Effects Of Different Amendments Research Articles

Soil fertility and spontaneous revegetation in lignite spoil banks under different amendments

In order to study the reclamation of mine sites, the short-term effects of different amendments on soil fertility (at 1 and 6 months) and spontaneous vegetation (at 3 and 6 months) were examined in spoil banks of a lignite mine in Galicia (NW Spain). Experimental plots were established on three spoil banks deposited in 1984, 1988 and 2007, and treated with compost, limestone, NPK or no amendment (control trials). Fertilizer type, time after application and bank age, and their mutual interactions, were found to have significant, early effects on soil quality and fertility in terms of pH, CECe, the organic matter, total nitrogen, and exchange cations contents, as well as on vegetation establishment, composition, and species richness and diversity. The effects of each type of amendment, its ability to correct limitations to plant production and its influence on the successful establishment of spontaneous pioneer species are discussed. Compost gradually corrected P limitations (from 4 to 37 mg kg −1, in the oldest spoil bank) and significantly improved plant production with respect to untreated spoils (from 1905.1 to 4165.3 kg ha −1 DM). Unlike NPK, compost contributed towards maintaining species diversity and richness. It was found to significantly boost metabolic activity in the edaphic flora, which was estimated from the soil respiration rate as determined by infrared gas analysis (IRGA). Limestone facilitated the establishment of legumes and other dicotyledons, and corrected pH (from 5.3 to 7.0) and Al saturation in CEC (from 37.62% to 0.20%) in the most recent spoils, but produced imbalances in exchange cations (Ca/Mg = 25.7) due to excessive Ca supply. Based on our results, using compost in recent lignite spoils requires the gradual correction of soil pH with magnesium limestone to avoid Mg limitations.

Do amended, polluted soils require re-treatment for sustainable risk reduction? — Evidence from field experiments

The use of in situ amendments for chemical stabilization of inorganic pollutants requires some indication of the longevity and sustainability of their effects. The efficiency and residual effect of different amendments for chemical stabilization of trace elements was evaluated in a contaminated soil under field conditions, based on single or repeated applications. Three amendments, two organic (biosolids compost and leonardite) and one inorganic (sugarlime), were applied to a soil contaminated by the tailings dam spill at Aznalcóllar (S. Spain), together with an unamended control. Amendments were applied in 2002 and 2003 to replicated test plots. In 2005 each plot was halved: one half received further amendments in 2005 and 2006 (4 treatments, D4) and the other received no further treatment (2 treatments, D2). The efficacy of the different treatments was evaluated in surface (0–15 cm) and sub-surface (15–30 cm) soil horizons. Both organic amendments significantly increased pH and TOC contents of amended soils, accompanied by reduced trace element extractability (CaCl 2 extraction). The inorganic amendment reduced extractable trace element pools and maintained alkaline conditions, but did not affect TOC. The need for repeated amendment applications to sustain these conditions depended on the type of amendment. Two consecutive applications, D2, of the inorganic amendment showed sustained efficacy. Both organic amendments required repeated applications for full effectiveness. These results demonstrate that there are clear differences in the potential long-term sustainability of in situ amendments in field conditions and that treated soils require an effective monitoring programme as part of any post-treatment management.

Effect of organic amendments of soil on growth and productivity of three common crops viz. Zea mays, Phaseolus vulgaris and Abelmoschus esculentus

The study was aimed at understanding the effect of different amendments to soil on the plant growth and productivity. The paddy straw and Ageratum conyzoides residues were used as direct mulch, compost, and vermicompost in different plots planted with Zea mays, Phaseolus vulgaris and Abelmoschus esculentus, separately in three experimental plots. The different treatments affected the seed germination of the three test crops significantly. Plant height, basal area, productivity and biomass allocation in above ground parts were highest in vermicompost treated plots and lowest either in control or in mulched plots. The significant positive correlation between biomass accumulation and nutrient mineralization pattern but negative correlation between productivity and available nitrogen was observed. The study revealed that different amendments affected crops differently and the pre-treatment of crop/plant residues like vermicomposting are invariably beneficial and contributed to crop growth and available N in soil.

Effect of different amendments on growth and heavy metal accumulation in <I>Vicia villosa</I> Roth <I>varglabrescens</I> cv Yunguangzao in soils pol-luted with lead/zinc mine tailings

A pot experiment was conducted to determine the effect of four amendment substances (organic manure,lime,vermiculite and dolomite) on growth and heavy metal (Cu,Cd,Pb and Zn) accumulation in Vicia villosa Roth varglabrescens cv Yunguangzao in soils contaminated with lead/zinc mine tailings.Changes in soil pH and available heavy metal content induced by the amendments were also analyzed.The results show that the four amendments significantly increase soil pH while reducing available heavy metal content in soil.Hence transportation of Cd and Pb from the root to shoot of V.villosa is limited,which reduces heavy metal accumulation in the shoot.The amendments significantly improve growth of V.villosa,while increasing plant height,shoot and root fresh weight and chlorophyll content of V.villosa.The induced changes in plant height and shoot fresh weight are significant (P 0.05) compared to CK.Amendments significantly affect heavy metal accumulation in the root of V.villosa.The effects of the four amendments on root heavy metals content in V.villosa are also significant.

Chemical fractionation and translocation of heavy metals in Canna indica L. grown on industrial waste amended soil

A pot experiment was carried out to assess the effect of different amendments of industrial sludge on the growth of Canna indica L. as well as the translocation potential of heavy metals of this plant. The accumulation of metals (Cr, Fe, Cd, Cu, Ni, Zn, Mn and Pb) in different parts of C. indica L. grown on industrial sludge-amended soil increased with time and increasing doses of sludge amendments. Sequential extraction method was followed to estimate the different fractions of heavy metals in sludge-amended soils collected from different periods of this study. The results showed that Mn, Zn, Cd, Cr and Pb were mostly associated with Fe–Mn oxide fraction in all amendments, whereas, Ni was mostly found in residual (RES) fraction. Cu and Fe were found to be higher in organically bounded form (OM) and RES fraction. The metal concentration in C. indica L. after 90 days of experiment started, was in the order of Fe > Cr > Mn > Zn > Ni > Cu > Cd > Pb and the metal translocation was found lesser in shoot. With the increasing percentage of sludge amendments in soil the metal concentrations increased in different parts of plants. Overall, the plant C. indica L. was found to be well adapted in industrial sludge amendments and it may be recommended that this plant was found suitable for phytoremediation of most of the studied metals.

Trace element availability and plant growth in a mine-spill-contaminated soil under assisted natural remediation: II. Plants

In this second part, we evaluated the effects of different amendments on plant growth ( Agrostis stolonifera L.), and trace element accumulation and removal by plants in a trace element (As, Cd, Cu, Pb and Zn) contaminated soil. Description of the various treatments is given in Part I of this work. The plants were grown for consecutive periods (2002, 2003, 2004), 5 months each and harvested twice in each period. Results showed that plant growth was enhanced and trace element concentrations in plant were reduced in SL, MWC, BC and LEO treatments in the first period. No significant differences were observed in subsequent periods. This seemed to be related with changes in soil pH. Removal of trace elements was higher in SL, MWC, BC and LEO treatments due to higher biomass production in the first period. In following years no significant differences between treatments were found. Data from Part I of this study were also used to compare trace element bioavailable concentrations extracted with 0.01 M CaCl 2 and 0.05 M EDTA with trace elements in plant. We observed that 0.01 M CaCl 2 was more suitable for determination of bioavailable concentrations and that extraction with EDTA overestimated biovailability of trace elements in amended treatments, especially in those where composts were added.

Trace element availability and plant growth in a mine-spill contaminated soil under assisted natural remediation I. Soils

We evaluated the effects of different amendments and/or a plant cover on reclamation of a trace element contaminated soil. Seven treatments were established: four organic (leonardite (LEO), litter (LIT), municipal waste compost (MWC), biosolid compost (BC)), one inorganic (sugar beet lime (SL)) and two controls (control without amendment but with Agrostis (CTRP) and control without amendment and without Agrostis (CTR)). Results showed that total organic C was significantly higher in organic treatments in all samplings. Water-soluble C was lower in CTR compared to other treatments, but no significant differences were observed between organic treatments and SL and CTR. SL, BC and MWC treatments increased soil pH and reduced 0.01 M CaCl 2-extractable Cd, Cu and Zn concentrations more efficiently, especially in the first 2 years. At the end of the experiment 0.01 M CaCl 2-extractable trace element concentrations were similar in all treatments. 0.01 M CaCl 2-extractable As and Pb were below the detection limit. Addition of amendments showed no clear reduction in 0.05 M EDTA-extractable trace element concentrations and some amendments even increased 0.05 M EDTA-extractable As and Cu with time. Pseudo-total trace element concentrations were higher for As in controls. On the other hand, mean values of Cu and Zn were higher in MWC treatment. BC and SL treatments also showed higher Zn mean concentration than controls. No amendment effect was observed for Cd and Pb.

Translocation of metals and its effects in the tomato plants grown on various amendments of tannery waste: evidence for involvement of antioxidants

A field experiment was conducted to study the effect of different amendments of tannery sludge on physiological and biochemical parameters of tomato plant ( Lycopersicon esculentum L. Mill). The accumulation of metals (Cr, Fe) in different parts of tomato plants grown on tannery sludge amended soil increased in a concentration and duration-dependent manner. The accumulation of both the metals was found lowest in the fruits of the plant. The statistical analysis of the results showed an increase in chlorophyll and protein contents in lower sludge amendment ratio at all exposures followed by a decrease at highest (100%) sludge amendment ratio. Lipid peroxidation enhanced in both root and leaves of sludge grown plants of tomato at all the sludge amendments and exposure periods, which is evidenced by increased malondialdehyde content, however the maximum increase was found in the roots (43.63%) and leaves (56.66%) of the plant grown on 100% tannery sludge at 60 d, over respective controls. The level of antioxidants, cysteine, non-protein thiol and ascorbic acid increased in the sludge grown plants of tomato to cope up with stress induced by the excess amount of the heavy metals present in the tannery sludge. The maximum increase was found in cysteine content (75.53% in the leaves), non-protein thiol content (92.68% in the roots) and ascorbic acid content (29.66% in the roots) of the plant at 75% tannery sludge after 30 d. The tomato plants were found well adopted for minimizing damage induced by reactive oxygen species, when grown on tannery sludge amendments in the present study.

ORGANIC AMENDMENTS AND PHOSPHORUS DYNAMICS: III PHOSPHORUS SPECIATION

Previous studies have shown that organic amendments decreased P sorption and affected distribution of P fractions in soils. The objective of this study was to determine the effects of different amendments on the chemical speciation of P in soil solution. Soil samples of Jory (Xeric Haplohumult) and Tolo (Typic Vitrandept) were treated with 5% manure or 3 times the CaCO 3 or CaSO 4 required to neutralize exchangeable Al and incubated for 28 d. After incubation the samples were air-dried and subsequently brought to field capacity with deionized water or with a P solution of KH 2 PO 4 (33 mmol P kg -1 soil) and allowed to react (equilibrate) for 12 h. Soil solutions were extracted by centrifugation. Total concentrations of metals, inorganic ligands and DOC were measured in the soil solution. The computer program GEOCHEM was used to calculate the concentrations of the free metals, ligands and their complexes. Adding manure decreased the total soluble Al and Fe in soil solution and increased base cations and SO 4 . Total P in solution increased in : the samples that received manure or CaCO 3 in Jory soil ; and manure or CaSO 4 in Tolo soil. Phosphorus was oversaturated with respect to strengite and the percent distribution of phosphate with respect to this solid tended to decrease in the presence of manure. Calculation of the ion activity product (IAP) for variscite showed that P was in equilibrium with an amorphous analog of variscite. Citrate of the organic acids measured (malic, maleic, malonic, citrate, succinic, formic, and acetic) was the only organic acid that had a significant effect on P speciation. Model calculations suggest that citrate forms soluble complexes with Al, Ca, and Fe, preventing precipitation of strengite and solid Ca-PO 4 .

Population dynamics of Fusarium spp. in pea rhizosphere as affected by soil amendments.

In nonamended soil, vegetative growth and sporulation of Fusarium spp. were higher in the rhizosphere than in the soil. Sporulation was favoured by young plants and decreased with increasing plant age. Amendments with low C/N oil-cakes enhanced vegetative growth and sporulation in root-free soil. The extent of stimulation varied with the nature of organic matter used and the stage of its decomposition. Sporulation was suppressed by castor cake and sawdust with urea amendments. Rhizosphere cf pea altered the effect of different amendments.