The effects of the severe drought of 1976 on the vegetation of some moorland pools in The Netherlands

The effect of the extreme drough of 1976 has been studied to obtain information on the reaction of the vegetation of moorland pools following a fall in the ground water level. The degree of change appeared to be dependent on the nutrient status of water and soil and on the relief. The vegetation of metatrophic and guanotrophic moorland pools showed the most drastic change.     

Weathering and mobility sequence of minor elements on a basaltic pedomorphic surface,Galilee, Israel

A number of minor elements was determined in 21 samples of several soil profiles of a young pedomorphic surface on basalt, Upper Galilee, Israel, ranging from red basaltic Lithosols to lithic Red Mediterranean soils and montmorillonitic Grumusols (Xerorthents, Lithic Xerochrepts, and Chromoxererts).Strontium and to a lesser extent barium are lost during the weathering of the feldspars; Sr continues to be leached out on the slope. Titanium concentrates in the non-clay residue and follows iron during its redistribution on the slope. Manganese is more mobile than iron. Cobalt is partially correlated with manganese, but like Ni, Cr, Cu and V, these elements do not show any definite trend and appear to be rather immobile under the moderate weathering conditions of the Mediterranean environment where montmorillonite is the major clay mineral.     

INVESTIGATIONS ON THE DRYING OF HERBAGE AT TEMPERATURES UP TO 50°C*

Experiments to determine the exposed layer drying rate of cut leaves and stems of a tetraploid (Sabel) and diploid (S23) ryegrass are described. Drying was achieved by passing air through the crop; the changes in weight were monitored continuously. Airflow was fixed throughout the experiments at 37·5 ft/min (0·190 m/s) and the temperatures were controlled in the range 25°C to 50°C. Comparisons were also made of the drying rates at different stages of maturity. Drying curves were determined and moisture content was shown to decay exponentially with time, the relationship approximating closely to a two term exponential.     

THE EFFECT OF PESTICIDES ON THE YIELD AND BOTANICAL COMPOSITION OF A NEWLY-SOWN RYEGRASS LEY AND OF AN OLD MIXED PASTURE

Newly-sown S24 perennial ryegrass at Hurley and old established ryegrass-dominant mixed pasture at Rothamsted were treated with several pesticides, singly and in combination, over the period 1969–73. Yields were either unaffected or increased by up to 30% in any one year, depending on the treatment, the newly-sown sward giving the more consistent response from year to year.     

The chemistry of humic and fulvic acids extracted from argentine soils—I. Analytical characteristics

Five humic and three fulvic acids were extracted from Argentine Chestnut, Brunizem, Solod and Solonetz soils and analysed by electrometric, spectroscopic and spectrometric methods. There were great similarities in elementary analysis, functional group content, absorption characteristics in the visible region and in the IR, and in the ESR measurements between the humic acids and, similarly, between the fulvic acids. There were distinct differences between the humic and fulvic acids in C, H, N and O content, distribution of oxygen in functional groups, E₄/E₆ ratios and free radical content.     

STUDIES OF RESPONSE TO FERTILIZER NITROGEN

The effects of 59, 118 or 177 kg N/ha were measured on 7 occasions from 8 to 57 days after application to a perennial ryegrass sward in terms of changes in composition. The first increase Dt of N significantly raised percentages of CP, non-protein N, K, P, Ca, Na and Mg and significantly depressed percentages of DM, OM and OM digestihility. The second increment of N resulted in a further rise in the percentages of CP, true protein, non-protein N, K, P, Ca, Na and Mg; the percentages of DM and OM were further depressed but OM digestihility was not significantly depressed. Percentages of P and Na showed increased responses for the more mature herbage; while percentage non-protein N showed a more marked response in younger herbage. As herbage matured percentages of OM and Na rose, the latter only from days 16 to 45. All other attributes showed falling percentages to levels which could be inadequate for a 500 kg dairy cow yielding 15 kg milk. CP percentage reached this critical level (1.4% N) at days 37, 45 or 56 given 59, 118 or 177 kg N/ha; P percentage became critically low (< 0.36%) at days 27, 35 or 38, respectively; Mg percentage fell to the critical level (0.12%) at days 23, 35 and 46. Na percentage showed the reverse trend, being deficient (< 0.13%) in the earliest samples and becoming satisfactory from days 23 or 27 at 118 and 177 kg N/ha but it remained inadequate at 59 kg N/ba.