Browse on keywords: soil quality IA
Search results on 12/12/18
7103. Vandecaveye, S.C. and C.D. Moodie. 1942. Occurrence and activity of Azotobacter in semiarid soils in Washington.. Soil Sci. Soc. Am. Proc., 7:229-236.
The Azotobacter population in any of the nonirrigated semiarid soils tested was too small to contribute significantly to nitrogen fixation.
178. Alef, K. and D. Kleiner. 1989. Rapid and sensitive determination of microbial activity in soils and in soil aggregates by dimethylsulfoxide reduction.. Biol. Fert. Soils 8:349-355.
Based on the reduction of dimethylsulfoxide (DMSO) to dimethylsulfide (DMS) by microorganisms, a simple, rapid, sensitive and inexpensive method for the determination of microbial activity in soil samples was developed. When DMSO was added to samples, DMS appeared immediately in the gas phase, which was quantitatively analyzed by gas chromatography. The DMS liberation rate was constant for several hours. The reaction immediately starts and its linearity indicate that neither the physiological state nor the number of organisms were changed by the assay. The method is sufficiently sensitive to allow measurements of activity in very small samples.
404. Anon.. 1989. Algae: companion crop for reduced compaction.. Journal of Sustainable Agriculture (CA) 2:16..
Soil Technologies Corp. of Fairfield, IA is marketing strains of green algae to reduce compaction and improve soil aggregation. The algae produce polysaccharides which help bind soil particles together. The product Microp is applied in the spring or fall, and must be undisturbed by tillage for 3-4 weeks. Polysaccharides will leach down into the soil. Their field results show a 15% reduction in compaction at 8" depth after the first year. The cost is $6/ac.
906. Blake, J.. 1989. Reading the soil.. Seattle Times p. F1, 7/24/89.
Describes in popular style the highlights of the long-term plots at Pendleton, OR. The importance of organic matter is stressed.
978. Bolton, H., L.F. Elliott, R.I. Papendick and D.F. Bezdicek. 1985. Soil microbial biomass and selected soil enzyme activities: effect of fertilization and cropping practices.. Soil Biol. Biochem., 17:297-302.
The microbial properties of two adjacent fields were compared, one being under organic management, the other conventional management. Microbial indices tended to be more favorable on the organic field, with higher microbial biomass and enzyme activities.
1266. Chandra, P., W.B. Bollen, and L.T. Kadry. 1962. Microbial studies of two Iraqi soils representative of an ancient site.. Soil Sci. 94:251-257.
Alluvial soils cultivated for 4-5000 years. No fertilizer, crop residues removed. Low OM, N, and total bacteria and fungi. After 5 days incubation, micorbial levels increased to values similar to more humid, fertile soils. Azotobacter was present. Decomposition of native and added organic matter was relatively slow. Measured soil properties, microbial levels, ammonification, nitrification, denitrification, S oxidation, P mineralization, decomposition of various added organic materials.
1378. Conacher, A. and J. Conacher. 1983. A survey of organic farming in Australia.. Biol. Agr. Hort. 1:241-254.
Describes a survey that sought to determine whether there were any farmers applying organic methods on a commercial basis in Australia, and what their motivations, practices, and success and problems were. Farms were identified, with 24 being grain/sheep operations. Results are similar to U.S. surveys. Farmers felt they had improved soil fertility, reduced erosion, and improved crop and livestock health. The environmental costs of modern agriculture are considerable in Australia. A 1975 estimate places land remediation for cropland and pasture at $675 million for that one year. Annual production losses were estimated in western Australia at $94 million.
2284. Greenland, D.J.. 1971. Changes in the N status and physical condition of soils under pastures.. Soils and fertilizers, 34(3): 237-251.
In the U.S. continuous cropping with inorganic N and herbicide use results in high yields. Would such practices work in Australia or would they result in soil degredation? This paper examines the role of pastures in maintaining soil quality. The study concludes that legume pastures are needed to maintain soil fertility in wheat growing areas. This is due to the high silt/fine sand content of the soil and the relationship between organic matter polysaccharides and soil structure necessary for maintaining soil porosity and water infiltration. T: Effects of a nitrification inhibitor (N-serve) on loss of N from soils during incubation. Mean annual soil N incements in soils under pasture. Changes in N content of soil under continuous fallow-wheat pasture and pasture-wheat rotations.
2578. Peeters, J.F., A.R. Van Rossen, K.A. Heremans and L. Delcambe. 1975. Influence of pesticides on the presence and activity of nitrogenase in Azotobacter vinelandii.. J. Agric. Food Chem., 23(3):404-406.
The influence of various pesticides on the growth of Azotobacter vinelandii was tested under nitrogen fixing conditions. Growth was stimulated in nearly all cases. The presence of nitrogenase in bacterial extracts was greatly reduced. Inhibition experiments showed that organochlorine compounds have no influence on the reduction of acetylene. Derivatives of 2,4-dinitrophenol inhibit in a specific way. A wide range of pesticides were tested.
3210. Bhatti, A.U.. 1990. Spatial variability and geostatistical estimation of soil properties and wheat yield on eroded lands in the Palouse region.. Chpt. 3, PhD. Dissertation, Dept. of Agronomy & Soils, Washington State Univ., Pullman, WA 99164.
Spatial variability of organic matter, soil P, and wheat yields was studied using classical statistical and geostatistical approaches on two commercial wheat farms in the Palouse region of eastern Washington. Geostatistics indicated strong spatial relationship of soil properties and wheat yields with a range of influence of 50-200 m. The two sites differed greatly in spatial patterns due primarily to differences in topography and the extent of erosion and topsoil loss. As a consequence of topsoil loss and reductions in organic matter, it was demonstrated that spatial patterns in yield and soil phosphorus were strongly correlated with organic matter patterns. Remote sensing of soil organic matter and the use of geostatistics offers a way to quickly assess spatial patterns in grain yield and available phosphorus.