We developed a simulation model to estimate the carrying capacity (CC) and stocking rate (SR) from different arid and semi-arid rangelands, using worksheets of Microsoft Excel, from the information available about the relationship between rainfall (mm) and forage production in dry matter per hectare (DM·ha-1). We designed a qualitative model of range management, identifying the main stages within it to estimate CC and SR. The study was carried out in URUZA-UACh from October 2010 to October 2011. After calibration of the model, only two scenarios and two real-life situations were evaluated. For the latter, the percentage differences were 8.3 and -25.5 % compared to the reality for adjusted and unadjusted values respectively. The simulation model with regard to the real had differences of 20 %. It is considered that the model simulated the CC and SR, and the settings depending on the percentage of slope and distance from water. The results show that production varies between types of vegetation because of the variability of precipitation. It is observed that evaluated pasture productivity is very low because it can only support UAA 96.86, but with adjustments to % slope and distance from water, it decreases of 60.06 and 29.73.

The shortage of water in the reservoirs of northern Tamaulipas can cause a decrease in yield and phytosanitary problems such as aflatoxins (Aspergillus flavus) and charcoal rot (Macrophomina phaseolina) in corn production. The aim of the study was to determine the response of 10 commercial corn hybrids to aflatoxins and charcoal rot, and in terms of yield, under limited irrigation conditions with two irrigation applications. The evaluated hybrids were: Gorila, Gstar 8802, DK 3000, Pionner 30P49, P3097, Syngenta 8285, Pionner 30R50, Canguro, Garañón and Tech Ag 8535. The variables measured were plant height, yield, charcoal rot incidence, water use efficiency, and grain protein and aflatoxin contamination level. The corn hybrids showed a similar response in aflatoxin contamination level, grain protein and yield, averaging 2.8 μg·kg-1, 6.9 % and 7,318 kg·ha-1, respectively. Although Garañón had the highest water use efficiency value (2.31 kg·m-3), DK 3000, 30R50 and Canguro recorded the lowest charcoal rot incidence (25-35 %). In general, the corn hybrids showed good productivity with limited irrigation; however, charcoal rot may pose a threat to production.

Large semi-arid rainfed areas of Mexico with degraded soils require productive conversion alternatives. Also, goat production systems need to be integrated into agricultural areas to conserve rangeland in times of drought. The aim of this study was to evaluate the conversion of degraded soils by using a combination of annual crops such as corn and cereals, with brush and prickly pear cacti established in strips. Contour strip cropping reduced water erosion and runoff (P<0.05) by 50 and 70 % respectively, compared to a soil under continuous tillage. Soil moisture storage was 23 to 35 % (based on volume) higher than with conventional soil management. Moreover, the number of goats that can be fed with forage produced in a 10-ha area in the dry season (December to May) was estimated. The values range from 17.4 goats·ha-1 in a year, with higher than average rainfall, up to 3 goats·ha-1 in dry years, with an average of 9.6 goats·ha-1 in five years of study.

Several authors have studied the influence of hydration-dehydration (HD) treatments on the germination of various plant species. Certain seeds preserve a “hydration memory” in order to retain, during dehydration, the physiological changes produced during hydration. The hypothesis is that the seeds of desert species will have a higher germination percentage and a lower mean germination time after being subjected to hydration-dehydration treatments. The aim of this study was to evaluate five species of plants, namely Frankenia gypsophila (I.M. Johnst.), Muhlenbergia arenicola (Buckl.), Muhlenbergia villiflora (Hitch.), Senna demissa (Rose) and Aristida adscencionis L., after being subjected to the following HD treatments: T1= 8h·day-1, T2= 8h·day-1 + 8h·day-1 + 8h·day-1, T3= 24h·day-1 and T4= control. HD treatments applied to the five species did not result in an increase in germination percentage. The hydration-dehydration cycles increased the germination rate and decreased the mean germination time (t50) of seeds of F. gypsophila, S. demissa and M. arenicola, which could be interpreted as one of the adaptations of these seeds to rain and drought intervals that occur in arid and semi-arid areas.

Natural resource management in arid areas as elsewhere must be supported by an appropriate analysis of the real needs of the site. The aim of this study was to identify and evaluate different natural resource management alternatives, in order to develop management options to improve the physical conditions of the soil in rangeland and, in turn, contribute to the productive activities of the population. The study was carried out in the community of Roma-Texas, located at 25° 52’ 25.83” N and 103° 43’ 33.8” W at an elevation of 1,168 m. Field trips were made to identify the main natural resource problems in the area. Using the RMS Planning Tool-SWAPA, possible alternatives that could be implemented at the site were defined, while with the help of experts in the field of natural resource management and the DSS Facilitator tool, the best alternatives for helping solve the problems of natural resource management in the area were evaluated and defined. Taking into account physical, social, economic and environmental factors, the best evaluated practices for their feasibility, viability and ease of implementation were: the establishment of woody plants (Prosopis spp) and grazing species, particularly buffelgrass (Cenchrus ciliaris L.), which are able to adapt to the arid conditions of the area.

The low and erratic rainfall in rainfed areas in Mexico, categorizes the production systems in these areas as high risk. This leads to the need for improved agricultural planning in order to increase productivity of rainfall. In this study, we proposed a method to characterize crop sensitivity to water stress and its impact on crop’s yield. The method uses functions of water stress index (WSI) based on water balance (Pp – Et0) from where crop sensitivity (λ) and the impact on relative yield it is deduced. We found that maize is the crop with the less sensitivity to water stress in all its stages of development; on the other hand, beans shows an evident sensitivity in all its stages of development. For all the crops analyzed, the stage of development shows the highest sensitivity to water deficit. In addition, we found the accumulative effect to water stress in all the stages of crop development. We consider that the method may be useful in the planning process of impact amelioration.