• A Hand-Portable Single Nozzle Rainfall Simulator Designed for Use on Steep Slopes

      Wilcox, B. P.; Wood, M. K.; Tromble, J. T.; Ward, T. J. (Society for Range Management, 1986-07-01)
      The objective of this study was to develop a small plot (1 m2) rainfall simulator operational on steep terrain in the Guadalupe Mountains of New Mexico. The simulator developed is hand-portable and consists of a spray head assembly mounted on 3 adjustable legs. A 946-liter tank equipped with a gasoline powered pump was connected to the spray head assembly via rubber garden hoses. On steep slopes gravity provided sufficient pressure to operate the simulator. Site selection was limited to areas where the water tank could be located in a suitable upslope position. The simulator has been used for 2 years on 170 plots and has proved durable. Advantages of this device are the low cost of construction and operation, and the flexibility in plot-site selection it provides. The principal disadvantages are associated with the single stationary nozzle, such as uneven application of water at small drop sizes and low kinetic energies.
    • An Inexpensive Tool for Unrolling Barbed Wire

      Knight, R. W.; Wood, M. K.; Blackburn, W. H. (Society for Range Management, 1980-01-01)
      A hand tool for unrolling barbed wire is described which is advantageous in that it requires only one person to operate, snags are easily corrected, works in tight places, and can be constructed totally from scrap materials.
    • Comparative Infiltration Rates and Sediment Production on Fertilized and Grazed Blue Grama Rangeland

      Wood, M. K.; Donart, G. B.; Weltz, M. (Society for Range Management, 1986-07-01)
      This study determined the impacts of fertilization and livestock grazing on infiltration rates and sediment production. Infiltration rates and sediment production varied across years, depending on precipitation conditions, but were not different between fertilized and unfertilized rangeland within a year. Livestock production and stocking rates were 2 times greater on fertilized than on nonfertilized rangeland. Soil bulk density was only greater on the fertilized areas than the control at the end of the grazing period in 1982. Microtopography or roughness was not different between treatments. Increases in plant production mitigated any impacts from increased livestock numbers in fertilized areas.
    • Factors influencing infiltrability of semiarid mountain slopes

      Wilcox, B. P.; Wood, M. K.; Tromble, J. M. (Society for Range Management, 1988-05-01)
      The objective of this research was to determine the effects of selected vegetation, soil, rock, and slope variables on infiltration of semiarid rangelands with slope gradients ranging from 0-70%. Analyses were made on 2 sets of data collected a year apart in the Guadalupe Mountains of New Mexico and consisted of Pearson and partial correlation analysis of the dependent infiltration variables and independent site variables. In addition, infiltration was regressed against uncorrelated factors produced by factor analysis. Vegetal cover and biomass strongly influenced infiltration. The relative importance of grasses, shrubs or litter was dependent on their respective abundance, especially grass. Soil depth also limited infiltration especially as soil water storage became satisfied. Infiltrability was negatively correlated with rock cover and the smallest rock size fragments were the most negatively related. When the effects of vegetal cover and slope were removed (using partial correlation analysis) however, the median sized rock fragments (26-150 mm) were positively related to infiltrability, and the smallest rock fragements (2-12 mm) were negatively related. Partial correlation analysis also suggested a positive correlation between infiltrability and slope gradient.
    • Factors influencing interrill erosion from semiarid slopes in New Mexico

      Wilcox, B. P.; Wood, M. K. (Society for Range Management, 1989-01-01)
      This rainfall simulation study evaluates the effects of slope, vegetation, rock, and soil characteristics on interrill erosion of semiarid slopes of the Guadalupe Mountains of New Mexico. A single-nozzle rainfall simulator applied rainfall on slope gradients ranging from 0-70%. Multicollinearity in the data was corrected for by using partial correlation analysis. Interrill erosion was most influenced by slope gradient; however, the effect of slope gradient was modified by other factors, particularly vegetation. Vegetation greatly lessened interrill erosion, especially during the initial stages of runoff. Shrubs decreased interrill erosion more than did either grasses, litter, or forbs. Sediment concentration was greater from erosion pavements than from well-vegetated plots. Increases in rock cover, however, without corresponding decreases in vegetal cover, afforded additional protection against interrill erosion. Soil texture and soil depth were the most influential soil factors, particularly on steep slopes.
    • Grazing Systems: Their Influence on Infiltration Rates in the Rolling Plains of Texas

      Wood, M. K.; Blackburn, W. H. (Society for Range Management, 1981-07-01)
      Water infiltration rates into soils after 30 min in shrub canopy areas and in shortgrass interspaces on the Rolling Plains were similar across grazing treatments of heavy and moderate stocking, continuous grazing; rested and grazed deferred-rotation; rested and grazed high intensity, low frequency (HILF); and two live-stock exclosures which had been grazed for 20 years. The mid-grass interspace infiltration rates for the deferred-rotation treatments approached rates in the exclosures and exceeded rates in the heavily stocked, continuously grazed, and grazed HILF pastures. Infiltration rates in the HILF grazing treatments were similar to those of the heavily stocked, continuously and moderately stocked continuously grazed pastures. Infiltration rates in the rested HILF pasture were similar to those of the deferred-rotation pastures; however, the grazed HILF pasture had rates lower than the deferred-rotation pasture rates or rates of the exclosures. Aggregate stability, organic matter content, mulch, standing crop, bulk density, and ground cover significantly influenced infiltration rates.
    • Hydrologic impacts of sheep grazing on steep slopes semiarid rangelands

      Wilcox, B. P.; Wood, M. K. (Society for Range Management, 1988-07-01)
      Infiltration, sediment concentration of runoff, and sediment production from lightly grazed and ungrazed semiarid slopes were compared using a hand-portable rainfall simulator. The study slope was located in the Guadalupe Mountains of southeastern New Mexico. Average slope steepness was 50%. The objective of this study was to determine the impacts of light grazing by sheep (10 ha/ AU) on steep slope infiltrability and sediment production. Infiltrability on the grazed slopes was 12-17% lower than on the ungrazed slopes. These results are comparable to what has been reported from moderate slope gradients. Sediment concentration of runoff from the lightly grazed slopes was significantly higher than from the ungrazed slopes only at the end of the dry run (45 min). Sediment production was significantly greater from the grazed slopes for the dry run, but not the wet run. Percentage difference of sediment production between the grazed and ungrazed slopes was well within the range published for moderate slope conditions. These data give no indication that steep slopes (30-70%) in semiarid regions are any more hydrologically sensitive to light grazing than are moderate slopes (<10%).
    • Impacts of Off-Road Vehicles on Infiltration and Sediment Production of Two Desert Soils

      Eckert, R. E.; Wood, M. K.; Blackburn, W. H.; Peterson, F. F. (Society for Range Management, 1979-09-01)
      Impacts of motorcycle and 4-wheel drive truck traffic on infiltration rate and sediment production were evaluated on two desert soils. Infiltration was similar for both soils; however, more sediment was produced from a surface with exposed mineral soil than from a gravel-mulched surface. Infiltration was 3 to 13 times greater on the coppice soil beneath shrubs than on interspace soil between shrubs, but sedimentation was 10 to 20 times greater on interspace soil. Infiltration was less and sediment yield was greater after soil was disturbed by vehicular traffic, and after reformation of the surface crust, particularly on interspace soil. High sediment production from interspace soil was attributed to reduced infiltration after 10 minutes. The soil then became saturated and unstable, was dispersed by raindrop impact, and particles were carried in runoff water for the remaining 20 minutes of the test period. Coppice soil had a high infiltration rate for the entire test period and did not become saturated. In addition, the high organic matter and aggregate stability of coppice soil prevented soil movement, though some runoff occurred.
    • Impacts of tracked vehicles on sediment from a desert soil

      Fuchs, E. H.; Wood, M. K.; Jones, T. L.; Racher, B. (Society for Range Management, 2003-07-01)
      Off-road military vehicle traffic is a major consideration in the management of military lands. The objective of this study was to determine the impacts of military tracked M1A1 heavy combat tank vehicles on sediment loss from runoff, surface plant cover, and surface microtopography in a desert military training environment. A randomized block design was used which had 10 blocks with 4 plots (0.5 m2) in each block. Each block had randomly selected treatments that included an untreated control, 1 pass by a M1A1 tank under wet seasonal conditions, 3 passes by a M1A1 tank under wet seasonal conditions, 1 pass by a M1A1 tank under dry seasonal conditions, and 3 passes by a M1A1 tank under dry seasonal conditions. Data were analyzed using mean separation and stepwise regression techniques. Most sample periods showed that sediment losses from M1A1 tank treatments, single or triple passes under wet or dry seasonal conditions, did not differ statistically from natural sediment losses under nominal rainfall events. However, comparatively intense rainfall events often generated significantly (P 0.05) greater sediment losses from the M1A1 tank triple pass treatments. Triple pass M1A1 tank impacts had detrimental effects that could last many years, particularly when disturbances were imposed under dry seasonal conditions. Seasonal drought for the area, occurring 2 out of 3 years during the study period, may have exacerbated the effects of triple pass M1A1 tank impacts. Analysis showed that grass cover, litter cover, and microtopographic variance were highly and negatively correlated (R = -0.62) with cumulative sediment loss. Depending on precipitation availability, a minimum of 3 years for most triple pass M1A1 tank impacts is suggested for suitable vegetation recovery and soil stability. It is recommended that site repetitious M1A1 tank training maneuvers should be conducted with particular attention to site recovery. Furthermore, the influence of climate, drought in particular, should be among the topics addressed by future military training land use models.
    • Infiltration and Sediment Production Following Chemical Control of Sagebrush in New Mexico

      Balliette, J. F.; McDaniel, K. C.; Wood, M. K. (Society for Range Management, 1986-03-01)
      Terminal infiltration rates under sagebrush canopies were about 35% higher than interspace areas at 3 study sites in northern New Mexico. Differences in infiltration rates among strata may largely be attributed to a greater amount of litter yield and basal cover, and 2 to 3 times higher percentage of organic carbon under the canopy of sagebrush compared to the interspace. Infiltration rates and sediment concentration of runoff within the canopy zone and interspace areas were not affected chemical control treatments. Total sediment production was about 29 to 41% higher under the canopy of tebuthiuron treated sagebrush compared to the canopy zone of untreated rangeland. However, these differences were not consistent and were significant at only 1 study site. Total sediment production was related primarily to a combination of soil texture, sagebrush canopy cover, and total vegetation production.
    • Influence of Crusting Soil Surfaces on Emergence and Establishment of Crested Wheatgrass, Squirreltail, Thurber Needlegrass, and Fourwing Saltbush

      Wood, M. K.; Eckert, R. E.; Blackburn, W. H.; Peterson, F. F. (Society for Range Management, 1982-05-01)
      Crusting soil surfaces with vesicular pores occur in arid and semiarid regions of the world where herbaceous vegetation is sparse. Morphological properties of crusting surfaces can impair seedling emergence and plant establishment. This study evaluated site preparation and seeding methods and species useful for encouraging successful stand establishment in such soils. Plowing to prepare a seedbed reduced seedling emergence on some soils but increased plant establishment on all soils. More seedlings emerged and established on non-crusting coppice soil beneath shrubs than on crusting interspace soil between shrubs. Crested wheatgrass was the most successful species followed closely by squirreltail and distantly by Thurber needlegrass and fourwing saltbush. Fourwing saltbush seedlings became established and grew well in some treatments. Seedling emergence and establishment were highest with the deep-furrow seeding technique on the non-crusting coppice soil. The standard-drill technique gave the best stand on the site with the largest surface cover of bare, crusting interspace soil.
    • Interrelations of the Physical Properties of Coppice Dune and Vesicular Dune Interspace Soils with Grass Seedling Emergence

      Wood, M. K.; Blackburn, W. H.; Eckert, R. E.; Peterson, F. F. (Society for Range Management, 1978-05-01)
      Vesicular soil surface horizons are found throughout the arid and semiarid areas of the world associated with sparse vegetation. In the Great Basin this horizon occurs in the surface 5 or 8 cm of dune interspace soil. Vesicular horizons are characterized by a high silt content, low organic matter, poor aggregation, and low infiltration rates. Our intent was to study the influence of organic matter removal on vesicular development and to determine the effect of a vesicular horizon on seedling emergence. Removal of organic matter from coppice dune soil resulted in a poorly aggregated vesicular soil with properties similar to those of the untreated interspace soil. Crested wheatgrass and squirreltail seedling emergence was poor and seedling stress was high in vesicular dune interspace soil.
    • Livestock grazing impacts on infiltration rates in a temperate range of Pakistan

      Bari, F.; Wood, M. K.; Murray, L. (Society for Range Management, 1993-07-01)
      This study was conducted in a temperate range of northern Pakistan in 1987 and 1988. The main purpose of the experiment was to determine a suitable residual phytomass level for the moist temperate ranges of Pakistan. Data were collected for 2 consecutive growing seasons. A completely randomized design, with 4 treatments and 2 replications, was used. The treatments were 4 different residual phytomass levels. A rainfall simulator applied rainfall to 48 flexible circular plots (1m2). Analysis of variance and the LSD multiple mean comparisons determined treatment differences, and stepwise multiple regression identified the important vegetation and soil variables affecting infiltration. The control (no grazing) resulted in the highest infiltration while the treatment having the lowest residual phytomass had the lowest infiltration. Among the independent variables, standing phytomass was the most important variable affecting infiltration. Foliar and basal cover were also highly correlated to infiltration.
    • Livestock grazing impacts on interrill erosion in Pakistan

      Bari, F.; Wood, M. K.; Murray, L. (Society for Range Management, 1995-05-01)
      This study was conducted for 2 consecutive growing seasons in a temperate region of Pakistan to determine a residual phytomass level necessary to adequately protect the soil against accelerated interill erosion A rainfall simulator was used to apply rainfall to 48 (1 m square) circular plots arranged in a completely randomized experimental design, with 4 residual phytomass levels and 2 replications. The residual treatment with 3,024 kg ha-l phytomass resulted in the lowest erosion rates, and the treatment with 624 kg ha-l phytomass produced the highest erosion. Standing phytomass was the most important variable affecting erosion with foliar cover and basal cover also highly correlated to erosion.
    • Native forage quality, quantity, and profitability as affected by fertilization in northern Mexico

      Rubio, H. O.; Wood, M. K.; Gomez, A.; Reyes, G. (Society for Range Management, 1996-07-01)
      Fourteen treatments of nitrogen (N) and phosphorus (P) fertilizers were applied in an overgrazed eight rangeland in northern Mexico, during 1990 and 1991. Eight treatments were applied using ammonium nitrate as a source of N (60-0-0, 60-30-0, 60-60-0, 80-40-0, 120-30-0, 120-60-0, 120-90-0 and 180-60-0 kg ha-1), 2 treatments with ammonium sulfate (60-30-0 and 120-60-0 kg ha-1), 2 with urea (60-30-0 and 120-60-0 kg ha-1), only P (0-30-0 kg ha-1), and the control (0-0-0 kg ha-1). Triple superphosphate was applied as a source for P. The 80-40-0 treatment was included because it was the commonly recommended rate for the area. Fertilizers were applied at the beginning of the rainfall season (July) and forage was harvested in late October (1990) and mid-November (1991). Dry matter production, crude protein (CP) content, and in situ digestibility were determined. An economic analysis was used to obtain the best economic treatment for forage production. In 1990 with a precipitation of 377 mm, dry matter production was significantly affected for both source and rate of N. The maximum amount of dry matter was obtained with a rate of 120-90-0 kg ha-1 using ammonium nitrate. However, the best treatment in terms of economic return was 120-30-0 kg ha-1 as ammonium nitrate. Urea did not produce as well as other N source treatments. Crude protein was highest in treatments with the higher N, but no significant trend was evident. In situ digestibility was not affected by rate or source of N fertilizer. During 1991, precipitation was higher than in 1990. Significant differences were determined among N rates but not in N source. In fact, urea produced greater in dry matter production than other N sources at the same rate. The maximum amount of dry matter was obtained with the 180-60-0 treatment using ammonium nitrate with 4,190 kg ha-1, but the best economic treatments were the 120-30-0 and 60-0-0 with a marginal return rate of 377% and 355%, respectively. Results of CP and in situ digestibility were similar to those of 1990.
    • Plot Numbers Required to Determine Infiltration Rates and Sediment Production on Rangelands in South Central New Mexico

      Wood, M. K. (Society for Range Management, 1987-05-01)
      Many studies have been made, and continue to be conducted, to determine infiltration rates and sediment production on rangelands. Most of these studies use small sample plots (<2 m2). This study determined the number of sample plots required to achieve confidence intervals of +/- 10, +/- 20 and +/- 30% of the sample mean at 80, 90, and 95% probability levels. For 80 and 90% probability levels, 20% of the mean could be achieved with 1 to 5 plots for infiltration rates, and as low as 1 or as many as 263 plots for sediment production. For dry soil moisture conditions, infiltration rates could be estimated with 4 or 5 plots, with 10 to 12 plots needed for field capacity conditions to achieve 10% of the mean with 95% confidence. Achieving 10% of the mean with 95% confidence was not considered practical for sediment production.
    • Rainfall interception by selected plants in the Chihuahuan Desert

      Wood, M. K.; Jones, T. L.; Vera-Cruz, M. T. (Society for Range Management, 1998-01-01)
      Water budget modeling usually requires quantification of all possible processes of the hydrologic cycle. This includes rainfall interception. The purpose of this study was to estimate the potential amounts of water transferred back to the atmosphere from interception for some common plants found in the Chihuahuan desert. Fifty plants of many sizes representing 10 common species of the Chihuahuan Desert were chosen for evaluation. Plants were submerged in a 2 X 2 m tank filled with water. After submersion, the plants were weighed, and the difference in weight was recorded as the maximum water storage capacity of the plant's canopy. Plants were also measured for maximum and minimum crown diameter (cm), height (cm), green weight (g) at time of submersion, and oven-dry weight (g). The forb, grass, and shrub species had different variables included in the prediction equations. Dry and green weight were the 2 variables which appear to have the strongest relationship with the amount of water intercepted for all species. Of the 7 grass species evaluated, dry and green weight were part of all equations, and height was included in only 2 equations.
    • Rainwater harvesting for increasing livestock forage on arid rangelands of Pakistan

      Suleman, S.; Wood, M. K.; Shah, B. H.; Murray, L. (Society for Range Management, 1995-11-01)
      This study determined forage production and cover of several plant species resulting from the use of water harvesting catchments with catchment: cultivated area ratios of 1:1 and 1.25:1 and contributing aprons with 7, 10, and 15% slope gradients. Plots with 1.25:1 ratios produced more forage and had more cover than plots with 1:1 and 0:1 ratios. Plots with 7, 10, and 15% slope gradients had similar forage production and cover. Tuft planted plots produced more forage and cover than seeded plots. Ghorka (Elionurus hirsutus (Vahl) Munro), blue panicum (Panicum antidotale Retz.), and buffer (Cenchrus ciliaris L.) grasses produced similar forage and cover, which was higher than khev grass (Sporobolus helvolus (Trin.) Th. Dur. & Schinz) production and cover.
    • Sediment Production as Influenced by Livestock Grazing in the Texas Rolling Plains

      Wood, M. K.; Blackburn, W. H. (Society for Range Management, 1981-05-01)
      The influence of livestock on sediment production was evaluated on a Clay Flat range site with shrub canopy areas, and midgrass and shortgrass interspace areas in the Rolling Plains near Throckmorton, Texas. Sediment production in the shrub canopy areas was similar across grazing treatments of heavy and moderate stocking, continuous grazing; rested and grazed deferred-rotation; rested and grazed high intensity, low frequency (HILF); and two livestock exclosures which had not been grazed for 20 years. Sediment production from the shortgrass interspace area was similar for all grazing treatments except from the heavily stocked, continuously grazed pasture, where sediment production exceeded that of the rested HILF treatment. The midgrass interspace sediment production for the heavily stocked, continuously grazed treatment exceeded that of the deferred-rotation treatments and the exclosures. Likewise, sediment production for the grazed HILF treatment was greater than that for the rested deferred-rotation treatment and exclosure. Soil and vegetation variables which significantly influenced sediment production included aggregate stability, organic matter content, mulch, standing crop, bulk density, and ground cover.
    • Short Duration Grazing in Central New Mexico: Effects on Infiltration Rates

      Weltz, M.; Wood, M. K. (Society for Range Management, 1986-07-01)
      The objectives of this study were to determine the influence of short duration grazing, continuous grazing, and grazing exclusion on infiltration rates on 2 range sites in southcentral and eastcentral New Mexico. Short duration grazing had no beneficial effect on the hydrology of 2 different range sites. The terminal infiltration rates of both short duration grazing systems, after the cattle had grazed the area, were about one-half the terminal infiltration rate of the same area before the cattle grazed the area. Cattle distribution within the different grazing treatments had no effect on infiltration rates at 0.4, 0.8, and 1.2 km away from water for a moderate continuous, heavy continuous, and a short duration grazing system. Moderate continuous grazing was superior to heavy continuous grazing and short duration grazing, based on the hydrologic variables evaluated.