Browse on keywords: soil quality nitrogen
Search results on 12/07/13
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.
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.
1987. Fireman, M.. 1945. Effect of sodium nitrate and ammonium fertilizers on the permeability of western soils.. .
Experiments on 51 western soils. Sodium nitrate reduced permeability 41-86%. Ammonium nitrate and ammonium sulfate also decreased permeability, but to a lesser extent. T; Permeability tests; variations in permeability.
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.
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.
2683. Holtz, H.F. and S.C. Vandecaveye. 1938. Organic residues and nitrogen fertilizers in relation to the productivity and humus content of a Palouse silt loam.. Soil Sci 45: 143-163.
T: soil carbon, soil nitrogen
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.
5715. Rasmussen, P.E., R.R. Allmaras, C.R. Rohde and N.C. Roager, Jr.. 1980. Crop residue influences on soil carbon and nitrogen in a wheat-fallow system.. Soil Sci. Soc. Am. J. 44(3):596-600.
Seven crop residue treatments were initiated in 1931 to measure long-term residue managements effects on soil organic matter in a wheat-fallow cropping system on Pacific Northwest semiarid soils. Organic carbon and total N were measured at approximately 11-yr intervals over a 45-yr period to determine residue effects on the rate of change in soil OM content. Only the addition of 22.4 metric tons of manure/ha to straw residue before incorporating prevented a decline in soil N and C. The addition of 45 or 90 kg fertilizer N or of 22.4 metric tons of pea vines/ha to straw residue before incorporation reduced N and C loss when compared to straw only incorporation. Burning of straw in the fall following wheat harvest accelerated the loss of N, but not C. Burning of straw in the spring just prior to tillage had no effect on N or C loss.
5744. Rasmussen, P.E., R.E. Ramig, R.R. Allmaras and C.M. Smith.. 1975. Nitrogen - sulfur relations in soft white winter wheat. II. Initial and residual effects of sulfur application on nutrient uptake and N/S ratio.. Agronomy J. 67(2):224-228.
This study determined S and N uptake and distribution in soft white winter wheat fertilized with S in combination with deficient, optimum, and excessive N. Residual uptake from 17, 34, and 68 kg of applied S/ha was evaluated in 3 subsequent wheat crops receiving optimum N fertilization. S uptake and concentration in the first crop was proportional to the rate applied, but accumulated primarily in vegetative tissue when present in excess of the amount required for grain protein. Uptake from residual S was lower than from applied S. Grain yield responses to S were poorly correlated with S concentration or N/S ratios in tissue, because of inconsistancy of S accumulation in plant parts and the dominant effect of N on yield. T: Effect of N and S fertilization on S concentration and uptake at 3 stages of growth in a first wheat crop. Effect of residual S on grain yield and S concentration in grain and straw of second, third, and fourth crops. Relationship between S concentration in mature whole plants and grain yield receiving optimum N fertilization.
6248. Sievers, F.J. and H.F. Holtz. 1922. The silt loam soils of eastern Washington and their management.. WA Agr. Expt. Sta. Bull. #166.
A broad treatment of agronomy and soil management during 39 years of cropping 22% N and 35% OM has been lost. T: Comparison of nitrogen content of virgin soil and soil cropped 30 years. Organic carbon in virgin soil and soil cropped 30 years. Straw vs. nitrate development in Palouse silt-loam. High N residue as supplement to straw in nitrate development. Effects of manure on N and C in Palouse silt loam, 18 years of results. Effect of legumes on N and C.