Amount Of Grass Research Articles

Effect of Grasshopper (Orthoptera: Acrididae) Density and Plant Composition on Growth and Destruction of Grasses

A study was conducted to determine the effects of grasshopper density and plant composition on grass growth and destruction by the mixed grass- and forb-feedinggrasshopper, Melanoplus sanguinipes (F.). Using a completely randomized design, 125l-m2 cages were placed on plots on mixed-grass rangeland in western South Dakota and stocked with 0, 5, 10, 15, or 20 fifth-instar M. sanguinipes . Grasshopper densities within the cages were monitored approximately weekly, and total grasshopper feeding-days were calculated for each cage for 68 d. Before adding grasshoppers, biomasses of grasses and forbs within the cages were estimated visually and after 68 d, final biomass of vegetation was determined. Results from analysis of variance with regression and multiple regression analysis indicated that grasshopper density and the initial biomass of western wheatgrass and shortgrasses within the cages significantly affected the final biomass and growth of western wheatgrass and the amount of grass removed by grasshoppers. However, significant reductions in grass biomass occurred only in cages stocked with 15 and 20 insects, equivalent to 845 and 1,112 grasshopper feeding-days, respectively. Grasshopper density had no significant effect on biomass of shortgrasses and Japanese brome, although growth of these species was affected by initial biomass of grasses in the cages.

The Composition and Energy value of Big Bale Grass Silages

In recent years the quantity of grass silage as big bales has increased substantially, both in the UK and elsewhere. Eyers (1989) reported that about 16% of the grass silage dry matter (DM) conserved in England and Wales was in the form of big bales.Whilst there is now considerable information on the composition, nutritive value and laboratory procedures for predicting the digestibility and energy value of clamp silage, there are few comparable data for big bale silages. The objectives of the present work were to examine the composition, digestibility and energy value of a population of big bale silages and to compare relationships between laboratory measurements and digestibility in vivo with those derived earlier for clamp silages (Givens et al., 1989).

Manipulation of ley pastures with herbicides to control take-all

The effect of grass-selective and broad-spectrum herbicides in pasture:wheat rotation experiments were studied from 1981 to 1986 at Esperance, W.A. The quantity of pasture and the proportion of grass present in the pasture phases were determined. Pastures were grazed by sheep. Incidence and severity of take-all and grain yield were measured in the wheat phases. The rotations studied were either a 2 year pasture: 1 year crop or 1 year pasture: 1 year crop. Herbicide treatments greatly decreased the grass content of pastures in the year of application, and this effect carried over to the second year in the 2 year pasture: 1 year crop rotation. Herbicide reduced total pasture yield in the year of application, but not in the year following. Herbicide treatment of pastures decreased the incidence and severity of take-all in the following wheat crop. Crop yields were increased following treated pastures and to a greater extent than could be exdained bv decreased take-all alone. Incidence of take-all depended primarily upon the quantity of grass in the previous pasture (5.4% incidence of take-all per 100 kg ha-1 grass dry matter in the previous pasture). Incidence of take-all was also related to the incidence of take-all in previous wheat crops and the quantity of grass in the pasture in the preceding two years.

The colonization of a tropical grassland by Stylosanthes from seed transported in cattle faeces

The dynamics of the spread of four Stylosanthes species by grazing cattle from sown areas to nearby native grassland R& studied over ten years in the dry tropics of north Queensland. The first recruitment of Stylosanthes in the grassland occurred during the third growing season. Secondary colonization took place around the primary plants, and by the tenth year, 94% of the 0.25 m2 quadrats sampled in the grassland contained one or more species of Stylosanthes. Large seed numbers were produced by Stylosanthes on the sown areas during primary colonization. Mean yields of above-ground biomass were high (4000 kg ha-1year-1) despite heavy grazing pressures, and 6% of this biomass was channelled into seed production (25 000 seeds kg biomass-1). Seed content in the cattle faeces reached a peak at the end of the wet season and accounted for 8% of seed production. The numbers of seeds in the faeces were highly correlated with the numbers of seeds produced on the sown areas. Only 1.5% of the seed excreted in the grassland grew into established plants despite most seeds being viable. Varying the amount of grass had little effect on establishment. The two short-lived herbaceous species, S. guianensis and S. hamata, were more efficient colonizers (i.e. produced more seedlings per unit biomass) than the more perennial shrubby types, S. scabra and S. viscosa. The former two species produced more seeds per unit biomass and more plants per unit of seed in the faeces.

Pasture Characteristics Affecting Spatial Distribution of Utilization by Cattle in Mixed Brush Communities

Utilization patterns of cattle were related to pasture characteristics in a nonrandom and complex manner. Six mixed brush pastures on the Rio Grande Plains (244-356 ha) that were topographically flat and homogeneous in soil type and range sites were studied. Two experiments were conducted: the first experiment was conducted when green forage was abundant and the second under conditions of little vegetative regrowth. A total of 340 random points were characterized for amount, frequency, and greenness of both grasses and forbs, brush and shade tree density, and distance to nearest fence, road, and water. These are variables that can be altered with management practices. When green forage was abundant, factor analysis identified 5 orthogonal factors (green herbage availability, grass quantity, brush abundance, remoteness from roads, and water availability) which accounted for 70% of the communal variation. Six factors (brush abundance, grass quantity, green forb frequency, road location, fence proximity, and water availability) accounted for 70% of the communal variation when herbage was limited. Regression analyses predicting percent utilization from the orthogonal factors indicated that when green forage was abundant, utilization was related largely to green herbage availability, grass quantity, brush abundance, and remoteness (R2 = 0.54, RSD = 0.114). Remoteness, brush abundance, green forb frequency, and water availability were the factors associated with utilization when forage was limited (R2 = 0.45, RSD = 0.152). Green herbage availability was less important under conditions of limited forage. In mixed brush communities, the actual amount of grass, brush abundance, and remoteness were the major factors affecting utilization.

Feeding in the two phytophagous beetles Hydromedion sparsutum and Perimylops antarcticus from South Georgia

The consumption of fresh plant materials by adults and larvae of Hydromedion sparsutum and Perimylops antarcticus (Col., Perimylopidae) was estimated from the production of faecal pellets and amount of excreted plant remnants as dry weight. Adults and larvae of Hydromedion consumed large quantities of grasses, including the alien Poa annua, but smaller amounts of the indigenous great burnet, Acaena magellanica. Both stages of Perimylops consumed much smaller quantities of grasses and Acaena. Different species of mosses were eaten in both species, and appeared to be a major source of food for Perimylops in addition to microphytes on rocks. The consumption of mosses and microphytes reflects the adaptation of Perimylops to living in habitats at higher altitudes (e.g. above 200 m), where other plants are scarce.

Evaluation of management options for increasing the productivity of tropical savanna pastures. 3. Trees

The effect of killing trees upon the production and quality of native perennial grasses, Themeda triandra, Chrysopogon fallax, Sehima nervosum, and Sorghum plumosum, and oversown legumes from the genus Stylosanthes, was studied over 4 years at Katherine, in the semi-arid tropics of northwestern Australia. The pastures were either unfertilised or received low inputs of superphosphate, and for each fertility level were grazed at 3 stocking rates. At no time were legume yields affected by killing the trees but, in the first 3 years, the amount of grass was approximately twice as much when the trees were killed. During this period the mean grass yields declined 4-5 fold from about 2.2 t/ha. By the fourth year the advantage from tree killing upon grass yield was apparent only at the lowest stocking rates at each fertility level. Nitrogen concentrations of the grasses and legumes, with the exception of S. hamata, were increased 7 and 10% respectively above the mean annual values of 0.89 and 1.75% where the trees were killed, while the phosphorus and sulfur concentrations were not affected. Tree killing had no effect upon wet season liveweight gains during the last 2 years of the experiment. However, there were some benefits during the dry season when weight losses were lower for most treatments during the early dry season (June-September) and also lower for the lowest stocking rate treatment without fertiliser during the late dry season (October-November).

Mate choice and reproductive success of pikas

Factors affecting mate choice and female reproductive success were studied in a population of pikas, Ochotona princeps, in northeastern Oregon. Features of the den habitat (number of entrances to the den, size of the surrounding talus, distance to vegetation, amount of grass and forb present) and the mate or potential mate (weight and age) were analysed with respect to their effects on offspring production and survival, maternal survival and female mate choice. Female pikas chose mates primarily on the basis of the type of den available and the distance from the den to vegetation. These features were the primary determinants of the number of young weaned, but had no significant effects on maternal survival. Paternal weight was an important influence on offspring production, but its effect on female fitness was tempered by a negative effect on female survival. Characteristics important to female choice had no significant influence on the survival of young between weaning and natal dispersal and so cannot be considered to be male ‘handicaps’. Male pikas tended to be philopatric so that sons of males with territories that were attractive to females tended to inherit the attractive territories of their fathers. Female choice among pikas is thus best explained by Darwin's and Fisher's theories of intersexual selection.

The effect of level of concentrate supplementation in winter and grazing allowance on the milk production and financial performance of spring-calving cows

ABSTRACTAn experiment with a 2 × 2 factorial design was used to assess the effects of offering either 6 (L6) or 12 (H12) kg concentrates daily from day 13 of lactation until turnout to grazing with grass silage (600 to 620 g digestible organic matter per kg dry matter (DM)) ad libitum and either ad libitum (G) or restricted (g) quantities of grass from turnout to the end of August. In each of 3 years, 60 to 70 January- to March-calving British Friesian cows were used. From calving until turnout to grazing the mean daily DM intakes of silage were 7·2 and 8·9 kg, and of concentrates 8·5 and 4·9 kg for the H12 and L6 groups respectively, giving a mean substitution rate of 0·47 kg silage DM per kg concentrate DM. Mean daily milk yields were 26·7 and 22·9 kg giving a direct response of 0·85 kg/kg additional concentrate DM. Milk from the L6 group had a higher fat concentration and these cows were also lighter at the end of the winter. At pasture, there were no significant interactions for milk variates between winter treatments and grass availability. The stocking rate of cows with restricted grass availability was 0·33 higher from turnout to the end of August. It resulted in a 0·10 proportional reduction in milk yield per cow but per ha there was a 0·21 proportional increase. At pasture, the H12 cows gave more milk at both grass availabilities. The total responses to concentrates were 1·59 and 2·11 kg milk per kg concentrate DM at the ad libitum and restricted grass availabilities respectively. The good response to concentrate coupled with a 0·35 cow per ha increase in annual stocking rate as a result of restricting the grazing area ensured that gross margins and grass utilization were highest for the H12g cows. Conception rates were similar on all treatments and there were no significant differences in live weight at the end of lactation.

Yield and persistence of irrigated lucernes cut at different frequencies, at Tamworth, New South Wales.

Three irrigated lucerne cultivars, Pioneer Brand 545 (winter dormant), Condura 73 Brand (semiwinter dormant), and CUF 101 (highly winter active), were harvested at fixed cutting intervals of either 25, 28 ,35, 42 or 48 days from September to April in each of four years. This paper reports the effects of these cutting frequencies on the dry matter yield, leaf to stem ratio and persistence of these cultivars. The effect of cutting frequency on mean total yield (the sum of the mean yields for each harvest) was significant (P<0.05) in each year of the experiment, except year 3. Yields were highest in the 35-day cutting frequency in years 1 and 2. In the fourth year of the experiment the mean total yield of Pioneer Brand 545 and Condura 73 Brand was 29% higher (P<0.05) than CUF 101. By the fourth year substantial amounts of grass were present in the 25- and 28-day cutting interval plots. The contrasts between dormant and active cultivars for the dry matter yield of each of the individual harvests were not consistent in the first two years. In the third and fourth years the active initially outyielded the dormant cultivars at all cutting intervals, but yields of both were generally similar at the end of the season. Increasing the interval between successive harvests generally decreased the mean leaf to stem ratio. The ratio of leaf to stem for CUF 101 was significantly lower (P<0.05) than that for Pioneer Brand 545, with Condura 73 Brand tending to be intermediate. Within cutting intervals, mean declines in plant persistence were similar for cultivars from the different dormancy groups. Largest changes in plant frequency occurred in the fourth year when the mean frequency for the 25- and 28-day plots decreased from 69 to 12% compared with a mean decline from 74 to 65% for the 42- and 48-day cutting intervals. Productive stand life in this experiment was 3 years, even though disease was negligible. Under these conditions grass invasion was mainly related to harvest interval and much less to cultivar dormancy.

The influence of soil wetness on utilized output from grassland on commercial farms

AbstractRecords of grassland productivity have been used for 93 farms in 1975–76 (a dry year) and 117 farms in 1977–78 (a wetter year). The samples were selected to contrast well‐drained and poorly/ badly drained farms and were further subdivided into dairy and beef. The number of farms in each of the four subsamples for each year was between 19 and 32. In addition the number of days on which the soil was at meteorological field capacity (field capacity days) on each farm was calculated.The mean utilized metabolizable energy (UME) output within the dairy sample was 45 GJ ha−1 on both well‐drained and poorly/badly drained farms. Within the beef sample the output was 41 GJ ha−1 on well‐drained farms and 37 GJ ha−1 on the poorly/badly drained farms.The correlation between fertilizer N and UME output was stronger on well‐drained farms than on the poorly/badly drained farms in the wetter year (r = 0.69 v. 0.16 on dairy farms; r = 0.56 v.− 0.12 on beef farms). In the drier year the converse was found (r=0.15 v. 0.49 on dairy farms; 0.13 v. 0.44 on beef farms). The effect of field capacity days on output was inconsistent; only within the dairy sample in the wetter year did increased wetness appear to reduce output.It is suggested that soil wetness may have only a small effect on utilized output from grassland on a whole‐farm basis because (i) most farms have at least some well‐drained land, (ii) much of the utilization damage occurs in relatively short periods in spring and autumn and (iii) despite having utilization problems, badly drained land is capable of growing large quantities of grass.

A model of pasture utilisation and ewe performance at mating in an upland flock

The amount of grass 8 weeks prior to mating, the condition of the ewe at that time, the stocking rate and the rate of herbage growth in the late summer and autumn will determine the condition score and ewe liveweight achieved at mating and during the post-mating period. Evidence suggests that for Greyface ewes, lambing rate increases with an increase in condition score at mating up to 3 provided that the achieved condition score can be held for 4-6 weeks post-mating.

Influence of Range Seeding on Rodent Populations in the Interior of British Columbia

This study was designed to determine the influence of range seeding on rodent populations inhabiting cutover lodgepole pine forest land in the interior of British Columbia, Canada. Both deer mice and voles were strongly attracted to an area seeded with grass mixture in the early spring, even though overwinter mortality had dramatically reduced the average density to <2 animals/ha. Five rodents as well as several seed-eating birds appeared on this seeded area while no animals were recorded on a nearby control. Subsequent seeding experiments in the summer also produced significant increases (2 to 2.2 times) in rodent populations. Success of range seeding in B.C. can be quite variable, possibly due to seed predation by mice and voles. Consequently, both the quality and quantity of seed remaining for germination and forage production may be radically altered. Grass seeding of cutover forest land is designed to improve range conditions for cattle grazing in many parts of western Canada and the United States. These seedings are successful in some areas but do not produce the expected growth of forage in other localities. There are probably several factors responsible for this inconsistency, but one potential problem is rodent predation on the grass seed. Seed predation by the deer mouse (Peromyscus maniculatus) has contributed to the failure of several range seeding projects (Howard 1950, Casebeer 1954, Johnson 1961, Nord 1965, Nelson et al. 1970). Everett et al. (1978) have reviewed the range seed preferences of deer mice. Voles of the genus Microtus spp. also harvest large quantities of grass seed (Batzli and Pitelka 1970, Marshall and Jain 1970, Borchert and Jain 1978). These microtines usually inhabit grassland areas but may also occur on interior logged sites (Radvanyi 1973, Sullivan and Sullivan 1982). Little quantitative information is available on the response of rodent populations to range seedings. To determine the influence of range seeding on deer mice and voles and devise suitable control methodology for reduction of seed predation, a preliminary assessment of rodent populations is required. This study was designed to monitor rodent populations before and after grass seeding of cutover lodgepole pine (Pinus contorta) forest lands.

Influence of rest interval, grazing duration and mowing on the growth, mineral content and utilization of a lucerne pasture in a subtropical environment

SUMMARYThe influence of rest interval and grazing duration on herbage production of dryland lucerne (Medicago sativa L., cv. Hunter River) pastures was studied in a 6-year experiment on a black earth in subtropical southern Queensland. Rest intervals (R) of from 32 to 60 days were combined with grazing durations (G) of 4, 8 or 16 days, or with mowing (M), in the following treatments: (1) R32-4, (2) R32-G16, (3) R44-G4, (4) R44-G16, (5) R56-4, (6) R40-G8, (7) R36-M, (8) R48-M and (9) R60-M. Grazing was with sheep at a rate equivalent to 20/ha on a year-round basis. Amounts of dry matter of lucerne and of volunteer species on offer were measured prior to grazing or mowing, and some measurements of the residue remaining after grazing were made. Chemical composition of representative lucerne samples was also determined.Mean total amount of lucerne on offer declined from 10·8 to 7·2 t/ha/year between the first 2 years and the last 2 years, whereas total amount of volunteer species, principally grasses, increased from 3·0 to 18·2 t/ha/year over the same period. This difference was partly due to lower utilization of volunteer species. The decrease in amount of lucerne was due to loss of plants, and treatment effects arose through differences in the degree to which amounts from individual surviving plants increased to compensate for stand thinning. Concentrations of mineral elements in lucerne were always above critical levels for plant and animal growth.Treatment R40-G8 maintained the largest amounts of lucerne on offer to the end of the experiment, with treatments R32-G4 and R32-G16 then having least. Large amounts of grass were associated with 4-day grazing, and to a lesser extent with short rest periods. The results confirm the need for a minimum rest period between grazings in a subtropical environment and also show the need for grazing to control excessive grass growth as well as lucerne if lucerne productivity is to be ensured. Some requirements which would lead to more successful management of lucerne in the subtropics are discussed.

Survivorship, Spatial Pattern, and Habitat Structure of Field Crickets (Orthoptera: Gryllidae) in Two Old Fields

This study was designed to describe patterns in abundance and habitat structure of populations of field crickets (Orthoptera: Gryllidae) in old fields in northeastern Ohio. Vegetation and crickets were sampled at regular spatial intervals in two old fields in close proximity. Vegetation was sampled in June 1980. Crickets were sampled biweekly from 25 June to 17 October 1980 in the larger north field, and they were sampled sporadically from 17 July to 28 August 1980 in the south field. In the north field, the cricket assemblage was dominated by Allonemobius allardi . Abundance of all Nemobiinae peaked at mid to late July, and first adults appeared 21 August 1980. Immature Nemobiinae were spatially aggregated, and adults of the two species of Nemobiinae, A. allardi and Eunemobius carolinus carolinus , were independently distributed throughout the north field. Densities of immature Nemobiinae were positively correlated with amount of grasses in each quadrat and negatively correlated with total cover of vegetation. The south field differed from the north field in composition of vegetation, dominated by orchard grass, and in composition of crickets, dominated by E. c. carolillus . Nemobiinae nymphs were aggregated in mid-July, but adults of both species were randomly distributed at later dates. Density of Nemobiinae nymphs within each quadrat was related to grass dominance, peaking at intermediate levels of grass dominance, but density of nymphs was unrelated to total cover.

Comparison between tracer calves and herbage samplings for the assessment of pasture infectivity in trichostrongylosis of cattle

Two trials were designed in “Haute Normandie” to assess the value of the number of third stage larvae in herbage samples for monitoring the infection of cattle. Two techniques of sampling were used and were compared to the actual infection of tracer calves. An index of infectivity of the pasture was defined: the number of third stage larvae in 1 kg of dry matter of herbage multiplied by the quantity of grass (dry matter) ingested by calves. There was a significant correlation between this index and the actual worm burdens of tracer calves when parasites were numbered by genera, and for heerbage samplings done according to “classical” techniques. The correlation is improved when data are combined from samples taken “close to fecal pats” and “far from fecal pats”.

Forage and Livestock Production Following Oak (Quercusspp.) Control with Tebuthiuron

Aerial applications of 20% tebuthiuron JA/-[5-(1,1- dimethylethyl) - 1, 3, 4 - thiadiazol-2 -yl] -N, N' dimethylurea pellets at 2.2 or 4.4 kg/ha in the spring to heavy brush cover in Texas Post Oak Savannah did not increase the amount of grass, compared to that of untreated pastures, until the growing season after application. By the second growing season after tebuthiuron application, however, native grass stands were composed of a higher proportion of perennial species of good-to-excellent grazing value than were stands on adjacent, untreated rangeland. Tebuthiuron at 4.4 kg/ha did not improve botanical composition of grass stands, but increased the amount of grass during the second and third growing season after application compared to those where 2.2 kg/ha were applied. Daily steer gains were increased in one experiment in the fall after application of 2.2 kg/ha of tebuthiuron in the spring, but were unchanged after two growing seasons in another. Days of available grazing were increased, however, by the second or third growing season after treatment with 2.2 kg/ha of the herbicide in both experiments.

Observations on the Feeding Ecology of Impala

The distribution, habitat preference, and diet of impala in mixed wooded savanna were studied. In the wet season impala were evenly distributed through the different vegetation types and their diet was predominantly grass, but in the dry season they concentrated in areas of Acacia savanna and changed to a mainly browsing diet. The amount of grass in the diet was related to plant moisture content and recent effective rainfall. The impala selected succulent food rich in crude protein but preferred grazing to browsing when palatable grass was available. These factors and the presence of fallen Acacia pods probably attracted impala to the Acacia areas in winter.

A quantitative study of seasonal foraging by the grass harvesting termite, Trinervitermes geminatus (Wasmann), (Isoptera, Nasutitermitinae) in Southern Guinea savanna, Mokwa, Nigeria.

Trinervitermes geminatus (Wasmann) harvests standing grass tussocks which are cut into pieces and carried back to the nest. During this activity a certain proportion is left on the soil surface as litter whilst some is ingested. Foraging is mainly accomplished during the dry season (mid-October to the end of April) for periods of 2-4 h daily, either early in the morning, in the evening, or occasionally during both morning and evening. The duration and daily pattern of foraging is partly dependent on temperature, with a lower temperature threshold of 20° C and an upper threshold of 35° C below or above which foraging is restricted.The quantity of grass cut down and carried back to the nest by a population of 737 m-2 (3.08 g m-2) was estimated at 60.3 kg ha-1a-1 with approximately 18 kg ha-1a-1 cut and left as litter. Estimated consumption whilst foraging was approximately 20.4 kg ha-1a-1, giving a total consumption of about 81 kg ha-1a-1. Compared with a total estimated grass production of 3157 kg ha-1a-1 and consumption by cattle of 1404 kg ha-1a-1, the quantity of grass removed by T. geminatus, amounting to only 3.1% of the net primary production, did not appear to be economically significant in this locality.

ALFALFA DECLINE AND ITS CAUSE IN MIXED HAY FIELDS DETERMINED BY AERIAL PHOTOGRAPHY AND GROUND SURVEY

Methodology was developed utilizing remote sensing techniques to separate and quantitatively measure the various components of alfalfa (Medicago sativa L.) fields containing void areas as well as short grass and weeds. Infrared color film was exposed over mixed hay fields in the Carp and Vernon regions of eastern Ontario in the spring of 3 successive yr (1974–1976). Ground observations were made to ascertain field conditions to confirm the location and the interpretation of dense or sparse alfalfa, tall or short grass, weeds and void areas on the photographs. In 12 representative fields, the percentage of alfalfa, grass and void areas was determined for each year by image area measurements based on optical densities of the photographs. Analysis of soil and alfalfa root samples from these fields confirmed the absence of the root rot pathogen Phytophthora megasperma Drechs. or any other fungi pathogenic to alfalfa. Saprophytic species of Fusarium and Pythium were prevalent in each field. The genera of nematodes found in the samples were not considered harmful to alfalfa. Therefore, an estimated 14% loss of alfalfa was attributed to winter injury during the 3-yr period. The amount of grass increased by 28% and void areas decreased by 14% in these fields.