Estimating mass of temperate and tropical pastures in the subtropics

1993 ◽  
Vol 33 (7) ◽  
pp. 865 ◽  
Author(s):  
WJ Fulkerson ◽  
K Slack
Keyword(s):  
Substantial Reduction ◽  
Ground Level ◽  
Regression Equations ◽  
Tropical Pastures ◽  
Senescent Leaf ◽  
Temperate Pastures ◽  
Second Year ◽  
Single Regression ◽  
Separate Regression ◽  
Subtropical Environment

The feasibility of estimating, with acceptable precision, temperate and tropical pasture mass in a subtropical environment was evaluated. For the tropical grasses kikuyu (Pennisetum clandestinum) and setaria (Setaria ancepts), 3 different pasture meters were calibrated against 1 of 3 dry matter (DM) estimates. Temperate pastures (predominantly Lolium perenne and Trifolium repens) were evaluated using the Ellinbank rising plate meter (RPMl) calibrated against DM to ground level. A single regression equation was developed for syegrass-white clover pasture from data pooled within season over first- and second-year swards. The s.e. of estimate (s.e.e.) for assessing tropical grass pasture mass using RPMl was similar to that for a heavier Ellinbank meter and substantially lower than that for the electronic pasture probe. Using RPMl, separate regression equations were required for early (November-February) and late (March-May) season determinations for both kikuyu and setaria. The regression equations were based on calibrations against shoot DM (>5 cm stubble height for kikuyu and 6 cm for setaria) and are only applicable to well-managed and highly utilised pastures. Calibrations of all pasture meters over all months to green DM (senescent leaf and stem removed) gave a lower s.e.e. than total DM (kikuyu 138 v. 177 kg DM/ha, n = 171; setaria 211 v. 224 kg DM/ha, n = 177) whilst shoot DM gave a more substantial reduction in s.e.e. (kikuyu 95 v. 147 kg DM/ha; setaria 140 v. 193 kg DM/ha).

Relation Between Refractive Index, Specific Gravity, and Total Solids of Tomato Juice, Puree, and Paste

1967 ◽  
Vol 50 (3) ◽  
pp. 690-700
Author(s):  
Frank C Lamb
Keyword(s):  
Refractive Index ◽  
Specific Gravity ◽  
Tomato Juice ◽  
Regression Equations ◽  
Total Solids ◽  
Pectic Enzymes ◽  
Tomato Paste ◽  
Aoac Method ◽  
Solids Content ◽  
Separate Regression

Abstract Total solids by drying, refractive index, and specific gravity were determined on about 375 commercial samples of tomato juice, puree, and paste. Refractive index was determined with and without dilution of tomato paste; pectic enzymes were used to aid filtration and centrifugation. A new specific gravity bottle was used. The new AOAC method for total solids was compared with the former AOAC method on 115 samples. Variations from previous tables relating refractive index and total solids were of little significance up to 20% solids but were increasingly greater as solids increased above 20%. Data obtained in these studies showed lower values for total solids than the old tables in most instances. Separate regression equations had to be calculated for the solids content of the diluted and undiluted samples. Total solids by the official AOAC method was the most precise of the methods used. However, specific gravity and refractive index were both found to have satisfactory degrees of precision

scholarly journals Atmospheric Circulation Effects on Wind Speed Variability at Turbine Height

2007 ◽  
Vol 46 (4) ◽  
pp. 445-456 ◽  
Author(s):  
Katherine Klink
Keyword(s):  
Wind Speed ◽  
Pressure Gradient ◽  
Large Scale ◽  
Ground Level ◽  
The Arctic ◽  
Circulation Index ◽  
Regression Equations ◽  
Change Models ◽  
Wind Speeds ◽  
The North

Abstract Mean monthly wind speed at 70 m above ground level is investigated for 11 sites in Minnesota for the period 1995–2003. Wind speeds at these sites show significant spatial and temporal coherence, with prolonged periods of above- and below-normal values that can persist for as long as 12 months. Monthly variation in wind speed primarily is determined by the north–south pressure gradient, which captures between 22% and 47% of the variability (depending on the site). Regression on wind speed residuals (pressure gradient effects removed) shows that an additional 6%–15% of the variation can be related to the Arctic Oscillation (AO) and Niño-3.4 sea surface temperature (SST) anomalies. Wind speeds showed little correspondence with variation in the Pacific–North American (PNA) circulation index. The effect of the strong El Niño of 1997/98 on the wind speed time series was investigated by recomputing the regression equations with this period excluded. The north–south pressure gradient remains the primary determinant of mean monthly 70-m wind speeds, but with 1997/98 removed the influence of the AO increases at nearly all stations while the importance of the Niño-3.4 SSTs generally decreases. Relationships with the PNA remain small. These results suggest that long-term patterns of low-frequency wind speed (and thus wind power) variability can be estimated using large-scale circulation features as represented by large-scale climatic datasets and by climate-change models.

Perceived Social Norms for Intimate Partner Violence in Proximal and Distal Groups

2015 ◽  
Vol 30 (4) ◽  
pp. 691-698 ◽  
Author(s):  
Tricia H. Witte ◽  
Mazheruddin M. Mulla ◽  
Alicia A. Weaver
Keyword(s):  
College Students ◽  
Intimate Partner Violence ◽  
Social Norms ◽  
Partner Violence ◽  
Intimate Partner ◽  
Intervention Programs ◽  
Female College Students ◽  
Regression Equations ◽  
Same Sex ◽  
Separate Regression

This study investigated students’ perceived descriptive social norms for intimate partner violence (IPV) among proximal and distal groups at college. Male and female college students estimated the prevalence rates for IPV among same-sex friends (proximal group) and same-sex “typical students” (distal group). In separate regression equations for men and women, perceived estimates of IPV rates for same-sex friends, but not estimates for same-sex typical students, were positively related with the participants’ own IPV behaviors. Findings have important implications for IPV prevention and intervention programs for college students.

scholarly journals The job demand-control model of job strain across gender

2006 ◽  
Vol 32 (1) ◽  
Author(s):  
Gideon P De Bruin ◽  
Nicola Taylor
Keyword(s):  
Item Response ◽  
Job Strain ◽  
Regression Equations ◽  
Theory Analysis ◽  
Men And Women ◽  
Job Demand ◽  
Item Response Theory Analysis ◽  
Stress Inventory ◽  
Demand Control ◽  
Separate Regression

This study investigated (a) the structural and measurement equivalence of measures of the job demand-control (JDC) model of job strain for men and women (as operationalised by the Sources of Work Stress Inventory), (b) whether a common or separate regression equations should be used for men and women in the JDC model, and (c) the strain and buffer hypotheses associated with the JDC model. These objectives were pursued by means of factor analysis, item response theory analysis, and moderated hierarchical multiple regression analysis. The results show that the use of a common regression equation might give biased results. The results also provided stronger support for the strain hypothesis than for the buffer hypothesis. Opsomming Hierdie studie het ondersoek ingestel na (a) die strukturele en metingsekwivalensie van metings van die werkseisekontrole (WEK) model van werkspanning vir mans en vroue (soos geoperasionaliseer deur die Bronne van Werkstresinventaris), (b) die wenslikheid van ’n gemeenskaplike teenoor afsonderlike regressievergelykings vir mans en vroue, en (c) die spanning en buffer hipoteses wat met die WEK model geassossiëer word. Hierdie doelstellings is ondersoek aan die hand van faktorontleding, item responsteorie-ontleding en gemodereerde hiërargiese meervoudige regressie-ontleding. Die resultate wys dat die gebruik van ’n gemeenskaplike regressievergelyking sydige resultate mag oplewer. Die resultate toon verder sterker ondersteuning vir die spanning hipotese as vir die buffer hipotese.

Effect of soil fertility, weed competition, defoliation and legume seeding rate on establishment of tropical pasture species in south-east Queensland

1975 ◽  
Vol 15 (72) ◽  
pp. 54 ◽  
Author(s):  
RM Jones
Keyword(s):  
Soil Fertility ◽  
Low Fertility ◽  
First Year ◽  
Weed Competition ◽  
High Fertility ◽  
Tropical Pasture ◽  
Seeding Rate ◽  
Tropical Pastures ◽  
Prairie Soil ◽  
Second Year

An experiment was sown at two contrasting sites in south-east Queensland to study the response of tropical pasture species in the establishment and second year to treatments imposed during the establishment year. Sowing was into fully prepared seed-beds on a nitrogen deficient low humic gley at Beerwah and a fertile prairie soil at Samford. Limiting nutrients, other than nitrogen, were supplied by fertilizer. The treatments were: two pastures (Macroptilium atropurpureum cv. Siratro/Setaria anceps and Desmodium intortum cv. Greenleaf/setaria anceps), three legume seeding rates, two defoliation systems in the establishment year, and presence or absence of severe annual grass weed competition. In the establishment year there were large treatment effects on the yields of sown pasture species. Sown weeds had a great effect, particularly on the high fertility site where they reduced setaria, desmodium and siratro yields by factors of approximately 50, 10 and 2 respectively. Legume yields increased with legume seeding rates. The sum of legume yields from the regularly cut treatments was only one-half to one-quarter that of the single end of season cut, whereas total grass yields were similar in both treatments. However, all first year treatments had much less effect in the second year, when legumes comprised about 70 per cent of mixtures at the low fertility site and 30 per cent of mixtures at the high fertility site. Some comments are made about this role of soil fertility in the dynamics of pasture establishment and about future lines of research. Results from this and other experiments suggest that pasture establishment problems on fully prepared seed-beds are not a major limitation to the wider use of tropical pastures in south-eastern Queensland.

scholarly journals Allometric models for estimating the phytomass of a secondary Atlantic Forest area of southeastern Brazil

2008 ◽  
Vol 8 (4) ◽  
pp. 131-136 ◽  
Author(s):  
Déborah Moreira Burger ◽  
Welington Braz Carvalho Delitti
Keyword(s):  
Atlantic Forest ◽  
Pearson Correlation ◽  
Linear Regression Analysis ◽  
Tree Height ◽  
Ground Level ◽  
Dry Weight ◽  
Southeastern Brazil ◽  
Regression Equations ◽  
Aboveground Phytomass ◽  
Constant Weight

The purpose of this study was to develop and validate equations to estimate the aboveground phytomass of a 30 years old plot of Atlantic Forest. In two plots of 100 m², a total of 82 trees were cut down at ground level. For each tree, height and diameter were measured. Leaves and woody material were separated in order to determine their fresh weights in field conditions. Samples of each fraction were oven dried at 80 °C to constant weight to determine their dry weight. Tree data were divided into two random samples. One sample was used for the development of the regression equations, and the other for validation. The models were developed using single linear regression analysis, where the dependent variable was the dry mass, and the independent variables were height (h), diameter (d) and d²h. The validation was carried out using Pearson correlation coefficient, paired t-Student test and standard error of estimation. The best equations to estimate aboveground phytomass were: lnDW = -3.068+2.522lnd (r² = 0.91; s y/x = 0.67) and lnDW = -3.676+0.951ln d²h (r² = 0.94; s y/x = 0.56).

BIOLOGY OF STEREMNIUS CARINATUS (COLEOPTERA: CURCULIONIDAE), A REFORESTATION PEST IN COASTAL BRITISH COLUMBIA

1968 ◽  
Vol 100 (4) ◽  
pp. 386-394 ◽  
Author(s):  
S. F. Condrashoff
Keyword(s):  
British Columbia ◽  
Field Tests ◽  
Ground Level ◽  
Selective Feeding ◽  
Coniferous Species ◽  
Above Ground Level ◽  
Brood Development ◽  
Second Year ◽  
Coastal British Columbia ◽  
Root Collar

AbstractSteremnius carinatus (Boheman), once considered a scavenger, has become recognized as a pest of coniferous seedlings. The weevils breed in roots of fresh stumps and in buried slash on logged areas, and adults emerge by the end of the second summer after logging. Adults girdle young seedlings from near the root collar to 1 in. above ground level, but seldom attack the second year after planting. Adult weevils are long-lived, and can survive three or more winters, establishing broods each spring. They eat a wide variety of vegetation and fruits and other materials containing sugars and starches. Greenhouse trials demonstrated selective feeding on seedlings and field tests showed that the weevils breed in most coastal coniferous species in British Columbia. Rates of brood development ranged from 2 months at 80°F to 24 months in unheated outdoor conditions. Differences in rates of development, apparently related to temperature, were found between localities. Phloem may be suitable for oviposition 2 years after logging, but often is depleted by the feeding of other bark-mining beetles. Although some weevil damage is caused by emergents from stumps on rights-of-way, damage from larger populations emerging later from newly-cut sites may be reduced by planting immediately after cutting.

scholarly journals EFFECTS OF SPACING ON DRY MATTER YIELDS OF F1PENNISETUM HYBRIDS AND ELEPHANT GRASS (PENNISETUM PURPUREUM SCHUM)

2021 ◽  
Vol 11 (2) ◽  
pp. 105-109
Author(s):  
M. E. Aken'ova ◽  
H. R. Chheda
Keyword(s):  
Dry Matter ◽  
Linear Regression Analysis ◽  
Local Strain ◽  
Ground Level ◽  
Pennisetum Purpureum ◽  
First Year ◽  
Elephant Grass ◽  
F1 Hybrid ◽  
Second Year

Crown splits of three bulrush millet (Pennisetum americanum) (L) K Schum) x elephant grass F1 hybrid genotypes and an improved local strain of elephant grass were set every 30, 45, 60 and 90 cm in rows 90 cm apart to ascertain the effects of spacing on forage dry matter (DM) yield. Plants were harvested by cutting 30 cm above ground level every 5 weeks during the late rainy season of the first year (4 harvests) and the rainy session of the second year (7 harvests). There were significant differences in DM yields between spacing treatments, as well as between genotypes. When averaged over genotypes, total DM yield in the two years of study at 90 x 30, 90 X 45, 90 x 60 and 90 x 90 cm were 31.16, 27.27, 25.75 and 23.13 t/ha, respectively. Genotype x spacing interaction for DM yield was not significant. Spacing, in general, had no appreciable effects on forage quality so that linear regression analysis revealed no relationship between spacing on one hand and DM content, percent leaf, crude protein (CP) content, and in vitro organic matter digestibility (IVOMD), on the other. The results indicated that close spacing can be utilized to increase DM yields of F1 Pennisetum hybrids and elephant grass without detriment to quality. 

Comparaison des équations de régression. Application au cubage des arbres d'épinette noire.

1979 ◽  
Vol 55 (2) ◽  
pp. 54-56
Author(s):  
Richard Zarnovican
Keyword(s):  
Black Spruce ◽  
Regression Equation ◽  
Regression Equations ◽  
Soil Drainage ◽  
Total Height ◽  
Reduced Height ◽  
Bartlett Test ◽  
Single Regression

The Bartlett test, parallelism test and coincidence test were applied to compare four regression equations. The comparison dealt with regression equations for reduced height from total height of black spruce for four soil drainages, over till, in the High Subarctic of Quebec. It was found that form height can be extracted from total height by means of a single regression equation where soil drainage is good, moderately good or imperfect, but that a separate equation is required where drainage is poor.

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