Legume production and nitrogen fixation in hill pasture communities

Ledgard, Stewart; Brier, G. J.; Littler, R. A.

doi:10.1080/00288233.1987.10417951

Cited by 46 publications

(41 citation statements)

References 14 publications

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“…These values are lower than those measured by Gillingham (1978), but are consistent with observations of Ledgard et al (1987). The pattern of excretal deposition in the base scenario was based on the work of Gillingham (1978) with 67%, 27% and 4% of all excreta deposited on flat, easy and steep areas, respectively.…”

Section: Cj Hoogendoorn Et Alcontrasting

confidence: 39%

“…At the dry summer dry hill country site, Blennerhassett (2002) reported higher clover contents on easy sites than on steep sites that commonly had little or no clover in the sward. By contrast, Ledgard et al (1987) reported that at the summer moist site, which had higher annual rainfall, there was little difference between slope categories in total legume production but that there were marked seasonal and species difference between slope categories. Measurements of N fixation in hill country pastures have ranged from 13Á 85 kg N ha…”

Section: Introductionmentioning

confidence: 79%

“…The NHA data, herbage N concentrations and legume contents assigned to the 'summer moist' paddock (Table 1) in the base scenario are based on data presented by Ledgard et al (1987) for a hill country site at Whatwhata in the Waikato. The corresponding data for the 'summer dry' paddock are taken from Blennerhassett (2002) for a hill country site near Waipawa in Central Hawke's Bay.…”

Section: System Boundaries Definitions and Scenariosmentioning

confidence: 99%

“…Nitrogen fixation by legumes is proportional to clover dry matter (DM) accumulation. In hill country, the proportionality constants vary between campsites and sloping sites with Ledgard et al (1987) suggesting values of 0.040 kg N fixed per kilogramme of clover DM grown on sloping sites and 0.030 kg N fixed per kilogramme of clover DM grown on campsites. The lower proportionality constant values in campsites were associated with high soil inorganic N levels resulting from the transfer of dung and urine by grazing sheep to these sites.…”

Section: Introductionmentioning

confidence: 99%

“…Although symbiotic N fixation through clover is the main method of supplying N to the grass sward of New Zealand pastures, hill country pastures usually have low clover contents (Ledgard et al 1987;Roach et al 1996;Gillingham et al 2003) and these result in low N inputs through fixation. At the dry summer dry hill country site, Blennerhassett (2002) reported higher clover contents on easy sites than on steep sites that commonly had little or no clover in the sward.…”

Section: Introductionmentioning

confidence: 99%

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Simple models of carbon and nitrogen cycling in New Zealand hill country pastures: exploring impacts of intensification on soil C and N pools

Hoogendoorn

Bowatte

Tillman

2011

New Zealand Journal of Agricultural Research

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Concerns about climate change and water quality make it necessary to have a better understanding of the cycling of carbon (C) and nitrogen (N) within landscapes. In New Zealand, pastoral farming on hill country is a major land use, and there is little information available at a landscape level on the cycling of C and N within these systems, particularly the impacts of land use intensification. Published information on the individual components of C and N cycles in hill country pastoral systems was used to construct simple C and N models for two notional hill country paddocks with contrasting amounts of annual net herbage accumulation (NHA). These simple models of C and N cycling were used to explore the potential impacts of intensification on soil C and N pools. The C and N models constructed illustrate that both the C and N cycles in hill country pastoral farming are characterised by large fluxes in and out of the system and relatively small annual accumulations or depletions of their respective soil pools. The mechanisms by which these inward and outward fluxes are generated differ greatly between C and N. Most of the C cycling through the soil/plant/animal system in a year is sourced from the atmosphere through photosynthesis in that same year and the annual quantity of C ingested by grazing animals is only approximately 25% of that fixed annually. In contrast, the annual quantity of N ingested by grazing animals is 300Á400% of that added to the system annually by fixation, and most of this ingested N (!80%) is returned to the soil in animal excreta. This contrasts with B25% of ingested C returned in animal excreta. Grazing animals, with their propensity to exhibit camping behaviour, are therefore much more influential in the spatial redistribution of N than C in hill country pastures. The simple C and N models presented in this paper indicate that while land use intensification results in increased inputs of both C and N to the soil, intensification is also likely to result in increased losses of C and N from the soil pool. Which of these processes dominates in a given situation determines whether intensification will result in an increase or decrease of soil C and N. Based on a simple C model, we postulate that if intensification increases NHA by one unit there is likely to be an increase in soil C unless at the same time increased grazing pressure results in at least a three-unit increase in dry matter eaten/harvested. Keywords: carbon; nitrogen; hill country; grazing; intensification Introduction Two environmental issues of major concern are increasing concentrations of greenhouse gases in the atmosphere and increased concentrations of nitrogen (N) in receiving waters. These are affected by global carbon (C) and N cycles, and soil C and N are major components of these cycles. Hill country farmers are intensifying *Corresponding author. Email: coby.hoogendoorn@agresearch.co.nz Hill country pastoral landscapes occupy a large area of New Zealand, but compared with flat land, relatively little is known of nut...

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Section: Cj Hoogendoorn Et Alcontrasting

confidence: 39%

Section: Introductionmentioning

confidence: 79%

Section: System Boundaries Definitions and Scenariosmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Simple models of carbon and nitrogen cycling in New Zealand hill country pastures: exploring impacts of intensification on soil C and N pools

Hoogendoorn

Bowatte

Tillman

2011

New Zealand Journal of Agricultural Research

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Effects of nitrogen: phosphorus supply ratios on nitrogen fixation in agricultural and pastoral ecosystems

Smith

1992

Biogeochemistry

114

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Abstract. An analysis of data compiled from the literature confirms a strong inverse relationship between annual rates of nitrogen fixation and the soil nitrogen content in agricultural and pastoral ecosystems. However, this inverse relationship is strongly modified by the rate of application of phosphorus fertilizer, which strongly influences the activities of both symbiotic and non-symbiotic nitrogen fixing organisms. In the case of symbiotic legumes, the response of N-fixation to N and P is in part a result of changes in legume dominance within the plant community. These results, as well as supporting data presented from a review of experiments on nitrogen fixation in a variety of other terrestrial and aquatic ecosystems, provide important support for the hypothesis that phosphorus availability is a key regulator of nitrogen biogeochemistry.

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Transfer of fixed nitrogen from white clover to associated grasses in swards grazed by dairy cows, estimated using 15N methods

Ledgard

1991

Plant Soil

Self Cite

121

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Pasture swards containing perennial ryegrass (Lolium perenne L.) alone or with one of five different white clover (Trifolium repens L.) cultivars were examined for production and transfer of fixed nitrogen (N) to grass under dairy cow grazing. Grass-only swards produced 21% less than mixed clover-grass swards during the second year after sowing. Production from grass-only plots under a mowing and clipping removal regime was 44% less than from grass-only plots under grazing. Much of this difference could be attributed to N transfer. In swards without clover, the ryegrass component also decreased in favour of other grasses.The average amount of fixed N in herbage from all clover cultivars was 269 kg N ha -1 yr -1. Above-ground transfer of fixed N to grasses (via cow excreta) was estimated at 60 kg N ha -1 yr -1. Below-ground transfer of fixed N to grasses was estimated at 70 kg N ha -~ yr -1 by ~SN dilution and was similar for all clover cultivars. Thus, about 50% of grass N was met by transfer of fixed N from white clover during the measurement year. Short-term measurements using a 15N foliar-labelling method indicated that below-ground N transfer was largest during dry summer conditions.

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Legume production and nitrogen fixation in hill pasture communities

Cited by 46 publications

References 14 publications

Simple models of carbon and nitrogen cycling in New Zealand hill country pastures: exploring impacts of intensification on soil C and N pools

Simple models of carbon and nitrogen cycling in New Zealand hill country pastures: exploring impacts of intensification on soil C and N pools

Effects of nitrogen: phosphorus supply ratios on nitrogen fixation in agricultural and pastoral ecosystems

Transfer of fixed nitrogen from white clover to associated grasses in swards grazed by dairy cows, estimated using 15N methods

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