Managing Forages in Dry Years

Livestock producers are always aware of the need to put up enough forage. There is nothing worse than going into winter with inadequate forage inventories. This can be very challenging in extremely dry years. Dry weather creates even more immediate problems in pasture situations during the "summer slump". In dry years, strategies such as rotational grazing and the use of corn silage and other annuals, can help to ensure adequate feed inventories.

Forage Yield and Quality

"A dry year will scare you, but a wet year will starve you" is an old saying quoted by some dairy farmers. Excessively wet years often result in poor forage quality and challenges getting milk out of cows. In a dry year, second- and third-cut yields will be reduced, but quality is usually good - no rain damage, high leaf/stem ratio and reduced fibre. First-cut yields are largely a function of temperature, whereas second- and third-cut yields are more a function of moisture. One-half to two-thirds of total yield is typically from the first-cut.

Good agronomy goes a long way to improving our ability to produce forage in a dry year. Phosphorus (P) and potassium (K) fertility management is fundamental to optimum yields and producing enough forage to feed livestock, but it is often overlooked. Low fertility results in poor root systems that subsequently have little ability to withstand dry weather. Refer to Don't Lose Hay To Poor Fertility.

Harvest, fermentation, storage and feeding losses of forages are very significant, but in years of limited forage supplies every effort should be made to minimize these losses. This includes adequate packing of silage, the use of inoculants, proper face management, storing hay off the ground and under cover, and using feeder designs that minimize wastage. Refer to Forages: Harvest and Storage (OMAFRA Publication 811, Agronomy Guide for Field Crops).

Emergency Annuals - Summer Seeding Cereals, Corn Silage, Sorghums, Pearl Millet

By the time you know you're in a growing season that is seriously short of moisture and forage yield, it is usually too late to do much about it as far as seeding different crop species. Corn silage is the most commonly used annual for emergency situations and can provide significant digestible energy. Corn silage is usually cheaper, readily available, and is easily harvested, stored and fed. Silage piles and silo bags provide flexible storage options. Corn damaged by extremely dry weather with a low grain yield potential can be salvaged as silage. More information, including "Pricing Corn Silage", is available on the Ministry Adverse Weather page.

Seeding oats or other cereals in late-July or early-August following wheat for an early-October harvest can be a useful low-cost option for extending forage supplies. Oats can make good feed when harvested at the correct stage of maturity and made into "oatlage" or baleage. Peas are sometimes included to improve nutrient quality, but wilting to proper moisture can be a potential issue in the fall.

Warm season annual grasses such as forage sorghum, sorghum-sudangrass and pearl millet are sometimes summer seeded for extra forage. However, they are much less tolerant to autumn frost than cereals. Be aware of prussic acid risks with sorghums and sudangrass. Annual ryegrass or sorghum-sudan grass, have not had good success under Ontario conditions when planted after wheat harvest.

To Harvest or Not?

Moderate stress from dry weather can cause alfalfa plants to continue growth but with reduced stem numbers and stem elongation. The alfalfa plant produces carbohydrates which are stored in the root system, and are available as energy for regrowth after cutting and when moisture returns. If there is adequate alfalfa growth to economically justify cutting, and a 30 to 35 day harvest interval can be maintained, go ahead and cut.

Severe moisture stress will temporarily stop plant growth. When rains return, cutting alfalfa, (particularly at the flower stage),will stimulate regrowth, by encouraging growth of new crown buds.

On the other hand, cutting red clover during extreme dry conditions can cause stand reductions. Birdsfoot trefoil also maintains lower levels of root carbohydrates during the summer, so cutting at a more mature stage with a longer stubble, will improve regrowth potential.

Potato Leafhopper Control in Alfalfa

The significance of Potato Leafhopper (PLH) damage in alfalfa is greatly underestimated. PLH damage is often blamed on the hot, dry weather that accompanies it. PLH feeding affects the transportation of fluids and nutrients in the plant and significantly worsens the effects of dry weather. New seedings are very susceptible and can be permanently damaged for the life of the stand. Once the symptoms of "hopperburn" are noticed, the damage is already done. PLH can be managed by scouting and spraying at threshold levels, and by the use of PLH resistant varieties. Refer to Potato Leafhopper in Alfalfa

Summer Seedings Higher Risk

Early spring forage seedings are usually the most successful. Late spring seedings can be severely affected by dry weather. Summer seedings of perennial forages often fail when seeds germinate and then starve for moisture during extended dry weather. Delayed germination can result in inadequate growth before a killing frost in the fall to ensure winter survival. Lack of moisture is a risk, so if soil conditions are extremely dry with no rain in the forecast, consider abandoning plans for summer seeding. Refer to Summer Seeding Forages

Avoid Critical Fall Harvest Period If Possible

Cutting alfalfa during the 6 week Critical Fall Harvest Period (refer to OMAFRA Publication 811, Agronomy Guide for Field Crops) is usually not recommended, but sometimes done because of low forage inventories. This results in the plants using root reserves for regrowth and increases the risk of winterkill. The highest risk time to cut is three weeks after the start of the Critical Fall Harvest Period, so avoid this time if possible. Yield gained by harvesting during the Critical Fall Harvest Period is usually lost in first-cut yield the following year. The decision to cut should be weighed against the immediate need for forage. Leaving more stubble to hold snow, and adequate soil K fertility will also help winter survival. See Forage Winterkill

Using Corn Damaged by Dry Weather for Silage

Tremendous variation can occur in corn fields stressed by dry conditions. Some fields will have short plant height with more normal ears. Yields will be reduced, but forage quality may be close to normal. Other fields will be more normal in height but have very small ears or no ears. Growers attempting to salvage dry weather damaged corn fields by harvesting them as forage should be aware of some of the harvesting and nutrition implications. Ensiling at the correct whole plant moisture is critical, but often more difficult to determine. Sellers with Crop Insurance should contact Agricorp (1-888-247-4999) before harvest to determine how selling corn as silage will impact a claim.

Be aware of the potential for nitrate poisoning. Nitrates accumulate in corn plants and grasses when there is a large amount of soil nitrates and a lack of moisture that interferes with normal plant growth. The risk of nitrate accumulation is often greatest following a rain that ends a dry period. The increased nitrate potential also increases the risk of silo gas. Refer to Using Corn Damaged by Dry Weather for Silage.


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca
Author: Joel Bagg - Forage Specialist/OMAFRA and Jack Kyle - Pasture Specialist/OMAFRA
Creation Date: 2003
Last Reviewed: 2 August 2012