Distribution of maize root system in a kanduidalfic eutrudox soil: II. Comparison between irrigated and fertirrigated crops

A field experiment was carried out to evaluate the distribution of irrigated maize root system in a 1 m soil layer of terra roxa estruturada latossólica (Kanduidalfic Eutrudox soil) in Piracicaba, SP, Brazil (22° 43' S, 47° 5'W), at 126 days after plant emergence. The root system exposed in trenches was filmed and the pictures processed by a system SIARCS, specially developed to analyze root system distributions. Maize root density in the 0-60 cm soil layer was higher for the case of N application to the soil, whereas for the 60-100 cm fertirrigation promoted root development. Soil water matric potential and the water storage in the soil profile presented greater changes to the 50 cm depth, showing a good relation between tensiometry, neutron probe measurements and the picture processing method.A distribuição do sistema radicular do milho irrigado, até 1 m de profundidade, em uma terra roxa estruturada latossólica em Piracicaba, SP, foi analisada aos 126 dias após a emergência das plantas. As raízes expostas pela abertura de trincheiras longitudinalmente às Unhas de plantas foram filmadas e essas imagens digitalizadas e processadas para a contabilização de sua distribuição no perfil do solo, por meio do sistema SIARCS desenvolvido para esse fim. A densidade de raiz de milho a 0-60 cm foi maior para a aplicação de N via solo, enquanto que a 60-100 cm a fertirrigação proporcionou uma maior presença de raízes. Por meio de tensiômetros e da sonda de nêutrons, notou-se, respectivamente, que a maior amplitude de variação do potencial matricial da água no solo e da quantidade de água armazenada no solo ocorreu até a profundidade de 50 cm, evidenciando a boa correspondência dessas técnicas com o método de processamento de imagens

Crop water parameters of irrigated wine and table grapes to support water productivity analysis in the Sao Francisco river basin, Brazil

Energy and water balance parameters were measured in two commercial vineyards in the semiarid region of the São Francisco river basin, Brazil. Actual evapotranspiration (ET) was acquired with the Bowen ratio surface energy balance method. The ratio of the latent heat flux to the available energy, or evaporative fraction (EF), was 81% on average for two growing cycles in wine grape and 88% for two growing seasons in table grape. Energy partitioning in this last vineyard was higher due to microsprinkler irrigation conditions and greater soil cover promoted by the overhead horizontal trellis systems. The accumulated ET from pruning to harvest in wine grape was 438 and 517 mm for the first and second growing cycles, respectively. Table grape consumed less water than wine grape (393 and 352 mm for the first and second growing seasons, respectively) due to shorter crop stages. Beneficial transpiration (T) was 89 and 81% of total ET for wine and table grape, respectively. Brazilian semiarid climate allows 2.5 production cycles per year for vineyards. The yield was in average of 6183 kg ha¿1 for two cycles of wine grape and 11,200 kg ha¿1 for one short growing season of table grape, corresponding to a bio-physical water productivity per unit ET of 1.06 kg m¿3 (or 1.02 L wine m¿3) and 3.18 kg m¿3, respectively. Table grape showed a significantly higher economic water productivity (US$6.51 m¿3) than wine grape (US$ 0.93 m¿3). These values are much favorable than for staple crops