Felipe Gallardo

Evaluation of aluminum tolerance of three barley cultivars by two short-term screening methods and field experiments

Abstract Productivity of cereal crops growing in acid soils of Southern Chile have adversely being affected by acidification and aluminum phytotoxicity. For overcoming such constraints, farmers need to apply heavy amounts of lime and/or use AI-tolerant plants especially with AI-sensitive crops, as barley is. The objectives of this study were to determine the degree of Al tolerance of . three barley cultivars commonly grown in volcanic soils by using two shortterm screening methods and to relate their rankings with field experiments. Additionally, the amounts of citric and malic acids exuded from roots were determined for studying the mechanism involved in Al tolerance. Relative root length (RRL) was the criterion used to evaluate Al tolerance both in nutrient solution and in soil-based culture and yield for field experiments. Results showed a close relationship between the RRL values obtained with the three barley cultivars by applying the two short-term screening methods. Barley yields obtained in field ...

Chlorophenol degradation in soil columns inoculated with Anthracophyllum discolor immobilized on wheat grains

The white-rot fungus Anthracophyllum discolor immobilized on wheat grains was evaluated for chlorophenol (2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol) degradation in allophanic soil columns activated by acidification. Columns without inoculation were used as the control to evaluate the adsorption capacity of the soil columns. The chlorophenols were removed efficiently in soil columns by both adsorption and degradation processes. In inoculated soil columns, 2,4-dichlorophenol was highly degraded and this degradation is associated with a high production of manganese peroxidase. 2,4,6-trichlorophenol was degraded to a lesser extent compared with 2,4-dichlorophenol. Pentachlorophenol was first removed by adsorption and then through degradation by the fungus. Manganese peroxidase activity was lowest when the column was fed with pentachlorophenol and highest when the column was fed with 2,4-dichlorophenol. Laccase was also produced by the fungus but to a lesser degree.

Effect of pulp mill sludge on soil characteristics, microbial community and vegetal production of Lolium Perenne.

The effect of pulp mill sludge addition (10-30 Mg/ha) to soil derived from volcanic ash (Andisol) on soil characteristics, microbial community and Lolium perenne L. cv quartet. biomass production was evaluated in field assays. Soil without sludge was used as a control treatment. The sludge addition improved the chemical properties of the soil. Organic matter and phosphorous content increased in the soil with increasing amounts of sludge, obtaining 35% more organic matter content with the application of 30 Mg/ha than the control soil. The phosphorous was accumulated into the soil after the end of cultivation improving the phosphorous pool in the soil. When 30 Mg/ha sludge was added to the soil, a biomass of Lolium perenne, was 60% more than the control soil at the end of the experiment. The analysis of soil microbial community showed that the application of sludge did not modify greatly the microbial community of fungi and bacteria even when high doses were applied.

USE OF SLUDGE FROM KRAFT MILL WASTEWATER TREATMENT AS IMPROVER OF VOLCANIC SOILS: EFFECT ON SOIL BIOLOGICAL PARAMETERS

Sludge from kraft mill wastewater treatment was applied on two soils derived from volcanic ashes and, the effect on biological parameters of the soils was evaluated. The soils used in this study were an Andisol belonging of Gorbea Series and an Ultisol belonging of Collipulli Series. The sludge was added at rates of 0, 10, 20, 30 and 50 t ha -1 . Previously, germination of red clover (Trifolium pratense), white clover (Trifolium repens), alfalfa (Medicago sativa) and ryegrass (Lolium perenne) was tested to assess phytotoxicity of the sludge. The different soil-sludge mixtures were incubated at controlled temperature for 60 days and microbial respiration, microbial biomass carbon, fluorescein diacetate hydrolysis and acid phosphatase activity were evaluated throughout the incubation time. All biological parameters evaluated were sensitive enough to shown the effect of sewage sludge application on soil microorganisms. The sludge application at different rates increased significantly (P<0.05) the microbial activity and enzymatic activity of the sludge amended soils. The maximum levels of activity were observed between 15 and 30 days after sludge application in both Gorbea soil and Collipulli soil, obtaining the highest values when were applied between 30 and 50 t ha -1 . The results of this study suggest that sludge from kraft mill wastewater treatment may have potential as a beneficial soil amendment for improving biological properties of the soils.

Phosphorus-molybdenum relationship in soil and red clover (Trifolium pratense L.) on an acid Andisol.

We studied the phosphorous (P) and molybdenum (Mo) relationship in soil and red clover (Trifoliumpratense L.) in a non limed and limed acid Andisol of Southern Chile. In soil, we evaluated the effect of different liming (0 and 2000 mg kg-1), P (0, 200 and 400 mg kg-1), and Mo (0, 0.58 and 0.96 mg kg-1) doses supply on soil available Mo. In addition, the availability of P and Calcium (Ca) in treated soils was determinated. In red clover, we studied the Mo and P shoot concentrations and dry matter yield in response to the different treatments applied to the soil. Also, we measured the changes produced by Mo uptake in shoot Cu concentrations. The results showed that both, lime and more strongly P and Mo additions significantly (P ≥ 0.05) increased soil Mo availability. In contrast, soil available P was not significantly (P ≥0.05) affected by liming and Mo treatments. A significant high correlation (r = 0.579, at P ≥ 0.05) was observed among soil Mo availability and shoot Mo concentrations, as well as between soil available P and shoot concentration of P (r = 0.844, at P ≥ 0.01). In this study for all fertilization treatments, shoot Cu concentrations reached values which are considered as normal for forage species. We also shown that the simultaneous applications of high P and Mo rates could be produce red clover shoot Cu/Mo ratios that should provoke Mo-induced Cu deficiency (Molybdenosis) for the cattle. Red clover yield was no significantly different in limed and non limed soils. Nevertheless, red clover yield production increased at increasing rates of P and Mo in both, non limed and limed soil. The major practical implication of these results is that the application of Mo doses equal or superior to 200 g ha-1 to acid Andisols, are recommendable to obtain appropriate Mo shoot content on red clover. In addition, our results shown that P supply to these soils, rather than liming, is necessary to obtain sufficient values of shoot Mo concentrations in red clover.

Atrazine, chlorpyrifos, and iprodione effect on the biodiversity of bacteria, actinomycetes, and fungi in a pilot biopurification system with a green cover

ABSTRACT The use of biopurification systems can mitigate the effects of pesticide contamination on farms. The primary aim of this study was to evaluate the effect of pesticide dissipation on microbial communities in a pilot biopurification system. The pesticide dissipation of atrazine, chlorpyrifos and iprodione (35 mg kg−1 active ingredient [a.i.]) and biological activity were determined for 40 days. The microbial communities (bacteria, actinomycetes and fungi) were analyzed using denaturing gradient gel electrophoresis (DGGE). In general, pesticide dissipation was the highest by day 5 and reached 95%. The pesticides did not affect biological activity during the experiment. The structure of the actinomycete and bacterial communities in the rhizosphere was more stable during the evaluation than that in the communities in the control without pesticides. The rhizosphere fungal communities, detected using DGGE, showed small and transitory shifts with time. To conclude, rhizosphere microbial communities were not affected during pesticide dissipation in a pilot biopurification system.