Browse on keywords: soil quality organic matter
Search results on 05/25/13
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.
1024. Boyle, M., W. Frankenberger, L. Stolzy. 1989. The influence of organic matter on soil aggregation and water infiltration.. J. Production Agric. 2:290-299.
Describes a conceptual model for soil aggregate formation and stability. Soil organic matter contributes to improvement of soil structure in a number of ways. It enhances microbial action which produces more polysaccharides. Aggregation is the product of such forces as mechanical binding by roots and fungal hyphae, temporary adhesive properties by products of microbial synthesis and decay, and persistent cementing action by resistent humus components. Organic materials that decompose quickly (low C:N) had a rapid but ephemeral effect on soil structure. Plant materials that are more resistant to decomposition are slower but more persistent in changing structure. Soil polysaccharides are more complex and diverse than those derived from plants and microbes. Long-term pastures are ideal for aggregation. Good distribution of OM in soil is achieved from the fine roots of grasses, which can translocate as much as 50% of their photosynthate below ground. Green manuring rarely increases aggregate formation, but may inhibit its destruction. Cereals are similar to perennials in increasing % water stable aggregates formed during vegetative growth, but perennials are superior in maintaining the structure after the growing season. A grass-legume mixture is most effective at maintaining soil aggregation, while cereals and root crops are least effective.
1042. Bradfield, R.. 1954. Organic farming with chemical fertilizers.. J. Agric. Food Chem., 2:1216-1220.
An excellent discussion of soil organic matter and the question of fertilizer use. T: Comparative direct residual effects of manure and chemical fertilizers.
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.
1511. Davidson, J.M., G. Fenton and D.I. Pinson. 1967. Changes in organic matter and bulk density with depth under two cropping systems.. Agron. J. 59(4):375-378.
Measurement of BD and OM with depth after 24 years of continuous cotton and lespedeza were significantly different. The maximum compaction that could be given to a Reddish Prairie soil was directly related to its OM. Compaction was extremely sensitive to small changes in OM, caused by different cropping practices. This experiment should be repeated under wheat and alfalfa cropping in the Palouse. T: Average BD at 4 depth following 24 years continuous cotton and continuous lespedeza. Average OM at 4 depths following 24 years cotton vs. lespedeza. BD vs. soil water following a given load application. Maximum BD vs. OM.
1521. Davies, D.B.. 1977. Soil management. 3rd edition.. Farming Press Ltd., Suffolk..
Soil compaction increased chances of root disease (take-all, foot rot); problems of loss of soil structure; leads to reduced fertilizer use efficiency, especially N & P; winter cereals less sensitive to poor structure than spring cereals; 2-3 yr grass/alfalfa stand helps restore structure; benifits of subsoiling on silt soils; best time is when soil is dry.
1625. Dormaar, J.F. and S. Smolaik. 1983. Recovery of vegatative cover and soil organic matter during revegetation.. J. of Range Management 38(6):487-491.
An assessment of vegetation cover and soil transformations on former farmland abandoned in 1925, 1927 and 1950, with adjacent native range. Total C and N, water-stable aggregates between 1 and 5 mm, and polysaccharide contents increased. Chelating resin-extractable C, humic acid/fulric acid ratios, caloric content of the rootmass and dehydrogenase activity decreased in the successional sequence. More than 55 years will be required to allow soil to return to native range standards under moderate grazing. T: Below-ground biomass on native range and revegetated range. Characteristics of the organic matter of Ah horizons of native and revegetated range.
1810. Elliott, E.T.. 1986. Aggregate structure and carbon, nitrogen, and phosphorus in native and cultivated soils.. Soil Sci. Soc. Am. J., vol.50, p. 627.
Native sod soil had the same general structural characteristics as cultivated soil but the macroaggregates were more stable. The macroaggregate-microaggregate conceptual model is applied to help explain accumulation of soil organic matter under native conditions and its loss upon cultivation. Losses of organic C and N correlated with the reduction of soil structure and increases in erodability.
2406. Hanley, Paul (ed.). 1980. Earthcare: Ecological agriculture in Saskatchewan.. Earthcare Information Centre.
A well-written text covering all aspects of biological farming in the prairie region of Saskatchewan. Practices apply to small and large farms. Includes reports from selected farms. References at the end of chapters.
2607. Hilander, S. (ed.). 1989. Proceedings of AERO's soil building cropping systems conference. December 7-9, Lewistown, MT. AERO, 44 N. Last Chance Gulch #9, Helena, MT 59601.
Summarizes the talks given at the conference. Much information is from Canadian researchers in Saskatchewan who are working on low water use legumes as fallow replacements.