The total intercropped area reached a maximum of 33 million hectares in the 1990s. It is estimated that 1.5 million hectares of soybean-cultivated area were intercropped with various other crops in southern China by 2008. Interspecies interactions, including above-ground and below-ground competition and facilitation, play a key role in the structure and dynamics of plant communities in both natural and agricultural ecosystems. Organic phosphorus usually comprises 30 to 80% of the total phosphorus in most agricultural soils. Development of reclaimed desert soils using intercropping systems and rhizobia inoculations is a potentially important strategy for utilizing phosphorus-deficient soils and extending the arable land area. The results showed that the roots of intercropped wheat spread under maize plants and had much greater root length density at all soil depths compared to monocultured wheat. The roots of both intercropped wheat and jujube had less root length density at all soil depths than did the monocropped wheat and jujube trees.