Neutral Loam Soil Research Articles

A BLEND OF BIOASH AND GYPSUM UTILIZED FOR AGRO-ENVIRONMENTAL PURPOSES IN A SOIL INCUBATION EXPERIMENT

Soil impover, nutrient supplier and heavy metal stabilizer effects of ash residue remaining after the process for K recovery was examined in a soil incubation model experiment using two soil types (acid sandy soil and neutral loam soil) at 4 ash residue dose levels (0,1,3,5%). Possible environmental risks posed ba its application were also studied by ecotoxicological assays.

Sorption and dialysis experiments to assess the binding of phenolic xenobiotics to dissolved organic matter in soil

AbstractThe binding of two phenolic compounds, nonylphenol (NP) and bisphenol A (BPA), and the herbicide metabolite hydroxydesethyl terbuthylazine (HDT) to dissolved organic matter (DOM) as well as its impact on the environmental fate of the compounds in soil have been investigated. In sorption studies with an acidic silty loam soil and a neutral loam soil, no impact of added DOM on adsorption and desorption coefficients was observed. Adsorption coefficients normalized to soil organic carbon (Koc) of the compounds on the loamy silt soil spanned three orders of magnitude: 90, 890, and 9,140 L/kg for HDT, BPA, and NP, respectively. Significantly lower Koc values for HDT on the neutral loam soil as compared to the acidic loamy silt soil indicated additional polar interactions between the latter and the basic herbicide metabolite. In dialysis experiments with fulvic acid from silty loam soil (FA) and peat humic acid (HA), a formation of analyte‐DOM associates was observed only for HA. The degree of association was characterized by distribution coefficients normalized to the dissolved organic carbon concentration (KDOC). Values for NP (8,970 L/kg) and BPA (860 L/kg) corresponded with the respective soil sorption coefficients, suggesting similar binding mechanisms in both cases.

Sorption and dialysis experiments to assess the binding of phenolic xenobiotics to dissolved organic matter in soil.

The binding of two phenolic compounds, nonylphenol (NP) and bisphenol A (BPA), and the herbicide metabolite hydroxydesethyl terbuthylazine (HDT) to dissolved organic matter (DOM) as well as its impact on the environmental fate of the compounds in soil have been investigated. In sorption studies with an acidic silty loam soil and a neutral loam soil, no impact of added DOM on adsorption and desorption coefficients was observed. Adsorption coefficients normalized to soil organic carbon (Koc) of the compounds on the loamy silt soil spanned three orders of magnitude: 90, 890, and 9,140 L/kg for HDT, BPA, and NP, respectively. Significantly lower Koc values for HDT on the neutral loam soil as compared to the acidic loamy silt soil indicated additional polar interactions between the latter and the basic herbicide metabolite. In dialysis experiments with fulvic acid from silty loam soil (FA) and peat humic acid (HA), a formation of analyte-DOM associates was observed only for HA. The degree of association was characterized by distribution coefficients normalized to the dissolved organic carbon concentration (KDOC). Values for NP (8,970 L/kg) and BPA (860 L/kg) corresponded with the respective soil sorption coefficients, suggesting similar binding mechanisms in both cases.

Increases in extractable sulphate following soil submergence with water, dilute sulphuric acid or acid rain

A marked increase in the concentration of LiCl-extractable sulphate occurred when samples of two acid brown earth soils (one from a site exposed to heavy atmospheric pollution and the other from a relatively unpolluted site) were waterlogged in the laboratory with either deionized water, dilute sulphuric acid (pH 4·0) or acid rain (pH 3·8). The greatest increases in sulphate concentration occurred in the heavily polluted soils. However, no similar increases were found when two neutral loam soils were waterlogged. The pH of the brown earths increased on waterlogging, while soil Eh fell, but only slowly. Sulphate reduction eventually occurred in the brown earths following most treatments, resulting in a decrease in sulphate concentration. No free H 2S was evolved under these conditions, however. The acid rain treatment had the same effect as dilute sulphuric acid and deionized water on sulphate transformations in these woodland soils. The increases in the concentration of LiCl-extractable sulphate which occur when brown earths are waterlogged appear to result from a combination of organic sulphur mineralisation and increased desorption of adsorbed sulphate.

Biological control of Rhizoctonia solani on potatoes by antagonists. 4. Inoculation of seed tubers with Verticillium biguttatum and other antagonists in field experiments

Inoculation of seed potatoes with the mycoparasiteVerticillium biguttatum, isolate M73 (combined withGliocladium roseum in 1981, either alone or mixed with isolate M180 plus antibiotics-producing isolates ofAzotobacter chroococcum in 1982) repeatedly proved successful in reducingRhizoctonia solani on stolons and stems. In field experiments, this ultimately led to a reduced formation of sclerotia on new tubers, particularly in neutral sandy loam and clay loam soils. In 1981 inoculation with antagonists led, when compared with no inoculation, to average reductions of 22 and 42% for the harvest from clean, and 15 and 26% for the harvest from infected seed tubers grown on slightly acid sandy soils and on neutral loam soils, respectively. The harvest from clean, inoculated seed tubers had the lowest sclerotium index. In 1982 inoculation of seed tubers planted in slightly acid sandy soils gave reductions of the sclerotium index of up to 22%. In the neutral marine loam soils considerable reductions were often achieved, viz., in slightly infected loams 51–68% and in rather heavily infected ones 4–43%. Chemical disinfection of seed tubers proved effective only in loam soils that were slightly infested withR. solani. In both years inoculation of seed tubers with antagonists led to significantly lower sclerotium indices of the harvest (p=0.1% in 1981; p=5% in 1982).