Browse on keywords: fertility soil structure
Search results on 06/18/13
690. Bear, F.E.. 1931. Soil management.. J. Wiley, N.Y..
A fairly complete text on soil management - fertility, tillage, organic matter, fertilizers; describes proper plow, moisture content, and depth to improve soil tilth; describes weeds as a potential cover crop; field study in England - free living N fixers input ~44 lb/ac/yr (est.). Azotobacter critical pH = 6.4.
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.
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.
6001. Russell, J.S. and C.H. Williams. 1982. Biogeochemical interactions of carbon, nitrogen, sulfur, and phosphorus in Australian agroecosystems.. IN: J.R. Freney and I.E. Galbally (eds.). Cycling of C,N,S, and P in terrestrial/aquatic ecosystems..
An excellent review article looking at nutrient cycling and gains and losses over time under different agricultural management. Estimates that over 3 million tons C are tied up in soil organic matter additions each year in Australian farmland. SOM levels are higher now than the native condition under systems that have used a legume pasture in the rotation. There was a generally downward trend in the soil C:N over the first 25 yr of OM accumulation. A WWPP rotation slightly increased SOM, while WWWP decreased it slightly, and fallow systems decreased it significantly. Increases in SOM increased the water-stable aggregates in the soil and improved infiltration. Leguminous pastures had an acidifying effect on the underlying soil.
6638. Steel, S.. 1990. Your tiniest livestock.. Farm Journal (mid-January).
Discusses the importance of the microbial population for a number of factors. Available P levels have increased in low input systems years after the last commercial P was added, probably due to microbial action. The microbial biomass from a LISA system had a higher proportion of N than that from a conventional system. Microbes improve soil structure. A marked increase in infiltration was observed after only one application of manure. John Doran found 10-26% more microbes on manured plots than unmanured. Also, there were more microbes in the top few inches of land planted to oats and clover than to corn or soybeans. This is mostly due to carbon levels and C:N ratios.
6813. Thola, J.. 1958. Memo.. USDA - SCS, Pomeroy, WA.
Land taken out of brome grass in rotation soil tested up to 324 lb/ac available N; also shows more moisture with less tillage, better soil structure.