

<strong>Introduction:</strong> Evapotranspiration is key in the management of arid agricultural areas. In Chihuahua, the volume of irrigation water is based on reference evapotranspiration (ET_o) calculated with empirical methods and extrapolated to the cropped area, which is inaccurate. The alternative is to calculate ET_o variation by spatial interpolation.</br> <strong>Objective:</strong> To analyze the spatio-temporal variation of ET_o using empirical methods and spatial interpolation in Chihuahua, Mexico.</br> <strong>Methodology:</strong> Records from 33 meteorological stations from 1960-2013 and seven ET_o estimation methods were used. The results were compared with the Penman-Monteith method, modified by FAO (PMMF), ANOVA analysis (P ≤ 0.05), and homogeneous ET_o surfaces built from the point values by spatial interpolation.</br> <strong>Results:</strong> The Hargreaves method (R² = 0.91, RMSE = 1.16 and ME = -0.69 mm-day^-1) had a smaller bias with respect to PMMF. ET_o values ranged from 2.5 to 7.1 mm-day^-1 in a west-east direction, with maximum values at low elevations and minimum values at high elevations, which showed the influence of the Sierra Madre Occidental on ET_o. This characteristic was most noticeable in the warm months (June to September).</br> <strong>Limitations of the study:</strong> The use of estimated data needs field validation.</br> <strong>Originality:</strong> The ET_o estimation with seven empirical methods and one spatial interpolation method to extrapolate values to areas with scarce meteorological data.</br> <strong>Conclusions:</strong> The Hargreaves method allows estimating the spatio-temporal variation of ET_o in large extensions and areas with limited meteorological information.</br>

Agricultural tractor slippage measurement system using encoders

Introduction: Slippage is usually measured with a standard manual method, however, if it is required slippage information inline in extensive areas of cropland, mechanical and electronic equipment have to be developed. Objective: To design, assemble and evaluate (in laboratory and under field conditions) an encoder-based slippage measurement system. Methodology: The system was integrated and tested in the laboratory, where equations were generated to calculate the slippage. The system was installed in an agricultural tractor and its performance was evaluated on an asphalt track and working with tillage implements on various soil conditions. Results: The values obtained with the manual method and the encoder-based method showed very small differences. The results of field evaluation of the system are in congruence with the type of implement and with the moisture content in the soil. This indicates that the measurement of distances by the wheel turns and the calculation of the percentage of slippage are correct. Study limitations: The system was tested in short runs (up to 100 m). Still to be tested in at least 1 ha. Originality: Automated slippage measurement in extended crop areas. Conclusions: The slippage measurement system based on encoders is reliable for automatically measuring the slippage of agricultural tractor in different field conditions.

Forage yield and quality of three rainfed crops in four-row and six-row seedbeds using different fertilization methods

Introduction: In the temperate-semiarid region of Aguascalientes, Mexico, most of the rural population depends on rainfed agriculture related to the family milk production system. Objective: To evaluate the effect of different fertilization practices on forage yield and quality of three rainfed crops in four- and six-row seedbeds. Methodology: Five fertilization treatments were evaluated: T1) control (no fertilization), T2) chemical fertilization (40-40-00 kg·ha-1 of N-P-K), T3) mixture (28-40-00 kg·ha-1 and 26 kg of zeolite), T4) organic fertilizer (5 t·ha-1 of bovine manure) and T5) mycorrhiza (inoculation with 350 g·ha-1 of mycorrhizal substrate). Maize and sunflowers were planted in four rows, and sorghum in six rows. A randomized complete block design with four replicates was used. Results: Dry matter yield in relation to the control, in T2, T3 and T4 was 100, 84 and 26 % for maize, 123, 177 and 67 % for sunflowers, and 52, 49 and 91 % for sorghum, respectively. T5 was higher compared to T1, but without statistical difference. Forage quality of the three crops showed no increase, except for crude protein in T2 and T3. Limitations of the study: Results correspond to a single cycle (spring-summer). Originality: Good agronomic practices for forage production were established. Conclusions: Agronomic practices (minimum tillage, in situ rainwater harvesting, sowing methods and fertilization) generate a positive effect on yield and forage quality in rainfed crops.

Preservative postharvest solutions in two varieties of tuberose (Polianthes tuberosa L.) native to Mexico: ‘Mexicano’ and ‘Perla’

ntroduction: ‘Perla’ and ‘Mexicano’ are varieties of tuberose grown in Mexico that have potential for commercialization and export; however, no preservative solutions have been evaluated to increase their shelf life. Objective: To determine physical, physiological, and chemical changes that occur in postharvest tuberose when different preservative solutions are applied. Methodology: Tuberose flower spikes of varieties ‘Mexicano’ and Perla, with two open basal flowers, were placed in preservative solutions (Crystal®, sucrose [Sac] + citric acid [CA] + hydroxyquinoline citrate [HQC] and ascorbic acid [AAsc]). A group of tuberose flower spikes was kept as control, and in all cases destructive and non-destructive variables were evaluated during postharvest. Results: Relative fresh weight and water consumption increased with preservative solutions in both varieties. The appearance of the ‘Perla’ variety was excellent for 5 days with Crystal®. The ‘Mexicano’ variety had more open flowers with Crystal® and Sac + AC + HQC, while the ‘Perla’ variety had the same result with AAsc and Crystal®. Respiration in the Mexicano’ variety was high with Sac + AC + HQC, and in the case of ‘Perla’ variety, respiration was low with AAsc. The highest specific superoxide dismutase activity was detected with AAsc and Crystal® for ‘Perla’ variety. Study limitations: The results are valid without previous applications of pulse or hydrating solutions in tuberose varieties evaluated. Originality: This is the first study where the postharvest behavior of two Mexican tuberose varieties is evaluated in preservative solutions. Conclusions: ‘Mexicano’ and ‘Perla’ varieties can use Crystal® and AAsc solutions to maintain the quality for longer time in vase.

Spatial distribution of soil organic carbon by digital mapping: the case of the Medio Aguanaval river sub-basin

ntroduction: Carbon is found mainly in geological reservoirs, oceans, atmosphere and land. Soil organic carbon (SOC) is determined by the quantity and vertical distribution of vegetation, intrinsic soil properties and climate, but variability is influenced by anthropogenic interference. SOC stocks are not static; modeling their spatial, vertical and horizontal distribution involves the creation of baseline estimates to quantify these stocks. Objective: To estimate the magnitude of SOC stocks in the Medio Aguanaval River sub-basin (ScRMA) and to analyze the sensitivity of four interpolation methods to minimize the error of digital mapping for the ScRMA. Methodology: The study consisted of five stages: 1) search, download and analysis of soil data, 2) data processing, 3) selection of verification sites, 4) laboratory analysis and 5) processing of data from verification sites. Results: SOC values ranged from 9 to 133 t·ha-1, with a mean of 36.31 t·ha-1 and standard deviation of 23.83 t·ha-1. The ordinary exponential Kriging interpolator was the best representation for SOC of the ScRMA based onstatistics. The results of the analysis of the verification sites yielded a mean SOC of 24.4 t·ha-1. Limitations of the study: Soil profile density for the region and the lack of information on bulk density. Originality: The baseline distribution of SOC at the sub-basin level was used to analyze its dynamics. Conclusions: The highest concentration of SOC (61 to 129 t·ha-1) was found in the municipalities of Cuencamé and Santa Clara, while the lowest records (10 to 30 t·ha-1) were located in the municipalities of Torreón and Viesca.

Analysis of the NASA-POWER system for estimating reference evapotranspiration in the Comarca Lagunera, Mexico

Introduction: The FAO-56 Penman-Monteith (PM) is one of the most solid and commonly used methods for estimating reference evapotranspiration (ETo); however, it requires meteorological data that are not always available, so an alternative is the use of reanalysis data. Objective: To estimate the error that the NASA-POWER (NP) system data can generate in the ETo of the Comarca Lagunera, Mexico. Methodology: Daily and decadal average ETo were estimated in five different ways. In each case, a different method was used to estimate ETo (FAO-56 PM or Hargreaves and Samani [HS]) and a different meteorological data source (measured, NP data or combination of both). Results: NP data can be used to provide temperature, solar radiation and relative humidity variables, but not wind speed. The NP data overestimate the measured ETo, an RMSE of 1.15 and 0.89 mm∙d-1 was found for daily and decadal periods, respectively. Limitations of the study: A grid error analysis could not be carried out because the number of stations is limited. Originality: The use of reanalysis data to estimate ETo has not been analyzed locally. Conclusion: When measured data are not available, NP data and the HS equation can be used. When using the FAO-56 PM method and NP data, the in situ wind speed must be available.

Hydrologic modeling to measure the impact of climate change in the Yaqui River basin

Objective: To model and analyze the behavior of surface runoff in the Yaqui river basin under climate change scenarios. Methodology: Representative concentration pathways (RCP) of three sub-basins (La Angostura, El Novillo and El Oviachic) were shown using hydrologic modeling with SWAT, where the simulated variable was surface runoff. Results: A change in water availability of -67 % is expected in La Angostura for the period 2021-2040 (RCP2.6) and an increase of 60 % from 2041-2060 (RCP8.5), in El Novillo a decrease of 65 % is predicted for the period 2061-2080 (RCP4. 5) and a 42 % increase from 2061-2080 (RCP2.6), and in El Oviachic a 63 % decrease is predicted for the period 2041-2060 (RCP2.6 and 4.5) and a 47 % increase from 2041-2060 (RCP4.5). Limitations: Veracity and impact of basins studies depend on quality hydro-climatic information of unrestricted availability. Originality: The impact of climate change on the availability of water for agricultural use in the Yaqui River basin was projected. In addition, there is a technological platform for planning processes. Conclusions: The data collected can be used to generate adaptation and mitigation strategies for efficient water use in the basin and to propose long-term sustainable management alternatives.

3D computational fluid dynamics modeling of temperature and humidity in a humidified greenhouse

Introduction: Medium and low technology greenhouses use natural ventilation as a method of temperature and humidity control. However, at certain times of the year, this is insufficient to extract excess heat inside the greenhouse, so devices such as hydrophanes (humidifiers) have been implemented to reduce the temperature. It is necessary to know the behavior of temperature and humidity, since both factors influence the development of crops and, therefore, their yield. Objective: To develop a computational fluid dynamics (CFD) model of a naturally ventilated zenithal greenhouse equipped with hydrophanes to understand the spatial and temporal distribution of temperature and humidity inside the greenhouse. Methodology: The experiment was carried out in a greenhouse equipped with hydrophanes and grown with bell pepper. Temperature and humidity measurements were performed from March 7 to 25, 2014. The ANSYS Workbench program was used for the 3D CFD modeling. Results: The CFD model satisfactorily described the temperature and humidity distribution of the greenhouse, with an error of 0.11 to 3.43 °C for temperature, and 0.44 to 10.80 % for humidity. Limitations of the study: Numerical modeling using CFD is inadequate to model the temporality of the variables. Originality: There are few studies that model humidity behavior with CFD and the use of hydrophanes in Mexico. Conclusions: The CFD model allowed visualizing the distribution of temperature and air humidity inside the greenhouse.

Spatial behaviour of Hemiberlesia lataniae (Signoret) on ‘Hass’ avocado in Estado de Mexico

Introduction: Avocado exports have been affected by the presence of Hemiberlesia lataniae, the main damage is aesthetic and undermines fruit quality. Objective: To determine the spatial distribution of Hemiberlesia lataniae in a ‘Hass’ avocado crop in Estado de Mexico. Methodology: The experiment was developed in three avocado growing areas (Coatepec Harinas, Donato Guerra and Ixtapan del Oro). Sampling was carried out using the quadrat methodology, a total of 400 trees were sampled per zone from August 2019 to July 2020. The trees were divided into three strata (high, medium and low), and a terminal branch from each cardinal point was marked. Each tree was marked and georeferenced with a differential GPS. Results: A total of 24 samples per zone were generated, and all cases had an aggregated spatial behavior of Hemiberlesia lataniae. Semivariograms were fitted to spherical, exponential, and Gaussian models. Limitation of the study: Geostatistics is the only method that provides the exact location of the pest and the sample in density maps. Originality: The present study proposes to implement integrated management strategies to reduce ecological damage, due to indiscriminate use of insecticides, and presence of residues in fruits. Conclusions: The following study allowed us to know the spatial distribution of Hemiberlesia lataniae by means of density maps in three ‘Hass’ avocado producing areas in Estado de Mexico, where an aggregated spatial distribution was observed.

Influence of microwave drying process on microstructure and thermodynamic properties of nopal cladodes

Introduction: The drying of nopal offers an alternative for their preservation, storage, handling and consumption. Objective: The effects of microwave drying on the microstructural characteristics of nopal and their thermodynamic properties at the food-water interface were evaluated. Methodology: Nopal cladodes were microwave-dried by applying powers of 75 and 158 kW∙kg-1. Microstructure of the samples was evaluated by Scanning Electron Microscope. Adsorption isotherms were determined at temperatures of 10, 20, 30 and 40 °C. Net isosteric heat (q-st) was calculated using the Clausius-Clapeyron equation and the Peleg model. Results: Samples dehydrated at 75 kW∙kg-1 showed greater preservation of their internal and external structure. When applying a higher power (158 kW∙kg-1), greater damage was observed in the microstructure of the material. Type III adsorption isotherm curves were obtained according to the Brunauer classification. The q-st of the dehydrated nopal was 7.51 kJ∙mol-1 for a moisture content of 0.05 kgH2O∙kg-1. Limitations of the study: The results obtained are valid only for microwave drying by applying powers of 75 and 158 kW∙kg-1. Originality: This work proposes the microwave drying of nopal as an alternative method that reduces drying time and allows the preservation of the material’s structural properties. Conclusions: The power applied in the microwave drying of nopal had a direct impact on the microstructure of the samples. The use of a power of 75 kW∙kg-1 was the best drying condition to preserve the structures constituting the cladodes.