The objective of the present work was to perform an economic analysis of centre-pivot irrigation implantation on a sandy soil area with different previous land uses. Thus, it was possible to analyse three initial soil conditions inside (irrigated) and outside (rainfed) the centre pivot. The opening area (P1) was characterized by soybean planting for the first time after degraded pasture, P2 consisted of the second year of harvesting soybean/maize second season, and P3 consisted of the third year of harvest. Two crops were evaluated: soybean and maize. The centre-pivot irrigation system was not profitable at the earliest stage of soil recovery (P1) immediately after degraded pasture because soil fertility limited yields. There was a 23% and 33% increase in soybean yield for the areas with 2 years (P2) and 3 years (P3) of soil recovery, respectively, compared to the first year. However, second-season maize had an increased yield of 19% for the third-year area (P3) compared to the first year (P1).

ResumoEsta publicação apresenta uma análise financeira do sistema de irrigação por sistema linear móvel praticado por uma usina localizada no estado de Goiás, com o intuito de fornecer dados para alimentar um modelo que poderá ser utilizado posteriormente como uma ferramenta de análise econômica e de rentabilidade da irrigação na cana-de-açúcar. Foram avaliados os custos fixos e variáveis anuais e os benefícios diretos e indiretos da irrigação. O benefício direto advém do aumento da receita pelo aumento de produtividade da área irrigada e aumento da longevidade do canavial; e os benefícios indiretos são provenientes da redução de custos decorrentes da redução da área de produção e dos custos de colheita e transporte. Como resultado, a irrigação apresentou custos totais anuais de aproximadamente R$ 72,00 por tonelada. A relação benefício/custo da irrigação foi de 1,066, considerando somente o benefício direto de produtividade (Etapa 1) e de 1,313 ao considerar o benefício direto do aumento da longevidade e da produtividade (Etapa 2). Portanto, a irrigação apresenta uma boa rentabilidade financeira nesse caso estudado. Palavras-chave: matéria-prima, produtividade, sucroenergético, tecnologias AbstractThis paper presents a financial analysis of a linear mobile pivot irrigation system practiced by a plant located in the state of Goiás, Brasil, in order to provide data to feed a model that can be used later as a tool of economic and profitability analysis of sugarcane irrigation. The fixed costs, annual variables costs and the direct and indirect benefits of irrigation were evaluated. The direct benefit came from the increased revenue by productivity gains on irrigated areas and increased longevity of the cane field. The indirect benefits came from costs reduction due to the reduction of the area of production and of the costs of harvesting and transportation. As a result, the irrigation presented total annual costs of approximately R$ 72.00 per ton. The benefit cost ratio of irrigation with increased productivity was 1,066 in the first stage and 1,313 in the second stage, which includes productivity and longevity increase. Therefore, irrigation presented a good financial profitability in this study.

The application of water by an irrigation system always shows a degree of unevenness. Uniformity in conventional sprinkler systems depends on factors such as: the type of sprinkler and its operating conditions, the arrangement and spacing between sprinklers in the field, and the speed and direction of the wind during the period of application of water. The variation in soil moisture is dependent on the distribution and amount of water applied. The effect of irrigation uniformity on crop productivity is a significant factor to be considered in sprinkler irrigation projects. The objective of this work was to evaluate the effect of water application uniformity on the productivity of potato, beet and bean crops. For the three cultures, conditions of different spacings between the emitters (6 x 6m, 12 x 12m, 12 x 18m and 12 x 24m) were simulated resulting in different water application uniformity coefficients. Next, production functions were developed by other authors. The results indicated the spatial variability of productivity as a function of the distribution uniformity of the emitters. The productivity of potato, beet and bean crops were affected by the high disuniformities of water application via sprinklers. PALAVRAS-CHAVE:aspersão; distribuição; produção.

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ABSTRACT:The objective of this work was to determine the most adequate nitrogen dose in order to maximize fertilization profitability in six maize hybrids (Zea mays L.) under subsurface drip-irrigation. Six different hybrids were studied (H1, H2, H3, H4, H5 and H6) and four different nitrogen doses were applied (0; 60; 120; 180 kg ha