Variabilidade espacial e temporal da disponibilidade de água no perfil do solo aplicada por um sistema de irrigação localizada.

Abstract

The present work had the objective of studying the space variability of the water in the profile of the soil applied by an overhead irrigation type micro sprinkler, located in a property in the arid, for that it was analyzed three units of the project composed by twelve units cultivated with Cocos nucifera L tree Ann on a muricata L. and Psidium guajava L. At the beginning it was made a superficial evaluation of the irrigation subunit for determination of the coefficients of irrigation uniformity, coefficient of uniformity of the system, application efficiency and other, It was also certain in laboratory to the characteristics hydraulics of the originator EIN PAIN 861 new and with three years of use used in the project. Therefore after it was made an evaluation subsurface, the humidity readings in the profile of the soil were made with a neutrons probe, where 81 tubes of access of PVC were installed, forming two meshes of 28 tubes and one of 25 tubes. The outflow data, pressure and of the humidity in the profile of the soil of 0-20, 20-40 and 40-60cm before and after the irrigations in each emission point, monitored for four months they were interpreted using the casual statistics and the space (geoestatistics), making maps of the data collected in the units of irrigation appraised, where it was possible to verify that the outflow of the originator after three years of use decreased in 5,3% in relation to the new micro sprinkler; the coefficient of variation of production of the microsprinkler is considered as excellent, according to norms of ASAE, and after three years of use it became of average quality; the coefficient of application variation increased in the used microsprinkler; so much in the new microsprinkler as used us, the relationship pressure versus outflow, found at laboratory it is described by potential models with discharge coefficient characterized as of regime of turbulent flow. Already in field the values of those discharge coefficients are larger, classified as regime of semi-turbulent flow; the effective ray of the originator decreases after the three years of use; the coefficient of irrigation uniformity increased when it was changed in field the originators used by the new ones, as well as the coefficient of uniformity of the system and the application efficiency; at field level they happened great pressure variations and of outflow consequently was found coefficient of irrigation uniformity and statistical uniformity coefficient only only above 80% in the subunit two; In the subunit two as much the pressure as the outflow it increased when it was changed the originators used for new. For all the analyzed variables there was a normal distribution of the data; the coefficient of variation of readiness of water decreased after the irrigations; in the profile of the soil just k the depth of 40-60 cm the soil was with the readiness of water above the level of field capacity; in a general way the maps showed that the largest readiness of water is in the located lateral lines in the beginning of the derivation line; the adjusted mathematical models the semivariance of the readiness of water in the profile of the soil, in the subunit two, in your majority were lineal Suggesting that when the distribution of the data is normal a tendency of that model it exists to come to happen; in the subunit two, in the profile of the soil the maximum distance (it reaches) that the dear data of readiness of water space is correlated it was constant with exception in the layer 20-40 cm after the irrigation; when the originator was changed used for new, the minimum variance (nugget effect) it decreased among the equal ones dear with a strong space dependence so much for new originators as to have used; in the subunit five and ten, the dear space dependence for the adjusted mathematical models the semivariancias was strong; with the increase of the statistical coefficient of the outflow there was a tendency for the nugget effect and the landing to decrease, while the reach and the space dependence increase.