Erosion control and habitat restoration of retired farmland in the Anza-Borrego desert

Improving agricultural water management in response to diminishing groundwater resources is crucial for sustainable land use. In Borrego Springs, California, state-mandated water reductions are prompting farmers to retire or fallow their farms permanently. However, without proper management, retired farmlands are vulnerable to wind erosion and dust emissions, which hinder restoration efforts and pose risks to human health. Our team conducted a study where we implemented four different erosion control treatments in two blocks of permanently retired citrus orchards. The treatments included (1) rows of mulch (the standard practice), (2) felled citrus trees scattered across the site, (3) fences made from felled citrus trees, and (4) commercial sand fences, each consisting of ten rows oriented to face the dominant wind direction. Preliminary results show average dust control efficiencies of 93% and 94% for the Scattered Trees and Tree Fences, respectively, implying that most dust emissions are controlled within these two treatments. The Scattered Tree treatment creates the most effective wind barrier with porosity in a range (28-37%) known to reduce wind speeds while minimizing soil scouring. The Tree Fences showed the most significant reductions in wind speeds. Overall, the Tree fence and Scattered Tree treatments are the most cost-effective choice for controlling erosion, dust emissions, and promoting restoration.