Estimation of spring crops sowing calendar dates using MODIS in Northern Kazakhstan

Sowing period for spring crop lasts usually more than 40 days in Northern Kazakhstan. Calendar dates of sowing are important for final crop productivity, which can be varied about 30% in relation to this factor. IMODIS data and ground survey in 2003 were used as the base for developing of cropland sowing date estimation procedure. Spectral characteristics of crop fields are changed after sowing. Values of near infrared reflectance (band 2) increase during 40-60 days after sowing. This effect is used for estimation of cropland sowing dates. Cloudless MODIS images dated by June 15-25 are used for processing. Ground survey data used for creation of calibration curve between sowing calendar date and reflectance (MODIS, band 2) for separate fields. Accuracy of calibration procedure is enough for three classes of sowing calendar dates recognition namely: early, normal, late