Pasture Options, Short and Long-term

Major efforts of the Eastern Research Station over the past 15 years have focused on demonstrating the importance of including forage legumes in pasture systems. As an example, the forage system for the cow-calf herd has been maintained using minimal nitrogen fertilization and without purchased feed supplements, including hay. This included a managed grazing system to increase annual legume persistence. A short summary of this management practice is to terminate grazing in early summer to let the legumes produce seed. The pastures should be grazed short in late summer so that the seeds can germinate in the fall and establish prior to spring and early summer grazing. Hay feeding usually ends about April 1 the following spring.

In pastures without legumes, additional efforts have determined that an application of 50 pounds of N per acre in August to short bermudagrass can supply one ton of forage per acre. This stockpiled forage can be grazed prior to February to reduce the length of the hay feeding season. One acre of stockpiled bermudagrass will provide grazing for one cow for approximately 45 days.

In June 2001, there were 108 fall-calving cows, 30-bred heifers and 30 steers assigned to 180 acres of grass/legume mixed pastures. This stocking rate was approximately 30% above the production of the forage resources. In addition to being overstocked, the second major weakness of this system was the extended length of the hay feeding system, which oftentimes exceeded 150 days. A recent survey conducted by the OSU Cooperative Extension Service indicates that too much hay is fed in Oklahoma. A small percentage of producers responding to the survey fed hay less than 30 days. Also, less than 10% fed hay fewer than 60 days. Seventy seven percent (77%) indicated that feeding hay for longer than 60 days was common and 34% fed hay longer than 120 days.

The information in Table 1 provides a possible forage management plan for the pastures located at the Eastern Research Station. The general system is to manage one-half of the pastures (grass/legume) with no additional N inputs and one-half of the pastures (grass only) using N fertilization. If properly stocked, this forage production system would supply grazable for all but 45 days from January 1 through February 15.

The grass/legume mixed pastures (102 acres) grazed at the proper stocking rate should provide approximately 230 days of grazing for 75 cows beginning May 1 and continuing through December 1. This would require approximately $1,100 for P and K fertilizer to maintain the legume production in these pastures. Another possible option to increase the amount of forage produced in these pastures would be to over-seed cereal rye in three of the pastures in late August or early September. This practice would add 21 fall-grazing days at a cost of approximately $1350 for seed and fertilizer.

Managing the tall fescue pastures (39 acres) with 60 pounds of N per acre in August and an additional 90 pounds of N per acre in January would provide 79 grazing days of high-quality forage from February 15 through May 1. The cost fertilizer for this practice is approximately $1400 for N and $305 for P.

The bermudagrass pastures (42 acres), fertilized with 50 pounds of N in the fall, could be grazed for 30 days from December 1 through January 1. Application of 100 pounds of N per acre in May at a total cost of approximately $1041 would provide 60 tons of hay for the 45-day hay feeding period with 20 tons of excess hay.

Presently, the biggest limitation of this forage management plan is an lack of cool-season forages. Current fertilization management discourages growth of cool-season grasses. As an example, N fertilization after May 1 encourages bermudagrass forage growth. Although this increase in forage production is desirable, increased competition from bermudagrass results in lower tall fescue production the following year.

Short-term-goals at the eastern Research Station are to decrease the stocking rate to a number that is more consistent with the available forage resources and nutritional demands of the livestock. The two easiest methods to achieve this balance are to decrease the number of animals and increase N fertilization of the grass pastures. Another option for altering stocking rate is to sell calves at a lighter weight when forage is in short supply. However, when excess forage is available, additional stocker calves could be purchased to utilize the forage.

Properly timed fertilization can result in a better distribution of forage yield from both bermudagrass and tall fescue. The rule of thumb for fertilizing grass pastures is simple. Warm-season grasses, such as bermudagrass, require 50 pounds of actual N per to produce one ton of forage. Tall fescue and other cool-season grasses require 60 pounds of actual N per to produce one ton of forage.

Long-term goals include maintaining appropriate fertility levels in the grass/legume mixed pastures and also continuing to improve the seasonal forage yield distribution to maximize the number of grazing days. Even though this process is not complicated, the conversion of the forage resource base is still in transition.

Table 1. Pasture plan for the Eastern Research Station.

† Nitrogen applied only if fall-planting cereal rye

Daren D. Redfearn, Extension Forage and Pasture Management Specialist
Bob Woods, Area Extension Agronomist, Northeast District