DETERMINATION NUMBER OF SOIL SAMPLES THAT IS STATISTICALLY REPRESENTATIVE IN MIXED-SAMPLE DETERMINATION OF THE NITROGEN NUTRITION OF CROPS

The statistically representative numbers of individual soil samples (0 -30, 0-60, and 0-90 m layers) in a mixed sample used to determine the mean nitrogen concentration and to establish the required level of sup plementary nitrogen application to winter wheat are identified. In a S od-Podzolic soil, the smallest suitable number of individual samples i n a mixed sample is 10-12 on soils of heavy loam texture and 15-16 on medium-loam or sandy-loam soils.