Use of the Time Domain Reflectometry to evaluate the nitrate distribution in fertirrigated soils columns

Abstract

The monitoring of spatial and temporal variation of the soil water content (θ), of the soil bulk electric conductivity (CEs), of the soil solution electric conductivity (CEss) and of the ion concentration (Ci) enables to estimate the water loss by deep percolation and evapotranspiration, to determine the areas of nutrients extraction by plants and the possible nutrients loss by leaching. The of objective this work was to evaluate, using the TDR technique, the nitrate distribution in Typic Quartzipsamment (RQ) and Oxisol (LV) soil columns fertirrigated with calcium nitrate. Nitrate fertirrigations were accomplished in the columns, and the soil water content (θ) and the soil bulk electric conductivity (CEs) obtained with TDR. The nitrate concentration was estimated using the values of θ and of CEs. In the RQ soil, the nitrate reached 30, 21 e 12 cm when the fertirrigations were done at the beginning, at the middle and at the end of the irrigation period, respectively. In the LV soil, independently of the moment of the fertirrigation, the nitrate was retained in the layer from 0 to 12 cm deep.