Demonstration of Annuals in Monocultures and in Cover Crop Mixtures

Research Coordinator: Dr. Akim Omokanye

Location: Fairview Research Farm (NW5-82-3W6) on RR #35, MD of Fairview

From: Peace Country Beef & Forage Association 2014 Annual Report


Cover crops are an important tool that farmers can use to generate benefits and services on the farm and for society, including improved soil health, nutrient supply to cash crops, weed suppression, insect pest management, forage production, pollinator resources, and clean water and air. Planting a mixture of cover crop species is one strategy that can be used to enhance and diversify the benefits that a cover crop provides. To design a cover crop mixture with increased potential for biomass production, choose species with complementary growth periods, growth forms, and nutrient acquisition strategies. Many of the services provided by cover crops, including nitrogen retention, nitrogen supply, weed suppression, and erosion control are regulated by cover crop biomass production. In 2014, a variety of forage type annual crops was seeded in monoculture and in some mixtures to assess their forage production potential. This report provides a highlight of forage yield and quality from the demonstration.


Methods

The demonstration was carried out at the Fairview Research Farm (NW5-82-3W6) on RR #35, MD of Fairview. The site used was left to fallow in the summer of 2013. Prior to seeding, we took soil sample from 0-6” soil depth and sent it to Exova laboratory in Edmonton for soil analysis. The soil test showed an OM of 7.1% and a pH of 5.8. Prior to seeding, the site was rotor tilled and sprayed with Credit® as a pre-seed weed control. Soil temperature at seeding averaged 9 degrees Celsius.


We seeded the following crops on May 23, 2014 with a plot drill in small plots (8.5 m long 6 rows) at 23 cm (9 inches) spacing between rows:


Monocultures (11)-

1. CDC SO-I oat

2. CDC Baler oat

3. Bunker triticale

4. Tyndal triticale

5. Bumper triticale

6. Taza triticale

7. Proso millet

8. Siberian millet

9. CDC Horizon peas

10. Tillage radish

11. 40-10 peas


Cover crop mixtures (5)-

1. Mix 1 - CDC SO-I oat/CDC Baler oat/CDC Horizon peas

2. Mix 2 - Bunker triticale/CDC Horizon/CDC Baler oat

3. Mix 3 - 40-10 peas/CDC Baler oat/Bunker triticale

4. Mix 4 - Proso millet/CDC Horizon pea/CDC Baler oat/Bunker triticale

5. Mix 5 - Tillage radish (1lb)/Proso millet (2lb)/Kale (1lb)/Crimson Clover (1lb)/CDCD Baler oat (15 lb)/40-10 forage peas (15 lb)


We fertilized the monoculture cereals with a blend of 90N-30P-20K-30S (lbs/acre). The 2 forage peas (CDC Horizon and 40-10) were seeded with 30P-10K-15S (lbs/acre). The 5 cover crop mixtures were fertilized with a blend of 48N-30P-10K-15S (lbs/acre).

In crop spraying of the monoculture cereal plots was with Frontline XL. No spraying was done on the peas, tillage radish and cover crop mixture plots. Hand weeding was done once to remove visible volunteer canola plants in all plots.


In crop spraying of the monoculture cereal plots was with Frontline XL. No spraying was done on the peas, tillage radish and cover crop mixture plots. Hand weeding was done once to remove visible volunteer canola plants in all plots.


Harvesting for forage yield for the 2 monoculture oats and 2 monoculture millets was done on July 29 and on August 5 for the 4 monoculture triticale plots. About 0.5 kg of the freshly harvested forage was sub-sampled and air-dried for a few days for forage dry matter (DM) yield estimation. The forage quality (% dry matter basis) of all monocultures and mixtures was determined by Central Testing Laboratory Ltd. (Winnipeg) using standard laboratory procedures for wet chemistry analysis.


Results

Forage Dry Matter (DM) Yield

The forage DM varied from 2625 lbs/acre for monoculture tillage radish to 5916 lbs/acre for Mix 3 (40-10 peas/CDC Baler oat/Bunker triticale). The monoculture DM averaged 4680 lbs/acre, while the mixtures aver-aged 5544 lbs DM/acre, giving a difference of 864 lbs DM/acre between the means of monocultures and mixed crops.

Forage Quality

The forage protein (crude protein, CP) varied from 9.1% CP for Bunker triticale to 16.7% CP for CDC Horizon peas. Four of the 11 monocultures had less than 11% CP, while all mixtures had greater than 13% CP. All monocultures and mixtures had adequate protein for a dry gestating cow, which requires 7% CP in mid pregnancy and 9% CP in late pregnancy. Of the 11 monocultures, only 4 (all the triticale varieties) fell short of meeting the protein requirement of a lactating cow. All mixtures exceeded the 11% CP requirement of a lactating cow. Except for the 4 triticale varieties, all monocultures and mixtures had sufficient protein (12-13% CP) for a growing and a finishing calf.

The forage energy (total digestible nutrients, TDN) was highest for Tyndal triticale (77.4% TDN). Generally all monocultures and mixtures had >65% TDN, an indication that all monocultures and mixtures were therefore able to meet the 55-65% energy requirements of a mature beef cow as well as 65-70% TDN needed by growing and finishing calves.

Except for a few monocultures, the Ca requirements of a mature beef cow (0.18-0.42% Ca) have been met with all monocultures and mixtures.


Only 3 (CDC SO-I oat, CDC Baler oat and Taza triticale) of the 11 monocultures and 3 of the mixtures (Mix 1, Mix 3 and Mix 5) had sufficient P needed by a dry gestating cow (0.16% P). Generally, no monocultures or mixtures had sufficient P for a lactating cow (0.26% P).

The Ca to P ratio (Ca:P) for a mature beef cow should be within the range of 2:1 and 7:1, assuming actual required grams of each are adequate. Using a feed test, the ratio is calculated by dividing the dry matter Ca (%) by the dry matter P (%). Ratios outside this range need to be addressed using feed blends or commercial minerals. Four of the monocultures (CDC Baler oat, and 3 triticale varieties - Tyndal, Bumper and Taza) had lower than 2:1 Ca to P ratio, while the 2 forage pea varieties (CDC Horizon and 40-10 peas) and Mix 4 ex-ceeded the 7:1 Ca to P ratio. Other monocultures and mixtures were well within the recommended range of 2:1 and 7:1 Ca to P ratio for a mature beef cow.


All monocultures (except for 3 of the 4 triticale varieties) and mixtures had enough Mg for a mature beef cow (0.12% for a dry gestating cow and 0.20% Mg for a lactating cow).


All monocultures and mixtures far exceeded the K requirements a mature beef cow, which needs 0.6-0.7% Mg from mid pregnancy to after calving.


The primary advantage of a crop mix is biodiversity - the benefit that the soil receives from multiple species. Crop mixes will often contain a variety of different crop species, including but not limited to the species listed below:

  • grass plants: for building organic matter, sequestering nutrients, and preventing erosion

  • legumes: for nitrogen production - common legumes planted for cover crops are peas, vetch, and clovers (crimson, red, and sweet)

  • brassicas: for scavenging nutrients, providing a home for earthworms, excellent cover in the field


A secondary benefit of the continuous use of crop mixes may be the opportunity to lower nutrient costs. With the ability of these crops to produce N, as well as hold on to N and other nutrients, this may become a possibility for some producers.

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