Effects of rainfall, moisture stress, and stocking rate on the persistence of white clover over 30 years

1995 ◽  
Vol 35 (7) ◽  
pp. 1039 ◽  
Author(s):  
KJ Hutchinson ◽  
KL King ◽  
DR Wilkinson
Keyword(s):  
Soil Water ◽  
White Clover ◽  
Warm Season ◽  
Late Summer ◽  
Ground Level ◽  
Moisture Stress ◽  
Smoothing Splines ◽  
Water Model ◽  
Stocking Rate

The effects of spring rainfall, critical levels of summer moisture stress, and sheep stocking rates on the persistence of white clover (Trifolium repens cv. Huia) have been evaluated in a 30-year experiment (1964-93) based on sown, well-fertilised pasture. Plant species presence was measured each year as basal cover using a vertical 10-pin frame. Hits at ground level from 800 points/plot were recorded in late September on duplicate plots, which were set-stocked at 3 rates (10, 20 reduced to 15, 30 reduced to 20 d.s.e./ha). A soil-water model based on rainfall and tank evaporation was calibrated against on-site soil water measurements (0-260 mm) and used to predict soil water (mm) for weekly time steps over 30 years. Smoothing of long-term rainfall data (SYSTAT, Lowess) showed an overall decline in warm-season rainfall (October-March), which was punctuated by above-average (1969-74) and average runs of years (1983-90). Flexible smoothing splines (SAS) were used to indicate patterns of yearly white clover presence. For all stocking treatments, there were significant declines in the presence of white clover over 3 decades. At the highest stocking rate, the recovery of white clover following the 1965 drought was poor. Late summer (January-March) moisture stress, defined as the number of weeks when soil water (0-260 mm) was <15 mm, was critical in determining white clover presence in the following spring (September). Rainfall received from October to December generally had a positive effect. These climate-based relationships reinforce the importance of stolon growth and survival as a regenerative strategy for white clover. However, over the 30 years, the species showed decreasing resilience post drought, which suggests a long-term failure of seed-based regeneration. Annual rates of soil nitrogen build-up ranged from 29 to 54 kg N/ha.year and were poorly related to white clover presence in the stocking treatments. Governing mechanisms, based on interactions between seasonal moisture stress, sheep stocking rate, interspecific plant competition, and seed pool dynamics, are proposed to explain the nature of long-term decline in white clover presence in well-fertilised, sown pastures in the Northern Tablelands of New South Wales.

scholarly journals Multi-year objective analyses of warm season ground-level ozone and PM<sub>2.5</sub> over North America using real-time observations and Canadian operational air quality models

2013 ◽  
Vol 13 (5) ◽  
pp. 13967-14035 ◽  
Author(s):  
A. Robichaud ◽  
R. Ménard
Keyword(s):  
Air Quality ◽  
North America ◽  
Warm Season ◽  
Ground Level ◽  
Objective Analysis ◽  
Error Statistics ◽  
Ground Level Ozone ◽  
Air Quality Forecast ◽  
Background Check

Abstract. We present multi-year objective analyses (OA) on a high spatio-temporal resolution (15 or 21 km, every hour) for the warm season period (1 May–31 October) for ground-level ozone (2002–2012) and for fine particulate matter (diameter less than 2.5 microns (PM2.5)) (2004–2012). The OA used here combines the Canadian Air Quality forecast suite with US and Canadian surface air quality monitoring sites. The analysis is based on an optimal interpolation with capabilities for adaptive error statistics for ozone and PM2.5 and an explicit bias correction scheme for the PM2.5 analyses. The estimation of error statistics has been computed using a modified version of the Hollingsworth–Lönnberg's (H–L) method. Various quality controls (gross error check, sudden jump test and background check) have been applied to the observations to remove outliers. An additional quality control is applied to check the consistency of the error statistics estimation model at each observing station and for each hour. The error statistics are further tuned "on the fly" using a χ2 (chi-square) diagnostic, a procedure which verifies significantly better than without tuning. Successful cross-validation experiments were performed with an OA set-up using 90% of observations to build the objective analysis and with the remainder left out as an independent set of data for verification purposes. Furthermore, comparisons with other external sources of information (global models and PM2.5 satellite surface derived measurements) show reasonable agreement. The multi-year analyses obtained provide relatively high precision with an absolute yearly averaged systematic error of less than 0.6 ppbv (parts per billion by volume) and 0.7 μg m−3 (micrograms per cubic meter) for ozone and PM2.5 respectively and a random error generally less than 9 ppbv for ozone and under 12 μg m−3 for PM2.5. In this paper, we focus on two applications: (1) presenting long term averages of objective analysis and analysis increments as a form of summer climatology and (2) analyzing long term (decadal) trends and inter-annual fluctuations using OA outputs. Our results show that high percentiles of ozone and PM2.5 are both following a decreasing trend overall in North America with the eastern part of United States (US) presenting the highest decrease likely due to more effective pollution controls. Some locations, however, exhibited an increasing trend in the mean ozone and PM2.5 such as the northwestern part of North America (northwest US and Alberta). The low percentiles are generally rising for ozone which may be linked to increasing emissions from emerging countries and the resulting pollution brought by the intercontinental transport. After removing the decadal trend, we demonstrate that the inter-annual fluctuations of the high percentiles are significantly correlated with temperature fluctuations for ozone and precipitation fluctuations for PM2.5. We also show that there was a moderately significant correlation between the inter-annual fluctuations of the high percentiles of ozone and PM2.5 with economic indices such as the Industrial Dow Jones and/or the US gross domestic product growth rate.

scholarly journals Transpiration Rate of White Clover (Trifolium repens L.) Cultivars in Drying Soil

2021 ◽  
Vol 12 ◽  
Author(s):  
Lucy Egan ◽  
Rainer Hofmann ◽  
Shirley Nichols ◽  
Jonathan Hadipurnomo ◽  
Valerio Hoyos-Villegas
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Transpiration Rate ◽  
White Clover ◽  
Stomatal Closure ◽  
Significant Difference ◽  
Dry Climates ◽  
Daily Transpiration

Determining the performance of white clover cultivars under drought conditions is critical in dry climates. However, comparing the differences in cultivar performance requires equivalent soil water content for all plants, to reduce the water deficit threshold eliciting stomatal closure. In this study, the objective was to compare the rate of stomatal closure in eighty white clover cultivars in response to soil drying. Two glasshouse experiments were conducted, and the daily transpiration rate was measured by weighing each pot. The transpiration rate of the drought-stressed plants were normalized against the control plants to minimize effects from transpiration fluctuations and was recorded as the normalized transpiration rate (NTR). The daily soil water content was expressed as the fraction of transpirable soil water (FTSW). The FTSW threshold (FTSWc) was estimated after which the NTR decreases linearly. The FTSWc marks the critical point where the stomata start to close, and transpiration decreases linearly. The significant difference (p &lt; 0.05) between the 10 cultivars with the highest and lowest FTSWc demonstrates the cultivars would perform better in short- or long-term droughts.

scholarly journals Multi-year objective analyses of warm season ground-level ozone and PM<sub>2.5</sub> over North America using real-time observations and Canadian operational air quality models

2014 ◽  
Vol 14 (4) ◽  
pp. 1769-1800 ◽  
Author(s):  
A. Robichaud ◽  
R. Ménard
Keyword(s):  
Air Quality ◽  
North America ◽  
Warm Season ◽  
Ground Level ◽  
The United States ◽  
Error Statistics ◽  
Spatiotemporal Resolution ◽  
Ground Level Ozone ◽  
Air Quality Forecast

Abstract. Multi-year objective analyses (OA) on a high spatiotemporal resolution for the warm season period (1 May to 31 October) for ground-level ozone and for fine particulate matter (diameter less than 2.5 microns (PM2.5)) are presented. The OA used in this study combines model outputs from the Canadian air quality forecast suite with US and Canadian observations from various air quality surface monitoring networks. The analyses are based on an optimal interpolation (OI) with capabilities for adaptive error statistics for ozone and PM2.5 and an explicit bias correction scheme for the PM2.5 analyses. The estimation of error statistics has been computed using a modified version of the Hollingsworth–Lönnberg (H–L) method. The error statistics are "tuned" using a χ2 (chi-square) diagnostic, a semi-empirical procedure that provides significantly better verification than without tuning. Successful cross-validation experiments were performed with an OA setup using 90% of data observations to build the objective analyses and with the remainder left out as an independent set of data for verification purposes. Furthermore, comparisons with other external sources of information (global models and PM2.5 satellite surface-derived or ground-based measurements) show reasonable agreement. The multi-year analyses obtained provide relatively high precision with an absolute yearly averaged systematic error of less than 0.6 ppbv (parts per billion by volume) and 0.7 μg m−3 (micrograms per cubic meter) for ozone and PM2.5, respectively, and a random error generally less than 9 ppbv for ozone and under 12 μg m−3 for PM2.5. This paper focuses on two applications: (1) presenting long-term averages of OA and analysis increments as a form of summer climatology; and (2) analyzing long-term (decadal) trends and inter-annual fluctuations using OA outputs. The results show that high percentiles of ozone and PM2.5 were both following a general decreasing trend in North America, with the eastern part of the United States showing the most widespread decrease, likely due to more effective pollution controls. Some locations, however, exhibited an increasing trend in the mean ozone and PM2.5, such as the northwestern part of North America (northwest US and Alberta). Conversely, the low percentiles are generally rising for ozone, which may be linked to the intercontinental transport of increased emissions from emerging countries. After removing the decadal trend, the inter-annual fluctuations of the high percentiles are largely explained by the temperature fluctuations for ozone and to a lesser extent by precipitation fluctuations for PM2.5. More interesting is the economic short-term change (as expressed by the variation of the US gross domestic product growth rate), which explains 37% of the total variance of inter-annual fluctuations of PM2.5 and 15% in the case of ozone.

EVALUATION OF NEW ZEALAND BRED WHITE CLOVER CULTIVARS UNDER ROTATIONAL GRAZING AND SET STOCKING WITH SHEEP

1988 ◽  
pp. 203-206 ◽  
Author(s):  
J.L. Brock
Keyword(s):  
New Zealand ◽  
White Clover ◽  
Large Scale ◽  
Moisture Stress ◽  
Early Summer ◽  
Summer Drought ◽  
Stocking Rate ◽  
Rotational Grazing ◽  
Second Year ◽  
Clover Content

The four New Zealand bred white clover cultivars. Tahora, Hula, Pltau and Kopu were evaluated for two years under a high stocking rate in self contained sheep grazed farmlets comparing year round rotational grazing with set stocking. Tahora was clearly superior under set stocking, yielding 50% more than Huia and 140% more than Pitau and Kopu. Under rotational grazing all performed well with only Kopu showing a 20% advantage. An unseasonal early summer drought in the second year showed all cultivars to be highly susceptible to moisture stress at this time under rotational grazing. Large scale death of clover occurred reducing clover content to 2-3% in autumn with no recovery by mid winter. Under set stocking, although severely wilted, all clovers quickly recovered to their former level following rain The management implications are discussed. Keywords: Tahora. Huia, Pitau, Kopu, grazing management, drought, cultivar choice

General effects of management and grazing by domestic livestock on the rangelands of the Northern Tablelands of New South Wales.

1978 ◽  
Vol 1 (2) ◽  
pp. 174 ◽  
Author(s):  
RDB Whalley ◽  
GG Robinson ◽  
JA Taylor
Keyword(s):  
Species Composition ◽  
White Clover ◽  
Warm Season ◽  
Grazing Intensity ◽  
Application Rate ◽  
Grass Species ◽  
Stocking Rate ◽  
Cool Season ◽  
European Settlement ◽  
Natural Pasture

Three major pasture types probably occurred on the Northern Tablelands prior to European settlement. The dominants were probably Poa sieberana Spreng. and Themeda australis (R.Br.1 Stapf. at the higher elevations, T. australis, P. Sieberana and Sorghum leiocladum (Hack.) C.E. Hubbard on fine textured soils at lower elevations and T. australis, Aristida ramosa (R.Br.) and Cymbopogon refractus (R.Br.1 A. Camus. on coarse textured soils. The subsidiary species composition of these pasture types is also suggested, derived from fragmentary early accounts, earlier published work and observations on the behaviour under grazing of the different species involved. The characteristics of the important native and naturalised grass species are described. These species are classified into warm season perennials, warm season annuals, cool season perennials and cool season annuals. The native warm season perennials is the largest group of species at present on the Tablelands. The effects of grazing on the species composition of natural pastures is described. The grazing behaviour of merino sheep leads to a striking zonation of herbaceous species resulting from uneven grazing intensity and distribution of dung and urine. Data from an unreplicated stocking rate by superphosphate application rate trial at Shannon Vale are presented. This trial indicated that the proportion of white clover in the pasture depended on both stocking rate and superphosphate rate and that the proportion of Danthonia spp. increased when white clover decreased. Wool production data are also presented which show that high levels of pro- ductivity per hectare can be obtained from topdressed natural pastures. A number of different natural pasture types occur on the Tablelands. A schemeis presented showing the interrelationship$ between the original and the present pasture types as affected by grazing intensity and the addition or depletion of plant nutrients.

Superphosphate maintains soil fertility and beef production on grazed white clover pastures in the subtropics. 2. Liveweight responses of beef cattle

1993 ◽  
Vol 33 (4) ◽  
pp. 435 ◽  
Author(s):  
PT Mears ◽  
BR Cullis
Keyword(s):  
White Clover ◽  
Linear Response ◽  
Exponential Model ◽  
Response Model ◽  
Quadratic Trend ◽  
Stocking Rate ◽  
Soil P ◽  
Stocking Rates ◽  
Extractable Soil

Growth of cattle was measured between 1974-75 and 1980-81 on a white clover (Trifolium repens) and carpet grass (Axonopus affinis) pasture receiving superphosphate applied at 0, 12, 24, and48 kg P/ha annually. Hereford weaner steers grazed the pastures at 1.67, 2.5, and 3.3 steers/ha. Linear responses to superphosphate and stocking rate were significant (P<0.001). The model estimating steer liveweight response to superphosphate comprised a long-term quadratic trend with seasonal variations. The liveweight response to superphosphate application was greatest in liveweight response to superphosphate applied at12 kg P/ha increased from 6.1 kg/steer.45 days in year 1 to 10.6 kg/steer.45 days in year 7. Average liveweight responses to 48 kg P/ha also increased from 34.0 kg/steer.45 days in year 1 to 78 kg/steer.45 days in year 7. Annual liveweight gain of steers at the low stocking rate (1.67/ha) without superphosphate declined from 165 kg/steer in year 1 to 38 kg/steer in year 7, while 24 kg P/ha maintained liveweight gain at 120-220 kg/steer. Annual liveweight gain was negatively related to stocking rate, averaging -31.3 kg/steer for each increment in stocking rate. Calculated stocking rates giving maximum liveweight production (122-469 kg/ha) varied between 2.2 and 3.6 steers/ha. Annual liveweight gain of steers was related to bicarbonate-extractable soil P using the exponential model, which accounted for 19% spring and least in autumn each year. Seasonal of the variation.It was concluded that maintenance dressings of superphosphate would be required when available soil P levels fell below 30 mg/kg, in order to maintain liveweight gains on white clover-Axonopus pastures. The linear response model will assist producers to decide on rates of superphosphate.

Quantifying the value proposition for white clover persistence on a New Zealand summer-dry hill-country farm

2020 ◽  
Vol 82 ◽  
pp. 199-209
Author(s):  
Mike B. Dodd ◽  
Katherine N. Tozer ◽  
Iris Vogeler ◽  
Rose Greenfield ◽  
David R. Stevens ◽  
...  
Keyword(s):  
White Clover ◽  
Net Present Value ◽  
Moisture Stress ◽  
Simulation Modelling ◽  
Low Fertility ◽  
System Modelling ◽  
Value Proposition ◽  
Hill Country ◽  
The North ◽  
Farm System

The improvement in forage quality and quantity of summer-dry hill country pasture resulting from the introduction of clover is well recognised. However, ensuring the persistence of the commonly availablecultivars is challenging, in the face of seasonal moisture stress, intensive grazing, competition from established well-adapted pasture species, low soil fertility and low soil pH – conditions typical of the East Coast of the North Island. Here we quantify the value proposition associated with the introduction of white clover into a case study on a Gisborne sheep and beef farm, using a six-step process. A topographically explicit approach is taken, using an understanding of the underlying spatial variability, based on a combination of soil and pasture measurements, APSIM simulation modelling of pasture growth and farm system modelling of enterprise performance. We show that from a baseline of a typical low-fertility, diverse species hill country pasture, white clover introduction can increase spring and summer forage consumption by 17%, enabling inclusion of an additional 6-month bull finishing enterprise generating a 32% greater carcass weight production and leading to a 49% improvement in farm system EBIT. This represents a positive net present value of over $360,000 for the original investment in white clover establishment into existing pastures.

scholarly journals 87 Evaluation of two stocking rates for grazing heifers on mixed sward native warm-season grass pastures in the Black Belt Prairie region

2020 ◽  
Vol 98 (Supplement_2) ◽  
pp. 27-27
Author(s):  
Jane A Parish ◽  
Kalisha C Yankey ◽  
Libby S Durst
Keyword(s):  
Nutritive Value ◽  
Bos Taurus ◽  
Warm Season ◽  
Stocking Rate ◽  
Sorghastrum Nutans ◽  
Study Objective ◽  
Little Bluestem ◽  
Year Effect ◽  
Plant Persistence ◽  
Stocking Rates

Abstract Optimal use of native warm-season grasses in pasture systems involves stocking grazing livestock at suitable rates. The study objective was to evaluate forage nutritive value and heifer ADG at two stocking rates on mixed-sward pastures of big bluestem (Andropogon gerardi Vitman), little bluestem (Andropogon scoparius), and indiangrass (Sorghastrum nutans L.). Pastures (3 replications) were stocked for 56 d during June and July in 2 yr with crossbred (Bos taurus) heifers (n = 24 heifers/year) stratified by initial BW (288.3 ± 1.7 kg) to one of two continuous stocking rates: 1.9 heifers/ha (HIGH) and 1.2 heifers/ha (LOW). Mean forage nutritive values on a DM basis were not different between HIGH and LOW stocking rates, respectively, for CP (7.0 ± 0.2% vs 6.7 ± 0.2%; P = 0.27), ADF (41.0 ± 0.6 vs. 41.4 ± 0.6; P = 0.64), NDF (69.9 ± 0.5 vs. 68.7 ± 0.5; P = 0.09), or relative feed value (RFV) (76.0 ± 1.0 vs. 76.9 ± 1.0; P = 0.53). There was a year effect (P &lt; 0.01) and stocking rate x day effect (P &lt; 0.01) for TDN. At LOW, TDN decreased from day 0 to day 28 (P = 0.02) and day 28 to day 56 (P = 0.02). At HIGH, TDN decreased (P &lt; 0.01) from day 0 to day 28 but remained steady until day 56 (P = 0.21). There was a stocking rate x day interaction (P &lt; 0.01) with ADG: LOW day 28 to 56 (1.20 ± 0.08 kg/day), HIGH day 0 to 28 (0.89 ± 0.08 kg/day), HIGH day 28 to 56 (0.44 ± 0.08 kg/day), and LOW day 0 to 28 (0.30 ± 0.08 kg/day). Further assessment of cattle ADG using more divergent stocking rates and plant persistence measures is warranted to inform ideal native grass stocking rate recommendations.

scholarly journals 178 Use of silvopastures and woodlands to expand the grazing opportunity for small ruminants

2020 ◽  
Vol 98 (Supplement_2) ◽  
pp. 67-68
Author(s):  
Uma Karki
Keyword(s):  
Body Condition Score ◽  
Small Ruminants ◽  
Warm Season ◽  
Live Weight ◽  
Limited Resource ◽  
Ground Level ◽  
Vegetation Biomass ◽  
Meat Goats ◽  
Condition Score ◽  
And Behavior

Abstract Pasture-based small-ruminant farming is a popular enterprise in the Southeast, especially for small and limited-resource producers. Although woodlands occupy a majority of the land cover in the South and can be a promising resource for raising small ruminants, not much attention has been given on using such resources. A series of studies were conducted at the facilities of Tuskegee University with the overall objective of exploring the potential of using silvopastures and woodlands for raising small ruminants. Grazing studies were conducted from 2015 to 2019 using meat goats and hair sheep in silvopastures and woodland plots. Silvopastures were developed by thinning down the existing woodlands and planting suitable cool- and warm-season forages. Grazing facilities were installed in the study plots and animals were rotationally stocked each year during both cool- and warm-season grazing periods. In 2017, non-pine plants in woodlands were cut to three different heights (ground level and 0.9 m and 1.5 m from the ground level) or left uncut (control) to see the effects on understory vegetation biomass production and utilization by small ruminants. Data on vegetation biomass and quality, canopy height, animal performance and behavior, browsing height, and vegetation preference were collected and analyzed. Small ruminants were found to utilize all planted forages (silvopastures) well and most of the understory plants in woodlands. Vegetation biomass in woodlands increased in areas where non-pine plants were cut versus the control (36–106%; P &lt; 0.0001). Mature animals maintained a desirable body condition score (≥2.6) and FAMACHA score (≤2.6) in woodlands. However, young, growing animals showed a poor live weight gain, especially during some portion of the study. Animals performed well when they were stocked in silvopastures. Both species showed a similar preference for most plant species available in woodlands. Results show a tremendous potential of using silvopastures and woodlands for expanding the grazing opportunity for small ruminants. However, the provision of some supplements would be necessary while stocking young animals in woodlands.

scholarly journals 145 Stocker gains on diverse summer annual pastures

2020 ◽  
Vol 98 (Supplement_2) ◽  
pp. 28-29
Author(s):  
Kelly Mercier ◽  
Chris Teutsch ◽  
Ray Smith ◽  
Eric Vanzant ◽  
Kenny Burdine ◽  
...  
Keyword(s):  
Nutritive Value ◽  
Vegetative State ◽  
Block Design ◽  
Average Daily Gain ◽  
Complex Mixture ◽  
Warm Season ◽  
Late Summer ◽  
Sunn Hemp ◽  
Sorghum Sudangrass ◽  
Forage Utilization

Abstract The objective of this study was to determine if increasing forage botanical diversity improved stocker gains on warm-season annual (WSA) pastures. An opportunity exists to add extra gain on fall-born calves by grazing summer pastures after spring weaning and selling at a more favorable late summer market. However, cool-season perennial pastures in the Mid-South often have insufficient quality and yield to support desired summer gains. Therefore, the improved production and nutritive value of WSA forages shows promise in this system. A study was conducted near Princeton, KY, where calves (329, 366, and 297 kg in 2017, 2018, and 2019, respectively) grazed one of three WSA forage treatments without supplementation in a randomized complete block design with three replications. Treatments included 1) sorghum-sudangrass monoculture (MONO), 2) simple mixture (SIMPLE = sorghum-sudangrass, pearl millet, soybean), and 3) complex mixture (COMPLEX = SIMPLE + sudangrass, corn, crabgrass, cowpea, sunflower, sunn hemp, daikon radish, forage rape, Korean lespedeza). In 2017, MONO and SIMPLE calves had higher average daily gain (ADG) than COMPLEX calves (0.79 kg/day vs. 0.66 kg/day, P &lt; 0.03). In 2018, no differences in ADG were detected among treatments (P &gt; 0.3); however, calves only gained 0.01 kg/day. In 2019, MONO and SIMPLE calves again had higher ADG than COMPLEX calves (0.59 kg/day vs. 0.43 kg/day, P &lt; 0.03). The exceptionally low 2018 ADG was likely due to the higher nutritional demand of heavier calves and the lower nutritive value of mature forages compared to other years. In conclusion, complex WSA forage mixtures did not offer any improvement in animal performance, and proper management of all WSA forages (maintaining a vegetative state) is paramount to achieving adequate gains on stockers without supplementation; however, supplementation may be necessary to improve WSA forage utilization in the rumen, potentially leading to more favorable gains.

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