Demonstration of Cover Crop Types as Mono-crops for Forage Yield and Nutritional Value

Trial Site: Fairview Research Farm

Research Coordinator: Dr. Akim Omokanye

From: Peace Country Beef & Forage Association 2016 Annual Report


Annual crops for forages can be used to provide an additional source of hay, silage or pasture when perennial forage crops are in short supply. Many annual crops are suitable for inclusion in cocktail mixtures for forage production (for grazing, silage or greenfeed) and to improve soil health. Also, grain crops affected by extreme environmental conditions can be salvaged for livestock use. In the peace, barley and oat are the most common annual cereal forage; there are also acreages of millet, annual ryegrass and annual pulses used for forage. Because of the increasing number of acreages of cocktail mixtures in parts of the Peace, 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 livestock production. Most of the annual crop types tested in 2016 were those that PCBFA did not have much experience with in this region.

Methods

The study site was at the Fairview Research Farm (NW5-82-3W6) on RR #35, MD of Fairview. Soil test at 0-6” soil depth done at Exova laboratory (Edmonton) prior to seeding showed an organic matter content of 7.1%, a pH of 5.5 (acidic), an electrical conductivity of 0.35 dS/m and a base saturation of 55.2%.


A demonstration strip design was used in small plots. We seeded a total of 40 annual crops, which consisted of 9 grasses, 23 legumes, 3 brassicas and 5 other types of crops (Table 1). More legumes were seeded to mark the 2016 International of Pulses, in order to create awareness of the various available legume types.


Legumes were inoculated at seeding.

We seeded on May 18 with a 6-row Fabro plot drill at 9” row spacing. Seeding rates are shown in Table 1.


Fertility according to soil tests (actual lbs/acre):

Grasses - 56 N + 19 P + 46 K + 0 S

Legumes - 0 N + 33 P + 47 K + 0 S

Brassicas & others– 0N (adequate soil N) + 21 P + 31 K + 0 S.

- Soil test showed adequate amounts of S for the crops, so S was not applied.


Festulolium was cut twice. Other crops were only cut once.

Results & Interpretation

Forage DM yield

Cereals/Grasses - Among the group of grasses tested, Festulolium had the highest for-age DM yield (5248 lbs DM @ 1st cut & 3272 lbs @2nd cut), fol-lowed by Sorghum Sudangrass (5160 lbs DM/acre). The other types of grasses had 3498 to 4671 lbs DM/acre (Table 2). A total of 8520 lbs DM/acre was obtained from festulolium in the year.

Festulolium is a high (sugar) energy grass that is obtained by crossing a ryegrass (perennial or an Italian) with a meadow fescue or tall fescue variety. Festuloliums like fertile soils and respond well to nitrogen. They are better than ryegrass in drought tolerance but not as good as fescues. They are excellent for silage or balage and also very good for grazing. Can successfully be used to extend the growing season of hay fields and pastures.

Legumes - The forage DM yield of legume crops tested generally varied from 1318 lbs DM/acre for crimson clover to 4777 lbs DM/acre for CDC meadow pea (Table 2). Only 4 legumes (hairyvetch, red kidney dry bean, CDC Meadow pea, CDC Horizon pea) had 2.0 tons DM/acre or more. Other legumes had <2.0 tons DM/acre.


Faba beans can be used as either forage or silage for animals. Faba beans are the highest nitrogen fixing annual grain legume. Though broad Windsor faba beans and Vroma faba beans yielded more DM than the 2 other faba bean varieties tested (snowbird and snowdrop), they may not fit well into our field scale cropping systems because of their large seed size, which will pose a great issue going through seed drills. They are therefore only better seeded on a small scale in gardens. For field scale and for inclusion in cocktails, snowbird and snowdrop faba beans are suggested. Faba beans’ taproots also have the added benefit of being able to break-up hard compacted soil. Faba beans, like all legume plants have nitrogen-rich nodules on their roots and contribute to replenishing nitrogen in the soil.


Studies elsewhere have shown that hairy vetch can contribute 70 - 150 lbs N/acre. Hairy vetch can add enough nitrogen to provide almost all of the needs of the subsequent crop and can make K more accessible to subsequent crops. Hairy vetch adds to soil biological diversity and supports several beneficial insects.


Others (broadleaf) - Buckwheat had the highest DM yield (3957 lbs DM/acre), followed by flax (2331 lbs DM/acre) and then phacelia (1889 lbs DM/acre) (Table 2).


Buckwheat solubilizes and takes up phosphorus that is otherwise unavailable to crops, then releases these nutrients to later crops as the residue breaks down. The roots of the plants produce mild acids that release nutrients from the soil. These acids also activate slow-releasing, organic fertilizers, such as rock phosphate. Buckwheat’s dense, fibrous roots cluster in the top 10 inches of soil, providing a large root surface area for nutrient uptake. Buckwheat’s abundant, fine roots leave topsoil loose and friable after only minimal tillage, making it a great mid-summer soil conditioner preceding fall crops in temperate areas.


Phacelia has beautiful scented purple/blue flowers with dense fern-like foliage. It smothers weeds and has an extensive root system that improves the soil structure. However it does self-seed very easily so if it is used as a green manure dig in before flowering or cut down and compost the foliage. Phacelia is listed as one of the top 20 honey-producing flowers for honeybees and is very attractive to bumblebees.


Forage Quality (Table 2)

Forage Crude Protein (CP) - All grasses had high forage CP, which varied from 16% for Siberian millet to about 24% for Sorghum grazex III.


The legumes’ forage CP values were mostly >20% CP, reaching up to 29% CP for CDC Orion chickpea forage. Both hairy vetch and CDC Corrine chickpea forage also had impressive forage CP. The 3 peas tested (CDC Meadow, CDC Horizon & 40-10) had lower CP than other legumes.


The brassicas had between 19-26% CP.


For other crop group types, forage CP was similar for flax, buckwheat and phacelia.


Overall, the mean CP for each crop type showed the following order: Brassicas (24% CP) > legumes (22% CP) > grasses (20% CP) > others (14% CP).


Comparing the CP requirements of beef cattle (young & mature), the CP values obtained for all 40 crops test-ed here generally exceeded the CP requirements of young and finishing calves as well as mature beef cattle.


Detergent fibers (ADF & NDF) and non-fiber carbohydrates

The ADF values relate to the ability of an animal to digest the forage, while NDF values reflect the amount of forage the animal can consume. Lower values are preferred for both ADF & NDF.


Generally, NFC is more rapidly digested than fiber. NFC is a significant source of energy for the rumen microbes. The microbes also use NFC to make microbial protein.


Looking at the detergent fibers (ADF & NDF) and NFC values in Table 2, Festulolium seemed to fare better than other cereals/grasses in the cereal/grass group. The 3 forage type peas appeared to do better than other legumes in the legume group.

Energy

Except for flax (57% TDN) and broad Windsor faba beans (49% TDN), all crops tested here had 62% TDN or more (Table 2). CDC Corrine chickpea had the highest TDN (71%). Only broad Windsor faba beans fell short of the minimum TDN required by a mature beef cow (55% TDN). For a gestating cow in the late-pregnancy stage, which requires 60% TDN, only 2 (broad Windsor faba beans and flax) out of the 40 crops tested fell short of meeting the TDN requirements of this category of beef cow.


The mean TDN for each crop type showed that brassicas had 67% TDN, grasses - 65% TDN, legumes - 64% TDN and other crop types - 62% TDN (Table 2).


Minerals

The mean forage Ca, P, K, Mg and Na (macro minerals) values showed the following orders:

Ca - brassicas (2.46% Ca) > legumes (1.93% Ca) > others (1.78% Ca) > grasses (0.62% Ca)

P - brassicas (0.46% P) > grasses (0.34% P) > legumes (0.26% P) > others (0.20% P)

K - brassicas (2.97% K) > grasses (2.65% K) > others (1.52% K) > legumes (1.43% K)

Mg - others (0.86% Mg) > legumes (0.64% Mg) > brassicas (0.61% Mg) > grasses (0.52% Mg)

Na - brassicas (0.84%) > legumes (0.32% Na) > grasses (0.29% Na) > others (0.12% Na)


Except for both proso millet and buckwheat, all crops tested here had sufficient amounts of Ca needed by mature beef cattle.


All crops had adequate P contents for a gestating beef cow, which requires 0.16% P, but some crops were short of meeting the 0.26% P recommended for a lactating beef cow.


All crops had adequate K, Mg, S, Fe, Zn and Mn values for mature beef cattle.

The requirement for Na was not generally met by all crop types.

All crops fell short of 10 ppm copper (Cu) needed by mature beef cattle.


Poor Performers

The following crops did not do well in our tests (see Table 1): Balansa clover, Subterranean clover, Persian clover, Iron & Clay cowpea, Black-eyed peas, Ife brown cowpea, Sugar beet, Ethiopian cabbage and Teff. Some of them did not emerge, and for those that emerged, the seedling counts were very low relative to the seeding rates. These crops would not be recommended for inclusion in cocktails for now. Trials will continue on other or newer varieties for their suitability for the Peace.


Caution on the use of cover crop species

The fact that most of the cover crops that we use for cocktail mixtures are being introduced to us in the Peace region, the use of these cover crops therefore requires very good understanding of plant growth habits and management, particularly when seeded as monocrops.


Cover crops can cause serious problems if not managed carefully. They can deplete soil moisture; they can become weeds; and—when used as an intercrop—they can compete with the cash crop for water, light, and nutrients.


Some cover crops can become unwanted weeds in succeeding crops. Cover crops are sometimes allowed to flower to provide pollen to bees or other beneficial insects. Some cover crops or their mixtures if not harvested at the right time for silage or greenfeed, the plant can actually set seed, the cover crop may reseed unintentionally the following year in crop rotation systems. Cover crops that may become a weed problem include buckwheat and ryegrass. On the other hand, natural reseeding of crimson clover or hairy vetch might be beneficial in some situations.


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