Estimation of soil nitrate in the spring as a basis for adjustment of nitrogen fertiliser rates

Authors

• J. SIPPOLA

DOI: https://doi.org/10.23986/afsci.5648

Abstract

The performance of SOILN model, which simulates soil nitrogen dynamics, was evaluated in respect to its ability to predict nitrate content in soil in spring when growing barley. The data obtained in three year nitrogen fertiliser experiments on different soil types was used. Model was parametrised using the data of the first experimental year and validation results obtained in following years are presented. The results of the simulations of the springtime nitrate in the root zone showed a reasonably small deviation from the measured values. The coefficient of determination, R2 = 0.56 was significant. The regression equation was y = 4 + 0.66x where the constant term was not significantly different from zero and the slope deviated from zero. The mean value of measured nitrate in the root zone in spring was 16 kg/ha and that from the simulation was 15 kg/ha showing that the mean values were close to each other. The mean of deviations between measured and simulated values was 4 kg/ha and the maximum deviation 9 kg/ha. It is concluded that simulation estimated springtime soil nitrate concentration with reasonable confidence that further testing of estimating soil nitrate concentration in spring for adjustment of nitrogen fertilisation using SOILN model should be continued.;