The life cycle of wheat at the experimental site includes about 200 growth days from October to May, and we carried out our scattering measurements during an entire wheat growth cycle (Fig. 2). Growth stages are critical in the entire cycle of wheat growth; therefore, Feekes scale28 was used for selecting growth stages indicating different growth conditions after planting. Various parameters obtained for the 20th day (tillering initiation, November 16), 45th day (advanced tillering, December 10), 80th day (stem extension: jointing, January 15), 115th day (stem extension: booting, February 19), 145th day (heading, March 22), 165th day (flowering, April 12), and 190th day (ripening, May 8) are listed in Fig. 2. The backscattering coefficients were measured twice in an acquisition after calibration, and average values were used to guarantee robustness of data. Characteristics of the independent samples during the different wheat growth stages were adequately considered while obtaining wheat parameters in all the experiments. Data on fresh weight (total biomass and ear weight), structure (canopy length, leaf length, and ears length), leaf area index (LAI), and stem density were collected. More than 42 wheat samples were collected at each stage; the average values for the samples are shown in Table 2. Soil roughness was measured using two parameters: root-mean-square (RMS) height: 2.12 cm and correlation length: 15.26 cm. Soil roughness was only measured once (November 15, 2008, tillering initiation) during the entire wheat growth cycle, because it is considered to have little change during the entire growth cycle and could not be measured when wheat is high enough to block the device for roughness measurements.29 Soil moisture was measured using the gravimetric method and then converted to volume soil moisture. The last row in Fig. 2 shows the collected data on destructive sampling and soil roughness. Destructive sampling is critical for estimating biomass and retrieving detailed geometric characteristics of the various elements. Based on ASAR spatial resolution, we chose eight experimental points in the research area for measuring radar backscatter and ground parameters, which can be helpful to modify the water-cloud model, verify the accuracy of the retrieved biomass, and ensure the usability of the models.