Compatibility, Yield, and Nutritive Value of Matua Prairie Grass with Interseeded Legumes

J. F. Guay, Assistant Professor, Department of Animal Science, Berry College, Mount Berry, GA 30149; A. O. Abaye, Associate Professor, Department of Crop and Soil Environmental Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061; J. P. Fontenot, John W. Hancock Jr. Professor Emeritus, Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061; and P. R. Peterson, Associate Professor, Department of Agronomy and Plant Genetics, University of Minnesota, St. Paul 55108

Abstract

Matua prairie grass (Matua), Bromus willdenowii, can extend the grazing season in the mid-Atlantic region. The effects of legume overseeding on botanical composition, yield, and chemical composition of a 4-year-old Matua stand were investigated. Treatments consisted of ladino clover (Trifolium repens), red clover (Trifolium pratense), alfalfa (Medicago sativa), and annual lespedeza (Lespedeza stipulacea). Ladino clover and red clover increased total dry matter yield by as much as 56%, but decreased percentage Matua by as much as 64%. Ladino clover, red clover, and alfalfa treatments decreased fiber components (NDF and ADF) and increased crude protein and in vitro dry matter digestibility. Although annual lespedeza did not have a detrimental effect on the Matua component, it did not improve the nutritive value either. Of the legumes we tested, alfalfa appeared to be most compatible with Matua. Alfalfa resulted in a maximum of 40% reduction in the Matua component, and had a positive effect on the nutritive value of the forage.

Introduction

Matua prairie grass (Matua), Bromus willdenowi, is a short-lived, cool-season perennial with potential for high forage production (7). Matua can extend the grazing season, since it grows earlier in the spring and later in the fall than most other cool-season grass species (8). Extending the grazing season could save farmers money by reducing winter feed and hay costs.

The mechanisms by which Matua persists are not well known. However, natural re-seeding and increased tiller weights and numbers contribute to its persistence (2,7,10). Defoliation management is critical to stand longevity. Matua stands are weakened if defoliation is frequent, because of insufficient energy reserves for regrowth (2,4,7). Infrequent defoliation can also weaken the stand through reduced seedling and tiller survival due to excessive self-shading from the plant canopy and thatch accumulation. A 40- to 50-day rest period between defoliations is recommended (2).

A common practice in the mid-Atlantic region of the United States is to overseed existing grass pastures with legumes. However, the compatibility of Matua with legumes has not been documented. The objectives of the experiment were to evaluate the compatibility, yield, and nutritive value of a 4-year-old stand of Matua overseeded with various legumes.

Measuring Effects of Legume Overseeding on Matua

In 1994, Matua was established at a seeding rate of 39.2 kg/ha, at the Kentland Research Farm, Whitethorne, Virginia. From 1995 through 1997, the Matua was allowed to reseed once each growing season to maintain the stand. In May 1998, treatments consisting of four different legumes were imposed. The legumes consisted of ‘Regal’ ladino clover (Trifolium repens), ‘Cinnamon’ red clover (Trifolium pratense), ‘Triple Crown’ alfalfa (Medicago sativa), and annual lespedeza (Korean type, variety not specified; Lespedeza stipulacea). Legumes were chosen based on their frequent use in the mid-Atlantic region of the United States. Legumes were no-till drilled into the existing Matua sod at rates of 2.5, 5.6, 11.2, and 19.0 kg/ha (on a pure live seed basis), for ladino clover, red clover, alfalfa, and annual lespedeza, respectively. Control plots containing no legume treatments were included in the experimental design. Plots were 1.83 m by 7.62 m. Treatments were arranged in a randomized split block design, and replicated four times.

A sampling interval of approximately 28 days was used. In 1998, samples were obtained in June, July, August, September, and November. In 1999, samples were obtained in May, June, July, September, and October. The stands were not harvested in October 1998 because of limited forage production due to drought and to allow natural reseeding, and in August 1999 to allow reseeding. Immediately after the September sampling in each year, N was applied at a rate of 84 kg/ha (no N was applied to control plots).

Botanical composition and yield were determined by clipping two 0.25-m² quadrats per treatment within each replication, to a residual stubble height of 7.6 cm. After obtaining these samples, the entire plot area was mowed to a residual stubble height of 7.6 cm, and all clippings were removed from the plots. Samples were hand separated into grass species (Matua versus other grasses), legume species (treatment legume versus other legumes), broadleaf weed species, and dead material components. These components were dried in a forced air oven at 65°C and weighed. Percentage of each component and total yield were calculated on a dry matter (DM) basis.

The components of the samples were recombined and ground to pass through a 1-mm mesh screen in a stainless steel Wiley mill (Thomas Wiley, Laboratory Mill Model 4, Arthur H. Thomas Co., Philadelphia, PA.). The samples were analyzed for concentrations of DM (1), NDF (13), ADF (12), cellulose (5), hemicellulose (13), lignin (5), and CP (1). Neutral detergent fiber and ADF were determined using the fiber bag technology of Ankom (Ankom Technology Corp., Fairport, NY). Hemicellulose was calculated by difference (subtraction of percentage ADF from NDF). Cellulose and lignin were respectively determined by sequentially digesting the ADF residue in a 72% sulfuric acid solution followed by ashing in a muffle furnace at 500°C (5). In vitro dry matter digestibility (IVDMD) was determined using the first stage of the two-stage method of Tilley and Terry (11) as an estimate of ruminal digestibility of the forage. The Kjeldahl acid digestion technique was used to digest the samples (1). Total N was determined colorimetrically with an autoanalyzer by flow injection analysis (Lachat Instruments Inc., Hach Co., Loveland, CO). Total N (× 6.25) was used to calculate CP (1). All chemical composition values are reported on a DM basis.

Statistical analysis was performed using the GLM procedure of SAS (SAS Institute Inc., Cary, NC). Data for November 1998 were analyzed separately from the rest of the 1998 harvests, since it was the only harvest in 1998 to receive the N treatments. For the June through September 1998 data, analyses of variance were performed testing the fixed effects of block, legume treatment, harvest month, and all interactions. For the November 1998 data, analyses of variance were performed testing the fixed effects of block, legume treatment, N treatment, and all interactions. For the 1999 data, analyses of variance were performed testing the fixed effects of block, legume treatment, N treatment, harvest month, and all interactions. Means were then compared to find significant differences. The Student’s t-test was performed if comparing only two means, and the Tukey-Kramer Honestly Significant Difference (HSD) test was performed if comparing multiple means. Significance was declared at the P < 0.05 level. All data are reported as least squares means.

Impact of Legumes on Botanical Composition

In 1998, the growing season that the legumes were interseeded, the percentage Matua in the stands was not affected by legume treatments (Table 1). As the growing season progressed, the newly seeded legumes increased in their respective treatment plots. In June and July, legume proportions were never greater than 12%. The greatest proportion of annual lespedeza was observed in September, when it was greater than all other legume treatments. In November 1998, ladino clover and red clover proportions were greater than alfalfa and annual lespedeza proportions. No measurable annual lespedeza was present in November.

Table 1. The effect (%) of legume treatments on forage components.

Forage component	1998	Treatment					SEM
Forage component	1998	Ladino clover	Red clover	Alfalfa	Annual lespedeza	Control	SEM
Matua	June	45	55	62	53	52	2.2
	July	43	37	55	49	51	2.4
	Aug	62	55	44	55	48	3.8
	Sept	26	34	36	29	44	3.2
	Nov	28	30	30	32	37	1.8
Treatment legume	June	0	2	0	0	—	0.2
	July	9ab*	12a	3b	9ab	—	0.7
	Aug	4	12	5	18	—	2.0
	Sept	12a	7a	2a	33b	—	1.8
	Nov	14	13	4	0	—	0.5
Forage component	1999	Ladino clover	Red clover	Alfalfa	Annual lespedeza	Control	SEM
Matua	May	33a	30a	48a	75b	81b	1.8
	June	13a	15ab	25ab	38b	35ab	2.3
	July	20	31	22	33	39	2.4
	Sept	41	39	38	32	39	2.3
	Oct	49	42	47	46	53	1.8
Treatment legume	May	52a	56a	28b	0c	—	1.7
	June	65a	49b	12c	0c	—	1.5
	July	35a	18ab	14b	14b	—	1.7
	Sept	3a	2a	6a	32b	—	0.6
	Oct	10ab	6ab	3a	18b	—	1.4

* Means within months followed by the same letters are not significantly different (P < 0.05; Tukey-Kramer HSD).

In 1999, the legume treatments influenced Matua percentage during May and June. In May, Matua percentage was reduced by 59, 63, and 41% compared to the control where it was grown with ladino clover, red clover, and alfalfa, respectively. In June, ladino clover reduced Matua percentage by 64%. By the second growing season, the legumes were well established, at times exceeding 60% of DM. In May and June, ladino and red clover proportions were greater than for alfalfa and annual lespedeza. Ladino clover and red clover ranged from 49 to 65% of DM. Annual lespedeza, a warm-season forage, was first observed in July. In September, annual lespedeza was present at a higher percentage than all other treatment legumes. However, annual lespedeza appeared to have minimal impact on the Matua component.

The Matua used in the current study was a 4-year-old stand that had been allowed to reseed every year. Results of other research have shown mixed success maintaining Matua in combination with legumes. In an experiment conducted by Grof and coworkers (6), prairie grass (B. unioloides) was not able to survive in a stand that also contained ladino clover. However, experiments with B. unioloides and ladino clover (3), Matua and red clover (9), and Matua and ladino clover (4) showed prairie grass to be compatible with legumes. Differences in prairie grass proportions in the latter experiments may be due to management factors rather than the legume component. Experiments where prairie grass was successfully maintained in combination with legumes generally used livestock to graze the stands instead of mechanical defoliation and employed less intensive defoliation intervals.

Impact of Legumes on Yield

In 1998, legume treatments had no effect on yield. Dry matter yields per harvest averaged 1,227 kg/ha. In 1999, legume treatments influenced yield only in May, June, and September (Table 2). In May, ladino clover and red clover treatments had higher yields than alfalfa, annual lespedeza, and Matua grown alone. In June, only the ladino clover treatment increased yield. In September, the annual lespedeza/Matua mixture had greater yield than Matua grown alone.

Table 2. The effect of legume treatments on total dry matter yield (1999).

Month	Treatment					SEM
	Ladino clover	Red clover	Alfalfa	Annual lespedeza	Control
	Dry matter yield (kg/ha)
May	1797a*	2032a	1097b	850b	894b	45.3
June	2192a	1519b	1376b	1248b	1074b	52.4
July	434	374	456	526	501	17.2
Sept	1045ab	1097ab	1058ab	1200a	916b	23.4
Oct	1238	1230	1388	1516	1406	59.3

* Means within months followed by the same letters are not significantly different (P < 0.05; Tukey-Kramer HSD).

Impact of Legumes on Nutritive Value

In 1998 when legume proportions were small, few differences in fiber values were observed as a result of the legume treatments (Table 3). The ladino and red clover treatments tended to decrease the fiber components, but differences were not always significant. By 1999, the effects of legume treatments on fiber components were more evident. In general, annual lespedeza/Matua and Matua grown alone tended to have higher fiber values than the ladino clover and red clover treatments.

Table 3. Legume treatment effect on fiber components, DM basis, of Matua prairie grass/legume mixtures.

Component	1998	Treatment					SEM
Component	1998	Ladino clover	Red clover	Alfalfa	Annual lespedeza	Control	SEM
NDF	June	59.4	61.0	60.2	63.2	62.1	0.52
	July	59.4ab*	58.0b	61.1ab	61.2ab	62.3a	0.45
	Aug	61.0ab	58.8b	64.5a	62.0ab	64.5a	0.39
	Sept	54.6	56.9	56.7	54.7	59.4	0.60
	Nov	50.4b	49.6b	58.2a	57.8a	56.6a	0.44
ADF	June	35.4	35.4	34.6	37.0	36.2	0.31
	July	34.1	33.8	35.5	35.5	35.5	0.24
	Aug	34.4ab	33.6b	35.8a	35.4ab	35.9a	0.21
	Sept	32.9	32.8	33.1	33.7	35.1	0.34
	Nov	31.8b	49.6b	33.5ab	36.1a	35.0a	0.31
Component	1999	Ladino clover	Red clover	Alfalfa	Annual lespedeza	Control	SEM
NDF	May	39.6c	43.6c	50.7b	59.9a	59.2a	0.70
	June	41.1b	46.5b	54.0b	59.7a	60.1a	0.69
	July	50.6b	55.5ab	58.9a	57.6a	59.7a	0.69
	Sept	63.8a	61.2ab	60.3ab	54.1b	58.1ab	0.74
	Oct	56.2	59.0	59.5	57.1	58.2	0.35
ADF	May	26.5c	27.8c	29.5bc	33.7a	31.8ab	0.30
	June	30.1c	32.4b	33.6ab	35.1a	35.0a	0.16
	July	33.3ab	31.7a	35.7a	35.3a	35.3a	0.33
	Sept	35.7	35.5	34.9	33.3	34.0	0.48
	Oct	31.7	33.2	34.8	33.7	33.9	0.41

* Means within months followed by the same letters are not significantly different (P < 0.05; Tukey-Kramer HSD).

Adding a cool-season legume to a grass sward can be expected to lower the fiber values, as a result of the greater proportion of cell solubles in legumes than grasses (14). The ladino clover treatment decreased NDF and ADF values by as much as 33 and 17%, respectively. Alfalfa, in some instances, improved the quality of the forage, but at an intermediate level. The inclusion of legumes with Matua in our experiment resulted in intermediate fiber values when compared to the Matua and alfalfa hays as reported by LaCasha and coworkers (8).

In July 1998, the red clover treatment resulted in higher CP than the annual lespedeza and Matua grown alone (12.5 versus 10.4%). In June, August, and September legume treatments had no effect on CP. Average CP was 12.4, 11.2, and 19.2% for June, August, and September, respectively. In November of 1998, no differences in CP due to legume treatments were observed (average 10.7%).

In May 1999, the ladino clover treatment had higher CP than the annual lespedeza treatment and the Matua grown alone (Table 4). During June, the ladino clover treatment resulted in higher forage CP than the control. In October of 1999, the ladino clover treatment had higher CP than the red clover treatment and Matua grown alone. During the remaining months in 1999, no effect of legume treatments on CP values was observed.

Table 4. Legume treatment effect on crude protein content (%) and in vitro dry matter digestibility (%), DM basis, of Matua prairie grass/legume mixtures (1999).

Component	1999	Treatment					SEM
Component	1999	Ladino clover	Red clover	Alfalfa	Annual lespedeza	Control	SEM
CP	May	20.0a*	18.7ab	16abc	11.8c	13.2bc	0.57
	June	16.7a	16.3ab	14.9ab	12.4ab	11.2b	0.54
	July	21.2	22.0	16.3	17.1	16.2	0.63
	Sept	16.7	15.8	16.9	17.1	18.8	0.60
	Oct	18.6a	13.7b	15.4ab	14.9ab	14.5b	0.38
IVDMD	May	72.6a	14.5b	66.3b	62.6b	65.4b	0.41
	June	67.7a	60.8b	59.9b	58.2b	56.8b	0.41
	July	59.5a	54.6ab	51.9b	54.7ab	57.5ab	0.72
	Sept	58.7	60.1	59.2	61.1	62.1	0.80
	Oct	68.4	63.9	61.3	66.3	65.9	0.78

* Means within months followed by the same letters are not significantly different (P < 0.05; Tukey-Kramer HSD).

In August of 1998, the red clover treatment had higher IVDMD than the annual lespedeza treatment (59.0 versus 52.2%), while no differences were observed among the other treatments (average 55.3%). No differences in IVDMD values were observed in the other months in 1998 (average 64.7%).

By 1999, the legume treatments had an impact on IVDMD. In May and June, the ladino clover treatment had considerably higher IVDMD than the other legume treatments. In July, the ladino clover treatment had higher IVDMD than the alfalfa treatment. No differences in IVDMD values were observed for the September and October harvests.

The seasonal distribution of cool-season legumes might have impacted the nutritive value of the forage, as observed by a wide range of IVDMD values for the various treatments. The cool-season legumes that were abundant in spring and early summer (over 50% of DM for ladino clover and red clover) resulted in the greatest IVDMD values.

Conclusions and Recommendations

In general, the legume treatments that resulted in greater legume percentage also resulted in a lesser percentage Matua. After the legumes became well established during the second growing season, Matua dropped to as little as 13% in some instances. Alfalfa and annual lespedeza appeared to be most compatible with Matua.

Ladino and red clover were least compatible with Matua. During some months in 1999, ladino and red clover exceeded 50%. Alfalfa caused a reduction in the Matua component of the stands, but not to the same extent as ladino and red clover. Annual lespedeza appeared only during the latter part of the summer, was not present in an excessive amount, and did not cause a reduction in the Matua component.

Alfalfa improved the nutritive value of the forage, but at an intermediate amount compared to the clovers. Overall, with the management used in the current study, alfalfa appears to be the most appropriate legume to incorporate into Matua stands.

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