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Articles 1891 - 1920 of 16382

Full-Text Articles in Agronomy and Crop Sciences

Study Of Forage Plants' Initial Growth Using The Quantitative Development Analysis, V. De B.G Alcantara, A.R P. De Almeida Apr 2025

Study Of Forage Plants' Initial Growth Using The Quantitative Development Analysis, V. De B.G Alcantara, A.R P. De Almeida

IGC Proceedings (1977-2023)

The initial development analysis is destinated to the evalu­ation of net production in plants, derivated from the photosyntetic process and the perform results of the assimilat­ive system during certain time period (Watson, 1952). The factors that guide plant production, in general, may be classificated in three classes : genetic, ecological and physiologi­cal factors. The physiological factors are : leaf area index (LAI), net assimilation rate (EA) and relative growth rate (Rw) (Alvim, 1962). Some authors think that little genetic difference exist in relation to EA and that there is a little probability of increasing the production capacity of species through …

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The Development Of Medicago Polymorha L. As An Important Pasture Species For Southern Australia, M A. Ewing, J G. Howieson Apr 2025

The Development Of Medicago Polymorha L. As An Important Pasture Species For Southern Australia, M A. Ewing, J G. Howieson

IGC Proceedings (1977-2023)

Despite the importance of annual pasture legumes to the farming systems of southern Australia and efforts to select appropriate species and varieties (Cocks et al., 1980), well adapted pasture legumes have not been identified for all situa­tions. A particular need exists for species and varieties suited to light surface textured, acid soils in areas receiving between 250 -400 mm of rainfall annually. Soils of this general description are widespread in Western Austrafo, .. Subterranean clover performs well on similar soils where they occur in higher rainfall zones but often fails to persist in arid areas, especially where frequent cereal cropping …

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Negative Correlations Between Resource Allocation To Survival And Reproduction: Comparisons Between Annual And Perennial Species Of Medicago For Juvenile Vigor, I Olivieri, A Bory, F Angevain, M Angevian, J M. Prosperi, P Mansat Apr 2025

Negative Correlations Between Resource Allocation To Survival And Reproduction: Comparisons Between Annual And Perennial Species Of Medicago For Juvenile Vigor, I Olivieri, A Bory, F Angevain, M Angevian, J M. Prosperi, P Mansat

IGC Proceedings (1977-2023)

At any given age, a plant must allocate limited resources to growth, survival (e.g., disease resistance, root storage) and reproduction (through male and female functions). Growth may be viewed as a way of acquiring more resources (necessary for survival or reproduction at a later time). Response to selec­tion, whether natural or artificial, may well depend on the shape of the compensation curves that exist between those functions (Olivieri, 1987). Such a principle of resource allo­cation predicts the existence of negative correlations between these components of the life-cycle (see for instance Roach, 1986). As shown by Van Noordwijk and De Jong …

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Contribution A L’Etude Des Especies Spontanees Du Genre Scorpiurus L. En Algerie Ii. Durete Et Germination Des Graines Chez 29 Populations De S. Muricatus Subsp. Sulcatus (L.) Thell, M M'Hammedi-Bouzina, A Abdelguerfi, R Berrekia Apr 2025

Contribution A L’Etude Des Especies Spontanees Du Genre Scorpiurus L. En Algerie Ii. Durete Et Germination Des Graines Chez 29 Populations De S. Muricatus Subsp. Sulcatus (L.) Thell, M M'Hammedi-Bouzina, A Abdelguerfi, R Berrekia

IGC Proceedings (1977-2023)

Les especes du genre Scorpiurus L., tres recherchees par le cheptel, peuvent jouer un role important dans !'amelioration des parcours et de la production des jacheres. Outre leur inten��t fourrager, elles concourent au maintien de la fertilite des sols grace a leurs caracteristiques agronomiques (fixation d'azote, systeme racinaire puissant, port etale ... ). Mais !'utilisation de ces especes spontanees de legumineuses reste conditionnee par !'estimation de la proportion de graines dures et Jes moyens a mettre en ceuvre pour surmonter cet obstacle a la germination. Ainsi, et suite aux travaux de Bensalem et al. (1988) sur le genre Scorpiurus et …

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Grass Adaptation In Cuba. I. Characterization Of The Areas Dedicated To Livestock Production, J J. Paretas Apr 2025

Grass Adaptation In Cuba. I. Characterization Of The Areas Dedicated To Livestock Production, J J. Paretas

IGC Proceedings (1977-2023)

The present study is aimed to point out various aspects allowing to locate and learn the soil, climate, social and econ­omic conditions as well as the production characteristics of pastures and forages and their utilization for milk and beef pro­duction under Cuban conditions.

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Perennial Legumes And Grass-Legume Associations Adapted To Poorly Drained Savannas In Tropical South America, B Grof, D Thomas, R P. De Andrade, J.L F. Zoby, M A. De Souza Apr 2025

Perennial Legumes And Grass-Legume Associations Adapted To Poorly Drained Savannas In Tropical South America, B Grof, D Thomas, R P. De Andrade, J.L F. Zoby, M A. De Souza

IGC Proceedings (1977-2023)

Seasonally flooded areas and swamp grasslands constitute a significant percentage ot the savannas and represent an import­ant source of supplementary forage during the dry season. Approximately 21 % (170 million ha) of the central lowlands of tropical South America is poorly drained ; 82 % of these lands (139 million ha) is covered with forest and the remaining 31 million ha by native savannas (Cochrane et al.,1985). The poorly drained savanna lands have been used success­fully since colonial times for extensive cattle production. Sig­nificant areas are found in the Brazilian Pantanal, in Brazil's southwest Amazonia, the Casanare plains of northeast …

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The Effect Of Nitrogen And Clover Proportions On Yield Of Red Clover-Grass Mixtures, B E. Frankow-Lindberg Apr 2025

The Effect Of Nitrogen And Clover Proportions On Yield Of Red Clover-Grass Mixtures, B E. Frankow-Lindberg

IGC Proceedings (1977-2023)

Red clover is the most important forage legume in Swedish ley farming (c. 500 tonnes of seed certified in 1986/87). It is tra­ditionnally sown with a mixture of grasses, typically timothy and meadow fescue. Recommendations for maximum DM yields, obtained from extensive series of experiments, given no fertilizer nitrogen (Bengtsson, 1964; Arnemo and Steen, 1972) are 4-6 kg/ha red clover seeds ( of a diploid cul ti var) in a mixture of totally 20-24 kg/ha seeds sown. Red clover content in the established sward declines with time from c. 60 % in the first­year crop to c. 25 % in …

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Some Changes In Biological Soil Characteristics Of Grassland Ecosystem Under Different Management Intensity, L Ondrasek Apr 2025

Some Changes In Biological Soil Characteristics Of Grassland Ecosystem Under Different Management Intensity, L Ondrasek

IGC Proceedings (1977-2023)

The papers which are in our country engaged in problems of soil biological processes under treated seminatural grassland are orientated mainly on the determination of quantitative and qualitative extents of changes originated especially under infl­uence of application of increasing level of nitrogen fertilizers in relation to possible negative phenomenons in environments (Kopcanova et al., 1985, Tesafova and Gordienko, 1988). Our paper deals also with those problems. Its aim is to give a short information about some important changes in biologi­cal soil properties under long time differently managed grass­land.

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Dairying In New Zealand, A M. Bryant Apr 2025

Dairying In New Zealand, A M. Bryant

IGC Proceedings (1977-2023)

Many of you are visitors to this country. This afternoon you saw something of an industry quite different from yours back home. The objective of my talk is to help you identify what these differences are and why they exist. By the end of the day you should have a picture of how one industry • the dairy industry • has integrated a whole range of systems into a successful whole.

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Regrowth Sites Of Sulla (Hedysarum Coronarium L.) After Defoliation, H Krishna, P D. Kemp Apr 2025

Regrowth Sites Of Sulla (Hedysarum Coronarium L.) After Defoliation, H Krishna, P D. Kemp

IGC Proceedings (1977-2023)

Sulla is a semi-perennial herbaceous forage legume which has rarely been used for grazing. Field studies were undertaken to determine the relative importance of regrowth sites on sulla so that guidelines for grazing management could be refined. Regrowth was predominantly from the crown and most stems remaining after grazing subsequently died. It is concluded that grazing management should be severe and infrequent but, because regrowth is from the crown, treading damage needs to be avoided.

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Science And Information For Our Grasslands, G A. Nores, R R. Vera Apr 2025

Science And Information For Our Grasslands, G A. Nores, R R. Vera

IGC Proceedings (1977-2023)

This paper favours a view of grasslands, and agricultural research in general, that extends well beyond the limits of the scien1ific cummunity and promotes the active involvement of scientists in current societal debates from a ��cientific perspective. It is argued that in developed counuies environmental concerns rather than production growth will tend to dominnte future social debate, In developing countries there is a need to balnnce agricultural growth with responsible management of natural resources. Needs for new technology go beyond improving biophysical efficiency, and involve economic and social efficiency objectives. The relevance of grassland research is ��ssessed in terms of …

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Genetic Engineering For Pastures, W J. Peacock Apr 2025

Genetic Engineering For Pastures, W J. Peacock

IGC Proceedings (1977-2023)

The flrst genetically engineered food products frolll hotticultural production systems are now enlering the Market and field trials of genetically engineered crop species are well advanced. We can expect that a range of crop cultivars, in which genetic engineering is n component of the breeding process, will soon go into broad ncre agriculture. Pasture species are nut far behind. Gene transfer systems are in place for a number of temperate and tropical pasture legumes and even for a few species of more dlrficult grasses. Genetic transfer systems are In place for a numoec of temperate and tropical pastvce legumes and …

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Nitrogen Fixation And Transfer To Associated Grasses By White Clover Cultivars Under Dairy Cow Grazing, S F. Ledgard Apr 2025

Nitrogen Fixation And Transfer To Associated Grasses By White Clover Cultivars Under Dairy Cow Grazing, S F. Ledgard

IGC Proceedings (1977-2023)

New Zealand pastures obtain most of their nitrogen (N) from fixation of atmospheric N2 by white clover (Trifolium repens L.). Grasslands Huia has been the predominant cultivar used, but in recent years a number of new cultivars have become available. Studies under mowing and sheep grazing have shown that the large-leaved cultivars are the most pro­ductive (van den Bosh et al., 1986; Frame and Boyd, 1987). These cultivars have not been evaluated under dairy cow graz­ing. This paper describes a 2 year field experiment examining white clover cultivars under dairy cow grazing for production, N2 fixation and transfer of …

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N-15 Study Of Nitrogen Uptake By Tall Fescue Throughout A Spring Growth, J Salette, Marie-Laure Decau, Francoise Vertes Apr 2025

N-15 Study Of Nitrogen Uptake By Tall Fescue Throughout A Spring Growth, J Salette, Marie-Laure Decau, Francoise Vertes

IGC Proceedings (1977-2023)

In previous works, nitrogen uptake by a grass sward during regrowth has been studied and modelled (Salette and Lemaire, 1981 ; Lemaire and Salette, 1984). In this study, the use of N- 15 labelled fertilizer allows differentiation of two nitrogen sources for the plant nutrition : soil and fertilizer.

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Spring Nitrogen Uptake In Grass Swards In Relation To N Fertilizer Rates And Variation Between Years, J Salette, Marie-Laure Decau, G Lemaire Apr 2025

Spring Nitrogen Uptake In Grass Swards In Relation To N Fertilizer Rates And Variation Between Years, J Salette, Marie-Laure Decau, G Lemaire

IGC Proceedings (1977-2023)

No abstract provided.

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Ajustement De L’Azote Recolatable Dan Les Fourrages A L’Offre Minerale Dans Les Prairies Permanentes, P Loiseau, P Monteilhet Apr 2025

Ajustement De L’Azote Recolatable Dan Les Fourrages A L’Offre Minerale Dans Les Prairies Permanentes, P Loiseau, P Monteilhet

IGC Proceedings (1977-2023)

Une-serie de recherches-a-ete entreprise-dans-Je-but d\��value la reponse a l'azote des prairies dans l'etage collineen subatlan­tique. La contribution du sol a l'azote recoltable dans !es four­rages et Jes coefficients d'utilisation des apports mineraux sont etudies en fonction de differents parametres. Le but pratique est d'ameliorer le conseil de fumure azotee. Mais Jes recherches incluent aussi une connaissance plus approfondie du comporte­ment de l'azote dans Jes sols sous prairies. Une des recherches a ete appliques aux prairies permanentes de fauche en zone de piemont.

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Etude Du Stock D’Azote Mineralizable Dans Les Milieux A Teline Linifolia De La Suberaie En Mamora (Maroc)., M Qarro, A Harcharass Apr 2025

Etude Du Stock D’Azote Mineralizable Dans Les Milieux A Teline Linifolia De La Suberaie En Mamora (Maroc)., M Qarro, A Harcharass

IGC Proceedings (1977-2023)

Les facies de Teline linifolia (genet) couvrent actuellement de vastes etendues en foret de Mamora (63% de chene-liege, 24% d'eucalyptus, 5% de Coniferes et 8% de vides et dayas) avec des recouvrements tres eleves. Le developpement de cet arbuste est favorise par !'interdiction de la chevre qui regularise la den­site du sous-bois (Qarro, 1986). Notre etude, engagee dans ces milieux, vise a etudier le role ecopedologique de cette legumineuse (Teline linifolia) sur Jes sols sablonneux pauvres en elements mineraux (l'azote particu­lierement) et plus particulierement Jes relations entre le recou­vrement de Teline et le stock d'azote mineralisable. II convient de tester …

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Seasonal Variations In Soil Mineral Nitrogen And In The Response Of Grassland To Nitrogen Fertilization, O Oenema, J Postmus, W H. Prins, J J. Neeteson Apr 2025

Seasonal Variations In Soil Mineral Nitrogen And In The Response Of Grassland To Nitrogen Fertilization, O Oenema, J Postmus, W H. Prins, J J. Neeteson

IGC Proceedings (1977-2023)

Grassland is intensively used in the Netherlands. According to the fertilizer recommendation, the optimum N supply for such grassland is 250 kg ha-1 yr-1 for well-drained peat soils and 400 kg ha-1 yr-1 for all other soils. Environmental problems, associated with N losses from intensively used grass­land, necessitate a refinement of the general recommendations. This, in turn, requires understanding of the dynamics of soil mineral nitrogen. This paper reports on (1) seasonal dynamics of soil mineral N and (2) seasonal variations in the response of cut swards to N. Results of grazed swards will be dealt with elsewhere (Oenema et …

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Ammonia Volatilisation And Loss From Grassland Systems, S C. Jarvis, B F. Pain, D J. Hatch, R B. Thompson Apr 2025

Ammonia Volatilisation And Loss From Grassland Systems, S C. Jarvis, B F. Pain, D J. Hatch, R B. Thompson

IGC Proceedings (1977-2023)

There is considerable interest in monitoring flows of nitrogen (N) through various parts of grassland systems. Until recent developments in methodology it had been particularly difficult to assess the contribution of NH3 volatilisation to N cycling. Emission rates for NH3 over Europe are thought to have increased by 50 % over the past 30-40 years and to arise largely from livestock excreta. This occurs after the hydrolysis of excreted urea and, with cattle, takes place directly from grazed swards, animal houses (during overwintering) and stored or applied slurry. As well as the economic losses, NH3 fluxes have important environmental consequences …

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The Effects Of Fertilizer/Urine Interactions On Nh3 -N Losses From Grassland Soils, R D. Meyer, S C. Jarvis Apr 2025

The Effects Of Fertilizer/Urine Interactions On Nh3 -N Losses From Grassland Soils, R D. Meyer, S C. Jarvis

IGC Proceedings (1977-2023)

Recent studies (Black et al., 1984) have indicated that the vol­atilisation of ammonia (NH3) from urea granules broadcast on to pastures at application rates of 50-100 kgN/ha often exceeds 20 % of the N applied. The extent of this loss becomes an import­ant consideration when manipulating management systems to maximise N efficiency and minimise losses to the environment. This will become especially important as the use of urea fertiliser increases because of relative cheapness and as technological advances in production and in farm handling are made (Gould et al., 1986). The factors influencing the volatilisation of urea in simple systems …

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Nitrogen Losses From Cattle Dung, Y Sugimoto, P Roger Ball Apr 2025

Nitrogen Losses From Cattle Dung, Y Sugimoto, P Roger Ball

IGC Proceedings (1977-2023)

Nitrogen (N) recylcing through animal excreta has long been considered beneficial to soil fertility in pasture. However, it was revealed recently that substantial N loss occurred via urine pat­ches in intensively managed grass-clover pastures in New Zeal­and (Ball et al, 1979 and 1981; Ball and Ryden, 1984). Nitrogen flow through dung patches is another main process in N recycling, as one-third to a half ot the N excreted by cattle and sheep is voided in dung (Whitehead, 1970; Sugimoto et al, 1987). The objective of this research was to determine the nitrogen losses from cattle dung in a ryegrass-white clover …

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Balances Of Forms Of Mineral N In Grazed Grassland Soils Impact Of N Losses, S C. Jarvis, J H. Macduff, J R. Williams, D J. Hatch Apr 2025

Balances Of Forms Of Mineral N In Grazed Grassland Soils Impact Of N Losses, S C. Jarvis, J H. Macduff, J R. Williams, D J. Hatch

IGC Proceedings (1977-2023)

Improving the efficiency of nitrogen (N) utilization and reducing losses requires an understanding of N transform­ations in soils. A key process is nitrification, which qualitatively and quantitatively determines the fate of NH4 +. This is especially important in grazed grassland where returns of urinary N provide a large supply of NH4 +. After grazing has finished there may be accumulations of N which, if nitrified, will be lost by leaching (freely drained soils) or denitrification (poorly drained soils) in temperate regions. Where nitrification is restricted, opportunity for loss is correspondingly less. Field measurement of nitrification is difficult because of interactions …

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Modelling The Nitrogen Cycle Of Intensively Managed Grasslands To Estimate Nitrogen Losses, G.W J. Van De Ven Apr 2025

Modelling The Nitrogen Cycle Of Intensively Managed Grasslands To Estimate Nitrogen Losses, G.W J. Van De Ven

IGC Proceedings (1977-2023)

No abstract provided.

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Assimilation Du Nitrate Et Fixation Symbiotique Dans Les Associations Trefle Blanc- Ray-Grass Anglais, J F. Soussana, C Arregui, L Hazard Apr 2025

Assimilation Du Nitrate Et Fixation Symbiotique Dans Les Associations Trefle Blanc- Ray-Grass Anglais, J F. Soussana, C Arregui, L Hazard

IGC Proceedings (1977-2023)

Nous avons etudie par des techniques enzymatiques in situ !'assimilation du nitrate et la fixation symbiotique de l'azote atmospherique au cours de la repousse de peuplements purs ou associes de trefle blanc et de ray-grass anglais cultives en moyenne montagne et recevant ou non une fertilisation azotee.

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Effect Of Mineral Nitrogen On Dry Matter Yield And Nitrogen Fixation Of Four Stylosanthes Spp. In Antigua, A Belal, K J. Marshall Apr 2025

Effect Of Mineral Nitrogen On Dry Matter Yield And Nitrogen Fixation Of Four Stylosanthes Spp. In Antigua, A Belal, K J. Marshall

IGC Proceedings (1977-2023)

The use of inorganic nitrogen (N) usually increases the legume yield (Pettiet, 1971) and inhibits nodulation and nitrogen-fixation (Dart, 1974). In the tropics, the application of inorganic fertilizer may not always increase the dry matter yield of legumes. Informations on the extent to which the nitrogen­fixation is affected are also very few. Present studies were carried out to determine the effect of N on dry matter yield and nitrogen-fixation of four Stylosanthes spp. in a tropical soil.

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Comparative Performance Of Two Strains Of Rhizobium Meliloti And Their Transconjugants Having Multicopy Nif Plasmid On Symbiotic Properties Of Alfalfa Under Field Conditions, R P. Gupta, B S. Sidhu, P D. Mehndiratta, R K. Batta Apr 2025

Comparative Performance Of Two Strains Of Rhizobium Meliloti And Their Transconjugants Having Multicopy Nif Plasmid On Symbiotic Properties Of Alfalfa Under Field Conditions, R P. Gupta, B S. Sidhu, P D. Mehndiratta, R K. Batta

IGC Proceedings (1977-2023)

Rhizobium meliloti has got a single set of 17 nitrogen fixation (nit) genes located in seven different cistrons on megaplasmid. Dixon and Cannon (1976) transferred nif plasmid, RP41 to R. meliloti to see its effect on acetylene reduction efficiency. They found that the transconjugants containing this plasmid were not able to reduce acetylene under aerobic and anaerobic cond­itions. However, when the plasmid was transferred back to E. coli , it could express itself indicating that K. pneumoniae genes were present in R. meliloti. The failure of the nif genes of K. pneumoniae in R. meliloti may be due to the …

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Effect Of Grass And Legume On The Nodulation Of Gliricidia And Leucaena In Dryland Farming Area In Bali, M Suarna, T Ogo, K Lana, W Sukanten, S Putra, I M. Nitis Apr 2025

Effect Of Grass And Legume On The Nodulation Of Gliricidia And Leucaena In Dryland Farming Area In Bali, M Suarna, T Ogo, K Lana, W Sukanten, S Putra, I M. Nitis

IGC Proceedings (1977-2023)

Gliricidia and Leucaena are commonly grown in the tropics for shade, fence and fodder (NFTA, 1987). In dryland farming area, Cenchrus and Panicum grasses could reduce the nitrogen (N) status of the soil, while the presence of ground legumes Centrosema and Stylosanthes could increase the N status of the soil (Whiteman et al., 1974). Soil with high N status could reduce nodulation (Buckman and Brady, 1980), while soil with low N status could induce nodulation (Whiteman et al., loc. cit.). The objective of this experiment was to study the nodulation of 2 shrub legumes grown in association with 2 grass …

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Effect Of Azospirillum Brasilense Inoculation In Grasses And Binary Associations Lecerne + Grass, C Scotti, L Zannone, M Molinari Apr 2025

Effect Of Azospirillum Brasilense Inoculation In Grasses And Binary Associations Lecerne + Grass, C Scotti, L Zannone, M Molinari

IGC Proceedings (1977-2023)

The study of the biological N2-fixation associated with for­age crops, legumes and grasses has been started in our Institute since 1983 (Scotti et al., 1985, 1989) in order to define the char­acteristics of plants and meadow structures highly productive and persistent with low input of nitrate N. Legumes grasses binary associations have been found among the most interesting meadow structures for our regions. For this reason we started to study the system (Grasses - Azospirillum) + (Lucerne - Rhizobium) with the following objectives : a) to investigate the effect of inoculation with Azospirillum brasilense in pure stand and …

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Effect Of Burning On The Nitrogen Dynamics In An Indian Grassland, M K. Misra, M Malana, B N. Misra Apr 2025

Effect Of Burning On The Nitrogen Dynamics In An Indian Grassland, M K. Misra, M Malana, B N. Misra

IGC Proceedings (1977-2023)

The atmosphere and soil are possible sources of nitrogen for plant but nitrogen remains inactive until degraded and minera­lised. Fire acts as a mineralising agent. Fire-manmade or natu­ral is prevalent in the upland vegetations and forests of India. Very little work is available on the nitrogen budget of the Indian grasslands especially in the east coast of India. The objective of this study was to assess the effect of fire on the dis­tribution of nitrogen in soil and plant components and its dynamics in a coastal grassland of Orissa.

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Relationship Between Fertilizer Nitrogen And Nodulation Of Tropical Legumes, U R. Sangakkara, K B. Attanayake Apr 2025

Relationship Between Fertilizer Nitrogen And Nodulation Of Tropical Legumes, U R. Sangakkara, K B. Attanayake

IGC Proceedings (1977-2023)

Most tropical pastures are fertilized with N, primarily due to the response of grasses which form its major component. Many studies (e.g. Mahon, 1983) report the adverse effects of applied N on nodulation and N fixation of pasture legumes. Thus, with fertilizer N, the role of the legume is subdued due to reductions in N fixation and competitive dominance of the grasses (Atkins, 1984). Nodulation in tropical legumes begin after root develop­ment, and is expidited by enhancing the early growth of the legume. Due to the occurrence of N deficiency termed « N hunger» during early growth of legumes (Atkins, …

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