Research Coordinator: Dr. Akim Omokanye
Collaborating Producer: Thomas & Laura Claydon (MD of Smoky River)
From: Peace Country Beef & Forage Association 2014 Annual Report
Soil conservation, nutrient sequestration, weed suppression, improved soil health, quality feeds, among others, are reasons why cover crop usage is increasing in parts of the Peace Country region. The crop species we can use for cover crops and grazing is extensive. Common choices for covers include warm and cool season crops such as proso millet, sudangrass, sunflower, oats, annual ryegrass, peas, hairy vetch, brassicas, and clovers. Diverse mixes can serve the purpose of improving soil health, holding soil, and providing cheap forage. The decision to use cover crops as part of a grazing strategy will differ from farm to farm. Some important questions that producers ask include (1) how might a cover crop mixture affect both soil water use and soil quality? (2) how will a cover crop mixture affect forage yield & quality, and economic return? (3) what does each plant functional group in the mixture contribute to overall soil quality? The present demonstration was carried out to assess the benefits of cover crop cocktails mixtures in beef cattle forage production systems.
Methods
The demonstration site was at Thomas & Laura Claydon’s farm, MD of Smoky River. Demonstration strip design was used on a 5-acre piece of land. The soil analysis (0-6” soil depth) done by Exova laboratory, Edmonton showed a pH of 6.3 and an OM of 6.8%. The analysis also showed that the soil was deficient in N and P. We seeded crop mixes containing 5-8 crop species against a single species oat crop (please see table below).
The site used had been under mixed forage hay production for 15 years and had barley seeded the year be-fore the trial. The site was worked prior to seeding. Seeding was done with a Melroe disc drill (14-ft wide) at 6” row spacing on June 13. No fertilizer was applied. Assessment of each plot was done to account for the presence of all crop types seeded in a particular mixture.
Harvesting of the plots for estimation of forage yield was done on August 12 when barley was at the soft dough stage. Forage samples were analyzed for feed quality according to standard laboratory procedures by Central Testing Laboratory Ltd., Winnipeg, Manitoba.
Results
The forage moisture at harvest of the cocktail mixtures varied from 53.7% for Mixture 1 to 72.9% for Mixture 2 (Figure 1).
The forage dry matter (DM) yield was highest for Peas + oats mixture with a yield of 3833 lbs/acre and lowest for monoculture oats (check) with a DM of 1802 lbs/acre (Figure 2). Mixtures 1 to 4, which had 2-8 different crops in the cocktail mixtures had 1369 to 2031 lbs/acre more DM than Mixture 5 (oats - check).
DM was generally low in this study and this was caused by the dry weather in area.
The forage protein (crude protein, CP) of the cocktail mixtures was generally less than 10%. All mixtures had adequate CP for a cow in mid pregnancy. But for a dry cow in late pregnancy, which requires 9% protein, both Mixtures 2 and 4 fell short of meeting the requirement of this category of cow. All mixtures did not have sufficient CP for a nursing cow (which requires 11% CP) as well as growing and finishing calves (12-13% CP).
The forage Ca content was highest for Mixture 1 (0.98% Ca) and lowest for Mixture 2 (0.16% Ca). (Table 1). Of the 5 mixtures, only the forage of Mixture 2 did not have adequate Ca contents that are required by growing and finishing calves (0.31% Ca) and a mature cow (0.18% Ca for a dry cow and 0.42% Ca for a nursing cow).
The forage P content was generally low for all mixtures, varying from 0.12% P for Mixture 2 to 0.16% P for Mixture 3 (Table 1). Of the 5 mixtures, only Mixture 3 had sufficient amount of 0.16% P that is needed by a dry gestating cow. Both calves (growing and finishing) and mature cows respectively require 0.21 and 0.26% P, but none of the 5 mixtures met these requirements. The emanating forage 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. The calculated rations varied from 1.33:1 for Mixture 2 to 7.00:1 for Mixture 1, an indication that the Ca:P ratio obtained in the present study were mostly within the suggested range of 2:1 and 7:1. Only Mixture 3 fell outside this range and such needs to be addressed using feed blends or commercial minerals.
With the exception of Mixture 2, all mixtures had sufficient amounts of Mg that are needed by growing and finishing calves (0.10% Mg) and a mature beef cow (0.12-0.20% Mg). Both forage K and Na of all 5 mixtures were sufficient for growing and finishing calves as well as a mature beef cow.
The forage energy (total digestible nutrients, TDN) for all mixtures was generally above 60% TDN. Mixture 1 had the highest energy (73.2% TDN), followed by Mixture (69.3% TDN) and then Mixture 3 (67.9%) (Table 1). A dry gestating cow requires 55% TDN in mid pregnancy, 60% TDN in late pregnancy and 65% TDN after calving. The 55-60% TDN needed by a dry gestating cow have been met by all mixtures, but only Mixtures 1, 3 and 5 met and exceeded the 65% TDN needed by a nursing cow. Also, only Mixtures 1, 3 and 5 met the 65-70% TDN requirement of growing and finishing calves.
Some Notes
No one species can deliver all the advantages multiple cover crops deliver in combination. Cover crops offer many benefits to producers that increase farm profitability and environmental sustainability. Each cover crop has a niche or special purpose. Legume cover crops are typically used to produce nitrogen. Grass cover crops are used to increase soil organic matter, recycle excess nutrients, and reduce soil compaction. Brassica crops are grown to loosen the soil, recycle nutrients, and suppress weeds. Some other cover crops are grown to suppress insects, disease, weeds, or attract beneficial insects. Therefore, cover crops should be considered an integral part of any farming system that wants to efficiently utilize nutrients, improve soil quality, and increase farm profitability. Some crops help control specific weeds or attract beneficial insects. Each species provides a different food source for bacteria and fungi in the soil. More variety in the food source creates the habitat for a greater variety in soil organisms. Adding a diversity of roots to a soil that has seen only monoculture crops can awaken and ignite those organisms, and put organic matter production on the fast track. The diversity of plants above ground creates underground habitat with a healthy balance of predator and prey organisms in the soil, resulting in improved nutrient cycling.
A Brief description of some crops used in the mixtures
Crimson clover is winter annual or summer annual legume. Its roles include N source, soil builder and erosion prevention. With its rapid, robust growth, crimson clover provides early spring nitrogen for full-season crops. Rapid fall growth, or summer growth in cool areas, also makes it a top choice for short-rotation niches as a weed suppressing green manure. Popular as a staple forage in parts of US, crimson clover is gaining in-creased recognition as a versatile summer-annual cover in colder regions. Its spectacular beauty when flowering keeps it visible even in a mix with other flowering legumes. Crimson clover development is similar to tall fescue. It even can be established with light incorporation in existing stands of aggressive grasses after they have been closely mowed or grazed
Hairy vetch is cool season annual legume. It is the most cold hardy of the popular legumes. Great legume weed suppressor. Grows great with a non-legume like rye as a nurse crop. The favorite legume green manure of the north.
Kale is a great cheap, fast growing cool season annual non-legumes for lots of forage OM. A thick crop of kale is a great non-legume weed suppressor.