The nitrogen cycle in grassland soils

Walker, T. W.

doi:10.1002/jsfa.2740070113

Cited by 26 publications

(9 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While these data represent a single measurement in time, they are consistent with past studies that have demonstrated that nitrate and ammonium levels in unfertilized grassland soils are almost universally very low (Richardson 1938, Walker 1956, Woodmansee et al 1978). Nitrate-N concentrations were consistently Ͻ1 mg/kg in the soil profile, while NH 4 -N concentration were Ͻ5 mg/kg.…”

Section: Soil Responsesupporting

confidence: 89%

“…Nitrate-N concentrations were consistently Ͻ1 mg/kg in the soil profile, while NH 4 -N concentration were Ͻ5 mg/kg. While these data represent a single measurement in time, they are consistent with past studies that have demonstrated that nitrate and ammonium levels in unfertilized grassland soils are almost universally very low (Richardson 1938, Walker 1956, Woodmansee et al 1978).…”

Section: Soil Responsesupporting

confidence: 89%

See 1 more Smart Citation

Impact of Grazing Management on the Carbon and Nitrogen Balance of a Mixed-Grass Rangeland

Schuman¹,

Reeder²,

Manley³

et al. 1999

Ecological Applications

118

199

View full text Add to dashboard Cite

Rangeland grazing management strategies have been developed in an effort to sustain efficient use of forage resources by livestock. However, the effects of grazing on the redistribution and cycling of carbon (C) and nitrogen (N) within the plant-soil system are not well understood. We examined the plant-soil C and N balances of a mixedgrass rangeland under three livestock stocking rates using an area that had not been grazed by domestic livestock for more than 40 years. We established nongrazed exclosures and pastures subjected to continuous season-long grazing at either a light stocking rate (20 steer-days/ha) or a heavy stocking rate (59 steer-days/ha, ϳ50% utilization of annual production). Twelve years of grazing under these stocking rates did not change the total masses of C and N in the plant-soil (0-60 cm) system but did change the distribution of C and N among the system components, primarily via a significant increase in the masses of C and N in the root zone (0-30 cm) of the soil profile. The mass of soil C (0-60 cm) under heavy grazing was comparable to that of the light grazing treatment. Grazing at the heavy stocking rate resulted in a decrease in peak standing crop (PSC) of aboveground live phytomass, an increase in blue grama (Bouteloua gracilis [H.B.K.] Lag. Ex Steud.), and a decrease in western wheatgrass (Pascopyrum smithii [Rydb.] A. Love) compared to the light grazing treatment. The dominant species under light grazing was western wheatgrass, whereas in the nongrazed exclosures, forbs were dominant and appeared to have increased at the expense of western wheatgrass. The observed increase of soil C and N in the surface soil where roots dominate indicates a greater opportunity for nutrient availability and cycling, and hence enhanced grazing quality.

show abstract

Section: Soil Responsesupporting

confidence: 89%

Section: Soil Responsesupporting

confidence: 89%

Impact of Grazing Management on the Carbon and Nitrogen Balance of a Mixed-Grass Rangeland

Schuman¹,

Reeder²,

Manley³

et al. 1999

Ecological Applications

118

199

View full text Add to dashboard Cite

show abstract

“…Since the 15N content of the grass in the mixture is lower than that of the grass monoculture, it seems likely that the additional source of N is at, or near, natural abundance (0.366at.% and is derived from N fixed by the legume. This could involve direct transfer of N (Eaglesham, 1981;Haystead and Marriott, 1978;Ledgard et al, 1985;Ta and Faris, 1988), or indirect transfer via mineralisation of senescing clover roots and nodules (Haynes, 1986;Henzell, 1972;Walker, 1956). There is also evidence from 15N studies that N is released from the root-nodule system (Ruschel et al, 1979).…”

Section: Discussionmentioning

confidence: 99%

15N estimates of nitrogen fixation by white clover (Trifolium repens L.) growing in a mixture with ryegrass (Lolium perenne L.)

McNeill

Wood

1990

Plant Soil

View full text Add to dashboard Cite

The 15N isotope dilution technique and the N difference method were used to estimate N 2 fixation by clover growing in a mixture with ryegrass, in a field experiment and a controlled environment experiment. Values obtained using N difference were approximately 25% lower than those estimated using 15N isotope dilution. In the field experiment there was a measured N benefit to grass growing with clover, equivalent to 42.7 kgN ha -1. The grass in the mixture had a lower atom %15N content and a higher N content than grass in a monoculture; therefore values for N z fixation were different depending on choice of control plant i.e. monoculture or mixture grass. In the controlled environment experiment there were no significant differences between either the atom %15N contents or the N contents of monoculture grass and grass growing in a mixture with clover. It is concluded that there is a long term indirect transfer of N from clover to associated grass which can lead to errors in estimates of N 2 fixation.

show abstract

“…In studies on the nutrient economy of grasslands, Walker (1955Walker ( , 1956 has pointed out that under New Zealand conditions large accumulations of organic matter and organically bound nutrients are to be expected. It is generally recognised that mineralisation of organically bound nitrogen, phosphorus, and sulphur must take place to render them available to plants.…”

Section: Introductionmentioning

confidence: 99%

Organic matter stability and nutrient availability in Taupo Pumice

Jackman¹

1960

New Zealand Journal of Agricultural Research

View full text Add to dashboard Cite

Soils derived from rhyolitic Taupo pumice when under permanent pasture accumulate organically bound nutrients in the top soil to a high degree. The available nutrient supply is thereby reduced. Respirometry studies show that this accumulation is not due to a reduced microbial activity resulting from a deficiency of a major or minor nutrient element. Raising the pH increases the microbial activity of the soil and the rate of breakdown of the organic matter. These increases are due to a release of carbon into an available form. Available carbon is the limiting factor to microbial activity though the soil may contain 12 % total carbon. The inference is made that the stability of the organic matter in Taupo pumice soils is due to the formation of a stable complex. The possible nature of this complex is discussed. A greenhouse experiment showed that raising the pH releases useful amounts of nitrogen into available form but that a minor-element deficiency can be easily induced. The effect of raising the pH on the mineralisation of organic phosphorus is uncertain. The agronomic significance of these findings is discussed.

show abstract

The nitrogen cycle in grassland soils

Cited by 26 publications

References 22 publications

Impact of Grazing Management on the Carbon and Nitrogen Balance of a Mixed-Grass Rangeland

Impact of Grazing Management on the Carbon and Nitrogen Balance of a Mixed-Grass Rangeland

15N estimates of nitrogen fixation by white clover (Trifolium repens L.) growing in a mixture with ryegrass (Lolium perenne L.)

Organic matter stability and nutrient availability in Taupo Pumice

Contact Info

Product

Resources

About