V. Unimproved North Island hill country, “Ballantrae”

Grant, D. A.; Lambert, M. G.

doi:10.1080/03015521.1979.10426155

Cited by 26 publications

(9 citation statements)

References 7 publications

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“…The simple regression models for these relationships are (A) LPROD = 1.78 P + 718, r2 = 0.55, p < 0.001; and (B) %LPROD = 0.00012 P + 0.095, r* = 0.35, p = 0.033. changes in the N:P supply ratios also should have significant effects on measured rates of legume N-fixation (NFIX, kg N ha-' yr-'). This hypothesis was tested directly using measurements of nitrogen fixation and soil chemistry pooled from experimental studies of New Zealand pastures (Sears et al 1965;Ledgard et al 1987;Hogland and Brock 1978;Grant and Lambert 1979;Hoglund et al 1979;Crush et al 1982Crush et al , 1983. Prior to multiple regression analysis (Wilkinson 1998) the nitrogen fixation and soil nitrogen data were transformed to their common logarithms.…”

Section: Effects Of N:p Ratios On Rates Of Symbiotic N-fixationmentioning

confidence: 99%

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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Section: Effects Of N:p Ratios On Rates Of Symbiotic N-fixationmentioning

confidence: 99%

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

Smith

1992

Biogeochemistry

114

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“…It produces 70% of its annual herbage accumulation in the spring (Lambert et al unpublished data), is adapted to low P availability and summer drought conditions (Brock 1973), and can fix substantial amounts of N in hill pastures (Grant & Lambert 1979).…”

Section: Suckling Cjovermentioning

confidence: 99%

Influence of fertiliser and grazing management on North Island moist hill country 3. Performance of introduced and resident legumes

Lambert¹,

Clark²,

Grant³

et al. 1986

New Zealand Journal of Agricultural Research

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A grazing trial was conducted on 99 ha of steep, low fertility hilI country in southem Hawke's Bay, during 1975-81. There were 2 fertiliser treatments: low (LF) and high (HF) superphosphate application (plus lime on HF), and 3 grazing managements -rotational grazing by sheep (RGS) or cattle (RGC), and set stocking by sheep (SSS). A white clover (Trifolium repens L.) similar to Kent wild white, and annual suckling clover (T. dubium Sibth.) were already present in the pastures in small amounts. 'Grasslands Huia' white clover, 'Grasslands Turoa' red clover (T. pratense L.), 'Grasslands Maku' lotus (Lotus pedunculatus Cav.), and Woogenellup subterranean clover (T. subterraneum L.) were oversown into the pasture in 1974. Huia, Turoa, and Grasslands 4703 lotus were oversown again in 1977. Woogenellup subterranean clover was found to be unsuited to the environment. Lotus plants established, but contributed little to total herbage accumulation. Red clover was most important in RGC pastures. Its contribution was short-lived in sheep-grazed pastures, but was significant in the year after oversowing where fertiliser application history was short. Suckling clover produced a significant amount of herbage on steep NW sites during spring. Huia white clover was the most productive of the oversown legumes. However, the resident white clover was more productive than Huia in sheep-grazed pastures but not in RGC pastures. Huia was more responsive to HF (compared with LF) application in RGC than in sheep-grazed pastures -the converse applied for the resident genotype.

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“…Non symbiotic N fixation. Grant & Lambert (1979) suggested that in a poorly developed hill country pasture, N fixation by nonsymbiotic organisms and atmospheric deposition can be, together, as important as clover N fixation. They estimated that approximately 21 kg N ha…”

Section: Introductionmentioning

confidence: 99%

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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V. Unimproved North Island hill country, “Ballantrae”

Cited by 26 publications

References 7 publications

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

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

Influence of fertiliser and grazing management on North Island moist hill country 3. Performance of introduced and resident legumes

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

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