Browse on keywords: crop rotation soil structure
Search results on 05/20/13
1802. Elliott, L.F., R.I. Papendick, and D.F. Bezdicek. 1987. Cropping practices using legumes with conservation tillage and soil benefits.. IN: J.F. Power (ed.) The role of legumes in conservation tillage systems.
A review article covering examples from around the world as well as specific research from WA. Discusses the role of legumes in maintaining soil productivity, and the constraints on their use. Describes research with several rotations and several legumes in a wheat based system. Wheat yields following red clover were highest of any of the legumes. When any of the legumes was chemically killed, winter wheat yields planted into the residue declined dramatically. T: effect of Medicago on wheat yield; commonly planted legumes and their characteristics; effect of tillage, rotation, and N rate on wheat yield (WA); legume N production and water use (WA); residual soil water under various crops (WA).
1854. Emmond, G.S.. 1971. Effect of rotations, tillage treatment and fertilizers on the aggregation of a clay soil.. Canadian J. Soil Science, 51:235-241.
Soil aggregation was lowest in a wheat-fallow rotation and increased in other fallow-grain rotations with the second, third and forth crops after the fallow year. The best aggregation was under continuous wheat. Rotations containing hay crops increased aggregation significantly. Tillage treatments affected soil aggregation in the following order: green manure crop plowed under> cultivated with trash cover> crop residue plowed under > cultivated with crop residue burned off = crop residue disked in. Fertilizer (11-48-0) increased aggregation except where crop residue had been removed. Barn manure increased soil aggregation. T: Effect of barn manure and crop sequence on soil aggregation. Effect of 5 tillage treatments on soil aggregation.
2211. Goldstein, Walter. 1989. Thoughts on drought-proofing your farm: a biodynamic approach. Working paper No. 2, Michael Fields Agr. Institute.
Describes the influence of soil aggregate size on moisture retention and crop growth. Discusses the benefits of perennial grasses in the rotation to improve soil structure. Discusses management of sweetclover for grazing and green manure. Discusses stubble mulch tillage.
3107. Dormaar, J.F. and C.W. Lindwall. 1989. Chemical differences in dark brown chernozemic Ap horizons under various conservation tillage systems.. Can. J. Soil Sci. 69:481-488.
Soil properties were investigated in two long-term studies: a 19 yr study of till vs. no-till in wheat fallow, and a 9 yr study of till vs. no-till with 3 rotations, including continuous cropping. No-till had the predominant influence on improving various soil physical and microbial properties. There was little difference in continuous cropping versus wheat-fallow, with tillage. The study compared soil from the entire plow depth, and concluded that 19 yr was long enough for the entire Ap horizon to benefit from no-till. No-till in both studies led to 40% of the dry aggregates being >0.84 mm. Dehydrogenase and phosphatase activities were twice as high under no-till as under cultivatiion. No-till also led to the largest monosaccharide accumulation in the soil.
8559. Hammel, J.E.. 1989. Long-term tillage and crop rotation effects on bulk density and soil impedance in northern Idaho.. Soil Sci. Soc. Amer. J. 53:1515-1519.
Bulk density and soil impedance (measured with a penetrometer) were studied on a set of tillage x rotation plots after 10 yr of treatments. Tillage had a significant effect on bulk density, but not on soil impedance. Crop rotation did not significantly influence either property. There were differences with depth. Minimum and no-till soil impedance was greater than conventional till in the surface 5-15 cm. Higher impedance values under reduced tillage, while not preventing root growth, may limit root function when combined with typical cool, wet spring soils, and thus decrease crop growth potential.
10672. Huyck, L.M.. 1989. Effects of slope position, season, and long-term management on aggregate stability in an organically and conventionally farmed Naff silt loam.. M.S. thesis, Dept. Crop & Soil Sciences, Washington State Univ., Pullman, WA 99164-6420.
Aggregate stability was compared on adjacent fields under contrasting long-term management. Samples were taken in October, March, and June and tested for aggregate stability for the 0.5-1.0 mm size fraction. Stability decreased significantly going upslope, and also after freezing and thawing. Each farm had its own pattern of stability. Soil carbon was highly correlated with stability on the organic farm, but not on the conventional farm. While stability was significantly higher on the organic farm under certain instances, this was not always the case and no conclusion can be drawn about which system had better aggregate stability.