Estimation Of Biomass And C And N Accumulation At The Maturity Stage Of Corn Using Remote Sensing

In order to provide the basis for estimating the productivity of arable farmland,ecological protection and carbon and nitrogen cycles, remote sensing estimationmodels which estimated above-ground biomass, carbon and nitrogen accumulation atthe maturity stages of corn were constructed. The correlations between thesynchronous SPOT-5and HJ-1B in14kinds of selected spectral parameters and theaboveground biomass, carbon and nitrogen accumulation amount of maize at maturestage using Pearson correlation analysis and the result showed that the performance ofthe best based on SPOT-5images performed better than the performance of the bestbased on HJ-1B and then the suitable spectral parameters were screen out. Theregression analysis was used to fit suitable spectral parameters, and to compare andobtain the optimal estimation models of above-ground biomass weight, C&Naccumulation. Among the14spectral parameters, there are significant positivecorrelations between soil-adjusted vegetation index (SAVI) and the above-groundbiomass weight and carbon accumulation, and the correlation coefficients are0.831and0.846, respectively. So the fitting effect to SAVI as regression equation, the powerfunction models are the best of the estimations of biomass and carbon accumulation,and decision coefficients (R2) are0.698and0.722and the F test shows a significantunder the0.01level. The significant correlation with N accumulation amount isdetermined by the ratio index of near infrared band and green band (R3/R1), thecorrelation coefficient is0.844, thus nitrogen accumulation fitting appears the besteffect by R3/R1for the linear model variable, the coefficient of determination (R2) is0.713(significant).So we can think that it is feasible that the remote sensing modelsconstructed using soil-adjusted vegetation index (SAVI), ratio index (R3/R1) can bestestimated corn mature biomass, C and N accumulation amount in this study.Therefore, for the corn at the maturity stage, the power function estimationmodel of aboveground biomass at the maturity stage of corn based on SPOT5-SAVI can be established and the model formula can be shown as: Biomass=17723924*SAVI6.923. The power function estimation model of aboveground carbon at thematurity stage of corn based on SPOT5-SAVI can be established and optimalestimation model can be shown as: carbon accumulation=5302999*SAVI6.565.Weselected R3/R1ratio vegetation index which constructed by near infrared and greenband as the optimal spectral parameters for nitrogen accumulation estimating and theestimated model is: nitrogen accumulation=152.02*R3/R1+15.497.Finally, we used the remaining16samples measured aboveground biomass andcarbon and nitrogen accumulation to check models for testing the reliability anduniversality of the estimation models. We chose root mean square error (RMSE),relative error (RE%) and the coefficient of determination (R2) three indicators toexamine the overall performance of the model. At the same time, we drew1:1relationship diagram between measured values and predicted values to show thereliability and consistency of selected model. The results showed that: the decisivefactor (R2) was high and RMSE was small which by followed1414.226kg/hm2,708.285kg/hm2and30.828kg/hm2, respectively. So, we can think that the resultsmeet the accuracy requirements. Ultimately we made the thematic maps of remotemonitoring aboveground biomass, carbon and nitrogen accumulation corn at thematurity stage of corn in the study area in accordance with the best models weconstructed to achieve a visual representation of mature corn aboveground biomass,carbon and nitrogen accumulation in the spatial distribution of quantization.