Demonstration of Cover Crop Mixtures for Grain and Livestock Grazing

Research Coordinator: Dr. Akim Omokanye

Collaborating Producer: Mark & Tracy Vetsch (MD of Greenview)

From: Peace Country Beef & Forage Association 2014 Annual Report


Soil conservation, nutrient sequestration, weed suppression, improved soil health, and optimizing grain and forage production, among others, are some of the reasons why some producers have had a great interest in including cover crop usage in their beef cattle production systems. The crop species we can use for cover crops and grazing is extensive. Common choices for covers include cereal grains, oats, annual ryegrass, peas, vetch, sudangrass, brassicas, and clovers. Diverse mixes can serve the purpose of improving soil health, holding soil, and providing cheap forage. Properly timed plantings of annuals can make a great system to put weight on growing cattle. Gabe Brown, one of PCBFA’s guest speakers this year, is a cover crop guru, a cover crop promoter and is also in the beef cattle business and grazes cover crops has documented soil health improvements and at the same time realized significant savings in feeding costs.


Methods

The demonstration took place at Mark & Tracy Vetsch’s organic farm, near Valleyview on RGE Rd 215 by TWP Rd 720. Prior to this year, the producer had oats and peas rotation at the site (areas of the field have been designated by NW8 & SW8). Table 1 shows history of site, soil analysis from 0-6” depth (done by Exova laboratory, Edmonton) and cover crop cocktail mixtures used. For SW8, which had peas in 2013 and oats/green manure in 2012, appeared to have higher OM, N and P than NW8 which had oats in 2013.

This year, Natouche peas was directed seeded at 2 bushels/acre (7-9 seeds/ft2) at 2” in a N-S direction and oats was seeded at 1.6 bushels/acre (15.28 seeds/ft2) at 3/4” in a E-W direction (at 90 degrees) to Natouche peas on both fields. Row spacing was 12”. The peas were inoculated with Novozymes Cell Tech Peat. The intent of the oat and pea mixture was to harvest for a grain crop. The remaining crop seeds in the cocktail mixtures 2, 3 and 4 were broadcast with a Valmar and harrowed, with the intent to graze these mixtures.


Table 2 below shows the different crops used and their seeding rates in the cocktail mixtures. Seeding of the mixtures was done from May 19-22.

Cocktail Mixtures 2, 3 and 4 were grazed with 500 yearlings (with an average weight of 800 lbs) at 10 acres per day for a total of about 10 grazing days . Grazing of cocktail mixtures 2, 3, and 4 started after the oats headed out but before the milk stage in the mixtures were in the watery stage. Cocktail Mixture 1 (peas + oats) was combined for grain yield on August 28. Forage samples were sent Central Testing Laboratory Ltd., Winnipeg for feed quality analysis according to standard procedure for wet chemistry.


Results

Forage Dry Matter (DM) yield

The estimated forage DM just before grazing of the cover crop cocktail mixtures was in order of Mixture 2 (3509 lbs/acre) > Mixture 4 (3285 lbs/acre) > Mixture 3 (1557 lbs/acre) (Figure 1). Both Mixtures 2 and 4 respectively had 1952 and 1728 lbs/acre more DM than Mixture 3 (oats, peas, turnips).


Forage Quality (Table 3)

Generally, cocktail mixtures 2, 3 and 4 had more than 12% crude protein (CP). Mixture 2 had the highest protein (15.42% CP), followed by mixture 4(14.72% CP) and then Mixture 3 (12.58% CP). The forage CP of Mixtures 2, 3 and 4 had enough CP to meet the requirements of a mature beef cow (7-11% CP) as well as growing and finishing calves (12-13% CP).


The forage Ca was highest for Mixture 4 (0.75% Ca), followed by Mixture 3 (0.65% Ca) and then Mixture 2(0.55% Ca). Comparing the forage Ca for the mixtures to beef cattle Ca requirements, which is 0.31% Ca for growing and finishing calves, 0.18% for a dry gestating cow and 0.42% for a lactating cow, it is evident that the forage Ca obtained for cocktail Mixtures 2, 3 and 4 was adequate and exceeded the Ca requirements for all classes of beef cattle.

The forage P was 0.27%, 0.21% and 0.19% respectively for Mixtures 2, 3 and 4. All the mixtures had sufficient amount of P needed by a dry gestating cow, which is 0.16% P. Of the three mixtures, only Mixture 2 had adequate amount of P for needed by a lactating cow (0.26% P). For a growing and finishing calf, both Mixtures 2 and 3 had sufficient P needed by theses calves (0.21% P).


The forage Mg, K and Na of all the Mixtures 2, 3 and 4 generally exceeded the amounts required by all classes of beef cattle.


The energy (total digestible nutrients, TDN) for the mixtures varied from 61.2 to 63.6% TDN. All mixtures had sufficient energy needed by a mature beef cow in mid and late pregnancy, which are respectively 55 and 60% TDN. None of the mixtures had enough TDN needed by a lactating cow (65% TDN).

Grain Yield for Peas - Oats Intercrop

Grain yield for oats was 680 lbs/acre and grain yield for peas was 327 lbs/acre (Table 4). Seed weight (g/150) was 32.9 g for peas and 5.54 g for oats.

Some Notes on Potential of Intercropping Peas and Oats for Grain Production

Intercropping is an agricultural practice of cultivating two different crops in the same place at the same time. Benefits to intercropping can lead to greater yield and quality compared to the sole crop. However, carefully planning and suitable conditions need to occur for each crop to be complimentary (creating a higher overall yield), rather than antagonistic (lowering yields). Reasons for additional yield with intercropping may be the result of greater efficiency in the use of nutrients, light, and water. Feed Quality parameters such as crude protien (CP), neutral detergent fiber (NDF) generally improve compared to sole crop parameters. Harvest timing can be delayed with oat/pea intercrop silage as the peas will maintain a higher moisture value than oats. This intercrop helps lengthen the optimum time period for silage harvesting. Intercropping is not a new concept and has been used by farmers for several generations. However, recent improvements in farm machinery and individual variety characteristics have once again tweaked producer’s interests in intercropping.


Often, intercropping is not only measured by total yield of products, but as a total economical value (total $/acre) by combining each crop value, or by Land Equivalent Ratio (LER). The LER is a measure of how much land would be required to achieve intercrop yields with crops grown as pure stands. Grain harvesting issues may arise from threshing limits on harvest equipment when peas and oats are intercropped. Peas require a larger threshing gap between the concave and the threshing drum and a lower threshing drum speed com-pared to oats. Producers will have to take extra care with peas to ensure that splitting is not an issue.

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