Degraded Soil Restoration and Reforestation


Soil degradation is an ecological disturbance, usually human‐caused, that negatively affects the vegetation, climate of an ecosystem and also humans quality of life particularly in arid and semiarid environments. These degraded soils can be restored using native perennial plants inoculated with specific microorganisms.

The field chosen to test the method was a human disturbed, depleted and barren Sonoran Mexican desert field. The trail began on 2004 and its results are still evident two decades later.

For this field trial, native plants, legume trees and Cardon* cactus were chosen. The plants were inoculated with a mixture of PGPB (Azospirillum brasilense and Bacillus pumilus). A very little amount of compost was added to enhance the organic matter content because the soil was completely depleted and barren. During planting, a very limited irrigation water was added.

*Without inoculation Cardon cactus is a very slow growing plant and has a limited acclimation success, it usually withers and dies within few years after planting.

The positive effect of PGPB soil restoration method contributes to:

Nitrogen fixation improved to the level of pristine forest
Populations of diazotrophs significantly increased
It significantly increased the chances of the cacti to survive and grow in degraded soil

Eroded lands that lost the capacity of natural re-vegetation can be returned to productivity using PGPB

Planted trees after 10 years are equally strong as natural trees; nitrogen fixation capacity completely restored.

No foliar diseases, parasitic plants, ants, insects or spiders appeared in the reforested areas, despite close proximity to inoculum source.