Trial Site: Fairview Research Farm
Research Coordinator: Dr. Akim Omokanye
From: Peace Country Beef & Forage Association 2017 Annual Report
Because of the interest in cocktail mixtures, there is a need to regularly test new annual crops as they are introduced to the Peace for their adaptation, potential for forage yield, and suitability for soil health improvement and inclusion in cocktail mixtures. Forage-type legumes for cocktail mixtures include those of cool and warm season types. Cool season legumes include peas, faba beans and hairy vetch and warmseason legumes include crops like cowpeas and soybeans. These crops produce N and provide ground cover for weed and erosion control, in addition to the many other benefits of growing cover crops. Legumes are generally lower in carbon and higher in nitrogen than grasses. This lower C:N ratio results in faster breakdown of legume residues. Therefore, the N and other nutrients contained in legume residues are usually released faster than from grasses. Mixtures of legume and grass cover crops combine the benefits of both, including biomass production, N scavenging and additions to the system, as well as weed and erosion control.
Objective
To identify forage-type legumes that can be recommended for inclusion in cocktail mixtures.
Methods
Project Site: Fairview Research Farm (NW5-82-3W6) on RR #35, MD of Fairview.
Previous Crop: oats for greenfeed in 2016, forage grasses from 2010-2015
Site soil information (0-6” depth): Soil tests done at Exova laboratory (Edmonton) prior to seeding showed pH = 5.6 and soil organic matter = 8.0%.
The field was cultivated (disked and harrowed) before seeding.
Experimental Design: Randomized complete block design in 3 replications.
Treatments: 12 forage-type legume cover crops were tested:
1. Hairy vetch@ 18 lbs/acre
2. Chickling vetch @ 70 lbs/acre
3. Wolly pod vetch@ 27 lbs/acre
4. Fenugreek @ 27 lbs/acre
5. 40-10 Peas @ 8.8 seeds/ft2
6. Horizon peas @ 8.8 seeds/ft2
7. Meadow peas @ 8.8 seeds/ft2
8. CDC Leroy @ 8.8 seeds/ft2
9. Tabasco Fababean @ 5.2 seeds/ft2
10. Fabelle Fababean @ 5.2 seeds/ft2
11. Snowbird Fababean @ 5.2 seeds/ft2
12. Iron & Clay Cowpeas @ 100 lbs/acre
Seeding date was June 1.
Seeding Date & Rate: Seeding was done on June 1 and seed was inoculated.
Seeding method: 6-row Fabro plot drill with 9” row spacing
Fertility (actual lbs/acre): 50 lbs/acre of 11-52-0.
Plot size: 11.04 m2 (118.8 ft2 )
Sprayings: Pre-emergent with Roundup Weathermax. In-crop spraying was done with Basagran Forte once
The crops were harvested from August 12-22, corresponding to 76-82 days after seeding. Forage samples were analyzed for quality.
Notes were taken on soil cover, flowering and pod maturation, and lodging in peas. The legumes were assessed for their N fixation potential by digging the roots out of the soil and looking at their nodules.
Results and Interpretation
Forage Dry Matter (DM) Yield (Table 1)
The forage DM yield was highest for CDC Horizon peas (8660 lbs DM/acre). All peas had similar forage DM yield. The peas had more forage DM than other legumes tested.
Of the 3 vetches tested, woolly pod vetch produced a higher forage DM yield than chickling and hairy vetches. Woolly pod vetch had 1543-1648 lbs DM/acre more forage yield than chickling and hairy vetches. Our observation over 4 years has shown that hairy vetch does have an initial slow growth or establishment here in the Peace, but once established it grows vigorously and has excellent soil cover particularly into late summer. Once established, hairy vetch provides enough cover to suppress weeds and protect soil, and it does provides a longer window of protection than other cover crops. It is important to note that hairy vetch does have the potential to yield higher forage DM than what was obtained this year.
The 3 faba bean varieties produced similar forage DM yield. Iron & Clay cowpea (a warm season legume) and Fenu Greek produced far lower forage DM yield than other legumes.
With the exception of Iron & Clay cowpea, which did not have any nodules, all tested legumes produced nodules on their roots, indicating that the legumes could be fixing N. Reports elsewhere have shown that some of the legumes tested here, such as hairy vetch and faba beans, can add enough nitrogen to provide almost all of the needs of the subsequent crop. Reports have also indicated that hairy vetch can make K more accessible to subsequent crops. Other attributes of hairy vetch include overwintering ability and cold tolerance, as well as early spring growth in the second year following seeding.
Forage Quality (Table 1)
Crude Protein (CP): The forage legumes tested here had high forage CP, which was generally >17% CP. The forage CP was highest for Iron & Clay cowpea (26.3% CP). The 40-10 variety of forage-type peas had the highest forage CP among the 4 peas tested. The faba beans had similar forage CP.
All forage-type legumes tested here far exceeded the CP requirements of young and mature beef cattle.
Energy: The total digestible nutrients (TDN) varied from 60.1% TDN for chickling vetch to 74.7% TDN for fenugreek. The forage net energy for lactation (NEL), net energy for gain (NEG) and net energy for maintenance (NEM) seemed to be higher for fenugreek than other legumes, though some legumes had very close values to that of fenugreek.
Only 3 (woolly pod vetch, chickling vetch and fabelle fababean) of the tested forage-type legumes did not have enough TDN for mature beef cattle. Woolly pod vetch, chickling vetch and fabelle fababean were only able to meet the TDN requirements of dry gestating beef cattle and not that of a lactating beef cow.
In terms of net energy requirements for maintenance (NEM), all forage-type legumes tested here fell within the recommended 1.08-2.29 Mcal/kg NEM for growing and finishing calves. All legumes exceeded the 0.97- 1.10 Mcal/kg NEM for dry gestating cows, and the 1.19-1.28 Mcal/kg NEM for lactating beef cows.
Minerals: All the macro minerals (Ca, P, K, Mg, Na & S) and trace minerals (Cu, Fe, Zn & Mn) measured here were significantly affected by forage-type legume crops tested. Iron & Clay had the highest forage Ca, Mg, Fe and Mn. Hairy vetch had the most forage P, K, Cu and Zn. Tabasco faba bean had the highest forage Na content. Iron & Clay, fenugreek, and woolly pod vetch all had similar, high levels of forage S.
The mineral requirements of Ca, K, Mg, S, Fe and Zn were all met by all forage-type legumes tested here.
All forage-type legumes were able to meet the amount of P needed by a dry gestating beef cow, but only 3 (CDC Horizon peas, Meadow peas and snowbird fababean) fell short of meeting the P requirements of a lactating beef cow, which needs 0.26% P after calving.
A few of the legumes did not have enough forage Na and Mn for mature beef cattle. All legumes fell short of meeting the 10 ppm Cu needed by mature beef cattle.
Overall, fenugreek, chickling vetch, hairy vetch, woolly pod vetch, snowbird faba bean and tabasco faba bean were all able to meet most of the mineral requirements of mature beef cattle.
Estimated N Fertilizer Value (see Table 2 below)
When the forage-type legumes were assessed for their potential N fertilizer value based on their forage biomass and forage N content at harvest, all peas seemed to have higher N fertilizer value than other legumes. Please note that except for the peas, which were at an advanced stage of growth, other legumes (particularly Iron & Clay cowpea, hairy vetch and fenugreek) would have been able to produce more forage DM than what we obtained had they been harvested later. It is also important to note that Iron & Clay cowpea, hairy vetch and fenugreek were still actively growing (mostly vegetative stage) at harvest, so the estimated N fertilizer value reported here could still be higher if they were harvested later.
Should any of the forage materials from the legumes be used for green manure or rolled down, it is evident that at the time when the legumes were harvested here in this study, most legumes had enough N for a subsequent cereal crop production.
Conclusion
With the exception of Iron & Clay cowpea and Fenugreek, all the forage-type legumes tested here showed great potential for inclusion in cocktail mixtures for forage production for beef cattle. The vetches and the peas did provide very good to excellent soil cover. Iron & Clay cowpea and Fenugreek are not recommended for the area. Except for Iron & Clay cowpea, all legumes had nodules. Chickling and woolly pod vetches flowered earlier than hairy vetch and they both also produced mature pods, and therefore they have the potential to be grown for seed in Fairview and area.