Collaborating Producers: Conrad Dolen - Fourth Creek, Greg & Bev Wieben - Fairview & Allan McLachlan - Fairview
Research Coordinator: Dr. Akim Omokanye
From: Peace Country Beef & Forage Association 2016 Annual Report
Cover crops (CCs) and their mixtures (cocktail mixtures) are an important tool that producers can use to generate multiple benefits on the farm, including improved soil health, nutrient supply to companion or subsequent crops, weed suppression, insect pest management, forage production, pollinator resources, and clean water and air. There are many different CC species to choose from, and each CC species has different abilities to provide the benefits mentioned above. Cocktail cover cropping involves using complex mixtures of CC seeds, which can be up to 5, 8 or more varieties of seed in a single mix to achieve multiple soil health, production and profit goals. Three on-farm field scale demonstrations were carried out in 2016 with a variety of cocktail mixtures. Soil tests (except for one site) were carried out before seeding for base data. Subsequent soil tests (2017 & 2018) would be compared to the base data to assess any soil health improvements.
Site 1: Conrad Dolen, Fourth Creek: Cocktails for Silage
For this site, we used 4 fields for the trial. The cocktails seeded in those fields are shown in Table 1. Harvesting was done on August 3 for dry matter (DM) yield determination. Field #1 and Home N & S were harvested when barley was at the soft-dough stage. Field #6 was harvested when oat was at the late milk stage. Forage samples were analyzed for quality.
Results and Interpretation
Forage Moisture Content at Harvest
Forage from Field #1 was moister (74%) than forages from other fields. As expected, both Home N & S fields had similar forage moisture. This is because both Home N & S fields contained the same type of cocktails. Except for Field #1, which had higher moisture content than others at harvest, the forages from the fields had appropriate moisture content for ensiling. The higher moisture content observed for field #1 could be due to a combination of factors, including more hairy vetch seeded, some sunflower in the mixture and high soil fertility observed at the site following soil tests before seeding.
Dry matter (DM) yield (Table 2)
The forage DM yield was highest for Field #1 (6.09 tons/acre), followed by Home-S (4.52 tons/acre), Home-N ( 4.05 tons/acre) and then Field #6 (2.91 tons/acre). The impressive DM yield from Field #1 was due to the initial soil nutrients just before seeding. Field #1 had better soil nutrients than other fields used. Also, every crop included in the cocktail for Field #1 grew very well including sunflower, which grew taller than other crops and flowered as well. Sunflower is a warm season crop and our observation for about 3 years now in the Peace is that sunflower does well in cocktails in this region.
Crude Protein (CP, Table 2).
The forage CP was highest for Field #1 (15% CP). Field #6 had the lowest CP (7.81% CP). All fields had sufficient CP for a gestating beef cow at the second trimester stage, which re-quires 7% CP. For a gestating beef cow at the third trimester stage that needs 9% CP, only Field #6 fell short of meeting the 9% CP needed by this category of beef cow. Field #1 exceeded the CP requirements of mature beef cattle as well as growing and finishing calves that require 12-14% CP.
Detergent Fibers (ADF & NDF) and Non-fiber Carbohydrates (NFC)
Home-S had the lowest ADF (26.4%) & NDF (43.7%) and the highest NFC (34.7%) (Table 2). In terms of forage quality, lower values are preferred for both ADF & NDF, while a higher value is preferred for NFC.
The ADF value is important because it relates to the ability of an animal to digest the forage. As ADF increases, digestibility of forage usually decreases. The NDF value is important in ration formulation because it reflects the amount of forage the animal can consume. As NDF percentages increase, forage DM intake will generally decrease. NFC is more rapidly digested than detergent fibers. NFC is a significant source of energy for the rumen microbes. The microbes also use NFC to make microbial protein.
From Table 2, Home-S, followed by Home-N appeared to be of better forage quality then Fields #1 and #6. Considering that as ADF and NDF increase, both digestibility and consumption of forage usually decrease, it is reasonable to say that when all the cocktails are presented side by side to cows in a preference study, the cocktails in Home-N & S would likely be consumed before the cocktails in Fields #1 and #6. The cocktails in Home-N & S would also provide more energy and microbial protein sources in the rumen.
The forage energy was generally enough for a gestating beef cow, which requires 55% at mid-pregnancy stage and 60% at late-pregnancy stage. For a lactating beef cow, the cocktails (except for Field #6 cocktail) were able to meet the 65% needed by a nursing beef cow.
In terms of forage minerals, Field #1 had the highest Ca, P, K, S, Fe and Zn. Except for cocktails contained in Field #6, the Ca requirement of mature beef cattle was met by all cocktails tested here. Only Field #1 and Field #6 had adequate P needed by mature beef cattle. Generally, the requirements of K, S, Fe and Mn by mature beef cattle were sufficiently met by all cocktail mixtures. The requirements for Cu were not met by any of the cocktails tested here.
Site 2 (Greg & Bev Wieben - Redstar Farms Ltd, Fairview): Cocktails for Swath Grazing vs Corn
We tested 4 cocktail mixtures and we used corn as check. The cocktail mixtures seeded are shown in Table 1. Seeding was done on June 2, 2016. Corn was seeded with a Seed Master at 12” spacing. Ammonium nitrate was applied at 90 lbs/acre to each of the cocktails and check.
We harvested the cocktails on August 17, 2016 for dry matter (DM) yield determination, forage quality and nitrates (except for corn).
Results and Interpretation
Forage DM yield
The forage DM was highest for cocktail #3 (6.9 tons/acre), followed by cocktail #1 (6.01 tons/acre) and then corn (5.30 tons/acre) (Table 2). Cocktail #3 contained more cover crop types (7) than other cocktails, so the higher yield from Cocktail #3 over other cocktails could be the effect of a possible yield advantage of cocktails with more cover crops in the mixture.
Forage Protein Content (Table 2)
The forage crude protein (CP) was highest for cocktail #3 (24% CP). All cocktails tested had higher CP than corn (check). Overall, all cocktails as well as corn had sufficient CP for mature beef cattle. The higher CP values obtained for both cocktails #2 and #3 than cocktails #1 and #4 and corn was probably due to the presence of legumes (40% - hairy vetch & crimson clover) in cocktails #2 and #3. The four cocktails also had adequate CP for growing and finishing calves, which require 12-14% CP.
Overall, Cocktails #1, #2 and #3 far exceeded the CP requirements of both young and mature beef cattle, while corn fell short of meeting the CP requirement of calves.
Detergent Fibers (ADF & NDF) and non-fiber carbohydrates (NFC)
In terms of forage quality, lower values are preferred for both ADF and NDF, while a high value is preferred for NFC. Looking at Table 2 below, cocktail #2 appeared to have lower ADF and NDF values and higher NFC value compared to other cocktails and corn (check). This therefore indicates that cocktail #2 is of better quality than the other cocktails and corn.
Considering that as ADF and NDF increase, both digestibility and consumption of forage usually decrease, it is reasonable to say that when all the cocktails and corn are presented side by side to cows in a preference study, cocktail #2 would likely be consumed first, as well as provide more energy and microbial protein sources in the rumen.
Cocktail #2 had higher total digestible nutrients (TDN, 63%) than the other cocktails and corn. Corn and both Cocktails #2 and #3 had >60% TDN, while both cocktails #1 and 4 had lower than 60% TDN.
Using %TDN, the Rule of Thumb says that for a mature beef cow to maintain her body condition score through the winter, the ration must have a TDN energy reading of 55 per cent in mid pregnancy, 60 per cent in late pregnancy and 65 per cent after calving. This shows that from this demonstration, all cocktails and corn had sufficient TDN for a pregnant cow in the second trimester. For a pregnant cow in the third trimester stage, cocktails #2 and #3 as well as corn were able to meet the 60% TDN needed by this category of cow.
All cocktails had higher minerals than corn (Table 3). All cocktails had sufficient minerals (except Cu) for mature beef cattle. Cocktail #4 did not have enough Na for beef cattle.
Corn was only able to sufficiently meet the Ca, P and Mg requirements of a gestating beef cow, but not that of a lactating beef cow. Corn also fell short of meeting the S and Cu requirements of all categories of beef cattle.
The higher macro- and trace-minerals obtained by all cocktails compared to corn in this demonstration further confirms the potential benefits of cover crop mixtures in improving forage quality.
Site 3 (Allan McLachlan, Fairview): Cocktails for Silage
The site for this trial, which was about 120 acres, was on RR 44/TWP 804 (SE29 80 04 W6) in Fairview. In 2015, barley-pea mixture was seeded for silage. It was grazed in the fall. We had 5 treatments consisting of one crop (barley - check) to 7 cover crops in a mixture as shown in Table 1. In order to assess the potential benefits of including legumes in forage-based production systems, we decided to test mixtures of barley and hairy vetch (with or without innoculant) for forage yield and quality improvements as well.
Hairy vetch is a forage legume. It fixes nitrogen and can add enough nitrogen to provide almost all of the needs of the subsequent crop. Hairy vetch can contribute 70-150 lbs N/acre. Studies in US have shown that hairy vetch mixed with rye fixes almost the same amount of nitrogen as if it were grown without a companion. Hairy vetch can make K more accessible to subsequent crops. Hairy vetch is especially known for erosion control, bank stabilization, winter cover crop, and soil conditioning. It can be a suitable plant in organic and no-till pasture and cropping systems.
We harvested the cocktails on August 3, 2016 for dry matter (DM) yield determination, when barley was at the soft dough stage. Forage samples were analyzed for quality.
Results and Interpretation
Forage DM yield (Table 2)
Cocktail #3 had the highest forage DM yield (about 5.0 tons/acre). Though we did not look at the proportion of individual crop in the total forage DM yield, visual observation showed that triticale (Bunker variety, a forage type) probably contributed greatly to the higher DM yield obtained for Cocktail #3 over other cocktails and check. Bunker grew very tall and its growth was generally impressive. Bunker is an awnletted (reduced awn expression) standard height spring triticale line intended for use as a feed grain and conserved forage. The high silage yield and reduced awn expression in Bunker will diversify the use of spring triticale as a conserved forage (for silage and greenfeed/hay).
The DM yield as % of mono-crop barley (check) varied from 113% for cocktail #1 to 146% for cocktail #3. The forage DM yield as a result of inoculating hairy vetch over un-inoculated hairy vetch seed with barley was 857 lbs/acre in favour of inoculated hairy vetch. Overall, using hairy vetch as a companion crop with barley gave 1315 lbs DM/acre over mono-crop barley (check).
Generally in 2016, we observed that hairy vetch could have an initial slow establishment in the spring in the Peace, but once established, hairy vetch can be aggressive and competitive particularly going into early fall .
Research elsewhere has shown that:
Pure barley reduced N leaching but caused a low N availability in the soil.
Pure hairy vetch supplied a lot of N, but was ineffective in reducing the N leaching risk.
Barley–vetch mixture assured a stable N accumulation (buffered system).
Barley–vetch mixture reduced NO3-N leaching risk (buffering system).
An optimized “cover crop strategy” should always prefer mixtures to pure stands.
Crude protein (CP, Table 2)— Cocktail #4, which had more cover crops in the mixture had the highest forage protein (14% CP). All mixtures had 0.7 to 3.5% more CP than mono-crop barley (check). Inoculating hairy vetch seeded with barley did not improve forage CP over un-inoculated hairy vetch seeded with barley, as both mixtures had similar CP.
For a mature beef cow, 7% CP is required at mid-pregnancy stage, 9% at late-pregnancy and 11% during lactation. Looking at Table 2, all cocktails as well as mono-crop barley (check) were able to meet the protein requirements of a mature beef cow at different physiological states. For growing and finishing calves, only cocktail #4 had enough CP (14%).
The forage energy (%TDN) appeared to be higher for barley check and cocktails #1 & 2 than other cocktails. Barley check and cocktails #1 & 2 were able to meet the 65% TDN required by mature beef cattle. Both cocktails # 3 & 4 were only able to meet the 60% TDN needed by a gestating beef cow.
Minerals (Table 3)
The forage Ca appeared to be increased by including hairy vetch in cover crop mixtures (Cocktails #1, #2 and #4). The benefit in terms of forage Ca improvement was pronounced with inoculated hairy vetch (cocktails #2 and #4). Both barley check and Cocktail #3 (barley, peas & triticale) had lower for-age Ca than those cocktails with hairy vetch.
Similarly, forage P appeared to be increased by inoculating hairy vetch before seeding. Both cocktails #2 and #4, which had inoculated hairy vetch, had higher forage P than the other cocktails and check.
Generally, cocktail #4, which had more cover crops in the mixture, had higher forage Ca, P, K, Mg, Na, S and Fe than the other cocktails with less cover crops in them.
All cocktails as well as barley check were able to meet the Ca, P, Mg, K, Na, S and Fe requirements of a gestating cow.
The Zn requirements of a gestating cow were only met by Cocktails # 1 and #4. Other cocktails and check failed to meet the Zn requirements of a dry gestating cow.
None of the cocktails or barley (check) had enough Mn (40 ug/g) and Cu (10 ug/g) needed by mature beef cattle (40 ug/g).