Development of CAN-Based Distributed Control System for Variable Rate Technology in Agricultural Machinery

The number of electronic devices connected to agricultural machinery is increasing to support new agricultural practices tasks related to the Precision Agriculture such as spatial variability mapping and Variable Rate Technology （VRT）. The Distributed Control System （DCS） is a suitable solution for decentralization of the data acquisition system and the Controller Area Network （CAN） is the major trend among the embedded communications protocols for agricultural machinery and vehicles. The application of soil correctives is a typical problem in Brazil. The efficiency of this correction process is highly dependent of the inputs way at soil and the occurrence of errors affects directly the agricultural yield. To handle this problem, this paper presents the development of a CAN-based distributed control system for a VRT system of soil corrective in agricultural machinery. The VRT system is composed by a tractor-implement that applies a desired rate of inputs according to the georeferenced prescription map of the farm field to support PA （Precision Agriculture）. The performance evaluation of the CAN-based VRT system was done by experimental tests and analyzing the CAN messages transmitted in the operation of the entire system. The results of the control error according to the necessity of agricultural application allow conclude that the developed VRT system is suitable for the agricultural productions reaching an acceptable response time and application error. The CAN-Based DCS solution applied in the VRT system reduced the complexity of the control system, easing the installation and maintenance. The use of VRT system allowed applying only the required inputs, increasing the efficiency operation and minimizing the environmental impact.

Tolerance to Salinity of Sesame Genotypes in Different Phenological Stages

The sesame crop is usually avoided in salt-affected areas because of the various effects of saline stress on plants. Besides varying between species, salinity effects are known to vary for genotypes of the same species as well as plant development stages. Thus, through the irrigation of plants with saline water, this study evaluates tolerance to saline stress of new sesame genotypes in different phenological stages. Three experiments were carried out under greenhouse conditions, using the sesame genotypes BRS Seda, LAG-927561 and LAG-26514. Water with different levels of electrical conductivity (ECw = 0.6, 1.6, 2.6, 3.6 and 4.6 dS m-1) was used to irrigate plants during germination and initial growth stages, as well as the entire crop cycle. Tolerance to saline stress (3.6 dS m-1) during growth and production stages was also studied. Salinity did not affect sesame germination, but seedling growth was hindered from the ECw of 1.6 dS m-1 onwards, and plant height was the most affected growth variable. Seed production is affected by salinity, regardless of the phenological stage in which plants are exposed to salinity. The strains LAG-927561 and LAG-26514 show promising signs in studies on adaptation to saline stress.

Performance evaluation of a water erosion tracer using plot-scale experiments and process-based modeling

Socioeconomic and environmental losses caused by water erosion have highlighted the importance of quantifying and understanding the dynamics of soil redistribution in the landscape to develop effective soil management practices.Several methods are applied to estimate erosion/deposition rates and identify sources of sediments,among them,the one that uses rare earth elements(REE)as a tracer stands out.However,an alternative not yet explored that can benefit the accuracy of the estimates provided by the method is using a tracer containing a chemical signature composed of more than one REE.The present study aimed to evaluate the performance of a new water erosion tracer based on montmoril-lonite labeled with rare earth elements(La40-MMT).The innovative aspects of this La40-MMT tracer include its highly stable multi-chemical signature(Nd^(3+),La^(3+),and Pr^(3+)),which enhances tracer detection in the environment,and its low production cost due to the use of an industrial residue in the synthesis process.The tracer was evaluated for a typical soil of the Cerrado biome,using a natural rainfall field-scale plot-NRFP(5 m × 20 m)and a physical predictive erosion model(WEPP).The results showed that the La40-MMT tracer could be used to estimate erosion/deposition rates,with agreement between the values observed with the tracer and the WEPP model.Thus,this study confirmed the great potential of La40-MMT as a tool to identify patterns of soil redistribution at the field scale and aid in the validation of erosion models.