Biological nitrogen fixation in mixed legume/grass pastures

Ledgard, S. F.; Steele, K. W.

doi:10.1007/bf00011314

Cited by 387 publications

(187 citation statements)

References 64 publications

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“…The differences were probably caused by high δ 15 N values measured in samples from these legumes in 2002/03, but it is not clear why these high values arose. (Ledgard and Steele 1992;Giller 2001). The persistently poor N 2 -fixation by CBC1 was probably also due to it being a determinate variety.…”

Section: Legume Nitrogen Accumulation and N 2 -Fixationmentioning

confidence: 99%

Productivity and residual benefits of grain legumes to sorghum under semi-arid conditions in southwestern Zimbabwe

et al. 2007

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The productivity and residual benefits of four grain legumes to sorghum (Sorghum bicolor) grown in rotation were measured under semi-arid conditions over three cropping seasons. Two varieties of each of the grain legumes; cowpea (Vigna unguiculata); groundnut (Arachis hypogaea); pigeon pea (Cajanus cajan); Bambara groundnut (Vigna subterranea), and sorghum were grown during the first season. The same experiment was implemented three times in different, but adjacent fields that had similar soil types. At the end of the season the original plots were split in two and residues were either removed or incorporated into the subplots. The following season sorghum was planted in all subplots. In 2002/03 (314 mm rainfall) cowpeas produced the largest dry grain yield (0.98 and 1.36 t ha −1 ) among the legumes. During the wettest year (2003/04, 650 mm rainfall) groundnut had the highest yields (0.76 to 1.02 t ha −1 ). In 2004/05 (301 mm rainfall) most legume yields were less than 0.5 t ha −1 , except for pigeon pea. Estimates of % N from N 2 -fixation from the legumes were 15-50% (2002/03), 16-61% (2003/04) and 29-83% (2004/05). Soil water changes during the legume growth cycle were proportional to varietal differences in total legume biomass. Sorghum grain yield after legumes reached up to 1.62 t ha −1 in 2003/04 compared with 0.42 t ha −1 when following sorghum. In 2004/05, sorghum yields after legumes were also higher (up to 1.26 t ha −1 ) than sorghum after sorghum. Incorporation of crop residues had no significant effect on sorghum yield. Beneficial effect of legumes on yields of the subsequent sorghum crop were more readily explained by improvements in soil nitrogen supply than by the small observed changes in soil water relations. Our results demonstrate clear potential benefits for increasing grain legume cultivation in semi-arid environments through the use of improved germplasm, which also gave substantial increases in subsequent sorghum productivity (up 200% in a wet season and 30-100% in a dry season), compared with an unfertilized sorghum crop following sorghum.

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Section: Legume Nitrogen Accumulation and N 2 -Fixationmentioning

confidence: 99%

Productivity and residual benefits of grain legumes to sorghum under semi-arid conditions in southwestern Zimbabwe

et al. 2007

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“…Variation in vegetation δ 15 N reflects the net effect of different processes in the local nitrogen cycle, including the rate and δ 15 N of nitrogen inputs/sources and losses, and associated fractionation effects inside the system (Högberg 1997). Such effect may result from N fixation (Ledgard and Steele 1992), ammonia volatilization or assimilation (Frank and Evans 1997;Kerley and Jarvis 1996), nitrification/denitrification (Mariotti et al 1981;Stevens and Laughlin 1998), or the plants' nitrate and ammonia uptake (Kahmen et al 2008) among others. Thus, knowledge of the δ 15 N of grassland can reveal important information on biogeochemical cycling of nitrogen in an ecosystem (Robinson 2001).…”

Section: Introductionmentioning

confidence: 99%

15N fractionation between vegetation, soil, faeces and wool is not influenced by stocking rate

et al. 2010

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Understanding stable isotope fractionation in trophic networks is important for the interpretation of stable isotope composition of ecosystem components. This work explores the influence of grazing pressure on the nitrogen isotope composition (δ N of wool (from a yearly shearing) reflects vegetation at the whole-year grazing grounds-scale while faeces reflect that of the area grazed within a few days. Stocking rate had no effect on δ 15

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“…The fixation is also regulated by a feedback mechanism involving the soil inorganic N content and competition from associated grasses (Ledgard & Steele 1992). Field studies report fixation rates from as low as 2 kg N ha 21 yr 21 up to 315 kg N ha 21 yr 21 (Vinther & Jensen 2000;Ledgard 2001;Peoples & Baldock 2001).…”

Section: Legume Nitrogen Fixationmentioning

confidence: 99%

“…Manipulating the mixture of non-legume and legume species within a pasture, for example by using appropriate grazing strategies, can also enhance legume N fixation. Transfer of fixed N within a single season from legume to non-legume via rhizodeposition is recognized around the world as a vitally important component of nutrient cycling in low-input temperate pasture systems (Boller & Nösber-ger 1987;Ledgard & Steele 1992). Controlled environment studies have demonstrated that as much as 15% of total plant N in ryegrass can originate from N exuded from companion white clover (Paynel et al 2001).…”

Section: O P T I M I Z I N G U S E E F F I C I E N C Y O F N I T Ro Gmentioning

confidence: 99%

Nitrogen and sulphur management: challenges for organic sources in temperate agricultural systems

McNeill¹,

Eriksen²,

Bergström³

et al. 2005

Soil Use and Management

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Abstract. A current global trend towards intensification or specialization of agricultural enterprises has been accompanied by increasing public awareness of associated environmental consequences. Air and water pollution from losses of nutrients, such as nitrogen (N) and sulphur (S), are a major concern. Governments have initiated extensive regulatory frameworks, including various land use policies, in an attempt to control or reduce the losses. This paper presents an overview of critical input and loss processes affecting N and S for temperate climates, and provides some background to the discussion in subsequent papers evaluating specific farming systems. Management effects on potential gaseous and leaching losses, the lack of synchrony between supply of nutrients and plant demand, and options for optimizing the efficiency of N and S use are reviewed. Integration of inorganic and organic fertilizer inputs and the equitable re-distribution of nutrients from manure are discussed. The paper concludes by highlighting a need for innovative research that is also targeted to practical approaches for reducing N and S losses, and improving the overall synchrony between supply and demand.

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Biological nitrogen fixation in mixed legume/grass pastures

Abstract: Introduction

Cited by 387 publications

References 64 publications

Productivity and residual benefits of grain legumes to sorghum under semi-arid conditions in southwestern Zimbabwe

Productivity and residual benefits of grain legumes to sorghum under semi-arid conditions in southwestern Zimbabwe

15N fractionation between vegetation, soil, faeces and wool is not influenced by stocking rate

Nitrogen and sulphur management: challenges for organic sources in temperate agricultural systems

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