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ALTERNATIVE CROPS FOR DRYLAND CROPPING SYSTEMS
Winter wheat and grain sorghum are well-adapted dryland crops for the semiarid southern Great Plains. These crops generally produce good yields when they are grown in rotation, but overall water use efficiency is relatively low because much of the fallow-period precipitation is lost as evaporation. Also, a fixed cropping system involving these crops prevents growing alternative crops when adequate precipitation occurs early in the fallow period. This study was started after wheat harvest in 1994 and involves continuous wheat, grain sorghum, and triticale; rotations of wheat and grain sorghum, wheat and fall canola, wheat and spring canola, and grain sorghum and kenaf. In addition, some plots are used for other alternative crops that are planted whenever soil water contents become adequate and the growing season is suitable. These `opportunity' crops include forage sorghum, millet, oats, and beans. All cropping systems involve reduced tillage (tillage-herbicide combination) for weed control, except for the wheat-grain sorghum rotation for which no-tillage is used.
Paul W. Unger - USDA-ARS
CROPPING AND TILLAGE SYSTEMS FOR DRYLAND GRAIN PRODUCTION
No-tillage (NT) and stubblemulch (SM) management were compared on dryland wheat-fallow (WF), continuous wheat (CW), wheat-sorghum-fallow (WSF), and continuous sorghum (CS) rotations from 1984-1994. No-tillage increased soil water profile contents (0-6 ft depth) at crop planting on all rotations when compared to SM, with the differences attributed to reduced evaporation. The 10-yr average increases in plant available soil water due to NT management were 1.33 in. on CW, 0.7 in. on CS, 0.9 in. on WSF-sorghum, and 0.4 in. on WSF-wheat. NT management was most effective with wheat residues, with most of the increase in soil water content on NT occurring in the first four months of fallow. Soil water content differences due to rotational effects were minimal for sorghum with available planting soil profile (6 ft) water contents averaging 7.9 in. for CS and 8.6 in. for WSF. Rotational effects were greater for wheat with average planting profile water contents of 6.4 in. on CW, 8.5 in. on WSF, and 8.8 in. on WF.
The maximum average effect of tillage on grain yield was about 10% with NT on WSF increasing sorghum yields by 5 bu/ac. Wheat yields on WSF and WF were not affected by tillage system, but wheat yield on CW was increased 3 bu/ac with NT. Sorghum yield on CS was reduced with NT, primarily due to poor stands of sorghum resulting from herbicide damage.
Annual grain production, as differentiated from grain yield, is defined as annual grain produced per system acre, including fallow. Rotation had a 400% effect of crop on annual grain production, thus crop selection and rotation is a most important element of dryland farming.
O. R. Jones - USDA-ARS
SOIL PHYSICAL AND BIOLOGICAL CHANGES UNDER NO-TILL AND STUBBLEMULCH MANAGEMENT
Tillage and cropping system decisions affect the physical and biological properties of soils by altering residue inputs and frequency of soil disturbance. The area used for the dryland cropping system study described above (M) is being used to evaluate, changes in soil organic matter, nutrient availability, microbial properties, water infiltration, soil bulk density, and aggregate stability. These measurements are being made to evaluate changes in soil quality associated with dryland cropping systems and to evaluate how these changes might affect long term crop production.
O. R. Jones, Paul W. Unger, Harry H. Schomberg, and Steve R. Evett - USDA-ARS
EFFICIENT USE OF STORED SOIL WATER FOR GRAIN PRODUCTION EXPLORATORY STUDY
Three cropping strategies are being evaluated regarding efficient use of stored soil water to produce grain. The three strategies are early corn early, normal dryland sorghum (30,000 seed/ac, medium early hybrid planted in 30-in. rows), and high density - short season sorghum (early hybrid seeded at 64,000 seed/ac in 15-in. rows). In 1994 corn was planted in early April with essentially no rainfall in June, whereas July and August rainfall were ample for June planted sorghum. The best corn treatment produced 25 bu/ac whereas normal sorghum yield was 66 bu/ac and high density/short season sorghum produced 68 bu/ac in 1994.
O. R. Jones - USDA-ARS
TILLAGE SYSTEM EFFECTS ON WATER CONSERVATION AND RUNOFF WATER QUALITY - SOUTHERN HIGH PLAINS DRYLANDS
Infiltration, runoff, and water conservation effects of no-tillage (NT) with stubble-mulch (SM) tillage were measured from 1981 to present, on field-sized (5- to 10-ac) graded-terraced watersheds in a dryland, three-year, winter wheat-sorghum-fallow (WSF) sequence. There are three pairs of watersheds in the sequence, each with NT and SM treatments on the same watersheds each year. Runoff measurements with H-flumes began in 1984. Infiltration differences were measured with a rainfall simulator in 1990 and 1991. Terminal infiltration rates were similar for both tillage systems; however, infiltration rates declined much more rapidly with NT than with freshly tilled SM, primarily due to surface sealing even though residue coverage exceeded 50% on NT. Cumulative infiltration after 2 hours of simulated rainfall was 90% greater on SM than on NT during fallow after sorghum, and 26% greater during fallow after wheat. Infiltration was greater on SM because tillage destroyed the consolidated surface crust, decreased bulk density, and increased surface roughness and depression storage capacity. The first artificial rainfall application compacted and smoothed the surface on the SM treatment; thus, infiltration during subsequent tests was similar for both tillage systems. Storm runoff measured with H-flumes averaged 1.0 and 1.6 in./year for nine cycles of WSF for SM and NT treatments, respectively, with most runoff occurring during fallow periods. Despite greater surface runoff from NT than from SM, NT management improved water conservation due to reduced evaporation. Total plant available soil water storage during fallow after wheat was 18% greater with the NT and 10% greater during fallow after sorghum than for SM. Environmental impacts of using NT were minimal. No-tillage reduced total sediment loss by 54% in comparison to SM, although runoff volumes were greatest from NT. Nutrient concentrations and losses in runoff were extremely low from both tillage systems (loss < 5 lb/ac N and < 1 lb/ac P/yr) on these unfertilized watersheds. There was no evidence of atrazine accumulating in the soil or leaching below the root zone, and atrazine loss in runoff amounted to a maximum of 0.26% of total application. However, up to 1.5% of propazine applications were lost in runoff. Propazine, applied to both NT and SM sorghum when runoff probability was high, appears to have a greater potential for negatively impacting the environment under semiarid conditions than does atrazine, applied when runoff probability is low. Propazine accumulated in the soil profile but was not detected below 2 ft.
O. R. Jones - USDA-ARS
WINTER WHEAT-GRAIN SORGHUM ROTATION WITH NO-TILLAGE ON DRYLAND
Three separate but adjacent fields are used for this rotation involving no-tillage, which has been in place for over 14 years (16 years for the field where wheat stubble is present). Crop growth and grain and residue yields are determined. Smaller areas within these fields are used to determine planting pattern effects on soil water storage, sorghum and wheat cultivar effects on surface residue buildings, and mulch (paper pellet and crop residue) effects on soil water storage. Long-term effects of no-tillage cropping on soil conditions are also determined in these fields.
Paul W. Unger - USDA-ARS
WHEAT RESIDUE AND WATER APPLICATION EFFECTS ON SOIL WATER CONSERVATION
Different amounts of surface residues resulted from different irrigation amounts applied to the previous wheat crop (none to three irrigations). In addition, a no-residue condition was obtained by removing all surface residues from some areas. Water is applied through a single sprinkler irrigation line (line source), which results in decreasing amounts of water being applied to the soil with increasing distances from the line. Soil water contents are determined with neutron scattering equipment at different distances from the line. The water content determinations indicate the amount of water initially stored in soil and subsequent loss of the water by evaporation as affected by the amount of residues present and the amount of water applied.
Paul W. Unger - USDA-ARS
SOIL-PLANT-ENVIRONMENT RESEARCH (SPER) FACILITY
The SPER facility was designed to evaluate the interaction between different cropping/management systems and soil characteristics under a single climatic environment. It contains 48 lysimeters with three soil types from which rain can be excluded by a automated shelter. Lysimeters are contained boxes of soil that are weighable so that crop water use can be measured. The lysimeters of a 0.75-m 2 (8.3 ft 2 ) surface area and a 2.3-m (7.7 ft) depth. The three soil types are a silty clay loam from Garden City, KS; a clay loam from Bushland, TX; and a fine sandy loam from Big Spring, TX. The approximate drained upper limit soil water contents to a 1.8-m depth are 896 mm (35.3 in.), 738 mm (29.1 in.), and 573 mm (22.6 in.). The SPER facility has been used to evaluate yield responses of different sorghum varieties to limited irrigation, and of dryland corn to mulched and bare soil surfaces. It provides a unique opportunity to evaluate soil water use patterns as affected by soil characteristics.
Judy A. Tolk - USDA-ARS
CRP LAND CONVERSION TO CROPLAND
A study is being conducted on a farmer's field to determine the effects of different tillage methods on grain sorghum and wheat production after CRP land is converted to cropland. Besides the tillage treatments, nitrogen fertilizer is applied to subplots. Effects of treatments on various soil physical, chemical, and biological factors are also determined.
Paul W. Unger, Ordie R. Jones, and Harry H. Schomberg - USDA-ARS
UTILIZATION AND WATER QUALITY IMPACTS OF LAND APPLICATION OF ANIMAL BIOSOLIDS IN DRYLAND AGRICULTURAL SYSTEMS
The panhandle of Texas and Oklahoma is experiencing a rapid expansion of livestock feeding, rearing, and meat processing operations. Large-scale confined operations (CAFO) created imbalances between animal numbers and agricultural land area available for land application.
The research objectives are
The project documents the nutrient and residue values of animal biosolids to minimize the impact of biosolid land treatments on the quality of air and water resources. Risk assessment of various surface loading of composted and non-composted materials will be evaluated as well as composting and bioavailability to provide inputs to mathematical models while developping guidelines for optimal uses of organic nutrient resources.
Thanh H. Dao - USDA-ARS
POST-CONTRACT LAND USE OPTIONS FOR CONSERVATION RESERVE PROGRAM (CRP) LANDS
Under USDA-ARS coordination, a multi-agency (NRCS, CES, Oklahoma State Univ., the Noble Foundation of Ardmore, OK, and ARS) CRP project was initiated in May 1994. The goals are to identify best-management options and develop guidelines for environmentally sound cropping-livestock systems of production that will preserve the accumulated benefits to highly erodible lands (HEL) under the CRP. A project statement was prepared and submitted to the OK State Conservation Review Group. Concurrence from DASCO of the old ASCS was sought for CRP land release. Partial financial support was provided by the SR/SARE/ACE program for 1994-97.
Field and laboratory studies were conducted on two CRP fields under contract since 1987. One experimental site is located near Forgan, OK in a 500-mm precipitation zone of the panhandle. Another site was in the subhumid SW near Duke, OK in a 750-mm precipitation zone. After burning or swathing the old litter, field plots were established to evaluate:
at the Duke site, the conversion to cotton using row (strip) tillage in killed wheat cover.
The collaborative multi-agency approach provides an excellent opportunity to address CRP landowners concerns in the post-CRP area; it was also a unique opportunity to present alternate production systems on the field scale to illustrate conservation and production goals for managing HEL in the Southern Plains. The on-going project addresses the following questions:
During 1994, we found that:
WIND-POWERED WATER PUMPING FOR LIVESTOCK AND IRRIGATION
Multi-bladed windmills that produce mechanical power are used with piston pumps to lift water. Flow rates from mechanical piston pumps usually range up to 4 gpm (15 L/min) when the pumping head is 100 ft (30 m). The average daily volume of water pumped with the mechanical pump is 2275 gal/day (8600 L/day). Wind turbines that produce electricity are used with standard electric pumps and motors (submersible and single-stage suction centrifugal pumps). Flow rates vary from 6 gpm (22 L/min) for a 1 kW wind turbine to 100 gpm (385 L/min) for a 10 kW system at a pumping head of 100 ft (30 m). The average daily volume of water pumped with the electric pump is 3310 gal/day (12,534 L/day). Larger wind turbines are used to supplement electricity used for irrigation pumps. Power is produced 65% of the time and the machine was "on" available to run for 97% of the time during the last 13 years.
R. Nolan Clark, Brian Vick, and Eric Eggleston - USDA-ARS
SOLAR-POWERED WATER PUMPING FOR LIVESTOCK
Solar photovoltaic panels are used to produce DC electricity that is used directly to power electric pumps. Diaphram pumps and DC electric motors are used to pump water from small systems (less than 400 Watts) and submersible pumps with AC electric motors are used on larger systems (greater than 500 Watts). Average daily volume of water pumped for the small system was 290 gal/day (1,105 L/day) and the daily volume for the larger systems is being determined.
R. Nolan Clark - USDA-ARS
34-m VERTICAL-AXIS WIND TURBINE
The 34-m Vertical-Axis Wind Turbine (VAWT) has an equatorial radius of 110 ft (34 m) and a height of 165 ft (50 m). The extruded aluminum blades are 48 in (1.22 m) wide at the root and 36 in (0.91 m) at mid-section. The turbine begins producing power at 10 mph (4.5 m/s) wind speed and reaches 500 kW at 28 mph (12.5 m/s). The annual energy output is estimated at 1,090 MWh based on 95% availability. The turbine has been used to verify the computer programs used in design of new machines, performance of newly designed airfoils, variable speed operation, control strategies, etc. The turbine operates only when tests are conducted.
R. Nolan Clark and Ron Davis - USDA-ARS
NUTRITION AND MANAGEMENT OF FEEDER CALVES
Research in these areas concentrates on developing a better understanding of the effects of marketing-transport-feedyard adaptation stressors on feed intake, animal performance, immune function, nutrient metabolism, and endocrine response. This knowledge is used to develop practical nutritional and management procedures that negate the adverse effects of stressors on animal health and production. Studies have demonstrated that proper pre-shipment and post-shipment nutrition can significantly reduce the incidence and severity of BRD. The low feed intakes noted in "stressed" calves seem to be caused by a combination of decreased ruminal fermentative activity and endocrine (ie. insulin, growth hormone, thyroxine, triiodothyronine, prolactin) changes that occur during stress. Preliminary studies suggest that providing some nutrients in the water, rather than in the feed, may improve nutrient balance.
N. Andy Cole - USDA-ARS
DEVELOPMENT OF EFFICACIOUS VACCINES FOR BRD
Research in this area concentrates on obtaining a better understanding of the bacteria involved in BRD in order to develop improved pharmacological and biological methods to control the disease. Research concentrates on the study of Pasteurella haemolytica, the primary bacteria involved in BRD. Studies include characterization of potential virulence factors such as neuraminidase, and determination of enzyme profiles and DNA fingerprints of Pasteurella sp. isolates. Blood samples collected from feeder calves before and after marketing-transport stress are analyzed for complement activity, bacteriolytic capacity, heat shock proteins, acute phase proteins, and antibodies to various antigens of Pasteurella sp. An ultraviolet-killed Pasteurella haemolytica vaccine has been developed and tests are in progress to determine the efficacy of this vaccine when used with various carriers and(or) adjuvants.
C.W. (Bill) Purdy - USDA-ARS