Linear Regression of Incident Precipitation Explains the Throughfall, Stemflow and Interception by the Eucalyptus Canopy under Different Fertilization Management

The present work aims to quantify the precipitation partition after interaction with the Eucalyptus urophylla canopy under two fertilization treatments. The experimental design was completely causalized with two fertilization treatments. Each plot had a dimension of 30 m x 60 m, and the spacing of the seedlings was 3 m x 2 m. The study was developed in a arenizaded area located in the municipality of Maçambará, state of Rio Grande do Sul, Brazil. The duration of the study was one year (from April 2017 to March 2018). Biweekly over twelve months the volume of precipitation was quantified. The experiment consists of two fertilization treatments in a Eucalyptus urophylla stand: T1 with smaller and T2 greater fertilization. In each treatment 3 throughfall collectors were installed at one meter of the soil level and three stemflow collectors. In the open area 3 collectors of the incident precipitation were installed 1.5 meters from the ground level. The percentages of the throughfall, stemflow and canopy interception in relation to the incident precipitation were 95.3; 1.3 and 4.3% for treatment 1 and 91.7; 3.2 and 6.2% for treatment 2. The coefficients of determination for throughfall, stemflow and canopy interception were 0.99; 0.96 and 0.85 for treatment 1 and 0.99; 0.97 and 0.89 for treatment 2. The graphical analysis of the regression residues shows independence of the errors. The fertilization management described for treatment 2 results in a greater interception of rainfall due to the greater amount of biomass of the canopy.