Sewage Sludge Effects on Soil and Plant Quality in a Degraded, Semiarid Grassland

Abstract

A major problem affecting grassland productivity in the semiarid southwestern USA is the low quantity of soil organic matter and plant-available N. In this study, dried, anaerobically digested sewage sludge was applied at three rates (22.5, 45, and 90 Mg ha~') to a degraded semiarid grassland site to determine the effects of sludge on soil chemical and heavy metal properties, and vegetative yields and quality over two growing seasons. Most nutrients, including soil N, P, and K, increased linearly as a result of sludge amendment. Soil pH decreased linearly from 7.8 to 7.4 with the application of sludge after the second growing season, but did not significantly increase the solubility of soil heavy metals (Pb and Cd). On the other hand, the levels of DTPA-extractable soil micronutrients (i.e., Cu, Mn, Zn) increased linearly with sludge rates to levels recommended for adequate plant growth. Total herbaceous plant yields increased significantly with sludge amendment, particularly at the 45 Mg ha' 1 sludge rate, as compared with the control treatment. Blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Steud.] yields increased two-to threefold in amended plots over the unamended control after two growing seasons. The forage quality of blue grama, galleta [Hilaria jamesii (Torr.) Benth.], and bottlebrush squirreltail \Sitanion hystrix (Nutt.) J.G. Sm.], improved significantly as the levels of tissue N, P, and K, and crude protein increased linearly with sludge application. As expected, levels of Cd and Pb in all plant tissues did not increased significantly as a result of sludge amendment. All micronutrients increased to acceptable levels in deficient plant tissues. Sewage sludge applied at the rate of 45 Mg ha ' gave the most favorable soil and vegetation results. P.R. Fresquez, 2205 Columbia SE, Albuquerque, NM 87106; and R.E. Francis and G.L. Dennis, USDA Forest Service, Rocky Mountain Forest and Range Exp. St., Albuquerque, NM 87106.

Infrequent composted biosolids applications affect semi-arid grassland soils and vegetation

“…1), and was associated with reduced cover in other life forms such as perennial forbs and annual grasses. Others have found similar results with biosolids land application to semi-arid grasslands (Fresquez et al, 1990a(Fresquez et al, , 1990b. The stimulation of perennial grass growth by composted biosolids resulted in a slight reduction in plant species diversity (i.e.…”

“…Fresquez et al (1990a) also observed a decrease in soil pH and an increase in soil N with increasing biosolids rate applied to a semiarid grassland in New Mexico.…”

Successive Application Impact of Some Organic Amendments Combined with Acid Producing Bacteria on Soil Properties, NPK Availability and Uptake by Some Plants

“…Several investigators reported that the application of organic matter to different soils significantly increased their organic matter contents and improved the soil physical and chemical properties (Fresquez et al, 1990;Rehan et al, 2004;Youssef, 2011;Hadad et al, 2015). Also, Rashid et al, 2004 reported that, all phosphate solubilizing microorganisms (PSM) strains utilize carbon sources for production of organic acids…”

Biosolids effectiveness to yield ryegrass based on their nitrogen content

“…But regardless to the RE of each product, plants responded positively to all biosolids applied to both soils and reached yield plateaus for all treatments on the Spodosol (Figure 1). Osborne, (1996), Süss, (1997 and Fresquez et al, (1990) found sewage sludge being more effective for plant growth than fertilizers. On mining spoils, sewage sludge also out-performed the standard rehabilitation technique based on chemical fertilization (Phillips, 1994).…”