Figure 1. Productive and relatively tall Red River crabgrass grown in an adequate environment and with good cultural practices. The first season's stand was as good as could be expected and was broadcast planted during spring into graze-out winter pasture.

Data were collected from three or four replicated trials. Plants were irrigated by using rotating sprinklers and a specific volume of water. All fertilizer was applied as a pre- or postemergence topdressing. Demonstration results were from single-unit operations in which off-season renovation (soil tillage) was a part of the management scheme.

Producers' pastures were managed with usual farmer/stockman procedures for crabgrass production, including renovation, good fertilization, and rotational grazing. Unfortunately, we cannot secure precise management inputs, but the results portray upper-level yields.

'Red River' crabgrass in a two-year replicated study near Ardmore, Oklahoma, on loamy fine sand produced 10,595 pounds per acre the first year and 9,786 the second, for an average of 10,190 pounds per acre. Nitrogen input averaged 325 pounds per acre in split applications. The two-year average precipitation and supplemental irrigation was 28.3 and 8.1 inches, respectively, for a total of 36.4 inches of water from April through September. 'Red River' crabgrass produced an average of 280 pounds of grass per inch of water from April through September. The crabgrass yielded an average of 31 pounds of grass per pound of nitrogen without a check plot yield deduction. Under pasture conditions, there is an average of 1 pound of beef per 11 pounds of dry-land crabgrass forage when steers weigh 500 pounds on average. Using that conversion, we projected these 'Red River' crabgrass yields could have produced about 926 pounds of beef per acre with 500-pound (average) stockers or over 1,100 pounds per acre with 400-pound (average) steers. This forage was exceptionally lush all summer, with in vitro neutral detergent fiber digestibility (IVNDFD) being about 75 to over 80 percent all summer.

The highest yield recorded in research plots in Oklahoma was 12,582 pounds per acre, which was achieved on a fine sandy loam with supplemental irrigation of 14.0 inches of water, total summer rainfall/irrigation of 36 inches, and 118 pounds of nitrogen per acre. This combination produced 350 pounds per inch of water and 106 pounds of grass per pound of nitrogen. We surmise that the research plot area had some residual nitrogen available for conversions to be that high.

From 1980 through 1992, Dr. Herb Huneycutt at the University of Arkansas included forage ecotypes of crabgrass in replicated trials at Fayetteville, Arkansas, and from 1982 to 1992, 'Red River' crabgrass was in the trials (selection RR874). The trials included IVDMD comparisons from 1982 through 1984, during which time 'Red River' crabgrass yielded from 9,044 pounds per acre to 10,194 pounds per acre, for a three-year average of 9,513 pounds per acre and a three-year IVDMD of 73 percent. 'Midland' bermudagrass at a higher fertilization rate had a three-year average of 64 percent IVDMD, or nine percentage points lower than that of 'Red River' crabgrass, which had 14 percent more IVDMD. Nitrogen input averaged 202 pounds per acre in split applications. The three-year average precipitation and supplemental irrigation was 17.8 and 7.5 inches, respectively, for a total of 25.3 inches of total water for April through October. The Arkansas-produced 'Red River' crabgrass yielded an average of 376 pounds of grass per inch of water from April through October and produced 47 pounds of grass per pound of nitrogen without a check plot yield deduction. Projected beef yields on the basis of the preceding information would be similar to that reported. The highest 'Red River' crabgrass yield reported was 11,817 pounds per acre with 268 pounds of nitrogen per acre, for 44 pounds of grass per pound of nitrogen. All of these studies were on silt loam soils.

These examples of research yields depict possible 'Red River' crabgrass production in the southern plains in a sufficiently moist summer or with supplemental irrigation and potential dry-land yields in the wetter areas of the eastern and southeastern United States (figure 1).

The Noble Foundation Pasture Demonstration Farm has a double cropping forage demonstration consisting of cool-season winter annuals and 'Red River' crabgrass. It was a naturalized crabgrass ecotype stand until seed of 'Red River' crabgrass became available in 1990. The unit is dry-land and fertilization varies yearly to meet different demonstration objectives and production targets.

The average winter pasture beef yield per acre was 550 pounds with 206 pounds of nitrogen per acre, which yielded 2.7 pounds of beef per pound of nitrogen. The average beef yield per acre of crabgrass, after winter pasture, was 163 pounds with 80 pounds of nitrogen per acre, which yielded 2.0 pounds of beef per pound of nitrogen. Both of these nitrogen/beef yield conversions are low. In years when steers grazed winter pasture and crabgrass consecutively, beef yield from winter pasture was 643 pounds per acre and beef yield from crabgrass was 163 pounds per acre with 157 pounds of nitrogen per acre on winter pasture and 80 pounds of nitrogen per acre on crabgrass. Thus, the yearlong total beef yield per acre was 806 pounds with 237 pounds of nitrogen per acre, or 3.4 pounds of beef per pound of nitrogen. In the year with the highest production on record, beef yield per acre from winter pasture was 717 pounds at 156 pounds of nitrogen per acre and beef yield from crabgrass was 149 pounds per acre at 92 pounds of nitrogen per acre, for a total beef yield of 866 pounds per acre with 248 pounds of nitrogen, or 3.5 pounds of beef per pound of nitrogen. Cows and calves grazed residue that possibly could have produced more than 100 pounds more beef per acre. Beef yield then would have been about 966 pounds per acre. We believe this figure represents about 70 percent of the potential in this grassland management approach that uses minimal farm equipment inputs. This unit is on shallow loam to fine sandy loam soil.

A dry-land producer from Florida reported steer beef yield at over 2,000 pounds per acre from double-cropping winter pasture and 'Red River' crabgrass. By using grazing days per acre and his record of average daily gain, we calculated that the 'Red River' crabgrass produced over 10,000 pounds of forage per acre and over 1,000 pounds of beef per acre. This unit was well fertilized and rotationally stocked at a high management level.

A producer from Oklahoma reported steer beef yields at about 1,000 pounds per acre from 'Red River' crabgrass under supplemental irrigation and moderate nitrogen fertilization (actual amounts unknown). A producer from northeast Colorado reported forage yields of 8,000 to 9,000 pounds per acre from 'Red River' crabgrass taken for hay and grazing. Grazing yields were converted to estimated forage yields.

'Red River' crabgrass research forage yields and grazier experience have shown that the forage and beef yields from the variety can be from 10,000 to 12,000 pounds per acre, and about 1,000 pounds per acre in an upper-level production regimen. These yields depict production capability of the grass. We believe the yield potential is considerably higher.