Effects of surface-applied biosolids on grass seedling emergence in the Chihuahuan desert

Plant establishment in semi-arid rangelands is difficult because of low, unpredictable soil water and extreme soil temperatures. In these rangelands, biosolids disposal is limited to topical application; resulting soil coverage ameliorates microenvironmental conditions and may affect plant establishment. We investigated biosolids effects on soil water, soil temperature, and seedling emergence and growth of blue grama (Bouteloua gracilis) and green sprangletop (Leptochloa dubia) in a Chihuahuan desert grassland. Greenhouse and field experiments were conducted for 2 years. Biosolids did not affect mean soil temperature (at seed depth) but usually increased minimum and reduced maximum temperatures. Biosolids generally reduced soil water loss. These benefits may be insufficient under harsh conditions to promote seedling establishment, and unnecessary under favorable conditions. Under intermediate conditions, seedling establishment may be enhanced by biosolids application.