Abstract:The energy flow 、value flow and soil N、P、K dynamics have been evaluated and compared by collecting the agronomic data and determining the energy parameters of crop, pest and natural enemies in 7 types of cotton agroecosystems from Northern China. The results showed that the output of energy and pure monetary values in 7 types of cotton agroecosystems were 30 41×10 3~71 63×10\+3kJ/(m\+2·a) and 3565 80~8146 50 Yuan RMB/(hm 2·a), respectively. The output input ratio of energy and monetary values were 1∶...