Sorption of phosphate by aluminium and iron(iii)-hydroxy species on mica surfaces

Freshly cleaved mica sheets with aluminium- or iron(III)-hydroxy species on the cationexchange surface were prepared by suitable treatment with AlCl₃ or FeCl₃. These surfaces were considered as model soilk mineral surfaces and their interaction with phosphate studied using techniques previously developed for the study of single planar surfaces.Adsorption isotherms for both the iron(III) and aluminium systems were very similar and could be interpreted as two Freundlich isotherms indicating two different adsorption processes, one operating below a solution concentration of 10^?5 M and thee other above. Results obtained from the continuous monitoring of adsorption indicate that a rearrangement of adsorbed phosphate occurs with time on both the aluminium- and iron(III)hydroxy surfaces. This rearrangement reduces the rate of desorption and could be a cause of phosphate fixation in soils.     

Laboratory incubation studies of chlorophenoxyacetic acids in chernozemic soils

The relative persistence of 2,4-D, MCPA and 2,4,5-T in some Saskatchewan soils was assessed under laboratory conditions. Under moist conditions, 2,4-D and MCPA showed half-life times of between 14 and 41 days but the MCPA half-life was usually 1 or 2 days longer. 2,4,5-T exhibited a half-life period over twice the length of the other chemicals. The half-life times were directly correlated to microbial plate counts, the larger numbers of soil microorganisms being associated with shorter residence times. Half-lives depended on soil moisture content and the best moisture levels for chemical loss appeared to be just less than field capacity. The use of ¹⁴C in 2,4-D incubation studies showed that the initial cleavage of the 2,4-D molecule was associated with the ether linkage and was not a decarboxylation.     

Electron microscopical studies of chlamydospores of Fusarium solani F. cucurbitae formed in natural soil

Macroconidia of Fusarium solani f. cucurbitae were placed into natural soil, incubated for various times, recovered and examined by light and transmission electron microscopy. Lysis of macroconidia and formation of chlamydospores were studied and the fine structure of these propagules and their associated microflora was investigated. The two most obvious features of chlamydospore morphology were the sloughing of outer wall layers and the accretion of micro-fibrillar elements adjacent to the plasmalemma. Chlamydospore formation was partially suppressed by addition of nitrogenous compounds to the soil.     

The abundance of Trichoderma propagules and the distribution of species in forest soils

Propagules of Trichoderma generally formed less than 3 per cent of the total fungal propagules in a variety of forest soils in the southeastern U.S. and Washington State. The largest populations were found in the F and H organic horizons of the forest floor or under conditions of excessive moisture. T. viride Pers. ex S.F. Gray and T. polysporum (Link ex Pers.) Rifai were largely restricted to cool temperate regions; whereas, T. harzianum Rifai was characteristic of warm climates. T. koningii Oud. and T. hamatum (Bon.) Bain, were the most widely distributed species aggregates and were found in all the climatic regions investigated. Under conditions of excessive moisture, strains of T. hamatum and T. pseudokoningii Rifai were the dominant forms.     

The Adaptation of Boring Attachments on Motor-driven Chain-saws, for the Detection of Decay in Trees, and Other Uses

Standard boring attachments which can be fitted to chain-sawswere used to power increment borers. They were successfullyused to detect decay in trees, stumps, and logs, in a programmeof research in Fomes annosus.