Feb, 2000

FC 26.7

Pea and Small Grain Mixtures

Dan Undersander

Extension and Research Forage Agronomist

Many farmers have considered including peas with small grains used as a cover crop for establishing alfalfa or as an emergency silage crop. The resulting silage is more palatable and higher in quality than small grain silage. The following information summarizes research regarding the influence of variety selection, seeding rate and mixture proportion.

Influence of small grain varieties

Studies were conducted at the University of Wisconsin Arlington Research farm comparing different oat and barley mixtures with peas during 1986 to 1988. The small grain was planted at 20 seeds/sq ft (about 2 bu/a) both in pure stands and when mixed with peas. Peas (Trapper) were included at 10 seeds/sq ft (about 1.5 bu/a). Fertilizer applications were sufficient to ensure that N, P, and K levels were at least medium high. Alfalfa was seeded with 16 lb/a. The mixtures were harvested when three to five kernel of heads had emerged from the boot. Cutting height was 2.5 inches.

The data (in tables 1 and 2) clearly show that adding peas to oats improved forage quality by increasing protein content 3 to 5 points and reducing NDF by 4 to 8 points. Adding peas to barley increased protein 2 to 4 points and reduced NDF by 5 to 9 points. The addition of peas increased yield in only one of three years. Generally, it is expected that, unless nitrogen is limiting, adding peas to small grains will have minimal effect on total forage yield. Therefore the only reasons for adding peas are to improve small grain silage forage quality and palatability.

Peas do not dry as fast after cutting as small grain forage, so small/pea mixtures will dry slower than pure small grain forage.

Barley and oat varieties had the same average yields, both alone and in mixture with peas. Shorter, earlier heading varieties have lower forage yields and higher forage quality. Thus, varietal selection, not species selection, has the greatest effect on yield. Triticale (data not reported) also has about the same average yield with taller, later maturing varieties yielding more than early, shorter varieties.

On the other hand, alfalfa harvested following shorter, earlier small grains yielded more. The recommendation is to harvest small grain silage when at the boot stage for dairy cows and soft dough (slightly lower forage quality but greater tonnage) for other categories of animals. Small grain/pea mixes should be harvested by the stage of maturity of the small grain.

Influence of small grain and pea seeding rates.

Studies were conducted at the University of Wisconsin Arlington Research farm comparing different oat and barley mixtures with peas during 1986 to 1988. Fertilizer applications were sufficient to ensure that N, P, and K levels were at least medium high. Alfalfa was seeded with 16 lb/a. The mixtures were harvested when three to five kernel of heads had emerged from the boot. Cutting height was 2.5 inches.

Addition of peas increased yield moderately when adequate moisture was present. This was especially at lower seeding rates. It appears that increasing oat seeding rate above 45 to 60 lbs did not result in further yield increases (Fig1). Similarly, increasing pea seeding rates above 100 lb/a (8 seeds/sq ft) did not result in further yield increases, though forage NDF continued to increase with increases in pea seeding rate (Fig 2). Pea seeding rates not resulting in both yield and quality increases (above 100 lb) are not economical. In fact, as peas prices increase above 12¢ per pound, it may not be economic to seed more than 50 lb peas/acre. In addition to cost, higher pea seeding rates mean slower drydown during harvesting.

Under dry conditions oat seeding rates above 15 seeds/ sq ft (45 lbs) may decrease the alfalfa stand. Thus the recommended seeding rate for optimum yield and quality are for 10-15 oat seeds /ft2 (60 lb) and 8 pea seeds/sq ft (100lb) of trapper peas. The final seeding rates selected should be adjusted down if moisture may be limiting and seed cost is higher.

Peas vary widely in seed size. While the studies above were conducted with Trapper peas and seed rates are expressed for this variety, the actual seeding rate should be adjusted for the pea variety used as shown in fig 3.

In summary, small grain/pea mixtures produe forage higher in protein and lower in fiber than pure small grain silage with minimal yield changes. Further, the pea component does not change in quality as fast as oats, so the mixture has a longer harvest window than small grains by themselves. The silage is also more palatable. Disadvantages of the mixtures are greater seed cost, slower drying rate, and great lodging potential.

Table 1. Characteristics of oats and oat-pea mixtures harvested as forage at Arlington, Wisconsin in 1986-88.

Oat or oat-pea mixture	Cut date	Height at cut date	Forage yield	Forage crude protein	ADF	NDF	Alfalfa yield during establishment year 1/	Total 1^st year forage yield 2/	1^st cut alfalfa yield during year after establishment3/
	June	in	1b/a	%	%	%	1b/a	1b/a	1b/a
Webster	5	21	2197	15.4	27.5	48.5	2294	4491	5433
Webster/peas4/	5	21	2402	20.0	28.0	43.3	2092	4494	5612
Stout	7	21	2769	14.3	29.7	52.1	1955	4724	5658
Stout/peas	7	22	3035	18.1	29.3	45.9	1848	4883	5423
Ogle	9	24	2860	13.2	31.6	53.3	2156	5215	5951
Ogle/peas	9	25	3217	18.0	30.1	44.8	1998	5016	5778
Hazel	10	23	3154	12.9	31.3	54.6	1905	5059	5426
Hazel/peas	10	24	3450	16.7	31.0	48.3	1734	5184	5779
Centennial	11	25	3024	13.4	29.6	51.8	2061	5085	5925
Centennial /peas	11	25	3331	17.8	29.6	46.1	1980	5311	5446
Lyon	13	28	3359	12.9	29.4	51.0	1805	5164	5604
Lyon/peas	13	28	3581	17.1	29.5	46.6	1729	5309	5702
Porter	14	24	3519	13.1	31.3	55.2	1884	5403	5345
Porter/peas	14	25	3728	16.9	30.6	48.5	1771	5499	5416
Dal	15	26	3347	13.5	31.0	53.2	1739	5086	5467
Dal/peas	15	26	3719	16.6	30.9	46.7	1520	5238	5462
Lodi	15	30	3798	12.7	31.5	55.4	1523	5320	5769
Lodi/peas	15	30	3849	16.4	31.0	47.1	1346	5195	5599
SN404	16	28	3978	13.7	32.7	54.0	1824	5802	5504
SN404/peas	16	28	4096	17.8	31.1	45.7	1685	5781	5840
Oat average	12	25	3201	13.5	30.6	52.9	1915	5135	5608
Oat/pea ave.	12	25	3441	17.6	30.1	46.3	1770	5191	5591

1/ Alfalfa was harvested in mid to late August. To increase the probability of good winter survival, fall regrowth of alfalfa was not harvested in October in any year

2/ Total first year forage yield = forage yield from oats or oat – pea mixture harvested in June plus alfalfa yield harvested in August.

3/ Two year results

4/ Trapper field peas

Data from L.B. Chapko, M.A. Brinkman, E.T. Gritten, and K.A. Albrecht, 1989

Table 2. Characteristics of barley and barley-pea mixtures harvested as forage at Arlington, Wisconsin in 1986-88.

Barley or barley-pea mixture	Cut date	Height at cut date	Forage yield	Forage crude protein	ADF	NDF	Alfalfa yield during establishment year 1/	Total 1^st year forage yield 2/	1^st cut alfalfa yield during year after establishment 3/
	June	in	1b/a	%	%	%	1b/a	1b/a	1b/a
Morex	7	28	2932	14.0	31.0	56.9	1800	4733	5730
Morex/peas4/	7	28	3149	17.2	30.2	50.7	1639	4788	5786
Hazen	8	27	3467	13.4	32.4	58.2	1776	5244	5572
Hazen/peas	8	27	3587	16.4	31.3	52.1	1536	5054	5410
Robust	8	28	3023	13.7	32.2	57.7	1897	4919	5825
Robust/peas	8	28	3201	16.5	31.3	51.0	1600	4801	5820
Chopper	10	28	3848	13.3	33.7	59.6	1642	5491	5815
Chopper/peas	10	28	3940	15.6	32.1	53.0	1531	5471	5600
Barley average	8	28	3318	13.6	32.3	58.1	1779	5097	5736
Barley/pea ave.	8	28	3469	16.4	31.2	51.7	1577	5029	5654

1/ Alfalfa was harvested in mid to late August each year. To increase the probability of good winter survival, fall regrowth was not harvested in mid-October in any year.

2/ Total first year forage yield = forage yield from barley or barley-pea mixture harvested in June plus alfalfa yield harvested in August.

3/ Two year results.

4/ Trapper field peas.

Data from L.B. Chapko, M.A. Brinkman, E.T. Gritten, and K.A. Albrecht, 1989

Undersander©2001