Abstract: Based on the experiment data of alfalfa planting in 2003-2004,the relationship of growth of alfalfa rhizotaxis to soil environmental conditions had been analysed.The results showed that the alfalfa root growth depended both on time of growth beginning of the plant and the growth of branches and leaves above the ground.The quickest period of the main root growth was in winter as the alfalfa branches and leaves stopped growing,while the slowest period of the main root growth was from bifurcation to mowing period as the alfalfa branches and leaves were in hearty growing season.The accumulated biomass of the rhizotaxis had a non-lineary correlativity with the soil thermo status.The increment of the accumulated biomass of the rhizotaxis speeded up as the accumulated temperature(≥0℃) at 20cm soil depth was with 3360℃.The soil water consumption in alfalfa field was 30% higher than that in the wheat field.The dry layer trace in the alfalfa field was deeper and lasted longer than that in the wheat field.The long term planting of the alfalfa or lack of soil moisture supply in time was likely to lead to an overdraft of the soil moisture.

Key words: Alfalfa, Alfalfa, Rhizotaxis, Growth, Soil environmental condition