Evaluation of Forage Type Soybeans and Peas for Forage Yield and Quality

Research Coordinator: Dr. Akim Omokanye

Location: Fairview Research Farm (NW-5-82-3-W6)

From: Peace Country Beef & Forage Association 2013 Annual Report


Annual forage legume crops can complement annual cereals or perennial forages or they can be utilized as emergency feed. Using annual legumes can provide additional rotational benefits with about 25% of the over-all nitrogen fixed by the legume plant remaining in the soil. Utilizing annual forage legumes in a portion of the forage based cropping systems will also allow the producer to diversify without taking land out of annual crop production. The objective of this trial was to assess the performance of forage type soybean and pea varieties for forage yield and quality for beef cattle production.


Methods

Trial Site: Fairview Research Farm (NW5-82-3W6) on RR #35, MD of Fairview. The site had no crop planted in 2012, but had a canola variety trial in 2011. The site had a pH of 5.4 and 8.8% organic matter. Prior to seeding, a pre-seed weed control was carried out with Credit® after the site had been harrowed.


Crop Variety, Seeding and Crop Management:

Three forage/silage type roundup ready soybean varieties (P001T34R (from Pioneer), Mcleod R2 (from Secan) and Mammoth R2 (from BrettYoung) and two forage type pea varieties (40-10 and CDC Horizon) were used for the trial. The crop varieties were arranged in a random-ized complete block design with two replications in plots measuring 1.4 m in width and 8.5 m in length. Seeding and fertilizer application were done on May 23, 2013 with a Fabro plot drill equipped with double shoot Atom jet openers. Inoculated soybean and peas seeds were used. Fertility was 40 lbs/acre of 11-52-0. Seeding rate was 104 lbs/acre for 40-10 pea, 115 lbs/acre for CDC Horizon pea, 48 lbs/acre for P001T34R soybean, 75 lbs/acre for Mcleod R soybean and 62 lbs for Mammoth R2 soybean. Seeding rate was based on 4 seeds/sq ft for soybeans and 10 seeds/sq ft for peas. In crop weed control in soybeans involved the use of roundup and for peas, Basagran Forte was used. Hand weeding of volunteer canola took place twice in the soybean plots.


Field Notes and Measurements:

Notes were taken on seedling emergence, flowering, lodging and plant height. Crop harvest for forage yield estimation and feed quality test was done on August 18 and August 31 respectively for peas and soybeans.


Results and Discussion

Seedling Emergence and Crop Growth

Both pea varieties germinated at the same time and 7-10 days earlier than soybeans. Soybeans are warm season crops that require warmer soil temperature (about 10oC) to germinate. Peas generally grew taller than soybean varieties. 40-10 pea variety lodged heavily, while no lodging was observed for CDC Horizon and any of the soybeans. All crop varieties (except for P001T34R) flowered and had their pods filled to some extent at harvest.


Forage Yield

The DM yield was highest for 40-10 pea and lowest for P001T34R soybean. The lowest DM yield recorded for P001T34R probably resulted from its inability to flower during the growing season and absence of pods at harvest. This is probably an indication that DM would generally decrease for later maturing soybean varieties in this environment. But generally, pea varieties appeared to have higher forage DM yields (3.9 - 4.1 ton/acre) than soybean varieties (2.9-3.3 tons/acre). 40-10 pea out yielded CDC Horizon pea by 428 lbs DM/acre.

Forage Quality

Protein content was between 11.4 and 11.9% for pea varieties and > 17.0% for soybean varieties. Soybean varieties had 5.9 - 6.8% more protein than pea varieties. Protein was highest for P001T34R (18.2% CP). The protein values obtained for both peas and soybeans were sufficient for a dry gestating (7-9% CP) and lactating (11% CP) cow. All soybeans far exceeded the protein requirements by these categories of cows. For growing and finishing calves, which require 12-13% CP, all soybeans even far exceeded the required values.


The forage Ca content was lowest for CDC Horizon (1.30%) and highest for Mcleod R2 (1.78%). All the crop varieties exceeded the suggested Ca requirements for various categories of beef cattle (0.31% for growing & finishing calves, 0.18% for dry gestating cows and 0.42% for lactating cows).


For a dry gestating cow which requires 0.16% P, only two of the crop varieties (Mcleod R2 and Mammoth R2) met P requirement. Other varieties fell short (0.13-0.15%) of meeting what is needed by a dry gestating cow.


The requirements of both 0.12 % Mg and 0.6% K by a dry gestating cow were both met by all crop varieties. Of the five crop varieties, only 40-10 pea variety met the suggested Na content for a dry gestating cow.


Forage energy content (TDN) was >61% for all crop varieties and sufficient for cows in the mid and late pregnancy stages, but all crops had insufficient TDNs needed by a lactating cow (65% TDN).


Generally, though no significant differences were observed for all feed quality parameters analyzed for in the present study (except protein), soybean varieties appeared to be favoured by all feed quality parameters than pea varieties (Table 1).

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