Cooperative Extension Publications

By Jaime Garzon, Assistant Extension Professor and Forage Educator, University of Maine Cooperative Extension

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Introduction

Grasslands in livestock operations require a nutrient return after each grazing or cutting to perform adequately, especially nitrogen (N). In previous years, forage managers relied on the Maine poultry industry to fulfill this N requirement or purchase urea, ammonium diphosphate, or other N fertilizers in conventional productions. However, Maine’s poultry industry has withered, and fertilizer prices continue to rise, causing a notorious lack of N sources for forages and hayfields. Consequently, more farmers are seeking to establish legumes in their grasslands to benefit from the biological N fixation process and the increase in quality in livestock diets, improving the passage rate and digestibility for the animal.

However, there is a lack of knowledge about the performance of different legume varieties in Maine-specific soil and weather characteristics. Massachusetts, Pennsylvania, and New York states have reported performance and nutritive value results of alfalfa, birdsfoot trefoil, and clovers. Differences in climatic and soil conditions may impact the biomass accumulation and nutritive value of forages cropped in different states, and there are no reports of legume variety performances in Maine.

Therefore, this study’s objective seeks to evaluate the performance, nutritive value, and N fixation of several varieties on four legume species used as forages in Maine.

Trial design, varieties, and measured variables

The study was conducted in two locations from September 2023 to October 2024. The first place was at the University of Maine, Rogers Farm, located in Old Town (ME) (44° 55’ 43” N; 68° 41’ 45” W), under conventional management. The second location was at the Wolfe’s Neck Center for Agriculture & the Environment, located in Freeport (ME) (43° 50’ 03” N; 70° 04’ 52” W) under organic management. The varieties and species are detailed in table 1.

Table 1. Legume varieties used for the Maine legume variety trial.

Location	Species	Variety	Provider
Rogers Farm	Alfalfa	Kingfisher Stronghold	King’s AgriSeeds
		FSG Shockwave	Seedway
		FSG SW 407	Seedway
	Red clover	Freedom MR	King’s AgriSeeds
		Medium	King’s AgriSeeds
		FSG 402	Seedway
	White clover	Alice	King’s AgriSeeds
		Ladino	Seedway
		Crusade	Seedway
	Birdsfoot trefoil	Bull	King’s AgriSeeds
		Dawn	King’s AgriSeeds
Wolfe’s Neck Center	Red clover	Medium	Lakeview Organic Grain
		Manitoba	Lakeview Organic Grain
		Mammoth	King’s AgriSeeds
	White clover	Rivendell	Lakeview Organic Grain
		Ladino	Lakeview Organic Grain
		Klondike	King’s AgriSeeds

In each location, legume varieties were evaluated in a randomized complete block design with three replicates, which means each variety was planted in three separate plots. Each plot measured 12 ×12 feet, with six feet of alleyways.

Before planting, a soil test was conducted in each place to determine nutrient levels in the experimental area. Results are shown in table 2.

Table 2. Soil characteristics at the two locations selected for the Maine legume variety trial.

Location	Soil type	pH	Organic matter	P	K	Ca
			(%)	(lb/ac)
Rogers Farm	Pushaw-Boothbay silt-loam	6.0	4.0	6.0	203	1878
WNC	Scantic silt-loam	6.4	1.9	2.5	358	2594

In Rogers Farm, the area was disked several times until no vegetation remained on the soil surface. On August 24, 2023, legume varieties were seeded in a prepared seedbed with a cone seeder, using 35, 19, 7, and 13 pounds of seed per acre for alfalfa, red clover, white clover, and birdsfoot trefoil, respectively.

Additionally, the equivalent of 1000, 90, and 300 pounds per acre of dolomitic lime, phosphate (P₂O₅), and potash (K₂O) were applied in the plots, following the recommendations of the Analytical Lab and Soil Testing Service at the University of Maine. Dolomitic lime was applied two weeks before planting.

In the Wolfe’s Neck Center, the top layer of the designated area was removed to eliminate weed competition. Red and white clover were planted by broadcasting on August 16^th, 2023, using 25 and 10 pounds of seed per acre for red and white clover. Neither alfalfa nor birdsfoot trefoil was planted in this location because the soil is too moist and clayey for alfalfa to thrive, and no organic trefoil seed was available at the experiment establishment time.

After one year of establishment, two areas of 20 by 20 inches were harvested with a sickle knife at ground level in each plot and used to calculate the yield on a dry matter basis. Two subsamples were also taken, dried at 176 °F for 72 h, and used for nutritive value and N fixation determination. Crude protein (CP), neutral detergent fiber (NDF), NDF digestibility at 30 hours, and non-fiber carbohydrates (NFC) were determined by NIR analyses in the DairyOne® lab. Nitrogen fixation was determined using the natural abundance technique, where the N isotopic ratios were processed by the University of Florida North Florida Research and Education Center Forage lab.

Before the biomass sampling, preharvest canopy height and cover were evaluated using a measuring stick and a frame with 25 4-by-4-inch quadrats.

Sampling began in June 2024, with all plots being sampled and then cut homogeneously to four inches of stubble height. Harvests were made every 35 days until September 2024, when the plants grown were stunned due to the air temperature and day length.

Statistical analysis

All data were analyzed using mixed-model Analysis of Variance (ANOVA), in which blocks and their interactions were considered random effects. Treatments were considered different to a significance level ≤ 0.05

Results

Birdsfoot trefoil Dawn showed minimal germination at Rogers Farm despite being subjected to the same environmental and management conditions as the other varieties. Therefore, the analyses were conducted without considering this variety for the trial.

Cover and yield

None of the varieties showed significant differences in yield and cover, possibly due to the great variation in each treatment. Still, trends in responses were observed, such as lower white clover yield compared to other legumes at Rogers Farm (778 vs. 1029 pounds of dry matter (DM) per acre) and Wolfe’s Neck Center (217 vs. 421 pounds DM per acre) (Figure 1).

(a)

(b)

At Rogers Farm, alfalfa, birdsfoot trefoil, and red clover produced similar biomass, with slightly greater cover for red and white clover (figure 1a). This indicates that white clover devoted more of its growth to the horizontal axis than the vertical, promoting greater cover but lower biomass yield. At Wolfe’s Neck Center, white clover varieties outperformed red clover in yield and cover (Figure 1b), possibly due to the clayey and low-drainage characteristics of the soil. On average, legume heights at cutting were 14, 12, 9, and 10 inches for alfalfa, red clover, white clover, and birdsfoot trefoil, respectively, observing an increase in July and August, but a decrease in September and remaining below four inches at the time of clipping in October.

Nutritive value

There were significant differences between the nutritive parameters within the legume species, with a similar tendency observed for yield. At Rogers Farm, alfalfa, birdsfoot trefoil, and red clover reported similar crude protein and digestibility ratios (26 and 49%, respectively), with higher NDF and lower NFC for red clover (42 and 17%, respectively) (Figure 2a). Additionally, white clover showed the best nutritive value, with greater digestibility and NFC, and lower NDF at both locations.

(a)

(b)

Biological N fixation

No statistical differences were observed due to variation within each variety. However, in most species, more than 80% of the N contained within the plant came from the air, thus denoting the high fixing capacity of most of the varieties evaluated (table 3).

Table 3. Nitrogen derived from the atmosphere (NDFA) and atmospheric N fixed (ANF) of all the varieties evaluated in this legume trial.

Location	Species	Variety	NDFA	ANF
			(%)	(lb N/ac/harvest)
Rogers Farm	Alfalfa	Stronghold	88.7	34.6
		Shockwave	76.3	34.1
		SW 407	82.5	34.5
	Birdsfoot trefoil	Bull	83.2	33.8
	Red clover	Freedom	81.3	40.4
		Medium	84.8	27.4
		FSG 402	82.8	33.8
	White clover	Alice	53.4	20.7
		Ladino	51.0	17.5
		Crusade	53.7	12.3
Wolfe’s Neck Center	Red clover	Medium	96.3	10.2
		Manitoba	94.3	6.9
		Mammoth	95.5	7.7
	White clover	Rivendell	95.2	11.2
		Ladino	92.0	15.0
		Klondike	93.3	11.9

A direct relation was also observed between biomass production and the amount of nitrogen available in each variety. Thus, Wolfe’s Neck Center clovers had less than half the atmospheric N fixed than those at Rogers Farm (25.4 vs. 10.5 pounds of nitrogen/acre/harvest). Additionally, white clover had lower N deposition than alfalfa, birdsfoot trefoil, and red clover at Rogers Farm, averaging 16.8, 34.4, 33.8, and 33.8 pounds of nitrogen/acre/harvest, respectively.

Discussion

Grazing legumes have gained importance in livestock operations in recent years due to the ecosystem services they provide to pastures. The different varieties evaluated in Maine showed these benefits, with average annual yields of 860 to 4,300 pounds DM per acre, depending on the species and management. The varieties under organic production showed lower performance but greater N fixation, probably due to a lower concentration of soluble nutrients in the soil due to the lack of fertilization. In addition, the clay soil at Wolfe’s Neck Center created harder conditions for growing plants and a higher incidence of flooding.

Moreover, alfalfa, birdsfoot trefoil, and red clover performed similarly, with great yield and good nutritive value. This shows that, under the right conditions, the selection of trefoil or red clover can match the performance of alfalfa without the strict limitations on soil type and texture. On the other hand, white clover had the lowest biomass production but it showed better adaptation for use as a cover crop and greater resilience to adverse conditions, such as those reported at the Wolfe’s Neck Center. This lower growth was compensated with a higher nutritional quality by depositing less insoluble fiber in its tissues. This resulted in greater digestibility and soluble carbohydrate content.

Finally, all species showed an average deposition of 80 pounds of N per acre annually. The minimum N recommendation for grazing is 50 pounds per acre, so establishing legumes in the field would meet this requirement within the pasture.

Conclusions

There was great variability in biomass and nitrogen fixed among legume species. However, trends showed similar performance for alfalfa, red clover, and birdsfoot trefoil. White clover reported a greater nutritive value, but this does not detract from the good nutritional quality of the other species. Additionally, white clover showed greater resilience to adverse factors, having extra points as a cover crop.

Kingfisher Stronghold alfalfa, Bull birdsfoot trefoil, Freedom MR red clover, and Alice white clover were the best-performing varieties within each legume species evaluated for 2024. Under organic management, Medium red clover and Ladino white clover performed the best.

This trial will continue for two more years to evaluate the effect of year, winter survival, and performance of the different legume varieties. Therefore, the values ​​shown in this report correspond only to 2024 and will probably be modified to include results from subsequent years.

Acknowledgements

The University of Maine Cooperative Extension would like to thank Ana Paula Jimenez, Ph.D. Student, School of Food and Agriculture, University of Maine, Mr. Marco Chusho, Research Scholar, School of Food and Agriculture, University of Maine, and Thomas Molloy, Research Associate in Sustainable Agriculture, University of Maine Cooperative Extension for their assistance in establishing the trial and conducting subsequent samplings.

This project was supported by the USDA National Institute of Food and Agriculture Hatch/McIntire-Stennis/Animal Health project number ME0-5255745 through the Maine Agricultural and Forest Experiment Station.

Annexes

Annex 1. Monthly values ​​assessed across 11 legume varieties at Rogers Farm in 2024.

Variety	Month	Yield	Cover	CP	Digest	NDF	NFC	NDFA	ANF
		(lb DM/ac)	(%)						(lb N/ac)
Stronghold	Jun	512	46	22.1	47.0	30.6	32.1	98.6	18.2
	Jul	1393	85	21.7	46.3	39.7	25.4	96.8	46.4
	Aug	1289	94	26.3	53.3	43.3	15.1	78.2	40.9
	Sep	918	68	27.5	49.1	38.7	20.1	81.2	32.9
Average		1028	73	24.4	48.9	38.1	23.2	88.7	34.6
Shockwave	Jun	414	69	23.5	46.3	27.3	32.7	93.2	14.3
	Jul	1627	80	22.2	46.0	39.3	25.2	89.5	51.9
	Aug	1521	92	27.3	51.8	41.5	16.5	72.2	47.6
	Sep	936	74	30.3	55.1	37.0	18.0	50.1	22.6
Average		1124	79	25.8	49.8	36.3	23.1	76.3	34.1
SW 407	Jun	478	61	22.7	47.0	30.6	31.6	99.1	18.3
	Jul	1606	85	21.5	41.7	39.5	25.6	94.1	51.2
	Aug	1330	94	27.0	51.8	42.6	15.6	76.2	42.2
	Sep	938	69	28.9	52.2	38.5	19.0	60.8	26.5
Average		1088	77	25.0	48.2	37.8	23.0	82.5	34.5
Average Alfalfa		1080	77	25.1	49.0	37.4	23.1	82.5	34.4
Bull	Jun	397	38	25.1	42.0	25.1	33.6	92.7	14.6
	Jul	1571	80	22.4	44.0	36.9	27.1	87.7	48.6
	Aug	1455	84	27.5	53.0	41.1	18.8	82.6	52.3
	Sep	628	70	29.0	54.1	33.8	23.4	69.9	19.6
Average trefoil		1013	68	26.0	48.3	34.2	25.7	83.2	33.8
Freedom	Jun	1318	93	25.7	45.0	42.1	19.6	92.5	50.6
	Jul	1493	99	25.1	48.7	49.0	12.3	86.3	51.5
	Aug	1097	99	26.8	44.5	41.0	16.0	80.6	37.5
	Sep	717	96	29.3	50.7	40.2	15.3	65.8	22.0
Average		1156	97	26.7	47.2	43.1	15.8	81.3	40.4
Medium	Jun	371	43	28.8	54.0	37.8	18.5	93.8	15.7
	Jul	1429	65	21.8	45.3	47.2	19.6	88.6	43.2
	Aug	831	64	26.4	47.8	45.1	12.4	74.6	27.0
	Sep	625	57	29.1	46.3	36.4	18.5	82.2	23.5
Average		814	57	26.5	48.4	41.6	17.3	84.8	27.4
FSG 402	Jun	758	84	28.6	46.7	40.4	17.1	93.7	32.6
	Jul	1772	85	21.5	40.0	48.6	18.6	88.0	53.8
	Aug	869	92	25.7	44.5	44.9	13.5	74.7	27.2
	Sep	636	82	28.9	43.8	36.4	17.9	74.5	21.6
Average		1009	86	26.2	43.7	42.6	16.8	82.8	33.8
Average red clover		993	80	26.5	46.4	42.4	16.6	82.9	33.9
Alice	Jun	873	82	26.7	62.0	26.5	30.1	89.8	33.0
	Jul	1313	83	23.8	55.0	35.3	26.1	67.6	33.6
	Aug	803	96	27.5	65.4	38.0	19.3	44.3	12.6
	Sep	481	94	31.2	57.8	33.2	20.2	11.8	3.8
Average		867	89	27.3	60.1	33.3	23.9	53.4	20.7
Ladino	Jun	199	41	26.0	60.3	26.5	31.5	86.7	7.1
	Jul	1615	86	23.9	50.7	33.2	28.7	68.6	42.2
	Aug	947	91	27.7	70.7	42.4	14.2	22.2	10.0
	Sep	737	89	30.8	59.6	33.7	20.2	26.3	10.7
Average		874	77	27.1	60.3	34.0	23.7	51.0	17.5
Crusade	Jun	85	41	25.4	58.0	28.2	30.4	90.3	3.3
	Jul	1112	88	25.1	57.3	31.1	28.2	73.3	30.7
	Aug	833	87	25.0	64.0	38.5	20.9	32.5	11.0
	Sep	461	78	29.4	59.8	36.7	17.6	18.9	4.1
Average		623	74	26.2	59.8	33.6	24.3	53.7	12.3
Average white clover		788	80	26.9	60.0	33.6	23.9	52.7	16.8

Annex 2. Monthly values ​​assessed across six legume varieties at Wolfe’s Neck Center in 2024.

Variety	Month	Yield	Cover	CP	Digest	NDF	NFC	NDFA	ANF
		(lb DM/ac)	(%)							(lb N/ac)
Medium	Jun	340	19.1	25.4	50.0	30.8	31.0	97.7	13.4
	Jul	273	14.6	20.7	47.0	41.0	27.6	97.1	8.8
	Aug	63	17.6	21.3	48.4	41.0	24.7	91.3	2.0
Average		271	17.1	23.6	49.1	34.9	29.1	96.3	10.2
Manitoba	Jun	238	8.0	24.5	52.7	29.7	32.3	97.5	9.1
	Jul	208	6.3	21.1	41.0	36.3	31.2	87.6	5.8
	Aug	75	18.0	21.3	47.3	40.0	25.1	97.9	2.5
Average		201	10.8	22.8	47.9	33.6	30.7	94.3	6.9
Mammoth	Jun	271	41.6	28.5	51.0	30.4	28.8	95.4	11.7
	Jul	49	26.1	25.3	56.2	35.2	25.5	95.5	1.9
Average		182	33.9	27.2	53.1	32.3	27.5	95.5	7.7
Average red clover		218	20.6	24.5	50.0	33.6	29.1	95.3	8.3
Rivendell	Jun	495	19.5	19.1	60.0	35.7	32.9	93.3	13.9
	Jul	398	10.4	18.7	48.5	38.2	32.0	97.3	11.6
	Aug	55	30.0	23.8	62.2	31.0	32.0	96.7	2.0
Average		389	20.0	19.7	56.5	35.7	32.4	95.2	11.2
Ladino	Jun	835	31.3	21.9	57.0	33.6	31.5	93.2	26.9
	Jul	378	11.3	20.0	50.7	37.9	30.4	92.1	11.0
	Aug	99	17.7	22.6	63.3	33.6	29.2	89.9	3.2
Average		480	20.1	21.3	56.2	35.2	30.5	92.0	15.0
Klondike	Jun	472	27.4	21.5	57.3	28.4	36.6	94.6	15.5
	Jul	528	5.2	19.3	46.7	37.3	31.6	93.5	15.3
	Aug	167	24.7	20.3	54.5	36.3	29.9	91.7	4.9
Average		389	19.1	20.4	52.8	34.0	32.7	93.3	11.9
Average white clover		419	19.7	20.5	55.2	35.0	31.9	93.5	12.7

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© 2024

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