Introduction: The FAO-56 Penman-Monteith (PM) is one of the most solid and commonly used methods for estimating reference evapotranspiration (ET_o); 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 ET_o of the Comarca Lagunera, Mexico.
Methodology: Daily and decadal average ET_o were estimated in five different ways. In each case, a different method was used to estimate ET_o (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 ET_o, 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 ET_o 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.

Introduction: 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.

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.

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.