William A. Berg

Nitrogen fertilizer use efficiency in steer gain on old world bluestem.

Old World bluestem (Bothriochloa ischaemum L.) is the major grass being planted for improved pastures on marginal farmland in western Oklahoma and adjacent areas in Texas. The farmland is often deficient in plant available N as a result of up to 100 years of cultivation and erosion. This study determined N fertilizer use efficiency on steer gain when grazing Old World bluestem in northwestern Oklahoma where average annual precipitation is 575 mm yr(-1). The study was conducted over 4 summer grazing seasons on Pratt soils (sandy, mixed thermic Psammentic Haplusalfs). Nitrogen rates of 0, 34, 68, and 102 kg N ha(-1) yr(-1) were applied to paddocks in a randomized complete block design with 4 blocks. Steer gain averaged 220 kg ha(-1) yr (-1) and 3.3 kg per kg N applied at the 34 kg N ha(-1) yr(-1) rate. Steer gain ranged from 2.3 to 4.3 kg yr(-1) per kg of N applied at the rate of 34 kg N ha(-1) yr(1). About an additional kg of steer gain per kg N applied was realized for the second 34 kg N ha(-1) yr(-1) increment from 34 to 68 kg N ha(-1)yr(-1). Gain was negligible from the third 34 kg N ha(-1) yr(-1) increment from 68 to 102 kg N ha(-1)yr(-1). Early summer grazing of N-fertilized Old World bluestem has high stocker production potential.

Response of a mixed native warm-season grass planting to nitrogen fertilization.

Plant available nitrogen limits production of native warm-season grasses on marginal farmland in the Southern Plains. In this western Oklahoma study, N was applied at 0, 35, 70, or 105 kg N ha-1 yr-1 to a mixed stand of blue grama (Bouteloua gracilis (H.B.K.) Lag. ex Griffiths), sideoats grama (B. curtipendula (Michx.) Torr.), little bluestem (Schizachyrium scoparium (Michx.) Nash), sand bluestem (Andropogon hallii Hack.), switchgrass (Panicum virgatum L.) and indian grass (Sorghastrum nutans (L.) Nash). The grass was established on sandy loam soil farmed an estimated 90 years. With near-normal precipitation the first year, production of perennial grasses increased linearly with 26 kg herbage produced kg-1 N applied. In drouth conditions, the second and third years, production averaged 10 kg herbage kg-1 N applied. The fourth and fifth year the stand was not fertilized and residual effects measured. Herbage production increased 10 kg for each kg N applied over the previous 3 years. Blue Grama made up much of this increased herbage production along with warm-season annuals (Panicum capillare L. and Amaranthus retroflexus L.). With increasing N rates the residual N effect increased the proportion of blue grama and decreased the proportion of taller perennial grasses. Thus, N fertilization of mixed native warm-season grass stands established on marginal farmland, typical of stands established on sandier soils under the USDA Conservation Reserve Program, can result in substantial herbage yield increases, however, some of the increased yield may be from weedy species.

Seedbed and seeder options for old world bluestem establishment.

Seedbeds of graze-out wheatland and herbicide-killed wheat (Triticum aestivum L.) were evaluated as were use of a grass drill and the Woodward chaffy grass seeder for Old World bluestem (Bothriochloa ischaemum (L.) Keng) establishment. Seedings were made in 3 consecutive years in western Oklahoma. Steer grazing days on the seedbed treatments, seedling establishment, and second year grass herbage production were measured. Adequate stands were established in either seedbed. Economics favor the graze-out wheat seedbed treatment which produced an average of 189 steer grazing days ha-1 year-1. Adequate stands were established with either the grass drill or the Woodward seeder. Denser stands were usually established with the Woodward seeder--this was unexpected since it is a broadcast seeder. Results with the Woodward seeder are attributed to a requirement for very shallow planting of Old World bluestem and the protected environment of wheat drill furrows and wheat residue. Seedbeds of graze-out wheatland are recommended for Old World bluestem establishment in the Southern Plains.

Herbage yields and water-use efficiency on a loamy site as affected by tillage, mulch, and seeding treatments.

The effects of surface treatments alone and with seeding of an introduced bluestem (Bothriochloa i&aemum) on herbage yields and water-use efficiency on a loamy range site in poor condition were studied. The study was in a 560-mm average annual precipitation area in the Southern Great Plains. Prior to treatment, buffalograss (Buchloe dactyloides) and silver bluestem (Bothriochloa saccharoides) produced the bulk of the herbage on the site. Disking or furrowing the native range produced no measureable change in herbage yields or in water-use efftciency as compared to no treatment (control) over the g-year study period. Furrowing plus sand fill in the furrows or a rock mulch resulted in greater (K.05) herbage yields than from the control. However, most of the increased yield was by silver bluestem, a species that is ranked low In paiatabiiity. Establishment of the introduced bluestem ‘Plains’ increased herbage yield 2to 4-fold and significantly increased water-use efficiency. Sandy soils of the Great Plains have the potential to produce more aboveground phytomass than finer-textured soils (Heerwagen 1958, Harlan 1958, Tomanek 1964). This is apparently because Authors are soil scientist and research range scientist, U.S. Department of Agriculture, Agricultural Research Service, Southern Plains Range Research Station, ZOOO18th Street, Woodward, Okla. 73801. This study was initiated by P.T. Koshi and E.H. Mcllvain, both now retired. Their work in planning and setting up the study is gratefully acknowledged by the authors. Manuscript received August 2, 1982. on sandy soils the infiltration rate is greater, evaporation is less, and little water is lost to percolation because much of the precipitation is received during the growing season. If herbage production on loamy soils in poor range condition is to be increased, an approach would be to emulate the morefavorable soil-moisture conditions of sandy soils. Thus, treatments or management to increase infiltration, decrease water loss by evaporation, and favor taller-growing grass species over the short grasses might be considered. Soil surface manipulation, such as contour furrowing, to detain and infiltrate water has been successful in increasing forage production on some soils. The greatest plant growth responses have been reported on medium to fine-textured soils (Langley and Fisher 1939, Branson et al. i966) and in areas where snow is a substantial part of the effective precipitation (Neff and Wight 1977). Rauzi (1975) hypothesized that more intensive treatments than pitting or furrowing were needed to improve some range sites. He found that moldboard plowing or rotovating increased herbage yields over a 5-year period on clay loam and fine sandy loam soils dominated by blue grama (Bouteloua grads) in northeastern Wyoming. Mulches can enhance infiltration and reduce evaporation rates. Sand and gravel 2to S-cm thick over unvegetated clay loam soils conserved about 70% of the 58 cm of precipitation falling in a 180 JOURNAL OF RANGE MANAGEMENT 37(2), March 1984 I-vear neriod as comnared to !Syc on bare fallow fCorev and ,--r-----_-___ r---\---ma Kemper 1968). Similar results were shown by Linden (1970), who found that 2.5 cm of gravel over a nonvegetated sandy loam soil in eastern Colorado resulted in soil retention of 50% of the precipitation over a 2-year period while retention in fallow was 13%. Interseeding sideoats grama (Bouteloua curtipendula) into a mixture of grasses which had invaded abandoned cropland increased herbage yield by 60% on a clay loam soil on the Texas High Plains (Willard and Schuster 1971). Seeding and management of weeping lovegrass (Eragrostis curvula) or the Old World bluestems (Bothriochloa spp.) in monocultures have greatly increased forage and beef production on sandy soils in northwestern Oklahoma (Shoop et al. 1976, Sims and Dewald 1982). In our study, tillage, sand and rock mulch treatments, and combinations of these treatments plus interseeding of an introduced bluestem were applied to a loamy range site which was in poor range condition. The objective was to measure herbage yields bv maior species as a function of the treatments which were applied m, ~~~ .V to increase water-use efficiency. Study Area and Design The study site was on an upland with a 7% north-facing slope in Harper County, northwestern Oklahoma. The plots were on the middle third of a smooth, 160 m long slope. Moderate to heavy grazing and major drouths in the 1930’s and 1950’s probably influenced the species composition, which was dominated by buffalograss (Buchloe dactyloides). Other perennial species present in decreasing order of aboveground phytomass production were silver bluestem (Bothriochloa saccharoides), blue grama, purple threeawn (Aristida purpurea), sand dropseed (Sporobolus cryptandrus) and sideoats grama. The annual, Japanese brome (Bromus japonicus), was common in years with greater fall and winter precipitation, Although Japanese brome is naturalized, its yield is included as part of the native vegetation in this discussion. Western Table 1. Herbage yields on native range as affected by surface treatments. Treatment Year Buda St Bogrt Bosa Spcr Species Arpu Other grasses Forbs Total

Soil nitrogen accumulation in fertilized pastures of the Southern Plains.

Marginal farmlands seeded to grasses in the Southern Great Plains usually have been depleted in N by cropping, cultivation, and erosion. This study measured soil N accumulation over 20 to 22 years in N fertilized weeping lovegrass (Eragrostis curvula) or Old World bluestem (Bothriochloa caucasica) pastures seeded into old flelds as compared to adjacent unfertilized old field pastures dominated by sand dropseed (Sporobolus cryptandrus). Significantly more (P<O.05) total N was found in the surface 5 cm of soil from the fertilized pastures. Total N was not signiflcantly different between the old fleld and N fertilized pastures at greater depths. Two different samplings resulted in an estimated 8 and 5 kg N ha-lyrl (standard error of the mean difference 2.4, n=4 and 2.0, n=10, respectively) greater N accumulation in the N fertilized pastures as compared to the old fleld pastures. Nitrogen input into the N fertilized pastures as fertilizer and protein supplement was 45 kg N ha-lyrl greater than into the old fleld pastures. Thus, a relatively small proportion of the N input into the N fertilized pasture was accounted for as increased soil N. The N accumulation rate in the N fertilized pastures appears to be considerably slower than the N depletion rate under past farming practices.

Plant soil microsite relationships on a salt grass meadow.

Highlight: At least one million acres of potentially productive The purpose of this study was to d&ermine relationships meadows in the central great plains are dominated by low value between existing vegetation and soil characteristics within a saltgrass. Soil chemical and physical factors have been measured to establish a microsite classification of vegetation-soil relations. The saltgrass meadow. Then, revegetation could be more readily