Nutrient balance in maize cropping systems and challenges for their sustainability
Balance de nutrientes en sistemas de cultivo de maíz y retos para su sustentabilidad
Ma. Antonia Perez-Olvera
Available online: 2019-06-24 / pages 097-109
Introduction: Nutrition management in the maize crop in Guanajuato, Mexico, is based on mineral fertilization, with high doses of nitrogen and reduced application of phosphorus and potassium.
Objective: To diagnose the management of mineral nutrition and residues from the maize cropping system, and identify opportunities for their efficient use.
Methodology: 68 maize farmers from the municipalities of Salvatierra and Valle de Santiago, Guanajuato, were surveyed. Plot soils were sampled, and yield, nutrient concentration and C mineralization were estimated. With the data obtained, graphs of the balance of N, P, K and C were made.
Results: Nutrition management and biomass production varied among farmers. Currently, P and K are not limiting factors, unlike N, since the soil only contributes 11 % of the total available nitrogen. Residue management showed that there is an imbalance between soil C mineralization and the incorporation of residues.
Study limitations: The analysis focused on only one agricultural cycle.
Originality: The focus of the study, including the graphical analysis, is scarcely applied in the region’s maize farming systems.
Conclusions: An integral vision is required for the management of organo-mineral nutrition and residues to contribute to their efficient and sustainable use.
Microencapsulation of grape seed oil by spray drying using whey protein and hawthorn pectin
Microencapsulación de aceite de semilla de uva mediante secado por aspersión utilizando proteína de suero lácteo y pectina de tejocote
Juan Carlos Cuevas-Bernardino;
Available online: 2019-07-15 / pages 127-145
Introduction: Grape seed oil (GSO) contains unsaturated fatty acids that make it susceptible to degradation, causing it to deteriorate. In this sense, microencapsulation in biopolymer matrices is a good alternative to protect it.
Objective: To microencapsulate GSO by spray drying of emulsions stabilized with biopolymer complexes formed from whey protein concentrate (WPC) and hawthorn pectin (HP) from two different cultivars.
Methodology: Emulsions were developed with different wall material: GSO ratios (2:1 and 3:1) and percentage of total solids (30 and 40 %). The wall materials were WPC-citrus pectin and WPC-HP from two cultivars (HP55 and HP100, with an esterification degree of 70.3 and 61 %, respectively). The factors evaluated were viscosity, mean surface diameter (d3,2) and morphology of the emulsions, and d3,2, microencapsulation efficiency (MEE) and electron microscopy of the microcapsules.
Results: The d3,2 of the emulsions ranged from 1.45 to 2.54 μm, where EWPC-HP100,3:1 exhibited the smallest d3,2. These values were related to the type of pectin and were inversely proportional to the viscosity and solids content. The highest MEE was presented by MWPC-HP100,3:1 (71.29 %), which had the highest viscosity and the lowest d3,2 in the emulsion.
Study limitations: The behavior of only two hawthorn cultivars is presented.
Originality: There are no reports of the use of HP biopolymer complexes from national cultivars and WPC as wall materials for the protection of bioactive materials.
Conclusions: The use of novel biopolymers such as HP (HP55 and HP100) allowed obtaining microcapsules with adequate morphology and high ME
Evaluation of a mathematical model to predict growth and nitrogen content in tomatoes (Solanum lycopersicum L.) under greenhouse conditions
Evaluación de un modelo matemático para predecir el crecimiento y contenido de nitrógeno en jitomate (Solanum lycopersicum L.) de invernadero
José A. Mancilla-Morales;
Mario A. Tornero-Campante;
Irineo Lorenzo López-Cruz
Available online: 2019-08-23 / pages 111-125
Introduction: Mathematical crop modeling allows selecting different simulation environments and analyze
the response of different variables over time to estimate, predict and potentiate the growth of a crop.
Objective: To simulate and evaluate a dynamic mathematical model to predict tomato growth and nitrogen
content in the plant under greenhouse conditions.
Methodology: The simulation was performed with the VegSyst model, for which climate variables and
greenhouse tomato crop variables were recorded during two cycles, for the evaluation a local sensitivity
analysis and non-linear parametric identification were applied.
Results: The sensitivity analysis allowed identifying the most sensitive parameters of the model and with
the parametric identification the values of the parameters were found, which allowed fitting the simulations
to the measurements made in the greenhouse.
Limitations of the study: The VegSyst model only allows simulating nitrogen in the plant. In addition,
it is necessary to calibrate the model to the climatic conditions of the site for experiments in other areas.
Originality: Based on the VegSyst model, equations were proposed and calibrated to estimate height,
number of fruits, nodes, dry matter of fruits and dry weight of fruits.
Conclusions: The model predicts the growth of the tomato crop and the nitrogen content in the plant
under greenhouse conditions.
Analysis of reference evapotranspiration behavior during the rainy season at five weather stations in the Lerma-Chapala basin
Análisis del comportamiento de la evapotranspiración de referencia durante el periodo de lluvias en cinco estaciones meteorológicas de la cuenca Lerma-Chapala
Francisco Javier Pelayo-Cortés;
Available online: 2019-08-23 / pages 147-159
Introduction: Estimating evapotranspiration of cultivated areas is commonly based on the calculation of reference evapotranspiration (ETo), and is essential in climatic and hydrological studies, as well as in projects related to water management in agriculture.
Objectives: To evaluate ETo and analyze its behavior during the rainy season on a daily, monthly and seasonal basis.
Methodology: Daily data series on temperature, radiation, atmospheric pressure, relative humidity and wind speed from five weather stations in the Lerma-Chapala basin were used. The ETo calculation was based on the application of the Penman-Monteith method.
Results: ETo during the rainy season followed a decreasing pattern, characterized by being non-linear. At the beginning of the season, values higher than 6 mm∙day-1 were observed, and at the end they were lower than 2 mm∙day-1. Correlation analysis showed that ETo depends on relative humidity and radiation.
Study limitations: The number of stations used was very low for the size of the basin because the network of automatic weather stations is still under development.
Originality: There are very few studies focused on evapotranspiration variation as a function of elevation and meteorological variables, in addition to a specific analysis in the rainy season.
Conclusions: The seasonal behavior of ETo shows important changes related to the behavior of relative humidity and radiation, which can have a significant impact on crop water needs.<
Development of a water pipe network serving as a conductive cooling system applied to dairy farms
Desarrollo de una red de tuberías de agua utilizada como sistema de enfriamiento por conducción aplicado a granjas lecheras
Christopher Y. Choi;
Xavier A. Ortiz;
Robert J. Collier
Available online: 2019-11-21 / pages 161-179
Introduction: In desert climates, high temperatures can cause heat stress on dairy farms. Aviable alternative to this problem is to develop a network of water pipes connected to heat exchangers (HEs) that operate as a conductive cooling system. Objective: To propose a water supply system connected to a series of HEs, installed under bedding in a dairy barn freestall system, and analyze heat transfer along a large-scale water pipe network. Methodology: The EPANET water quality module was used to design the system. Temperature predictions were validated with experimental data from a network of four HE pipes installed under the bedding. A network was then designed to supply water to 1 000 HEs in order tocalculate the efficiency of the system for a real dairy farm. Results: Insulations with values of 0.095 and 0.0475 W∙m-1∙°C-1 increased the cooling capacity of water-carrying pipes by 7 and 12 %, respectively. Increasing the flow rates from 1 to 7 L∙min-1 increased the cooling capacity; however, the cooling efficiency decreased by at least 12 %. Study limitations: A validation was performed on a section of the pipe network and a simulation for the entire network. Originality:V EPANET was implemented for a mass and heat balance in a pipe network supplying water to HEs. Conclusion: The conductive cooling system is viable in areas with a desert climate and its efficiency depends on the level of thermal insulation and flow in the pipe network.
Agricultural water productivity in the central zone of the Calera aquifer, Zacatecas
Productividad agrícola del agua en la zona centro del acuífero Calera, Zacatecas
Benjamín de León-Mojarro;
Jorge Victor Prado-Hernández
Available online: 2019-11-21 / pages 181-199
Introduction: The Calera aquifer is overexploited, and irrigated agriculture uses 90.2 % of the extracted water with a use efficiency of 43.5 %. Objective: To determine the productivity of irrigation water in the main crops of the central-southern zone of the Calera aquifer to know the efficiency of its use and identify savings opportunities. Methodology: The physical and economic productivity of water for garlic, onion, alfalfa, green pepper, dry bean and corn crops was calculated using the volume of irrigated water, yield, and production costs and value. The valuation was performed using June 2012 as the base period and was expressed in constant Mexican pesos (MXN). Results: The physical and economic productivity of water was higher in onion (5.48 kg∙m-3 and 13.42 MXN∙m-3) and lower in dry bean (0.30 kg∙m-3 and 2.44 MXN∙m-3), corn (1.37 kg∙m-3 and 1.54 MXN∙m-3) and alfalfa (1.53 kg∙m-3 and 1.77 MXN∙m-3). Without subsidizing electricity for pumping, alfalfa had the lowest economic productivity (-4.23 MXN∙m-3). Study limitations: Lack of official information about water productivity in the Calera aquifer prevented studying a longer period of time and carrying out a more in-depth analysis of the results. Originality: This study updates and improves the results obtained in 2011 within the Plan de Manejo Integral del Acuífero Calera (Calera Aquifer Integrated Management Plan). Conclusions: Crop production with low efficiency in the use of water jeopardizes its availability in the Calera aquifer