7Hilde D. Fine-tuning Sugar Beet Fertility Management in the Red River Valley. Better Crop with Plant Food.1994,78(4):26～28
8Wright N A. New Mobile Sampler Compared to Hand Probes and Augers for Fertility Evaluation. Precision Agriculture ,1996. 631～639
9Algerbo, Sweden P A. Variable Nitrogen Application:Effects on Crop Yield and Quality. Proceeding of the Fourth International Conference on Precision Agriculture.1999. 709～717
10Leclerc H Laurent. F Dannis Biosgotier. France . Using Field and Crop Characteristics for Site Specific Nitrogen Management on Winter Wheat Crop. Proceeding of the Fourth International Conference on Precision Agriculture.1999. 719～731
