Browse on keywords: moisture soil quality
Search results on 07/22/18
3524. Kardos, L.T.. 1948. Lysimeter studies with cultivated and virgin soils under subhumid rainfall conditions.. Soil Science, 65:367-381.
Pullman, WA study. Lateral flow beneath the soil was significant, enough to cause erosion, but none was noticed. Less silaceous and compact layers in virgin soil. Total N in leachate water tended to be higher from the cultivated plot - cultivated ranged from 1-15 ppm, virgin 2-3 ppm. 2-5 times more total solids in cultivated leachate. Nitrate N higher from cultivated. Nitrate N leaching subsurface from slopes and concentrated in basins. Does not occur on virgin area. Subsurface leaching 20-30 inches below surface. W-P rotation encouraged erosion loss and subsurface nutrient loss. T: leachate chemical analysis.
4807. Nelson, A.L.. 1950. Methods of tillage for winter wheat.. WY Agr. Expt. Sta. Bulletin 300.
Fallow/winter wheat production decreased soil N by 33% in the top 6" over 35 years. Continuous cropping lost 24% of the soil N. Crop rotations using green manure every 4th year did not decrease the loss of soil N. Average winter wheat yields (bu/ac) over 34 years for 3 rotations were: oats/rye(GM)/winter wheat/corn - 12.9; oats/peas(GM)/winter wheat/corn - 12.7; fallow/winter wheat - 13.7; oats/corn/winter wheat/rye - 13.2; oats/corn/winter wheat/peas - 14.1; oats/corn/winter wheat/fallow - 13.2. It was observed that green manure took years to break down. Tillage with an eccentric one-way increased winter wheat yields 2 bu/ac over 10 years compared to plowing. The eccentric one-way conserved moisture. Continuous cropping resulted in winter wheat yields 55% of biennial yields following fallow. Soil moisture was 3-4% lower in October after continuous cropping versus fallow.
5264. Pikul, J.L. Jr., R.R. Allmaras and C.R. Rohde. 1983. Water movement through tillage pans after 52 years of crop residue management.. OR Agr. Expt. Sta. Special Report 680, p.8-13.
The objective of this study was to measure and compare the saturated hydraulic conductivity in and below the tillage pan produced in plots which have received different treatments of crop residue management. Soil hydraulic conductivity was 35% lower on plots which had been fall burned as compared to plots into which strawy manure plus straw was incorporated. These results are consistent with the measured declines in soil organic matter and the development of denser tillage pans. Once a tillage pan is created (no matter how slight) mechanical compaction, water flow, and soil chemical changes (silica migration) may interact to form a nucleus for subsequent accelerated pan formation. T: Bulk density of soil where the straw residue was burned in the fall or straw plus 10,800 kg/ha strawy manure was plowed under in the spring. Saturated hydraulic conductivity and percent organic matter change since 1931.
6311. Skidmore, E.L., W.A. Carstenson and E.E. Banbury. 1975. Soil changes resulting from cropping.. Soil Sci. Soc. Am. Proc. 39:964-967.
T: soil properties X management; infiltration.
6929. Unger, P.W., C.W. Lindwall, D.W. Anderson, and C.A. Campbell. 1989. Mechanized farming systems for sustaining crop production and maintaining soil quality in semiarid regions.. unpublished manuscript, USDA-ARS, Conservation and Production Research Lab, Bushland, TX 79012.
This review paper presents research results primarily from the Northern Plains, Southern Plains, Pacific Northwest, and Australia, addressing issues of soil quality and organic matter, erosion, water storage and utilization, and how these are affected by tillage choices, crop rotations, and other management aspects. Cultivation of semiarid soils generally leads to soil organic matter (SOM) losses of 40-60%, with most loss in the first 20 years. The active fraction of SOM will change faster than the total SOM. The fraction of N that is readily mineralizable decreased more quickly than total N, indicating a reduction in the nutrient-supplying power of the soil over time. Cultivation decreases the proportion of soil aggregates >1 mm. Dry-stable aggregates >0.84 mm are needed to prevent wind erosion. In the Northern Plains, about 60% of the precipitation falls in the May to August growing season. The crop-fallow system here is relatively inefficient at water storage, storing only 20-25% of the precipitation during the fallow period. Crop stubble is crucial to snow trapping and moisture retention. Alternating strips about 5 m. wide of tall and short stubble increased snow depth and density and resulted in 30% more water storage compared to a uniform medium-height stubble. No-till improved yields in many cases by increasing stored moisture, but suitable herbicides are necessary for weed control. Flex cropping in Montana was the most efficient system for using moisture. In the Central Plains, increased evapotranspiration makes ample surface residue very effective. Yields for wheat in a fallow system were more than double those for continuous wheat, making the fallow system more economic. In the Pacific Northwest, major losses result from runoff and from evaporation, due to capillary action in undisturbed surface soils. Water storage efficiencies were 50-75% during the first winter, and 10-50% during the second winter at Pendleton, OR. Surface residues resulted in greater evaporative losses during the summer. To control erosion, innovations such as the slot mulch system, the paraplow, and basin pitters (dammer-diker) have been used. The paper has an excellent list of references on dryland cropping.
7018. USDA Agricultural Research Service. 1974. Summer fallow in the western United States.. Conservation Research Report #17.
This is an excellent summary of the research to date on the impact of summer fallow on dryland cropping. Each chapter covers a separate geographic region, and uses the following categories: introduction, climate, soils, cropping practices, water conservation, erosion, water, soil fertility, crop yields, summary. In general, research points to the feasibility of eliminating summer fallow in certain areas where moisture storage efficiency is extremely low and N needs can now be met with fertilizer. Summer fallow is beneficial in many cases in terms of yield stability and can protect the soil from erosion by guaranteeing a crop and adequate residue cover. The need for a flex cropping system is stressed as a way to maximize water use efficiency. In the great basin area of Utah, summer fallow has a clear yield advantage over continuous cropping. Reduction in tillage operations can help minimize the destructive effects of summer fallow on soil organic matter and structure. This report is clearly written and full of solid information and references.