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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 …

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 …

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 …

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 …

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.

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.

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.

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 …

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 …

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 …

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.

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, …

Seasonal Variation In Symbiotic Nitrogen Fixation Of White Clover, K Sugawara, T Isawat, Y Yashima, I Ito

IGC Proceedings (1977-2023)

Legumes may supply considerable amounts of nitrogen (N) by symbiotic fixation to the pastures and be indispensable species for inexpensive production of forage. White clover (Tri­folium repens L.) is the most popular perennial forage legume, especially in grazing fields, in Japan. But we have little infor­mation on the actual state of N fixation ability in managed field (Brock et al., 1981; Murphy and Ball, 1985). In this study, N fixation was measured in white clover field during 4 successive years and the seasonal patterns of the activity were investigated in relation with the changes of the atmospheric conditions : …

Dinitrogen Fixation And Nitrogen Transfer In Temperate Legume-Grass Communities, G H. Heichel

IGC Proceedings (1977-2023)

Perennial forage legumes fix atmospheric dinitrogen (N₂) and, in mixed swards of legumes and grasses, may transfer nitrogen (N) to the companion grass (Brophy et al., 1987; Ta and Faris, 1987). The amounts of N₂ fixed by legume-grass mixtures in the temperate North Central U.S. are not known. Further the amounts of N transferred from legumes to com­panion grasses are not known. The purpose of this research was to quantitate N2 fixation of and N transfer in legume-grass swards.

Etude Des Relations Entre Le Deficit Hydrique Et La Fixation D’Azote Chez Le Trefle Blanc, Ch Robin, Liza Shamsun-Noor, D Schontz, A Guckert

IGC Proceedings (1977-2023)

L'alimentation hydrique est un facteur limitant important de la fixation symbiotique chez Jes legumineuses (Pankhurst et Sprent, 1975; Sprent, 1976; Albrecht et al., 1984). Le trefle blanc, ne possedant pas de systeme racinaire puissant, subit des phases de deficit en eau !ors des secheresses estivales. Cette note rapporte le role du facteur varietal dans la tolerance au deficit hydrique du trefle blanc.

Quantifying The Nitrogen-Supplying Capacity Of Legumes To Non-Legumes In Crop Rotations Using 15n, O B. Hesterman, G H. Harris, T S. Griffin

IGC Proceedings (1977-2023)

Economic and environmental concerns are prompting a heightened interest in using forage legumes in crop rotations to provide nitrogen (N) to subsequent non-legume crops. Yet there is a lack of information on the amount or proportion of N from forage legumes available to subsequent crops. Many fertilizer recommendations base legume N contributions on a fertilizer replacement value (FRY), which is the amount of inorganic N required to produce a subsequent non-legume crop yield equivalent to that produced following a legume. Legume N contributions based on FRY methodology typically exceed 100 kg N ha-1 (e.g. Bruulsema and Christie, 1987; Voss and …

Legume Breeding Strategy For Increased Nitrogen Fixation In New Zealand Temperate Pastures, J R. Crush

IGC Proceedings (1977-2023)

The energy level actually achieved at any site in grassland is governed by the mass flow of nitrogen (N) through the biota (O'Connor, 1967). As nitrogen limits pasture production, at all stages of pasture development, the aim of pasture management is to maintain the maximum amount of effective nitrogen in the system (Jackman, 1971). Prospects for increasing symbiotic N fixation in temperate grasslands have been reviewed (Ball and Crush, 1985). Of two strategies, growing more legume or reduc­ing the legumes ability to use mineral nitrogen, the former was favoured. This was because mineral nitrogen is thought to be important, in …

Factors Affecting Isotopic Fractionation During Nitrogen Fixation By Pasture Legumes, S F. Ledgard

IGC Proceedings (1977-2023)

The ¹⁵N natural abundance method for measuring N₂ fix­ation by legumes has compared favourably with other methods (reviewed by Shearer and Kohl, 1986). This method is based on the small difference in ¹⁵N abundance between nitrogen (N) derived from N2 fixation and N derived from soil. The pro­portion of legume N fixed from atmospheric N2 (PN) is cal­culated using :

PN = (o¹⁵Nref - o¹⁵N1egume)/(0¹⁵Nref - B)

where o¹⁵N is the per mil ¹⁵N excess over atmospheric N₂ ; ref is a reference plant which obtains all …

Nitrogen Fixation By "Grassland Kopu" And "Grassland Huia" White Clover As Affected By Nitrogen Regime, S F. Leggard, A M. Eltilib

IGC Proceedings (1977-2023)

During the past 20 years, almost all white clover sown in New Zealand has been« Grassland Huia », which is a medium­small leaved cultivar (Williams, 1987). A large leaved, upright growing cultivar called « Grassland Kopu » has recently become available and this should be better suited for intensive rotationally-grazed pastures. Van den Bosch et al., (1986) measured increased clover growth from Kopu in a mixed clover/grass sward. However, little is known about the relative tolerance ofKopu and Huia to nitrogen (N) fertiliser use. West et al., (1986) measured greater N2 fixation from Kopu than Huia under low and high …

La Definition De La Date Optimale De La Premiere Pature De Quelques Especes Et Varietes De Graminees Fourrageres, B Rutkowska, E Lewicka, A Kolakowska

IGC Proceedings (1977-2023)

La rationalisation du piiturage depend aussi de la date de la piiture, particulierement au printemps, au moment de la pre­miere ou de la deuxieme piiture quand !es tiges floriferes des graminees commencent a se developper (Allerit, 1978 ; Gillet, 1980). On sait que la meilleure periode pour debuter le piiturage se situe lorsque les plantes ont 20-25 cm de hauteur, !es ani­maux mangent mieux et !es pertes par pietinement sont limi­tees. En dehors de cela !es resultats des experiences frarn;aise et suisse (Caputa, 1975; Gillet et al., 1980) montrent qu'a cette hauteur !es jeunes tiges floriferes ont une hauteur de …