Forage Report – July 21, 2014

Sulphate on alfalfa (right) at FarmSmart Expo plots.
Sulphate on alfalfa (right) at FarmSmart Expo lpots.

Forage yields have been quite variable across the province. Some areas have excess hay, while others are still rebuilding inventories. Quality is generally good. The weatherman got it wrong the weekend of July 19th and considerable acres of hay were cut and rain-damaged. 

 Summer Seeding Alfalfa

Summer seeding alfalfa-grass mixtures can be a good way to establish new fields so that full season yields can be harvested the following year. The challenge following wheat is getting the volunteer wheat controlled and the new seeding done in a timely manner. Competition from volunteer wheat can be a significant problem. One approach is to do some light tillage to encourage the grain to germinate, followed by a burndown with glyphosate 7–10 days later. Alfalfa needs at least 6 weeks of growth after germination to develop a crown before killing frost to survive the winter. Recommended summer seeding dates in areas > 2,900 CHU areas is August 10th – 20th and 2,500 – 2,900 CHU areas is August 1st – 10th. Summer seeding works best on light to medium textured, well-drained soils. Lack of moisture for timely germination and growth can be a significant risk. If soil conditions are extremely dry and no rain is in the forecast, plans for summer seeding should be abandoned. Conserving soil moisture is critical, so use as little tillage as possible to create a fine, firm seedbed, drill the seed rather than broadcasting it, and follow with a press wheel or packer to ensure good seed-soil contact. Do not use companion crops with summer seedings, as they compete for available soil moisture and reduce stand establishment. Seeding alfalfa after alfalfa is not recommended because of autotoxicity and disease.

Summer Seeding Oats For Double-Crop Forage

Seeding oats in early-August following wheat for an early-October harvest can be a useful double-crop, low-cost option for producing additional forage supplies. Oats can make excellent feed when harvested at the correct stage of maturity and made into “oatlage” or baleage. Peas can be added where higher forage quality is required.The challenges can sometimes be lack of adequate moisture in August for germination and growth, and having dry enough weather in October for adequate wilting.

Sulphur On Alfalfa

There are more situations occuring where there is a yield increase by applying sulphur (S) to alfalfa.The response in field trials is sometimes quite dramatic, while in others there is no response. S deficiencies are more likely to occur on low organic matter soils, and soils that have not had a recent manure application. S deficient alfalfa plants will be spindly and light-green. S deficiencies can be diagnosed by tissue testing alfalfa at mid-bud to early-flower stage. Sample the top 6 inches of 30 – 40 stems and send them to a laboratory. The critical level below which alfalfa is considered S deficient is 0.25%. A general rule for S rates on alfalfa is 5 lb/ac per ton of dry matter yield. The sulphur must be in the sulphate form to be taken up by the plant. Sulphate fertilizers include ammonium sulphate (34 – 0 – 0 – 24), potassium sulphate (0 – 0 – 50 – 18), sulphate of potash magnesia (Sul-Po-Mag or K-Mag) (0 – 0 – 22 – 20) and calcium sulphate (gypsum) (0 – 0 – 0 – 17). Sulphate-S should ideally be applied in the spring at green-up to improve plant utilization, minimize losses due to leaching, and receive a first-cut yield boost. Elemental sulphur (0-0-0-90) consists of finely ground sulphur that has been pelletized. It is much cheaper than sulphate, but must be slowly converted by oxidation to sulphate by soil bacteria before plants can utilize it. A single application of elemental-S, provides a cheaper, longer term S source and reduces the need for annual applications. An application of 50 lbs/ac of elemental-S should last the life of a productive 3 year alfalfa stand. Applying elemental-S bulk blended with other fertilizer is the most cost effective method of providing S, but an application of sulphate provides a more immediate yield response.

Sulphate on alfalfa (right) at FarmSmart Expo lpots.
Sulphate on alfalfa (right) at FarmSmart Expo lpots.