Balanço de água no solo em arroz de terras baixas irrigado por aspersão

Abstract

The sprinkler irrigation is an alternative to reduce costs and enables more sustainable rice cultivation system in the lowlands.. Therebythe study aimed to characterize and develop a mathematical model to determine the water moisture in the soil, with irrigated rice cultivation by spraying in rice fields in the lowlands experiments were conducted in Itaqui-RS in the crop years 2014/15, 2015/16 and 2016/17. O design was a randomized block (DBC) with five blades irrigation sprinkler 0%, 50%, 100%, 150% and 200% etc. In the years 2014/2015 and 2015/2016, and 50% 100 %, 150%, 200% and 250% of the year etc. in 2016/17. The need for irrigation was determined from the culture evapotranspiration (ETC), multiplying the reference evapotranspiration (ETo) by the crop coefficient (Kc). The CC and the PMP were performed in Richards chamber after samples were taken to dry in an oven at 105 ° C to conduct the soil density. The water holding capacity (CAD) was calculated by the equation: C = (CC - PMP) * Zr * Ds.To perform the water balance model on the ground, they were considered the entries and exits of water in the soil. The rainfall and irrigation water intakes were in the soil and the water outlets in the soil etc.The water balance model was conducted on the ground by the equation: ADS = ADS(n-1) + Prec(n-1) + Irri (n-1) - ETc. To evaluate the model's performance, the root was used the mean square error (RMSE) calculated as Janssen & Heuberger (1995). The model used to characterize the water balance in the soil showed a good performance, but it has limitations, especially considering the plant biology. smaller water depths than 100% lead in humidity near or below the permanent wilting point, increasing the likelihood of drought stress in plants, so their use is not indicated. The model used had a higher correlation with observed data of soil moisture on the blades of 0 to 250% of crop evapotranspiration.