Soil Science

Kofoed et al, A. Dam

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Jumikis, A. R.

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SINGH, B. B.; TABATABAI, M. A

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Studies of the effects of various soil pretreatments on soil rhodanese activity showed that storage at −20°C or 5°C is a satisfactory method of preserving field-moist samples for assay of rhodanese activity. Air-drying of field-moist soils resulted in a marked decrease (average, 44 percent) of rhodanese activity. Rhodanese activity decreased markedly with depth in five soil profiles studied. This decrease was associated with a decrease in organic C. Preincubation of six soils for 24 h and 48 h with glucose (0.1 percent) resulted in average rhodanese activity increase of 9 and 23 percent, respectively. When the buffer was made to contain 1mMwith respect to inorganic compounds tested, NaNO2, NaN3, Na2SO4, NaF, and NaCl activated rhodanese activity in soils, and NaNO3, Na2SO3, Na2S, KH2PO4, and NaHCO3inhibited it.

Young, A.

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Marshall, C. E.

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WEST, D. W.; BLACK, J. D. F.

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Salinity (NaCl) and soil-oxygen-deficiency stresses were applied to tobacco plants, and water uptake by the plants was measured for 10 days. After 10 days Na+and Cl-concentrations were measured in different plant parts. The plants were irrigated at 8 A.M. or 8 P.M. with or without salinity stress (90 me/l), and were allowed to drain or remain undrained (soil oxygen deficiency).

ALLGOOD, F. P.; GRAY, FENTION

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Two programs, the Soil-Properties Model and the Soil-Classification Model, were used in making productivity indices for Oklahoma soils. The Soil-Properties Model utilized laboratory and published yield data; the Soil-Classification Model utilized diagnostic soil properties of the soil pedon as the independent variables in determining evaluations.

MARTYNIUK, STEFAN ; WAGNER, GEORGE H.

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Soil samples from field plots under long-term management systems were examined using standard plate count procedures. Samples collected at monthly intervals from the different plots showed a mean value for bacteria plus actinomycetes of 7 × 107/g soil. The mean for fungi was 4 × 105/g soil. Microbial populations were low for untreated soils, intermediate for soils treated with chemical fertilizers, and high for soils that received annual applications of manure. Soils cropped to wheat had greater numbers of microorganisms that those cropped to corn. Seasonal fluctuations in microbial numbers are discussed in relation to cultivation practices and to change in soil moisture and temperature. A total of 63 different fungal isolates representing 48 genera were identified; the Penicilliumand Aspergillipredominated. The frequency of occurrence of some of the fungi is discussed in relation to the crop under cultivation, the soil treatment and/or the season of the year.

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