Multi-species Cover Crop Mixtures (Cocktails) for Silage

Trial Site: Fairview Research Farm, Municipal District of Fairview

Research Coordinator: Dr. Akim Omokanye

From: Peace Country Beef & Forage Association 2016 Annual Report

Interest in the potential for a multispecies cover crop (CC) blend for silage, swath grazing and greenfeed has been growing amongst beef cattle producers in the Peace. The idea of CC mixtures (cocktails) is new, indicating that the concept of a CC cocktail mix is an area where local research for local producers is needed. Re-search elsewhere and reports from producers who have experience with CCs have shown that CCs can provide many environmental and agronomic services within agroecosystems. These include reduced soil erosion, increased biological diversity (e.g., microbes, insects), increased nutrient cycling and biological N2 fixation, increased soil organic matter (SOM), improved weed control, and increased crop yield. Forage quality of CC mixtures for beef cattle has also been reported. Legume cover crops are an essential component of good soil management. Cereals grow very quickly and provide quick ground cover. They can provide a tremendous amount of biomass that not only smothers weeds and prevents soil erosion, but also puts huge amounts of green matter, or green manure, back into the soil which improves the soil's tilth. These cover crops are nature's great nutrient recyclers. This year, we tested several cocktail mixtures for forage yield and quality.

Methods

The study site was at the Fairview Research Farm(NW5-82-3W6) on RR #35. Soil tests at 0-6” prior to seeding showed SOM of 7.1%, a pH of 5.5 (acidic) and an electrical conductivity of 0.35 dS/m.

Randomized complete block design in 3 replications was used. Thirteen (13) CC mixtures (cocktails) and a barley crop (check) were seeded. Table 1 shows cocktail mixtures seeded and each crop seeding rates.

A cocktail mixture is a number of cover crop species mixed together to take advantage of each of its species' unique offering to the farmer's soil. A cocktail mixture provides multiple agronomic benefits. Cover crop species for cocktails are commonly grouped into 6 major categories: cool season grasses, cool season legumes, cool season broadleaves, warm season grasses, warm season legumes and warm season broadleaves. For a list of crop varieties that belong to each category, please see the cover crop chart below:

The cocktails were pre-mixed before seeding. A 6-row Fabro plot drill at 9” row spacing was used to seed. Seeding was done on May 18. No fertilizer application was done to any of the mixtures, even the CDC Hay-maker oat (check). Except for cocktail #7, where legumes were included in the mixtures - the legumes were inoculated before seeding.

Roundup WeatherMAX® was used as pre-emergent 7 days after seeding. In-crop spraying was done with 2, 4 - D 700 at 0.35 L/acre only on CDC Haymaker oat (check). Forage harvest was done on August 2, 2016 and dry samples were shipped out to the laboratories for feed tests.

Prior to harvest, efforts were made to identify the crop varieties in each cocktail mixture and we compared these crop varieties to the supposed list of seeded crop varieties in the mixtures. This was done to ensure that the final result of a particular cocktail mixture reflects the intended crop composition.

Results and Interpretation

Forage DM Yield

Cocktail #1 had higher DM yield (9600 lbs/acre) than other cocktails as well as check (Table 2). Three (Cocktails #1, 4 & 8) had >8000 lbs/acre, while others had <8000 lbs/acre. Six (6) cocktails produced more DM yields (109-137%) than check (CDC Haymaker oat) (Table 2).

Cocktails #6 & #7 contained only barley and hairy vetch. The hairy vetch in Cocktail #6 was inoculated, while that of cocktail #7 was not. The differences between the two, which was in favour of cocktail #6 (inoculated) was high, resulting in a yield advantage of 1076 lbs/acre over cocktail #7. This confirms the need to inoculate legumes before seeding.

The lowest DM yield obtained for cocktail #13 was due to the fact that 20% of what was seeded contained crop varieties which did not germinate or varieties that performed very poorly such as BMR hybrid sorghum, berseem clover, Teff Grass and Laser Persian clover.

Forage Quality

Crude Protein (CP) - All cocktail mixtures had higher protein than CDC Haymaker oat (Check, Table 2). The forage CP was highest for cocktail #12 (24% CP), followed by cocktail #13 (21% CP) and then cocktails #9 and #10 (19 and 18% CP). All cocktails had 11% CP or more, while CDC Haymaker oat (check) had less than 10% CP. The differences obtained in forage CP between all cocktails and check show the benefits of seeding mixtures of different cover crop types for the purpose of improving forage protein.

Generally, all cocktails were able to meet the 11% CP needed by mature beef cattle, and in most cases, the CP requirements of mature beef cattle were exceeded by cocktails tested. For growing and finishing calves, most cocktail mixtures fell within the required 12-14% CP by these calves. CDC Haymaker oat (check) was only able to meet the CP requirements of a dry gestating beef cow (7% at 2nd trimester & 9%, 3rd trimester).

Macro-Minerals (Table 3)

The forage Ca was lower for check (CDC Haymaker oat) and cocktail #7 (barley + un-inoculated hairy vetch) than other cocktails. But both check (CDC Haymaker oat) and cocktail #7 were only able to meet the Ca requirements of a gestating beef cow (0.18% Ca). Other cocktails exceeded the Ca requirements of mature beef cattle (0.42% Ca). For growing and finishing calves, the Ca requirements (0.31%) have been met by all cocktails as well as check.

All cocktails as well as check only had sufficient P for a gestating beef cow (0.16% P). The P requirements of a lactating cow (0.26% P) were not met by any of the cocktails or check. The P requirements by growing and finishing calves were only met by 7 of the cocktails tested as well check.

The K and Mg requirements of a gestating cow were met by all cocktails and check. All cocktails and check also met the K requirements of a lactating beef cow. For the Mg requirements of a lactating beef cow, CDC Haymaker oat, cocktail # 6 (barley + inoculated hairy vetch), cocktail #7 (barley + un-inoculated hairy vetch) and cocktail #8 all fell short of the 0.20% of Mg needed by this category of cow.

The forage Na was as high as 0.57% for the cocktails tested. In terms of Na requirements by mature beef cattle, only cocktails #7 and #9 did not have enough Na for mature beef cattle. All other cocktails as well as check did have adequate Na for all categories of mature beef cattle.

The S requirements of all categories of mature beef cattle have been met by all cocktails as well as check (CDC Haymaker oats).

Trace-Minerals (Table 3)

The forage Cu, Fe, Zn and Mn respectively varied from 3.16 - 6.25 ug/g Cu, 91 - 186 ug/g Fe, 25-80 ug/g Zn and 32 - 107 ug/g Mn. All cocktails and check had adequate Fe and Mn for growing and finishing calves. For mature beef cattle, the requirements for Fe were met by all cocktails and check, but cocktails #5 and #7 fell short of meeting the Mn requirements of mature beef cattle.

Only CDC Haymaker oat (check) fell short of meeting the Zn requirements of young and mature beef cattle, which all require 30 ug/g Zn. All cocktails exceeded the 30 ug/g Zn needed by mature beef cattle. None of the cocktails or check had enough Cu for a mature beef cow as well as growing and finishing calves.

Detergent Fibers (ADF & NDF) and Non-Fiber Carbohydrates (NFC)

The acid detergent fiber (ADF) content is important because it reflects the ability of an animal to digest the forage. As the ADF content increases, digestibility of a forage decreases along with the energy. The neutral detergent fiber (NDF) content is important in ration formulation because it reflects the amount of forage the animal can consume. As NDF content increases, dry matter intake (DMI) will decrease. Lower values are pre-ferred for both ADF and NDF. From Table 4, cocktail #11 seemed to be of better quality than other cocktails and check. The ADF and NDF values obtained for check compared to all cocktail mixtures indicate that check (CDC Haymaker oat) was of lower forage quality than any of the cocktails tested in this study.

NFC is more rapidly digested than fibers (ADF & NDF) and it is a significant source of energy for the rumen microbes. The microbes also use NFC to make microbial protein. Cocktail #11 had the highest NFC (Table 4).

Looking at the cocktails and check tested here Table 4, cocktail #11 (with the lowest ADF & NDF values and highest NFC value) seemed to fare better than other cocktails and check in terms of potentially available microbial protein in the rumen, amount of forage an animal would consume and better forage digestibility.

Energy

The forage energy (% TDN) was highest for Cocktail #11 (70% TDN) and lowest for check (CDC Haymaker oat, 60% TDN). All cocktails tested here had >60% TDN (Table 4).

All cocktails and check had sufficient %TDN for a gestating beef cow, which requires 55% TDN at mid-pregnancy stage and 60% TDN at late-pregnancy stage. But for a lactating beef cow, which requires 65% TDN, only 8 of the 13 cocktails tested had at least 65% TDN needed by this category of cow.

Conclusion

From forage DM yield and quality obtained in this trial for all cocktails and check (CDC Haymaker oat), it is evident that all cocktails had higher DM yield as well as better quality than CDC Haymaker oat (check). Six (6) cocktails (#1, 4, 6, 8, 10 and 11) produced more DM yields (109-137%) than check (CDC Haymaker oat). Overall, Cocktail #1 produced the most DM yield in this study. Generally, all cocktails had 11% CP or more, while CDC Haymaker oat (check) had less than 10% CP. All cocktails were able to meet the protein requirements of mature beef cattle, and in most cases, cocktails were well within the protein requirements of 12-14% CP for growing and finishing calves. The cocktails in most cases, had enough TDN for mature beef cattle. On the other hand, the check was only able to meet the protein and TDN requirements of a gestating cow. Looking at the forage minerals of check and the cocktails, the benefits of cocktails were obvious with higher forage minerals than check. The differences in forage DM and quality between cocktails #6 and #7 further confirms the need to inoculate legumes before seeding. Taking into consideration the higher forage DM yields obtained from of cocktails #1, 4, 8 and 10 and their ability to meet the protein, energy and minerals (except for Cu) of a gestating beef cow, cocktails #1, 4, 8 and 10 are therefore suggested for growing in the Peace. It is important to note that nitrates may need to be tested before feeding to cows in a situation where brassicas are included in the mixtures. Care needs to be taken if including Persian clover, BMR hybrid sorghum, berseem clover and teff grass as these crops did very poorly.

Some Notes on Tillage Radish

The tillage radish has been bred/developed to produce a large taproot and penetrate compacted soil layers in an effort to increase soil aeration and water infiltration, decrease compaction and provide increased rooting depth opportunities to successive crops. Although tillage radish may not penetrate and grow as deeply in some of our “gumbo” type soils as we might hope, they can serve another useful purpose that can be of great value to producers; nutrient retention. The large taproot that is developed by tillage radish can absorb and retain a significant amount of macro- and micronutrients that might otherwise be prone to leaching or other loss mechanisms. Think of the tillage radish taproot as a giant sponge that will absorb residual nutrients from the soil and hold them until termination in the fall. The other nice thing is that the nutrients which are absorbed by the taproot are readily available to the following crop as the taproot is mostly water and desiccates and decays, quickly releasing those nutrients for uptake and utilization by the following crop. However, care needs to be taken on the amount of tillage radish used in cocktails because of the competitive nature of tillage radish, which results from its deep tap root sucking up nutrients from the soil at the expense of nearby or surrounding crops.