Perennial Grass Pastures Research Articles

Development of a model to predict forage intake by grazing cattle.

A mathematical model to predict daily DMI and account for effects of energy supplementation on forage intake has been developed in several stages. A previously evaluated dynamic rumen model for sheep was adopted as the fermentation component of the intake model. Intake was adjusted to reach a given level of DM fill, which is the sum of the concentrations of each of the dietary fractions within the rumen. Differential equations described the rate of change of each nutrient fraction. Genetic size scaling rules based on mature body size relationships were used to adjust rate and fill parameters of the intake model from sheep to beef cattle. Nutrient fractions were partitioned into those that flow at the particulate passage rate vs the fluid passage rate. Forty-two data points representing perennial ryegrass, wheat pasture and range grasses were used to parameterize and evaluate the model. The model was relatively sensitive to the coefficient relating DMI to particulate rate of passage, the rate constant for the use of the potentially degraded fiber fraction of the forage, and to the composition constants for the amount of carbohydrate and nitrogen in the microbial mass. Relative insensitivity was observed for starch and protein nutrient use rate constants, for the coefficient relating DMI to fluid passage rate, and for constants relating to the growth of the microbial mass in the rumen. Feed intake of grazing cattle may be predicted by mechanistic models describing various nutrients' contribution to ruminal fill.

Seasonal variation in denitrification in a clay soil under a cultivated crop and a permanent pasture

Biological denitrification in a clay soil was measured under the annual crop black gram ( Vigna mango) and the perennial pasture grass green panic ( Panicum maximum var trichoglume). The soil treatments were: water, water plus C 2H 2, or water plus C 2H 2 plus glucose applied down brass tubes to depths of 7.5, 22.5, 52.5 and 112.5 cm. Soil gas samples were taken just before and 24 h after treatments were applied. Treatments and samplings were repeated every 3 months for 2 years. In untreated soil, the amounts of N 2O from crop and pasture were highest in spring and summer with approximately 75% of the total amount being measured. For black gram, this represented equal amounts in spring and summer (approx. 34g N 2O-N ha −1) whereas for green panic, 25.9g N 2O-N ha −1 was found in spring and 9.2g N 2O-N ha −1 in summer. Soil water was correlated with N 2O concentration beneath black gram ( r = 0.87, d.f. = 6, P < 0.01) and CO 2 concentration under green panic ( r = 0.69, d.f. = 6, P < 0.05). Multiple regression analysis showed that 87.8% of the variation in N 2O concentration from beneath black gram was associated with monthly rainfall and NO 3 −concentration. Gas samples collected 24 h after the application of the treatments showed that N 2O and CO 2 concentration did not vary between treatments. However, treatment application did increase the N 2O found beneath black gram. A mean increase of 29 g N 2O-N ha −1 was observed in January, 1986. Concentration of N 2O changed little after the application of the treatments to green panic. N 2O due to microsite activity represented 11% of the measured loss of nitrate from the subsoil in the field.

Supplementation of steers grazing Stylosanthes hamata pastures at Katherine, Northern Territory

Native perennial grass pastures were oversown with Stylosanthes hamata cv. Verano at 3 fertility levels, i.e, without fertiliser or with suboptimal levels of superphosphate or rock phosphate. Brahman steers, of varying ages, grazed the pastures and their responses to fertility level and direct supplementation with phosphorus and sulfur were determined over 4 years. Phosphorus supplementation doubled liveweight gains during the early and late wet season periods to about 0.9 and 0-7 kg/day, respectively. Pasture fertility level did not affect gains in the early wet season in most years but superphosphate increased the late wet season gains by about 0.1 kg/day. Small weight losses usually occurred in all treatments during the early dry season, with losses increasing with animal age. Weight losses were highest during the late dry season, particularly for the older, phosphorus supplemented, steers. This response was attributed to size rather than to age or supplementation per se. Sulfur supplementation had no effect upon liveweight gain or upon the pastures at any time. In unfertilised pastures, Verano increased to about 25% of the dry matter composition whilst pastures fertilised with superphosphate and rock phosphate became legume dominant after 2 and 3 years, respectively. Fertiliser also increased the nitrogen, phosphorus and sulfur concentrations in the forage, particularly the Verano, with superphosphate more effective than rock phosphate. In pastures where steers were supplemented with phosphorus there was a higher proportion of the naturalised legume Alysicarpus vaginalis and a lesser quantity of forage on offer. Blood inorganic phosphate and rib cortical thickness were reliable indicators of responsiveness of steers to phosphorus supplementation when measured during, or immediately after, the period of active growth.

A simulation model for managing perennial grass pastures. Part I—structure of the model

A simulation model has been structured to facilitate stochastic evaluations of grazing management systems on perennial grass pastures. The output data, stored in a direct-access data set, can be used as input to statistical programs which will perform desired statistical analyses of the data. The model was originated to provide a practical method for estimating the effects of grazing frequency, duration, and grazing rate on the performance of grazing systems for perennial grass pastures. The model provides 32 different attributes for characterizing the performance of a grazing system.

A simulation model for managing perennial grass pastures. Part II—a simulated systems analysis of grazing management

A model for managing perennial grass pastures was used to simulate a grazing experiment on common bermudagrass pastures at Booneville, Arkansas. The experiment used sixteen years' weather data from this location. The management variables included number of fields, rotation period, and simulated grazing rate. The grazing season was from 1 June to 22 September each year, and simulated performance data were obtained for successive six-day periods throughout the grazing season. The attributes of performance data included: daily harvest rate, digestible dry matter and cell content nitrogen harvested, potential tissue production, reserve carbohydrates at the end of the year and the ratio of forage on offer to the simulated grazing rate. Analyses of these simulated performance data provided an inference base to support a recommendation concerning the management variables. The recommendation is as follows: a four-field system, a nine-day rotation period and 84 kg/ha/day simulated grazing rate. The results along with other simulated grazing scenarios will be used to plan field experiments at Booneville, Arkansas.

A winter hardy, aluminum tolerant, perennial pasture grass for reclamation of acid mine spoils

Abstract Limpograss, Hermarthria altissima, (Poir) Stapf & C. E. Hubb (PI 364344) was tested for Al tolerance in acid, Al‐toxic Tatum subsoil (pH 4.1), in an acid mine spoil (pH 4.0) and in nutrient solutions containing 0 to 24 ppm Al added at initial pH 4.5 or 4.0. The grass was exceptionally tolerant to Al in all three media and can therefore be considered a “calcifuge”;, or perhaps more accurately, an “alumicole”;. In both Tatum soil and mine spoil, liming to pH values above 4.5 decreased growth, but the reasons for this were not determined. In our nutrient culture experiment (initial pH 4.0), the yields of plant tops were not significantly reduced by added Al concentrations up to 6 ppm but roots were injured by 4 ppm Al added. At initial pH 4.5 Al concentrations up to 4 ppm added appeared beneficial to root growth. Both tops and roots produced 50% of maximal yield with a final solution pH of 4.1 and with 17 ppm Al in the solution filtrate. Maximal growth was associated with plant‐induced pH increases to 7.0 or above, and with final Al concentrations below about 0.61 ppm in the solution filtrate. Tops of plants injured at pH 3.‐3 on acid mine spoil had higher concentrations of Al, Zn, Fe, Mn, Na, Ca and Mg than did those of uninjured plants grown at pH 4.5. Plant tops showing reduced yields at pH 7.0 on mine spoil had lower concentrations of Zn, Mn and B than those making maximal growth at pH 4.5. The tops of plants injured by 24 ppm Al in nutrient solution had higher concentrations of Al and K and sometimes Fe, Na and Cu than those grown with no Al. Growth reductions by Al were consistently associated with higher concentrations of Al and K and lower concentrations of Ca, Mg, Mn and Zn in both tops and roots. Roots of Al‐injured plants also tended to accumulate higher concentrations of P and Fe than those of non‐injured plants. Limpograss (PI 364344) did not accumulate Al in its tops, even when yields were reduced by 50% with Al stress, but trapping of Al in roots may partially account for its Al tolerance. Limpograss (PI 364344) has demonstrated outstanding winter hardiness, insect resistance, ability to compete with other species and tolerance to excess Al. Hence, the evidence suggests that it has a potential for use in revegetating strongly acid mine spoils at medium to high elevations in temperate climates.

Herbicide and Planting Date Influence Establishment of Sod‐Seeded Alfalfa1

AbstractYield and quality of perennial grass pastures can be improved through sod‐seeding of alfalfa (Medicago sativa L.). Herbicides have been widely used for grass suppression in sod‐seeding; however, the influence of the time of application on herbicide effectiveness requires study. Our objective was to determine the effects of planting dates and rates and types of herbicides on alfalfa establishment and yield when interseeded into perennial grass sod. A field study was conducted for 2 years on a Typic Halaquol, fine loamy, over sand, mixed, mesic soil. Alfalfa was sod‐seeded into a mixed smooth bromegrass (Bromus inermis Leyss.), Kentucky bluegrass (Poa pratensis L.), and quackgrass (Agropyron repens L.) sod on 21 April, 10 May, 19 May, and 2 June in 1978; and 19 April, 4 May, 21 May, and 2 June in 1979. On each planting date, paraquat (1,1′‐dimethyl‐4,4′‐bipyridinium ion) and glyphosate [N‐(phosphonomethyl) glycine] were each broadcast sprayed at 0.6, 0.8, and 1.1 kg ha−1. Dalapon [2,2‐dichloropropionic acid] was broadcast sprayed at 3.4, 5.6, and 9.0 kg ha−1. Greatest seeding year legume yields were obtained with the medium or high dalapon rates for the April seeding dates or with the medium or high glyphosate rates for the late May seeding date. The lowest average legume yields across all herbicides occurred for the June seeding date each year. Dalapon was the most effective herbicide across all rates for suppressing grass and increasing alfalfa yields for the April planting dates each year when grass regrowth was limited. For the early May planting date, dalapon treatments had the lowest grass yields. Alfalfa yields for dalapon and glyphosate treatments were not consistently different. For the late May planting date, glyphosate provided the greatest grass suppression and alfalfa yields. Herbicides and herbicide rates can be selected for grass suppression and legume establishment based on extent of grass vegetative development. Under low rainfall conditions, grass suppression may not insure successful legume establishment.

Weed Control on Warm Season Perennial Grass Pastures with Clovers1

Spring weeds in perennial grass pastures compete for limited nutrients and moisture and may lower palatability of the available for age. Mowing and a limited number of herbicides are the principal available methods of control in established pastures. Cool season clovers, which emerge in the fall and form a solid canopy during the winter, should have a competitive advantage over spring weeds. ‘Coastal’ bermudagrass (Cynodon dactylon (L.) Pers.) and ‘Pensacola’ bahiagrass (Paspalum notatum Flugge) sods were 1) overseeded with ‘Yuchi’ arrowleaf (Trifolium vesiculosum Savi.) or ‘Mt. Barker’ subterranean (Trifolium subterraneum L.) clovers, 2) fertilized with 0, 84, 168, 252, or 336 kg N/ha or 3) fertilized with 0, 84, and 168 kg N/ha and sprayed with 1.1 kg/ha of simazine [2‐chloro‐4,6‐bis(ethylamino)‐s‐triazine]. Simazine substantially reduced spring weed yields to less than 500 kg/ha on Coastal bermudagrass and 200 kg/ha on Pensacola bahiagrass. Weed production on grass sods overseeded with clovers was not significantly different from the simazine treated plots. By the second year, weeds were essentially elimated from the plots overseeded with clover. These data demonstrate that clovers can play a major role in integrated pest management programs for warm season perennial grass pastures.

Genetics of total seed yield and its components in Phalaris aquatica L

Eight plants within each of 55 half-sib families in a diverse breeding population of this perennial pasture grass were assessed for total seed yield in bagged inflorescences, numbers of panicles and spikelets per plant, weight per seed, and for important agronomic characters. Total seed yield was moderately highly heritable (h2N = s.e. = 0.52 � 0.21), and was phenotypically variable. The mean seed yield of the progeny of the highest yielding 10% of the plants should be 44% higher than the mean of the original population. Seed yield was closely correlated genetically with the number of seeds per panicle or per plant, but not with weight per seed or number of panicles per plant. There was little variation for ovule fertility in the population. Visual estimates of spikelet number per plant were very highly correlated genetically with numbers of seeds per plant and total seed yield, but had a non-significant heritability (h2N = 0.30 � 0.20). Scoring for spikelet number per plant before anthesis would enable one generation of mass selection and recombination to be completed each year. Methods for increasing the accuracy of spikelet number estimation are discussed. Provided the true heritability value is greater than a quarter of the heritability of total seed yield, annual cycles of selection on spikelet number score would give a faster rate of genetic advance than direct selection for seed yield on seed parents only each year, or on seed and pollen parents every second year. Seed yields greatly exceeding those of current cultivars should be attainable by recurrent selection. There should be no deleterious correlated responses in flowering time, herbage yield or plant height; mature plant weight and harvest index would increase.

Ecological studies of root-nodule bacteria introduced into field environments—6. Antigenic and symbiotic stability in Lotononis rhizobia over a 12-year period

Rhizobia suited to Lotononis bainesii do not occur naturally in Australia. Two serologically distinct strains of African origin were introduced into an isolated field station where perennial Lotononis-pangola grass pastures are grazed. Paddocks varied in the period of rhizobial occupancy from 5–12 years. Stability of four rhizobial characters: colony colour, effectiveness, cell antigens and antibiotic sensitivity were assessed from nodules on persisting Lotononis. Both strains became established throughout the 782 ha. No changes were observed in colony colour or serological reaction. Symbiotically, 8.5% of isolates had a lower N fixing capacity than stock cultures held in the laboratory although there were no ineffective isolates. Change in effectiveness was unrelated to serotype or to time of occupancy. There was also little change in antibiotic sensitivity although one isolate was tolerant to 15 parts/10 6 streptomycin. The red bacterium Protaminobacter rubra was recorded for the first time as a cohabitant of Lotononis nodules. It is concluded that colony colour, serological and symbiotic properties are sufficiently stable to be of use in long-term ecological studies although antibiotic sensitivity appears less stable.

Establishment of Townsville stylo in native perennial grass pastures

In experiments where Townsville stylo (Stylosanthes humilis) was oversown into perennial grass swards dominated by Heteropogon contortus and Bothriochloa bladhii residual stubble reduced the survival of Townsville stylo seedlings. When this stubble was removed, Townsville stylo plants grew to maturity and made up 25 per cent of the dry matter of the sward, an increase of 500 per cent Townsville stylo yield. Frequency of defoliation from 3 to 12 weeks during the growing season had no effect on the proportion of legume in the sward but the yield of all species was less under frequent cutting. Of the two collections of Townsville stylo used, the erect type always gave the highest yield and there was no evidence of an advantage for the prostrate type under frequent cutting. Over a period of three years the erect type invaded plots sown to the prostrate type. The response of Townsville stylo to superphosphate was large whereas that of the perennial native grasses was only slight.

The seasonal growth of lovegrass (Eragrostis curvula) on deep sandy soils in a semi-arid environment

The potential of lovegrass (Eragrostis curvula) as a perennial pasture grass on deep sandy soils in the Western Australian wheatbelt was studied at 20 deep sand sites near Meckering. The seasonal growth pattern of lovegrass resulted in over 80 per cent of annual dry matter yield being produced outside the period of most effective rainfall (April-August). Yields were considerably higher than that of annual pastures on similar soils. Highest grass yields were obtained at sites with a water table within 150 cm of the ground surface. Lovegrass is unlikely to succeed at sites without a water table because of inadequate moisture availability in summer. Two features at present detract from its value as a pasture grass in the region. Slow growth rates in winter reduce its ability to compete with winter growing annual pasture species. Low nutrient concentrations during the warmer months, especially at the highest yielding sites are likely to limit its forage value to stock. The reasons for the low nutrient concentrations are discussed.

Role of Pensacola Bahiagrass Stolon‐Root System in Fertilizer Nitrogen Utilization on Leon Fine Sand1

AbstractAn experiment was conducted with Pensacola bahiagrass (Paspalum notatum Flugge) on Leon fine sand near Gainesville, Fla. for 6 years to determine residual effects of applied N on forage N uptake, and changes in stolons, roots, and soil N. Nitrogen was applied at 0, 112, 224, and 448 kg/ha/year. Except for the control, paired plots were used at each N rate. Nitrogen fertilization was dis. continued on one of each treatment pairs in 1969 and 1970 to determine the residual effect of N. These treatments were resumed in I971. The residual effect of N was small for all treatments, amounting to 8, 41, and 95 kg/ha total N in harvested forage above the control for the 2‐year period for the 112, 224, and 448 kg N rates, respectively. Unrecovered N through 1968 was approximately 200, 350, and 770 kg/ha for the three treatments, respectively. Nitrogen lost from the stolon root systems during 1969 and 1970 through decrease in mass and N concentrations was 60, 100, and 190 kg/ha for the three N treatments, respectively. Little of the unrecovered N could be accounted for by analysis of the surface soil. Lack of residual effect on plant growth confirmed that little available N was in the soil profile to rooting depth. Based on previous studies, leaching appears to have limited importance when N is applied to well‐established perennial grass pastures during the growing season. Conditions imposed in this soil by high water table, large amounts of plant residues, and rapid decomposition during the summer season could make denitrification a significant factor.

Establishment of perennial pasture grasses under a cover crip in a Mediterranean type environment

In a Mediterranean type environment, several cultivars of phalaris and cocksfoot were established successfully in each of three different years under wheat crops sown at 30 or 45 lb an acre. Phalaris was also established under lupins and early-flowering barley, but these crops were less profitable than wheat. Oats suppressed grass establishment more than the other crops. Sowing wheat and grass in alternate rows reduced wheat yield but increased the proportion of grass seeds that produced established plants. It also gave more vigorous growth of the grass plants in the second autumn and winter. Cocksfoot was less sensitive than phalaris to changes in the sowing rate or row spacing of the cover crop. Height, leafiness, or direction of the rows of the wheat cover crop had no effect on the density of grass stands that established. Two experiments indicated that the tendency for wheat to suppress the establishment of undersown grass was due more to competition among the root systems than to competition for light.

Studies on the use of Weedicides in the Eradication of Kikuyu grass in the Nilgiris

Kikuyu grass (Pennisetum clandestinum Hochst) is a vigourous spreading perennial pasture grass with very good soil binding characteristics, coming up well in areas of higher elevations above 5000 feet, such as on Nilgiris, Pulneys etc. Though its value as a pasture or fodder grass is undisputed, its presence in a cultivated field (as on the faces of terraces in the hills) is undesirable since it becomes a troublesome weed to eradicate, if not kept in constant check. Leaving the lands fallow for even a season or two results in the complete cover of the cultivable terraces of this grass, by means if its rapid growing underground shoot system, which goes even to depth upto 2. This makes it necessary that, for its eradication, the land should be dug upto not less than 2' depth, involving much labour and cost. It was estimated that it cost nearly Rs. 300/- per acre of level ground or Rs. 160/- per acre of cultivated terraces for the manual digging and removal of this grass. For the continued protection of the soil from the faces of the terraces in the hills, it is therefore, necessary to evolve suitable quick and economical methods of eradicating the Kikuyu grass and its replacement with other improved grasses. Chemical weedicides offer good scope in such a programme. The principles and methods of chemical weed control are dealt with in detail by Crafts and Robbins (1962). The results of a study in this direction, carried out in the hills at Ootacamund for the last two years is presented in this paper.

Environmental Control of Reproductive Development in Hordeum bulbosum, a Perennial Pasture Grass

Environmental Control of Reproductive Development in Hordeum bulbosum, a Perennial Pasture Grass

ENVIRONMENTAL CONTROL OF REPRODUCTIVE DEVELOPMENT IN HORDEUM BULBOSUM, A PERENNIAL PASTURE GRASS

Koller, D. (Hebrew U., Jerusalem, Israel), and H. R. Highkin. Environmental control of reproductive development in Hordeum bulbosum, a perennial pasture grass. Amer. Jour. Bot. 47(10): 843–847. Illus. 1960.—The interaction between growth temperature, daylength and vernalization in the control of reproductive development of Hordeum bulbosum was investigated under controlled conditions. The plants are completely vernalizable. Initiation of flowering in unvernalized plants was under strict photoperiodic control at warm growth temperatures and independent of it at cooler ones. Plants in which flowering had been induced, by whatever means, behaved as strict requirers of long days, as far as completion of heading was concerned. The possibility that induction of flowering by vernalization and by photoperiod operate along the same pathway is discussed.

A Very Promising Drought Resistant Fodder Grass for South India.

The problem of producing good fodder grasses and improving the pastures has been engaging the attention of many in the development of Indian Agriculture &amp; Livestock. Good pastures not only provide an excellent feed, but they reduce the labour and expense in- volved in Livestock production and maintenance by supplying the essential nutrients for body development. Improved pastures and improved live- stock always go hand in hand. In South India there are over a dozen good perennial pasture grasses of which only a few form the staple fodder for the South Indian breeds of cattle. The bulk of our cattle which are in the villages depend on the poor local natural pastures or grazing grounds which consist chiefly of annual gresses which spring up with the rains of the monsoons and die after seeding from October to January. There are no regular pastures as in the western countries where they are systematically grazed.