Based on the data of a long term field experiment of dryland crops, this article points out that yield fluctuation, expressed in fluctuating coefficient, is a regular phenomenon in dryland farming.

S. scientists said recent research, the reasons for this phenomenon may lie in these species signal the immune system and way of special immune regulation yield of different elements.

We introduced a structure equation with macroscopic parameters, which can explain both the yield point phenomenon and strain-ageing of low carbon steels.