Online Publications

PR-481

2002 Red and White Clover Grazing Tolerance Report

R.F. Spitaleri, J.C. Henning, G.D. Lacefield, N.L. Taylor, and E. Vanzant

Introduction

Red clover (Trifolium pratense) and white clover (Trifolium repens) are both high quality forage legumes that are used primarily in mixed stands with tall fescue or orchardgrass for improving yield and quality of pastures. Stands of red clover are generally productive for two to three years, while white clover can be productive for many years. Their high palatability cause them to be overgrazed easily. This report summarizes current research on the grazing tolerance of clover varieties when subjected to continuous grazing pressure.

Description of the Tests

Red and white clover tests for grazing were established in Lexington in the fall of 2000 and 2001. Soils at the test site are well-drained silt loams and are well suited to clover production. Plots were 5 ft x15 ft in a randomized complete block design with each variety replicated six times.

Red clover was seeded at the rate of 12 pounds and white clover at 3 pounds per acre into a prepared seedbed using a disk drill. All seed lots were inoculated prior to planting. Plots were grazed continuously beginning the first spring after seeding. In general, plots were grazed from mid-April to mid-September. Supplemental hay was fed during periods of slowest growth.

Visual ratings of percent stand were made in the fall and spring after each grazing season. Fertilizers (lime, P, K, and Boron) were applied according to University of Kentucky recommendations.

Results and Discussion

Weather data are presented in Table 1. After a wet spring, the 2002 summer was the fourth hottest and driest on record.

Data on percent stand are presented in Tables 2 and 3. Statistical analyses were performed on these data to determine if the apparent differences are truly due to variety or just due to chance. Varieties not significantly different from the highest numerical value in a column are marked with one asterisk (*). To determine if two varieties are truly different, compare the difference between the two varieties to the Least Significant Difference (LSD) at the bottom of the column. If the difference is equal to or greater than the LSD, the varieties are truly different when grown under the conditions at a given location. The Coefficient of Variation (CV), which is a measure of the variability of the data, is included for each column of means. Low variability is desirable, and increased variability within a study results in higher CVs and larger LSDs.

There were differences in persistence between red clover and white clover (Table 2). Red clover entries did not tolerate continuous, heavy grazing. In contrast, there were several white clover entries that persisted after one season, and one entry had significant stand after the second grazing season. The 2002 drought may have contributed to the lack of survival of entries.

Table 4 summarizes information about distributors and persistence across two years.

Summary

These studies indicate there are white clover varieties that express tolerance to overgrazing. Red clover entries have not shown the same tolerance to overgrazing.

Although these varieties were abused during the growing season, they were allowed to rest and regrow after September 15 to prepare for winter.

This information should be used along with yield and pest resistance information in selecting the best clover variety for each individual use. It is not recommended that clover be continuously grazed as was done in this trial. While several varieties expressed tolerance to the level of grazing pressure used in these trials, overgrazing greatly reduces yield and therefore profitability of these clovers.

Good management for maximum life from grazing clover would include:

• allowing clover to become completely established before grazing
• using rotational grazing where animals harvest available forage in seven days or less followed by resting for 28 days before regrazing
• adding any needed fertilizer and lime
• removing grazing livestock from clover fields from mid-September to November 1 to replenish root reserves.

Table 2. Percent stand of red and white clovers planted September 19, 2000, at Lexington, Kentucky, in a cattle grazing tolerance study.
Variety		Type	Percent Stand
			Apr 9, 2001	Oct 15, 2001	Apr 2, 2002	Oct 14, 2002
Commercial varieties>—Available for farm use
Starfire		red clover	89*	31	36	2
Red Gold Plus		red clover	86*	20	33	0
Certified Kenland		red clover	86*	15	31	0
Experimental varieties
AGRTR 205		white clover	72	63*	61*	48*
AGRTR 208		white clover	60	69*	63*	30
AGRTR 207		white clover	68	68*	58*	5
ZR 9908R		red clover	88*	35	43	3
RC 9803G		red clover	89*	47	52	2
AGRTP 101		red clover	82*	5	14	2
ZR 9906R		red clover	90*	40	40	0
Mean		-	81	39	43	9
CV, %		-	11.79	24.55	19.40	70.66
LSD, 0.05		-	11.11	11.19	9.66	7.40
*	Not significantly different from the highest value in the column based on the 0.05 LSD.

Table 3. Percent stand of red clover varieties planted September 12, 2001, in a cattle grazing study at Lexington, Kentucky.
Variety		Percent Stand
		Apr 4, 2002	Oct 15, 2002 **
Commercial varieties—Available for farm use
Emarwan		71*	5*
Starfire		64	5*
Certified Kenland		77*	3*
Duration		58	3*
Vesna		79*	2*
Uncertified Kenland		66	1
Experimental varieties
Freedom!		81*	3*
RC9301		57	5*
KNARS (cycle 1)		62	3*
RC9501		67	3*
RC9803G		64	3*
Mean		68	3
CV, %		14.90	80.88
LSD, 0.05		11.69	2.91
*	Not significantly different from the highest value in the column based on the 0.05 LSD.
**	These stands were depleted due not only to intensive grazing but also to extreme drought.

Table 4. Persistence of clover varieties under heavy grazing pressure across years.
			Lexington
			20001				2001
Variety		Proprietor/KY Distributor	Apr 20012	Oct 2001	Apr 2002	Oct 2002	Apr 2002	Oct 2002
Commercial varieties—Available for farm use
Duration		Cisco Companies						*
Emarwan		Turf Seed, Inc.					*
Kenland certified		University of Kentucky	*				*	*
Kenland uncertified		Public
Red Gold Plus		Turner Seed Inc.	*
Starfire		Ampac Seed Company	*					*
Vesna		DLF - Jenks					*	*
Experimental varieties
AGRTP 101		Ag Research (USA) Limited	*
AGRTR 205		Ag Research (USA) Limited		*	*	*
AGRTR 207		Ag Research (USA) Limited		*	*
AGRTR 208		Ag Research (USA) Limited		*	*
Freedom!		University of Kentucky					*	*
KNARS (cycle 1)		University of Kentucky						*
RC 9301		FFR Cooperative						*
RC 9501		FFR Cooperative						*
RC 9803G		FFR Cooperative	*					*
ZR 9906R		America’s Alfalfa	*
ZR 9908R		ABI Alfalfa	*
*	Not significantly different from the highest value in the column based on the 0.05 LSD.
1	Date study was planted
2	Date of measurement of percent stand.