Growth characteristics, nutrient uptake, and metal accumulation of ryegrass (Lolium perenneL.) in sludge-amended mudflats

Abstract

The objective of this study was to investigate the impact of sewage sludge amendment (SSA), with the rates of 0, 30, 75, 150, and 300 t ha (1 , on soil chemical properties and biomass, aboveground and root growth, and nitrogen and phosphorus uptake of ryegrass (Lolium perenne L.) seedling grown on a mudflat soil. Results showed that SSA modified the chemical properties of mudflat soil by decreasing soil salinity and pH, increasing soil organic matter, total and available N and P, and heavy metals. The biomass of root and aboveground parts of ryegrass showed increments with increasing SSA rates. Maximum increases of 5.6-and 1.3-fold in fresh weight of aboveground parts and root of ryegrass were observed at 300 t ha (1 rate. Root grown at all SSA rates showed positive response to higher nutrient availability in the mudflat soil with increasing root average diameter and volume. The root length and surface area at 30 t ha (1 SSA rate was significantly higher than those in other treatments. The sewage sludge amendment increased N and P content in both aboveground and root parts of ryegrass. Cd, Cr, Cu, Mn, Ni, and Zn accumulation in ryegrass was positively correlated with SSA rates. However, heavy metal concentrations in ryegrass did not exceed the safety standard for feed in China (GB 13078-1999), except for Cd at 300 t ha (1 SSA rate. The study suggests that sewage sludge can be applied for mudflat soil amendment, which provides an innovative solution pertaining to new arable land resources and solid waste disposal. The optimum SSA rate is 150 t ha (1 with maximum plant yield yet permissible metal accumulation.

Sewage Sludge Amendment Combined with Green Manuring to a Coastal Mudflat Salt-Soil in Eastern China: Effects on Soil Physicochemical Properties and Maize Yield

“…The pH in mudflat salt-soil decreased with increasing SSA rates, which was similar to our previous studies [9,20,21]. Other authors have also found lowering of pH with SSA [50][51][52].…”

“…Our previous studies also supported the results [9,20,21]. In farmland, soil fertility improvement by SSA has also been reported widely [50,51,54].…”

“…Agricultural application of sewage sludge is an effective waste disposal and soil amendment technique that can improve the chemical, physical, and biological characteristics of soils [16][17][18][19]. Sewage sludge is rich in organic matter and other nutrients and can be used for mudflat salt-soil amendment [9,20,21].…”

“…However, the application of sewage sludge combined with green manuring to amend mudflat salt-soils has received no attention. The impacts of applying sewage sludge alone to reclaimed mudflat soil on fertility development, growth of ryegrass, Sesbania, and maize and on heavy metals behaviors including their accumulation and fraction in soil and uptake by plants were investigated and evaluated in our previous studies [9,20,21,35]. This study was one of pioneering studies to investigate and evaluate the sustaining effects of sewage sludge amendment combined with green manuring on the soil aggregates, organic carbon, salinity, pH, and N and P of mudflat salt-soil, as well as yield of maize (Zea mays L.) in mudflats salt-soil in a rain-fed agroecosystem.…”

Evaluating Dairy Manure as Initial Fertility Driver for Mudflat Soil Amendment

“…The newly reclaimed mudflats are high in salinity and not suitable for cultivation as indicated by poor soil structure, extremely low organic matter (OM) content, low nutrient level, and lack of microbial diversity. The keys to mudflat reclamation to arable-lands are to reduce salinity, and to increase the soil OM content thus soil fertility [4]. Salinity reduction is often accomplished through freshwater irrigation.…”