Effect Of Acid Irrigation Research Articles

The effect of acid irrigation on enzyme activities of the single partners of ectomycorrhizas from a limed stand of Norway spruce (Picea abies [L.] Karst.)

The aim of our investigations was to elucidate the effects of acid precipitation on some enzymes of the primary metabolism of ectomycorrhizas. Mycorrhizas of the type of Piceirhiza nigra Gronbach and of Russula ochroleuca (Pers.) Fr. and Tuber puberulum Berk. and Br. were collected from a stand of Norway spruce (Picea abies [L.] Karst.) during the growing seasons of 1991 and 1992. The experimental plots had been limed (Ca: 22 kmol ha-1, Mg: 20 kmol ha-1) in 1984 and exposed to acid irrigation (pH 2.7–2.8, H2SO4: 2 kmol ha-1 a-1) from 1984 to 1990. Crude extracts of mycorrhizas were assayed for the activities of glucose-6-phosphate dehydrogenase (G6P-DH, EC 1.1.1.49), 6-phosphogluconate dehydrogenase (EC 1.1.1.44), NADP-dependent isocitrate dehydrogenase (EC 1.1.1.42) and NAD-dependent glutamate dehydrogenase (EC 1.4.1.2). The influence of the experimental treatments on these enzyme activities of the primary metabolism was generally low. For P. nigra, the activity of G6P-DH was decreased on the irrigated plot (photometric determinations). This seems to be a selective effect on the fungal partner, since quantitative enzyme electrophoresis revealed a decrease in the percentage of the fungal enzyme activity in relation to the total enzyme activity, whereas the content of the fungal compound ergosterol was not affected. A decrease in the fungal G6P-DH activity could also be detected in mycorrhizas of Tuber puberulum. There was also a seasonal variation in the proportion of fungal activity of G6P-DH in relation to the total G6P-DH activity. In the photometric assay (total activity) the effect was not discernible. This is indicative of a degree of regulation between the two partners, which could only be detected by quantitative enzyme electrophoresis. In addition, it could be deduced from the electrophoretograms, that in the case of G6P-DH and 6PG-DH the fungal enzyme activity was dominating in all mycorrhizas studied whereas in the case of ICA-DH the fungal band varied from being conspicuous to absent in different species of mycorrhizas. The banding pattern of G6P-DH was reproducibly different for all investigated species of mycorrhizas.

Effect of acid irrigation and liming on root growth of Norway spruce

The effect of acid irrigation and liming on fine root growth of Norway spruce (Picea abies [L.] Karst.) was studied in an approximately 80-year-old forest stand in southern Germany (Hoglwald). Root growth was measured mainly on root windows and in addition by soil core sampling. Root growth rate showed a typical pattern in the course of a year with a maximum in August. Acid irrigation depressed root growth rate, whereas liming, particularly in combination with acid irrigation, markedly increased root growth in the humic layer and the upper 0–5 cm of the mineral soil. The treatment effects on root growth in the mineral soil below 5 cm were small and not significant. Root growth rate was not correlated with the concentration of aluminium (Al) or the molar ratio of calcium (Ca) to Al in the soil solution. The results suggest that inhibition of root growth by acid irrigation is a direct effect of high proton concentrations in the irrigation water, and that enhancement of root growth by liming is caused by an improved supply of mineral nutrients and higher biological activity.

Cation concentrations of short roots of Norway spruce as affected by acid irrigation and liming

The longterm effect of acid irrigation and liming (dolomitic limestone) on the mineral element content of roots of Norway spruce (Picea abies [L.] Karst.) was investigated in an 80-year-old Norway spruce stand in South Germany (Bavaria). Soil cores of four soil depths (humic layer, 0–10, 10–20 and 20–30 cm) were taken over 2 years (August 1991 and August 1992) from six plots with different treatments (control, normal irrigation, acid irrigation solely or in combination with liming) and living short roots selected and analysed for calcium (Ca), magnesium (Mg), manganese (Mn) and aluminium (Al).

A long-term field study on the effect of acid irrigation and compensatory liming on the transport of Chernobyl-derived radiocesium in a forest soil

The effect of acid irrigation with and without liming on the vertical transport of Chernobyl-derived 134Cs in the soil was investigated in a Norway spruce stand by field experiments. For this purpose seven plots with different treatments were established. After 5 years of observation to detect differences in the residence half-time's of 134Cs in the various soil horizons with respect to the control sites, the plots were sampled at 18 individual pits. No effect on the residence half-time of 134Cs was observed for ‘normal’ irrigation (pH 5.3) as compared to the control in all organic horizons. Following acid irrigation (pH 2.7), the transport of 134Cs was slightly enhanced as compared to ‘normal’ irrigation. The most significant effect was found for the limed plots: the transport of 134Cs was strongly retarded in the organic layer, as well in irrigated as in non-irrigated plots. These effects are discussed with respect to the different physico-chemical and biological conditions in the various plots and the consequences for the external gamma dose rate in air due to radiocesium in the soil.

Effects of acid irrigation and liming on the migration of radiocesium in a forest soil as observed by field measurements

The effect of normal irrigation, acid irrigation, and liming on the vertical migration of radiocesium from Chernobyl and global fallout was investigated by determining the activity of 134Cs and 137Cs in the upper horizons (LOfl, Of2, Oh, Aeh, Alh, Al) of six experimental plots of a forest soil (spruce stand) as a function of time. For the Of2 and Oh horizons (but not for the LOfl horizon) of the control plots during our period of observation (600 days from 30 April 1986), we found a significant increase in the mean residence half-time (τ) of Chernobyl-derived cesium from ∼ 70 to 500 days, indicating that Cs is sorbed more strongly with time. The different types of soil management showed an effect only in the Of2 horizon. Irrigation, especially when acid, prevents the increase of τ with time. Liming reduces the rate of migration of Cs significantly, even if the plots are irrigated with normal or acid water. Cesium-137 from global fallout was present mainly in the Oh and Aeh horizons, but was less mobile than Chernobyl-derived Cs by one order of magnitude.

Effects of acid irrigation and liming on two clones of Norway spruce

The effect of acid irrigation on the growth of rooted cuttings ofPicea abies (L.) Karst, was investigated in a pot experiment lasting 3 years. It involved two clones of Norway spruce, H 253 Bogstad I and H 254 Bogstad II. Irrigation water of pH 5.4, 4.0, 3.0 and 2.5 was used. Liming was included in the experiment.