ABSTRACT: Since its inception approximately 50 years ago, the grape harvester has been one of the machines responsible for the expansion of viticulture in the world. In Spain, harvesters were introduced in the 1990s (there are now approximately 3,000 machines there as of 2017), while they were introduced in Brazil in 2010. Harvest mechanization requires specific crop adaption and new work features that deserve to be analysed from their very beginnings. The aim of this study was to evaluate the management of four commercial grape harvest machines under actual field conditions on an intercontinental basis in two locations in Brazil and Spain. Machine performance measured by work (ha h−1) and processing capacity (kg h−1), together with field efficiency (%) and task quality, as measured by grape losses (%), in soil and plant, as well as must release (%), were considered in relation to plot geometry, adaption of plots to mechanical harvesting, and machine type, in order to assess whether the initial steps towards harvest mechanization in Brazil have led to similar performance and quality levels compared to Spain, which represents an example of well-established mechanization. The theoretical work capacities were similar for towed equipment in both countries (0.81 ha h−1 in Brazil and 0.87 ha h−1 in Spain) and lower compared to self-propelled capacity (1.34 ha h−1). Significant differences were observed in terms of losses of grapes and must, with the highest values prevailing in Brazil (2 % grape losses in the ground; up to 23 % of the plant undetached grapes and must losses of 2-4 % (per kg vine productivity).

Com o objetivo de estudar a influência da distribuição vertical de semente na variabilidade espacial da implantação de uma cultura de milho em diferentes sistemas de preparação do solo (mobilização convencional, mobilização mínima e sementeira direta), realizaram-se nas campanhas de 2011 e 2012 dois ensaios de campo na região do Alentejo. A avaliação da distribuição vertical de semente fez-se pela determinação da profundidade de sementeira medindo o comprimento do mesocótilo em plântulas de milho. Em sementeira direta foram ainda testadas duas velocidades de trabalho. Os resultados demonstraram que o melhor desempenho de distribuição vertical da semente foi conseguido em sementeira direta com o aumento de velocidade de trabalho de 4 para 6 km h-1 (com um coeficiente de variação, CV, de 10,1%). Uma ANOVA de duplo fator demonstrou que a resistência mecânica do solo e a velocidade de trabalho determinaram diferenças significativas na profundidade de sementeira; a profundidade de sementeira causou diferenças significativas no tempo médio (TME) e percentagem de emergência (PE) da cultura. Os elevados CV observados sugerem a necessidade de uma melhor calibração dos dispositivos de controlo de profundidade dos semeadores por parte dos operadores em campo ou o aperfeiçoamento dos mesmos.

Among the various factors that contribute towards producing a successful maize crop, seed depth placement is a key determinant, especially in a no-tillage system. The main objective of this work was to evaluate the spatial variability of seeders vertical distribution and crop establishment in a maize crop under different tillage conditions, using precision farming technologies carried out in 2011 and 2012. Considering the lowest coefficient of variation of seed depth placement of 10.1%, best seeder performance was achieved in no-tillage condition increasing forward speed from 4 to 6 km h-1. A two factor ANOVA showed that the effect of soil mechanical resistance and work speed in no-tillage caused significant differences in seed depth placement. Seeding depth had a significant impact on mean emergence time and percentage of emerged plants and high coefficients of variation suggest a need for improvements in controlling the seeders sowing depth mechanism or more accurate calibration by operators in the field.

This article presents the evolution of potato cultivation in Spain and set out the main causes of damage as well as electronic devices available to control the loads to which they are subjected. Finally some considerations are made regarding the type of mathematical models that best fit the estimated damage.

En este artículo se presenta la evolución del cultivo de la patata en España y se exponen las principales causas de daño, así como los dispositivos electrónicos disponibles para el control de las cargas a las que se ven sometidos. Finalmente se realizan unas consideraciones relativas al tipo de modelos matemáticos que mejor se ajustan a la estimación de daños.