Infrequent Composted Biosolids Applications Affect Semi-arid Grassland Soils and Vegetation

Monitoring of repeated composted biosolids applications is necessary for improving beneficial reuse program management strategies, because materials will likely be reapplied to the same site at a future point in time. A field trial evaluated a single and a repeated composted biosolids application in terms of long-term (13–14 years) and short-term (2–3 years) effects, respectively, on soil chemistry and plant community in a Colorado semi-arid grassland. Six composted biosolids rates (0, 2.5, 5, 10, 21, 30 Mg ha?1) were surface applied in a split-plot design study with treatment (increasing compost rates) as the main factor and co-application time (1991, or 1991 and 2002) as the split factor applications. Short- and longterm treatment effects were evident in 2004 and 2005 for soil 0–8 cm depth pH, EC, NO3-N, NH4-N, total N, and AB-DTPA soil Cd, Cu, Mo, Zn, P, and Ba. Soil organic matter increases were still evident 13 and 14 years following composted biosolids application. The repeated composted biosolids application increased soil NO3-N and NH4-N and decreased AB-DTPA extractable Ba as compared to the single composted biosolids application in 2004; differences between short- and long-term applications were less evident in 2005. Increasing biosolids rates resulted in increased native perennial grass cover in 2005. Plant tissue Cu, Mo, Zn, and P concentrations increased, while Ba content decreased depending on specific plant species and year. Overall, the lack of many significant negative effects suggests that shortor long-term composted biosolids application at the rates studied did not adversely affect this semi-arid grassland ecosystem

Water treatment residuals and biosolids long-term co-applications effects to semi-arid grassland soils and vegetation

Water treatment residuals (WTRs) and biosolids are byproducts from municipal water treatment processes. Both byproducts have been studied separately for land application benefits. There are possible environmental benefits of WTRs and biosolids co-application but these studies are limited. Our objectives were to determine relative long-term (13–15 yr) effects of a single and short-term (2–4 yr) effects of repeated WTR-biosolids co-applications on soil chemistry, microbiology, and plant community structure in a Colorado semiarid grassland. Only relative changes associated between co-applications were studied, as we assumed WTR application would only occur if used as a management practice. Three WTR rates (5, 10, and 21 Mg ha–1) were surface co-applied (no incorporation) with a single biosolids rate (10 Mg ha–1) once in 1991 (long-term plots) and again in 2002 (short-term plots). Soil 0- to 8-, 8- to 15-, and 15- to 30-cm depth pH, electrical conductivity (EC), NO3–N, NH4–N, total C, and total N were not aff ected by WTR application in 2004, 2005, or 2006. Ammonium-bicarbonate diethylenetriaminepentaacetic acid (AB-DTPA)- extractable soil Al was unaffected by WTR application, but extractable P and Mo decreased with increasing WTR rate because of WTR adsorption. Plant tissue P and Mo content decreased with specific plant species and years due to adsorption to WTR; no deficiency symptoms were observed. Plant community composition and cover were largely unaffected by WTR application. Soil microbial community structure was unaffected by WTR co-application rate (total ester-linked fatty acid methyl ester [EL-FAME] concentrations ranged from 33.4 to 54.8 nmol g–1 soil), although time since biosolids-WTR application affected a subset of microbial community fatty acids including markers for Gram-positive and Gram-negative bacteria. Overall, WTR-biosolids co-applications did not adversely affect semiarid grassland ecosystem dynamics

Water treatment residuals and biosolids coapplications affect semiarid rangeland phosphorus cycling

Land coapplication of water treatment residuals (WTR) with biosolids has not been extensively researched, but the limited studies performed suggest that WTR sorb excess biosolids-borne P. To understand the long-term effects of a single coapplication and the short-term impacts of a repeated coapplication on soil P inorganic and organic transformations, 7.5- by 15-m plots with treatments of three different WTR rates with a single biosolids rate (5, 10, and 21 Mg WTR ha-1 and 10 Mg biosolids ha-1) surface coapplied once in 1991 or surface reapplied in 2002 were utilized. Soils from the 0- to 5-cm depth were collected in 2003 and 2004 and were sequentially fractionated for inorganic and organic P (Po). Inorganic P fractionation determined (i) soluble and loosely bound, (ii) Al-bound, (iii) Fe-bound, (iv) occluded, and (v) Ca-bound P, while organic P fractionation determined (i) labile, (ii) biomass, (iii) moderately labile, (iv) fulvic acid, (v) humic acid, and (vi) nonlabile associated Po. Pathway analysis showed that humic, fulvic, and nonlabile Po did not play a role in P transformations. Biomass Po and moderately labile Po contributed to the transitory labile Po pool. Labile Po was a P source for Fe-bound and WTR-bound inorganic phases, with the Fe-bound phase transitory to the occluded P sink. The Al-bound phase additionally contributed to the occluded P sink. The Ca-bound phase weathered and released P to both the Fe-bound and WTR-bound P phases. Overall, the WTR fraction, even 13 yr after the initial application, acted as the major stable P sink

Water treatment residuals and biosolids co-applications affect phosphates in a semi-arid rangeland soil

Co?application of biosolids and water treatment residuals (WTR) land has not been extensively studied but may be beneficial by sorbing excess biosolid?borne or soil phosphorus (P) onto WTR, reducing the likelihood of off?site movement. Reduction of excess soil P may affect the role of specific P?cleaving enzymes. The research objective was to understand the long?term effects of single co?applications and the short?term impacts of repeated co?applications on soil acid phosphomonoesterase, phosphodiesterase, pyrophosphatase, and phytase enzyme activities. Test plots were 7.5 × 15 m with treatments consisting of three different WTR rates with a single biosolids rate (5, 10, and 21 Mg WTR ha?1; 10 Mg biosolids ha?1) surface co?applied once in 1991 or reapplied in 2002. Control plots consisted of those that received no WTR–biosolids co?applications and plots that received only 10 Mg biosolids ha?1. Plots were sampled to a 5?cm depth in 2003 and 2004, and soil phosphatases and phytase enzyme activities were measured. Soil phosphodiesterase activity decreased in WTR?amended plots, and pyrophosphatase activity decreased with increasing WTR application rates. In contrast, acid phosphatase and phytase activity increased with WTR addition, with WTR application possibly triggering a deficiency response causing microorganisms or plants to secrete these enzymes. Biosolids and WTR co?applications may affect enzymatic strategies for P mineralization in this study site. Reductions in phosphodiesterase activity suggest less P mineralization from biomass sources, including nucleic acids and phospholipids. Increased acid phosphatase and phytase activities indicate that ester?P and inositol?P may be important plant?available P sources in soils amended with WTR

Infrequent Composted Biosolids Applications Affect Semi-arid Grassland Soils and Vegetation

Monitoring of repeated composted biosolids applications is necessary for improving beneficial reuse program management strategies, because materials will likely be reapplied to the same site at a future point in time. A field trial evaluated a single and a repeated composted biosolids application in terms of long-term (13–14 years) and short-term (2–3 years) effects, respectively, on soil chemistry and plant community in a Colorado semi-arid grassland. Six composted biosolids rates (0, 2.5, 5, 10, 21, 30 Mg ha?1) were surface applied in a split-plot design study with treatment (increasing compost rates) as the main factor and co-application time (1991, or 1991 and 2002) as the split factor applications. Short- and longterm treatment effects were evident in 2004 and 2005 for soil 0–8 cm depth pH, EC, NO3-N, NH4-N, total N, and AB-DTPA soil Cd, Cu, Mo, Zn, P, and Ba. Soil organic matter increases were still evident 13 and 14 years following composted biosolids application. The repeated composted biosolids application increased soil NO3-N and NH4-N and decreased AB-DTPA extractable Ba as compared to the single composted biosolids application in 2004; differences between short- and long-term applications were less evident in 2005. Increasing biosolids rates resulted in increased native perennial grass cover in 2005. Plant tissue Cu, Mo, Zn, and P concentrations increased, while Ba content decreased depending on specific plant species and year. Overall, the lack of many significant negative effects suggests that shortor long-term composted biosolids application at the rates studied did not adversely affect this semi-arid grassland ecosystem

Understory responses to mechanical treatment of pinyon-juniper in northwestern Colorado

Pinyon-juniper (Pinus spp.-Juniperus spp.) encroachment and decliningmule deer (Odocoileus hemionus) populations in western Colorado have necessitated management for increased forage. Pinyon-juniper removal is one such technique; however, it is unclear which method of tree removal most effectively promotes forage species. We conducted an experiment to quantify understory responses to mechanical pinyon-juniper removal and seed additions in a blocked design using three different methods: anchor-chaining, rollerchopping, and mastication. Blocks contained each mechanical and seeding treatment along with an untreated control. Seven blocks across two sites, North Magnolia (NM, 4 blocks) and South Magnolia (SM, 3 blocks), were treated during the fall of 2011. Half of each plot was seeded before or during mechanical treatment with a mix of grasses, shrubs, and forbs. After two growing seasons, biomass of perennial grasses was 90-160 kg · ha-1 in mechanically treated plots compared with 10 kg · ha-1 in untreated controls. There were no differences, however, between mechanical treatments for any perennial plant species. Response of annual plant species depended on mechanical treatment type and site. Rollerchopping had higher exotic annual grass cover than mastication or control at NM and higher exotic annual forb cover than chaining or control at SM. Rollerchopping was the only treatment to have higher native annual forb cover than control in the absence of seeding. Seeding increased native annual forb biomass in mastication compared with control. Seeding also increased shrub density at SM, which had fewer shrubs pretreatment relative to NM. Results suggest any type of mechanical removal of pinyon-juniper can increase understory plant biomass and cover. Seeding in conjunction with mechanical treatments, particularly mastication, can initially increase annual forb biomass and shrub density. Finally, different understory responses between sites suggests that pretreatment conditions are important for determining outcomes of pinyon-juniper removal treatments. © 2016 The Authors. Published by Elsevier Inc. on behalf of The Society for Range Management. This is an open access article under the CC BY-NC-ND license.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information

Water treatment residuals and biosolids co-applications affect phosphates in a semi-arid rangeland soil

Co?application of biosolids and water treatment residuals (WTR) land has not been extensively studied but may be beneficial by sorbing excess biosolid?borne or soil phosphorus (P) onto WTR, reducing the likelihood of off?site movement. Reduction of excess soil P may affect the role of specific P?cleaving enzymes. The research objective was to understand the long?term effects of single co?applications and the short?term impacts of repeated co?applications on soil acid phosphomonoesterase, phosphodiesterase, pyrophosphatase, and phytase enzyme activities. Test plots were 7.5 × 15 m with treatments consisting of three different WTR rates with a single biosolids rate (5, 10, and 21 Mg WTR ha?1; 10 Mg biosolids ha?1) surface co?applied once in 1991 or reapplied in 2002. Control plots consisted of those that received no WTR–biosolids co?applications and plots that received only 10 Mg biosolids ha?1. Plots were sampled to a 5?cm depth in 2003 and 2004, and soil phosphatases and phytase enzyme activities were measured. Soil phosphodiesterase activity decreased in WTR?amended plots, and pyrophosphatase activity decreased with increasing WTR application rates. In contrast, acid phosphatase and phytase activity increased with WTR addition, with WTR application possibly triggering a deficiency response causing microorganisms or plants to secrete these enzymes. Biosolids and WTR co?applications may affect enzymatic strategies for P mineralization in this study site. Reductions in phosphodiesterase activity suggest less P mineralization from biomass sources, including nucleic acids and phospholipids. Increased acid phosphatase and phytase activities indicate that ester?P and inositol?P may be important plant?available P sources in soils amended with WTR

Water treatment residuals and biosolids long-term co-applications effects to semi-arid grassland soils and vegetation

Water treatment residuals (WTRs) and biosolids are byproducts from municipal water treatment processes. Both byproducts have been studied separately for land application benefits. There are possible environmental benefits of WTRs and biosolids co-application but these studies are limited. Our objectives were to determine relative long-term (13–15 yr) effects of a single and short-term (2–4 yr) effects of repeated WTR-biosolids co-applications on soil chemistry, microbiology, and plant community structure in a Colorado semiarid grassland. Only relative changes associated between co-applications were studied, as we assumed WTR application would only occur if used as a management practice. Three WTR rates (5, 10, and 21 Mg ha–1) were surface co-applied (no incorporation) with a single biosolids rate (10 Mg ha–1) once in 1991 (long-term plots) and again in 2002 (short-term plots). Soil 0- to 8-, 8- to 15-, and 15- to 30-cm depth pH, electrical conductivity (EC), NO3–N, NH4–N, total C, and total N were not aff ected by WTR application in 2004, 2005, or 2006. Ammonium-bicarbonate diethylenetriaminepentaacetic acid (AB-DTPA)- extractable soil Al was unaffected by WTR application, but extractable P and Mo decreased with increasing WTR rate because of WTR adsorption. Plant tissue P and Mo content decreased with specific plant species and years due to adsorption to WTR; no deficiency symptoms were observed. Plant community composition and cover were largely unaffected by WTR application. Soil microbial community structure was unaffected by WTR co-application rate (total ester-linked fatty acid methyl ester [EL-FAME] concentrations ranged from 33.4 to 54.8 nmol g–1 soil), although time since biosolids-WTR application affected a subset of microbial community fatty acids including markers for Gram-positive and Gram-negative bacteria. Overall, WTR-biosolids co-applications did not adversely affect semiarid grassland ecosystem dynamics