Weed Science Commons^™

Some Initial Results Of Field Trials Conducted In Establishing A Pasture-Seed Industry In Cojedes State, Venezuela, E.J A. Khan, W H. Mark

IGC Proceedings (1977-2023)

In starting a pasture-seed industry on a farm located at lat 9°50' N that gets about 1,600 mm of rain yearly followed by a severe dry season from mid-December to April, four widely separated sites were selected to plant three grasses for commercial seed production in 1978. The objectives were to assess the fertility status of the soils, then to determine the fertilizer re­quirements of the grasses at each site and to establish an introduction garden with 70 cultivars of grasses and legumes to study their suitability for expanding seed production. Based on the results of soil analyses, a modified …

Influence Of Pesticide, Fertilizers, Row Spacings, And Seeding Rates On No-Tillage Establishment Of Alfalfa, L R. Vough, A M. Decker, R F. Dudley

IGC Proceedings (1977-2023)

Two experiments were conducted to investigate seeding techniques associated with no-tillage establishment of alfalfa (Medicago sativa L.) in barley (Hordeum vulgare L.) stubble. The objective of experiment 1 was to evaluate the influence of car­bofuran (CF) insecticide/nematocide and of P and N fertilizers on seedling weight, plant population, and forage yield. All materials were applied in the row with the seed. The largest seedlings at 10 weeks after seeding occurred with CF + P + N. The smallest seedlings were associated with the check and P treatments. The highest plant populations at 6 and 30 weeks after seeding …

Soil Nutrient Constraint For Legume-Based Pastures In The Brazilian Cerrados, W Couto, C Sanzonowics

IGC Proceedings (1977-2023)

Soil-nutrient deficiencies in two cerrados soils have been investigated as a preliminary to small-plot research oriented to estimate fertilizer requirements for establishment of legumes in grass-legume associations. The studies were conducted in the greenhouse, in 2-kg pots, with surface-soil samples taken from two sites representative of the dominant soils in the region. These are the dark red latoso1 (DRL) and the red-yellow latosol (RYL), which qualify as Haplustox and Acrusto:,:, respectively. Two kinds of e:,:periments were carried out. One consisted of a 1/4 replicate of a 28 factorial including potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), zinc (Zn), molybdenum …

Availability Of Soil Phosphate To Tropical Pasture Species, F W. Smith

IGC Proceedings (1977-2023)

Quantitative measurements of the amount of soil phosphate available to plants were made by an isotopic-dilution technique (L-value). Following very thorough mixing and equilibration of 32P with soil P, sequential harvests of perennial pasture species were used to monitor the available P pools in two alkaline clay soils. In initial experiments with Cenchrus ciliaris (buffelgrass), an apparent increase was noted in the size of the available P pool over a number of sequential harvests during a 3-month period. This finding suggested that P was being transferred from a previously unavailable pool to the available pool during the ex­perimental period. Planting …

Effect Of Fertilization On The Grass Tetany Potential And Organic Acid Composition Of Tall Fescue, D L. Grunes, S R. Wilkinson, P K. Joo, W A. Jackson, R P. Patterson

IGC Proceedings (1977-2023)

Grass tetany has caused the death of beef cattle grazing Kentucky-31 (KY-31) tall fescue (Festuca arundinacae Schreb) fertilized with high rates of ammonium nitrate (NH4NO3) and potassium chloride (KCl), or with broiler litter. A field experiment was carried out to determine the effect of fertilization on the chemical composition of the forage. The addition of either inorganic fertilizer or broiler litter markedly increased concentrations of nitrogen (N) and potassium (K) in the plants. Fertilization with 448 kg N/ha markedly increased the concentrations of magnesium (Mg) and, to a lesser extent, calcium (Ca) in the plants. Fertilization with broiler litter markedly …

Leaching Effects On Composition And Digestibility Of Leaf And Stem Of Alfalfa And Red Clover, Michael Collins

IGC Proceedings (1977-2023)

Rainfall during field drying of legume hay reduces both yield and nutritive value of the forage. An experiment was conducted to evaluate leaching effects on composition of dry leaf and stem tissue of alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.). Leaching increased neutral detergent fiber, acid detergent fiber, cellulose and acid detergent lignin concentrations in every case although leaf increased more. Stem tissue of red clover differed less from leaf in fiber composition than did leaf and stem of alfalfa. Leaching did not significantly affect nitrogen concentration but decreased in vitro true digestibility of both …

Soil Fertility And Beef Production In The Semi-Arid Sub-Tropics, P C. Kerridge, R W. Mclean

IGC Proceedings (1977-2023)

Two-thirds of the grazing lands in Queensland are on infer­tile soils, low in organic matter, phosphorus (P) and nitrogen (N) (Weston et al., 1981). Pasture quality is low and average liveweight gain (L WG) of steers on these soils ranges from 0.10 to 0.30 kg/day compared to 0.40 to 0.50 kg/day on more fertile soils. Low herbage production limits carrying capacity to 3-10 ha/animal. The nutritive value can be improved by (i) direct supplementation of animals with N and P, (ii) introduction of a legume together with fertilizer and/or supplement P or (iii) use of heavily fertilized improved grasses ± …

Developing Effective Nutrient Seed Coatings For Grasses And Legumes, J M. Scott

IGC Proceedings (1977-2023)

Seed coatings provide a unique opportunity to supply developing seedlings with a source of nutrients to which each sown seedling has preferential access compared to neighbour­ing weeds, thus providing the seedlings with a competitive advantage during pasture establishment. A study of commer­cially prepared nutrient coatings (containing nitrogen [NJ, phosphorus [P] and sulfur [SJ) applied to seeds of perennial rye­grass showed that whilst the S component of the coating was effective, the P component was only partially effective, and the N component was ineffective in alleviating the respective soil nutrient deficiencies (Scott et al., 1985). The successful development of nutrient seed …

Valorization Des Elements Mineraux Autres Que L’Azote Contenus Dans Les Effluents D’Elevage, J C. Taureau, D Ziegler

IGC Proceedings (1977-2023)

Les doses de lisier appliquees sur une culture sont generale­ment calees sur la valeur azotee du produit. L'apport comprend en plus des quantites importantes de P20s, MgO, CaO et oligo­elements dont le role fertilisant merite d'etre precise dans !es conditions de plein champ. L'efficacite fertilisante du phos­phore et du potassium a ete etudiee en pot (Amberger, 1982-83). Notre but est de montrer a partir de trois dispositifs de lon­gue duree, dont un seul sera detaille ici, !es consequences d'epandages plus ou moins massifs de lisier sur la composition des fourrages et !'evolution chimique des sols.

The Diagnosis Of Grassland Mineral Nutrient Status Through Herbage Analysis, J Salette, Lydie Huche

IGC Proceedings (1977-2023)

It appears more and more clearly that soil analysis is not sufficient to give a good approximation of the mineral status of grassland soils. In perennial crops leaf analysis and empirical critical levels are widely utilized. This grassland approach emphasizes the good results which can be obtained for nitro­gen, potassium, phosphorus not from leaf but from the whole herbage plant analysis. This paper deals with pure grass stands.

Effects Of Fertilization And Liming On The Improvement Of Native Pastures, Maria E.V Lourenco, R.J. M. De Carvalho, Maria De L.A.P Da Silva

IGC Proceedings (1977-2023)

Native pastures in Portugal have relatively low productivity. The yield and botanical composition of such grasslands, where some legumes species are present, can be improved by fertilization with phosphorus application and/or also liming (Carter, 1983). The presence of legumes in pasture can also be improved by molybdenum application (Lattan et al., 1984). Significant increases of phosphorus concentration in plants (Garden et al., 1978) and on soil available phosphorus (Gregan et al., 1980) due to phosphorus application have also been reported.

The objectives of this study were to evaluate the potential of such treatments on the improvement of native pastures.

An Effective P Application Method For Dactylis Glomerata, M Hojito, A Nishimune, M Noshiro

IGC Proceedings (1977-2023)

There are two practical ways to apply phosphorus (P) fertil­izer on cutting type grasslands in Hokkaido, Japan. The first one is to apply P at a rate of about I 00 kg P2Os/ha in the spring (April) in one application. Some reasons for this method have been explained (Hayakawa et al., 1951). However, in some cases, it is more convenient for practical management to apply three equal amounts of P, at three different times during the year (April, June and August) the same as other fertilizers such as nitrogen or potassium. That is a second way. Grassland soil is acidified …

Relationships Between Root Morphology And Nutrient Uptake In Winter-Flooded Mediterranean Grasslands, A J. Hernandez, J Pastor

IGC Proceedings (1977-2023)

One of the functions of roots directly related to the environ­ment is that of uptake. However, since legume are worse competitors than grasses for nutrients and water, root mor­phology may be an important factor in this competition in grassland systems. This has been very interesting for the study of the dynamics of flooded pastures in West-Central Spain. Their main root characteristics were studied in a previous paper (Hernandez and Pastor, 1988). Now we intend to approach the knowledge of the relationships between root morphology and nutrient uptake.

Deforestation In The Savanna Context: Problems And Benefits For Pastoralism, W H. Burrows

IGC Proceedings (1977-2023)

Deforestation is discussed from a savanna perspective, rather than in the usual rain forest connotation. Reasons for removing trees and shrubs from savannas are outlined with emphasis placed on the impacts that tree clearing has on livestock production. Other benefits and possible adverse consequences of removing woody plants are detailed. It is suggested that the importance of trees ln maintafning nutrient flows in grazed savanna may be overstated. Problems that arise from clearing trees from savannas often result from a lack of preclearing planning or post-clearing management, rather than the clearing operation Itself.

Role Of Vesicular Arbuscular Mycorrhizae In Leucaena Establishment, N J. Brandon

IGC Proceedings (1977-2023)

No abstract provided.

Large-Scale Property Demonstrations Of The Effect Of Sexa Stylo And Phosphorus On Beef Cattle Growth In Central Queensland, Australia, C H. Middleton, K J. Murphy, G W. Blight, Vicki-Lee Hansen

IGC Proceedings (1977-2023)

Seca style (Stylosanthes scabra) was oversown into black speargrass (Heteropogon comortus)•dominant pasture after a burn at 2 sites in central Queensland, and the pasture was continuously grazed. At one site with <5 ppm bicarbonate-extractable soil P, Seca growth was poor and gave only a small animal growth response (18 kg/steer/year) over native pasture. With the addition of superphosphate (27 kg P/ha) the Seca-native grass produced an additional live-weight gain of 70 kg/ steer/year over the native pasture control. At a second site with 6-8 ppm available soil P, Seca grew well, and with a P supplement given to steers, live-weight gains were 40 kg/steer/year more than for P­supplemented animals grazing native pasture. Oversowing Seca into native pasture with P as fertiliser or a supplement can dramatically improve animal performance. The project was conducted on private properties and was aimed to focus producer attention on this technology, which is suited to large areas of northern Australia.

Cattle Growth And Diet Responses To Legume And Phosphorus Supply, C P. Miller, R E. Hendricksen

IGC Proceedings (1977-2023)

Phosphorus was supplied to oversown pastures and steers grazing them, as supplement or as 3 rates of fertiliser over 2 years. Dry­season live-weight change was related to fertiliser rate and legume availability, with live-weight losses on unfertilised pastures, gains on moderately fertilised pasture and maintenance on low-fertilised pasture. Supplement had no effect. Wet-season live-weight gain was increased through fertiliser effects on legume availability and consumption (total response was 42 kg/steer) and through P supplement effects on phosphorus intake (total response was 34 kg/ steer). These and related studies have allowed rational and economical P management of oversown pasture systems in …

Use Of Natural 15n Abundance In Estimating Nitrogen Fixation By Centrosema Spp: Influence Of Phosphorus And Strain Of Bradyrhizobium, G Cadisch, S F. Ledgard, J Noseberger, R Sylvester-Bradley

IGC Proceedings (1977-2023)

Isotopic ¹⁵N fractionation during N2 fixation by Centrosema acutifolium, C. brasilianum and C. macrocarpum grown in N·free sand-nutrient solution was investigated as a prerequisite for the use 9f the natural ¹⁵N abundance method to estimate N2 fixation. The natural abundance of ¹⁵N was always lower in shoots than in roots and nodules, and there was little difference between species. In contrast, inoculation strongly influenced isotopic fractionation, leading to average o15N shoot values of -0.64 and -1.37 for Bradyrhizobiumstrains CIAT3101 and 1670 respectively, given adequate phosphorus. P deficiency led to a small legume x P interaction …

Impact Of Grazing Dairy Cattle On Phosphorus Cycling And Water Quality In A High Water Table Pasture, Bruce W. Mathews, L E. Sollenberger, C R. Staples, C B. Mathews, C G. Chambliss

IGC Proceedings (1977-2023)

During 1990 and 1991 Callie bermudagrass (Cynodon dactylon (L.) Pers.) pastures were used to determine the effects of 3 grazing management systems (short-duration rotational, long-duration rotational and continuous stocking) on P cycling and runoff water quality from intensively managed pastures used to raise replacement heifers (Bos taurus). A hay system also was included to compare soil responses under grazing and clipping. Soil P redistribution was not different among grazing systems, but accumulated in the third of the pastures closest to shade and water. Amounts of soil P were lower in the hay system than in the grazed …

Estimating Fertilizer Substitution Values From The Dissolution Rates Of Reactive Phosphate Rocks In New Zealand Pastoral Soils, J H. Watkinson, K W. Perrott

IGC Proceedings (1977-2023)

A relationship is developed between the substitution value of reactive phosphate rock (RPR) relative to triple superphosphate (TSP), both applied annually to pasture, and the dissolution rate of the RPR. The residual effect of dissolved phosphate is included. Residual RPR is calculated from the dissolution rate of the RPR in the soil, while residual phosphate from TSP or dissolved RPR is taken as a constant fraction of the value in the previous year. Calculations including the residual effect of dissolved fertiliser produce smaller substitution values and longer lag times for RPR than when the effect is omitted. The relationship derived …

Phosphorus Deficiency Affects The Growth And Development Of Temperate Pasture Species, P D. Kemp

IGC Proceedings (1977-2023)

Morphological and ontogenetic responses of temperate pasture species 10 P deficiency with the potential 10 affect the plant's persistence and productivity were examined. Plants were grown in pols in glasshouses. Two grass species, Lolium multiflorum and Phlalaris aquatica, were compared and 2 cullivars of Trifolium repens, Grasslands Huia and Grasslands Tahora, were compared under P-deficient and P-sufficient conditions. ShooVrool ratio and the number of tillers per plant were unaffected by P deficiency in P. aquatica but decreased in L. multiflorum. Reproductive development ceased at the double ridge stage in P-deficienl P. aq11alica. Huia was more sensitive than …

Evaluation Of North Carolina Reactive Phosphate Rock As A Phosphorus Fertilizer For Permanent Pastures, A G. Sinclair, P D. Johnstone, L C. Smith, P W. Shannon, M B. O'Connor, L Nguyen, W H. Risk

IGC Proceedings (1977-2023)

North Carolina phosphate rock (NCPR) was compared with triple superphosphate (TSP) as a phosphorus (P) fertiliser for permanent grass-clover pastures over a period of 6 years at 12 sites located throughout New Zealand. Pasture production was measured by mowing, and herbage P concentrations were measured on all harvests at 2 sites. In year 1, averaged over all sites, 1 unit of P in NCPR produced the same DM response as 0.24 units of Pin TSP (substitution value=0.24). In year 6 the mean substitution value was 0.80, and over the 6-year period it was 0.60. The site with highest pH (6.3) …

Defining Economically Optimal Phosphorus Fertilizer Rates For Permanent Grass-Clover Pastures In Spain And New Zealand, A G. Sinclair, M Rodriguez Julia

IGC Proceedings (1977-2023)

Economically optimal annual fertiliser phosphorus Prates for maintaining permanent pastures are calculated from a long-term maintenance response curve along with fertiliser price and pasture value. Parameters of the response curve are derived from nutrient balance considerations. The system provides a logical basis for maintenance P fertiliser policies, and results are in accord with limited experimental data.

Dynamics And Interactions Of Carbon, Nitrogen, Phosphorus And Sulphur Cycling In Grazed Pasture, A K. Metherell, C V. Cole, W J. Parton

IGC Proceedings (1977-2023)

There are close links between the carbon (C), nitrogen (N), phosphorus {P) and sulphur (S) cycles. This is especially evident in legume-based pasture in which ahe application of P and S fertilisers are required to achieve saaisfactory levels of N2 fixation and pasture production The dynamics of the nutrient cycles are controlled largely by the rates of pasture production and consumption, and by the rate of decomposition of organic matter. The CENTURY soil organic matter model integrates climate, soil and management driving variables to predict C, N, P and S dynamics. Simulated effecls of P and S fertiliser on nutrient …

Effects Of Vesicular-Arbuscular Mycorrhiza Inoculation, Nitrogen And Phosphorus On The Growth Of Seedlings Of Sesbania Sesban, E Akeampong, T Mamo

IGC Proceedings (1977-2023)

In the first of two pot experiments, growth of seedlings of Sesbania sesban in response to rates of P (0, 40, 120, 160 and 200 kg/ha) and of N (0 11nd 100 kg/ha) was examined. In a second trial the effect of inoculation with vesicular-arbuscular mycorrhiza (Glomus macrocarpus) and 2 levels (0 and 40 kg/hn) each of triple superphosphnte (TSP) and Egyptian rock phosphate (ERP) were studied. Response to P was linear to 80 kg/ha. Application of N improved the response of seedlings to P through enhanced P and N uptake. Application of N increased plant weight by …

Nitrogen And Phosphorus Nutrition Of Digitaria Eriantha: Is It Limited By Absorption Capacity Or Rate Of Supply?, M C. Scholes, R J. Scholes, J Retief

IGC Proceedings (1977-2023)

Digitaria eriantha was grown from seed collected from low and high nutrient habitats. The plants were grown with either a high or low nutrient supply for 12 weeks. Rates of nitrogen and phosphorus absorption were measured on excised roots using colorimetric assays. The grasses from the low nutrient areas achieved the same maximum uptake rates regardless of the level of N supplied, This was not so for the grasses from the high nutrient site which increased their uptake rates with increased N supply. Plants from the low nutrient site showed markedly increased P absorption when supplied with high levels of …

Effects Of Endophyte In Perennial Ryegrass On Pasture Establishment And Botanical Composition In Victoria, P E. Quigley, N M. Mcfarlane

IGC Proceedings (1977-2023)

Perennial ryegrass (Lolium perenne L.) plants, which contained an endophyte (Acremonium lolli), established at higher plant densities than ryegrass plants which seldom contained endophyte. Presence of endophyle did not affect ryegrass planl dry weight or tiller number. Application of phosphatic fertiliser, increased seeding rate, or use of seed which frequently contained endophyte could increase ryegrass tillers/m2• The growth of subterranean clover (Trifolium subterraneum L.), sown with the ryegrass, was reduced when endophyle was presenl in the grass. It is postulaled that the weaker growth of subterranean clover would prejudice its seed production and hence reduce the long-term …

Effects Of Phosphate And Stocking Rate On Mediterranean Grasslands In Northern Syria, A E. Osman, P S. Cocks

IGC Proceedings (1977-2023)

Three rates of phosphate (0, 11 and 26 kg/ha P) were applied to phosphorus-deficient native grassland in northern Syria, and botanical composition, biomass and legume seed production were monitored. The experiment was grazed at low and high ( 1.1 and 2.3 sheep/ha per year) stocking rates. The site is typical of native grassland within the cereal zone of west Asia where cropping is not possible because of shallow, stony soils and steep slopes. Results showed that annual applications of P, even as low as 11 kg P/ha, corrected the deficiency in soil P and improved pasture production. The practical Implications …

Influence Of Selected Horizon Combinations Of A Spodosol On Bahiagrass Yield And Quality, H Ibrikci, J E. Rechicigl, E A. Hanlon

IGC Proceedings (1977-2023)

In recent field studies, bahiagrnss (Paspalum notatum Flugge), a major forage crop in Florida, did not respond lo added Phosphorus fertiliser even though preplant Mehlich I (Ml) soil test indicated very low extractable P (<10 mg/kg). Surface (Ap), E, spodic (Bh) horizons of a Spodosol, limed spodic horizon (BhL), and commercial builders sand were packed into cylindrical plastic bags in selected combinations. The combinations were Ap-B-S, Ap-E-Bh, Ap-E-BhL, and sand. P was applied in 2 rates as O and 60 kg P/ha to selected bags. Bahiagrass sod with its stolon-root system was collected from an unfertilised bahiagrass field, then placed on the soil surface within the growth bags. The experiment was arranged in a completely randomised design with 4 replicates in a glasshouse. Total forage yield, root dry weight, root growth and distribution were determined in each bag over a period of 175 days. Total forage dry matter was increased with addition of 60 kg P/ha in all treatments. Root growth was not influenced by treatments but dry root weight was different in each treatment. Overall forage crude protein content was not influenced by treatments.

Effect Of Nitrogen Fertilizer Applied As Urea To Dryland Tropical Grass Pastures On Presentation Yield And Chemical Composition, G K. Reason, T M. Bowdler, K F. Lowe, J Chaseling

IGC Proceedings (1977-2023)

Pasture yields responded to applied nitrogen (urea) at either 200, 400 or 600 kg/ha/year of N under generally adverse seasonal conditions. Dry (DM) matter production differences were measured in each year, and in all seasons except spring for the 200 v. 400 kg N comparison. Autumn DM production increased by 25% with the increase from 200 - 400 kg N, and an additional 200 kg N resulted in a further 10.4% increase in dry matter yield. Botanical composition changes were consistent with expectations that Nitrogen would favour the more valuable pasture species. The expected improvement in feed quality as a …