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Search results on 12/13/13
1729. Douglas, C.L., R.R. Allmaras and N.C. Roager. 1984. Silicic acid and oxidizable carbon movement in a Walla Walla silt loam.. Soil Sci. Soc. Amer. J. 48:156-162.
Leachate concentrations and net transfers of silicic acid decreased as long term C additions and soil pH increased; liming reversed this; results in adverse physical properties below the plow layer - decreased hydraulic conductivity, increased cementation.
4058. Mann, F.. 1920. Frank Mann's soil book.. Prairie Farmer, Chicago, 180p..
A detailed description of sustainable soil management on an Illinois farm.
35. Anon.. 1949. Grasses and legumes for soil conservation in the PNW.. .
An excellent treatment of over 60 species - detailed descriptions. T: maps and photos.
261. Allmaras, R.R., K. Ward, C.L. Douglas and L.G. Ekin.. 1982. Long-term cultivation effects on hydraulic properties of a Walla Walla silt loam.. Soil Tillage Research, 2:265-279.
Hydraulic properties were significantly changed by 50 years of wheat-pea and/or wheat-fallow rotations. pH was reduced, dry bulk density was increased, more smaller soil pores were produced at the expense of larger pores, in the upper 30 cm soil hydraulic conductivity was reduced 10-fold increasing water runoff and denitrification.
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.
651. Bakken, L.R., T. Borresen and A. Njos. 1987. Effect of soil compaction by tractor traffic on soil structure, denitrification, and yield of wheat.s. J. of Soil Sci., 38:541-552.
Tractor traffic on wet soil reduced the pore volume, doubled the percentage of large aggregates (>20mm), reduced the wheat yield by about 25%, and increased the N-loss through denitrification by a factor of 3-4. None of these parameters was affected by tractor traffic at low soil moisture content. The weight of the tractor did not significantly alter the effect of compaction on the measured parameters.
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.
1015. Bowren, K.E. (ed.).. 1986. Soil improvement with legumes.. Saskatchewan Agriculture, Soils and Crops Branch.
This excellent publication summarizes research over the past 40 years pertaining to the use of legumes for soil improvement in Saskatchewan. The role of legumes in maintaining soil nitrogen was crucial prior to available fertilizer. But their value extends beyond their nitrogen contribution to the improvement of soil physical properties. One study found the tillage draft requirement to be up to one-third lower where legumes had been a regular part of the rotation. The positive effects of alfalfa were measured for over ten years in a series of wheat crops compared to plots with no alfalfa. Over 17 years, the average grain yield from a wheat-wheat/clover-clover green manure rotation with no fertilizer were 30% higher that a wheat-wheat-fallow rotation with fertilizer. Moisture depletion by legumes is the biggest hurdle to their use in very dry areas. Adequate fertility for the legumes is necessary to maximize their benefit. Use of selected Rhizobium strains can improve nitrogen fixation, especially on acid soils. Several varieties of sweetclover are mentioned with adaptation to forage or green manure use. The booklet has numerous color photos and many data tables and figures.
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.