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The CBT system uses level contour benches with terrace ridges to control erosion, and to capture, spread and infiltrate storm runoff from natural sloping contributing areas (watersheds) that are twice as large as the level bench. The CBT system at Bushland, consisting of 4 level benches and watersheds, was built in 1957 and is still very serviceable. Runoff from the stubblemulch tilled wheat-sorghum-fallow (WSF) cropped watersheds has averaged 1.3 in/yr over the 38-year life of the system, resulting in an additional 4 in/yr of available water for growing crops on the CBT level bench. This allows annual cropping on the level bench as opposed to WSF on the watersheds. Average annual crop yields on CBT level benches for the past ten years (1987-1996) were: grain sorghum -- 3030 lb/ac; wheat -- 22.5 bu/ac; sunflower -- 1480 lb/ac; and corn (3-yr avg.) -- 2790 lb/ac. Yields (10-yr avg) on sloping watersheds cropped in wheat-sorghum-fallow (2 crops in 3 years) were: sorghum -- 3040 lb/ac; and wheat -- 25.9 bu/ac. Annual cropped yields from nearby 1% sloping plots for the same period were: sorghum -- 2170 lb/ac; and wheat -- 15.9 bu/ac. Thus, runoff contribution to CBT level benches increased sorghum yield by 860 lb/ac and wheat yield by 6.7 bu/ac on an annual basis, a 40% increase in production. These results show that runoff conservation substantially increases annual cropped yields of both sorghum and wheat.
Ordie R. (Reggie) Jones, Soil Scientist
We used 32 years of historical soil water and yield data from stubblemulch tillage on wheat-sorghum-fallow (WSF) and continuous annual cropping of wheat and sorghum to evaluate the potential of opportunity cropping. With the opportunity system, the same crop (wheat or sorghum) is planted back to back if the soil is wet to 3 feet at planting as determined with a soil probe, otherwise land is fallowed and planted to the next scheduled crop in the WSF rotation. We compared grain production on the opportunity system with a fixed 3-year wheat-sorghum-fallow rotation. Average annual precipitation for the 32 years (1958-1978 and 1986-1996) was 18.5 in. Cumulative 32-yr production on the fixed WSF system was 193 bu of wheat (10 crops) and 463 bu of sorghum (11 crops). This compares to production with opportunity cropping of 135 bu of wheat (9 crops) and 524 bu of sorghum (16 crops). There were only 3 times in the 32 years that wheat crops could be planted back to back, but there were 10 times that sorghum could be repeated. We used the criteria of at least 3 inches of plant available water in the top 3 feet of soil, and with at least 0.5 in available in the 3rd foot before back to back cropping was allowed. These moisture conditions allow a steel rod to be inserted to a 3-ft depth in the Pullman soil. We assumed in this analysis that the yield of the second crop in back to back planting was the same as was obtained with annual cropping of sorghum or wheat. Our long-term evaluation indicates that a fixed wheat-sorghum-fallow rotation is preferable to opportunity cropping due to greater yields on the WSF crops and a reduced number of crop harvests, thus reducing expense. Adoption of a fixed rotation also allows a wider spectrum of herbicide use for reduced or no-tillage management.
Ordie R. (Reggie) Jones, Soil Scientist, and Thomas Popham, Biometrician, USDA-ARS
Winter wheat and grain sorghum are well-adapted dryland crops for the semiarid southern Great Plains. However, water use efficiencies for grain production often are low due to water loss by evaporation when these crops are grown in a rotation. Also, a fixed cropping system involving these crops prevents growing alternative crops when enough soil water becomes available soon after harvest of either crop. This study was started in 1994 and includes continuous cropping of wheat, grain sorghum, and triticale, and rotations of wheat and grain sorghum, wheat and fall canola, wheat and spring canola, and grain sorghum and kenaf. Alternative crops are planted in some plots whenever soil water contents become adequate and the growing season is suitable. These `opportunity' crops include forage sorghum, millet, oats, and pinto beans as well as grain sorghum and wheat. All cropping systems involve reduced tillage (tillage-herbicide combinations) to control weeds, except no-tillage (only herbicides) is used for the wheat-grain sorghum rotation.
Paul W. Unger, Soil Scientist, USDA-ARS
Contracts covering much of the CRP land in the region will expire soon, depending on the final regulations concerning the contracts. A study was started on a farmer's field near Wildorado (about 4 miles west of the Research Laboratory) in late 1994 to determine effects of different ways to prepare CRP land for winter wheat and grain sorghum production. Treatments include moldboard, disk, and sweep tillage without prior grass removal or with grass removed by mowing and baling; grass burning before disk or sweep tillage; and no-tillage with grass retained or removed. Because of little rain or snow before planting grain sorghum and little rain during the growing season in 1995, grain yields were low with all treatments and averaged only about 300 lb/ac. Poor weed control (bindweed) contributed to the low yields. The highest yield was 600 lb/ac. for a treatment involving sweep tillage followed by herbicides to control weeds. Severe plant water stress resulted in poor grass and weed control with herbicides on no-tillage plots. Sorghum was not planted in 1996 because of the drought. The 1995-1996 wheat yields were extremely low because of the drought. Wheat was planted in the fall of 1996 and grain sorghum will be planted in 1997.
Paul W. Unger and Ordie R. Jones, Soil Scientists , USDA-ARS
Cooperators -- John Janhsen, Farmer. USDA-Natural Resource Conservation Service (NRCS) personnel and USDA-Farm Services Agency (FSA) personnel
Soil water storage and erosion control improve with increases in amount of crop residues retained on the soil surface. Dryland crops such as winter wheat and grain sorghum, however, often do not produce enough residues to be of major benefit with regard to increasing water storage and controlling erosion. If more residues could be `carried over' from one crop to the next and a `buildup' of residues could be obtained when dryland wheat and sorghum are grown in rotation, improved water conservation and erosion control should occur. A study was started in 1995 to determine whether wheat and grain sorghum varieties differ with regard to amounts of residues carried over from one crop to the next when they are grown in a rotation in a no-tillage cropping system. Five wheat varieties and five grain sorghum hybrids are `cross planted' in the study. The amounts of residues remaining from each previous crop are determined at planting and harvest of each crop. Soil water contents and crop yields are determined also. The first `cross planting' was done in the fall of 1996, and no data are yet available.
Paul W. Unger, Soil Scientist, USDA-ARS
Winter wheat and grain sorghum have been grown in rotation under no-tillage conditions on three fields starting in 1979. One field has not been plowed since 1979 and two fields have not been plowed since 1981. Weeds and volunteer crop plants are controlled by applying herbicides. Wheat yields from 1985 through 1996 averaged 36.8 bushels per acre (2210 pounds per acre) and sorghum yields averaged 4000 pounds per acre. These averages include one year for wheat when the crop was destroyed by hail (no grain harvested), and one year for sorghum when the crop was planted late because of early drought and then killed by frost before the grain was mature (yield of 290 pounds per acre). The yields for wheat and sorghum are 900 to 1000 pounds per acre greater than those obtained where stubble-mulch plowing was used for these crops from 1983 to 1994 in other studies at the Laboratory. The straw and stubble of these crops that was kept on the soil surface by using no-tillage provided excellent control of soil erosion.
Paul W. Unger, Soil Scientist , USDA-ARS
Waste paper accounts for much of the material disposed of in landfills. Landfill space, however, is limited in many areas and some landfills no longer accept waste paper for disposal. Therefore, alternative means of disposal are needed. Applying waste paper to agricultural land is being considered. If applied to land, it must not result in a trashy appearance and it should provide benefits to land owners or operators. One such means is to use paper pellets, which are being used as a mulch for landscaping in some areas. Surface-applied paper pellets reduced soil water evaporation under laboratory conditions. A study was started in 1995 to determine whether surface-applied paper pellets would increase soil water storage under field conditions. Such application would increase the amount of organic materials on the surface, which should add to the benefits obtained from crop residues. It should also increase soil organic matter contents, which should improve soil conditions. The pellets are applied after wheat harvest in a wheat-grain sorghum rotation study. Pellets are applied at rates of 0 (check treatment), 4500, 9000, and 13500 lb/ac. to no-tillage plots where wheat resides are retained or removed by raking and to sweep tillage plots where wheat resides are retained or removed by raking. Effects of the pellets on soil water storage and on grain sorghum growth and yield are being determined.
Paul W. Unger, Soil Scientist, USDA-ARS
Research at the SPER facility, which is located at the NW corner of the USDA-ARS laboratory, evaluates how environment, management practices, crop characteristics, and soil properties control crop growth and yield. The facility has 48 lysimeters, which are large boxes (2.5 ft x 3.3 ft x 8 ft deep) that can be weighed to measure water loss. The lysimeters contain three major soil types of the southern and central High Plains--a silty clay loam from Bushland, TX; a silt loam from Garden City, KS; and a fine sandy loam from Big Spring, TX--each differing in important soil characteristics such as water holding capacity, density, and amount and depth of caliche. The facility also has a rain shelter, a large metal building which automatically moves down rails to cover the lysimeters when rainfall occurs. This allows control of the amount of soil water during an experiment. From 1994 to 1996, the facility was cropped to short season corn under limited and full irrigation. The corn in the silt loam produced the highest corn yields under all conditions. Under full irrigation, the corn in the clay loam produced yields similar to the crop in the silt loam but, under dryland conditions, the corn yields were greatly reduced because the crop failed to extract available water at depths below 4 feet, unlike the crops in the other two soils. The corn in the sandy loam did not produce yields as high as that in the other two soils, even under full irrigation, which was possibly due to the lower water holding capacity and high density which restricted rooting. In 1997 and 1998, short to medium season grain sorghum will be grown with irrigation treatments ranging from dryland to full irrigation.
J.A.Tolk, Plant Physiologist; S.R. Evett, Soil Scientist; T.A. Howell, Agricultural Engineer; USDA-ARS, Conservation and Production Research Laboratory, Bushland, TX
The majority of the contracts of the Conservation Reserve Program (CRP) lands in the Great Plains will expire between 1997 and 1998. Contract holders will have to choose whether to graze, to hay, or to re-crop CRP lands in the post-contract period. A multi-agency project was implemented to assess environmentally-sound systems for producing Old World bluestem or winter wheat on highly erodible lands. A minimum-input approach and the optimal management of Old World bluestem stands, conservation-tillage wheat, and no-tillage wheat into herbicide-killed sod were evaluated on two CRP fields located in western Oklahoma. Grass and crop growth, yield data, soil and weather condition data were collected during the growing season and non-cropped periods during 1994-96. Management actions needed to convert CRP fields into productive grasslands included fertilizer applications to improve low nutrient levels, forage quality, and sparse stand. Early spring suppression of the grass conserved stored water that was vital to the production of a fall-planted wheat crop. The amount of dry matter removed and regrowth was critical to how well we performed conservation tillage, killed the growing cover, and established a good crop stand. A cool-season crop such as wheat tends to minimize the risk of production better than a summer crop that has to compete with uncontrolled grass growth. No-till practices most efficiently conserved stored water and kept a smooth planting surface for at least the first-year crop. Maintaining the grass stand on CRP lands appeared to be the least-risk option. The chance of success for agronomic production accordingly decreased in the order of grass production, no-till wheat, and tilled wheat.
Thanh H. Dao, Soil Scientist, USDA-ARS
Jim H. Stiegler, Soil Management Specialist and J. C. Banks, Agronomist, Oklahoma State University
Laurie Bogle, Range Conservationist, and Bud Adams, District Conservationist, USDA-NRCS
Land application of liquid and solid wastes is the major avenue for disposing of the large volume of excreta produced by the livestock feeding industry. On the average, fresh animal manure contains about 2% nitrogen, 0.2% phosphorus, and 1.5% potassium. Composting or aerobic fermentation of animal manure result in 30 to 50% reduction in mass and a material more uniform in nutrient composition. However, volatile losses as ammonia-N accounted for up to 36% of the initial N content. Carbon mineralization of labile carbon fractions resulted in an enrichment of the N and P concentrations of the composted material. More stable N pools remain. Characterization and quantification of mineralization parameters are needed in order to arrive at optimal loading rates for land treatment of stockpiled and composted materials. Precise knowledge of crop requirements and yield goals, timing of field applications as function of plant needs and weather conditions, soil-mediated mineralization-immobilization turnover processes, and nutrient characteristics of the manure or compost are important for optimal use of these organic sources of plant nutrients. In May 1996, equivalent N applications of manure and composted manure, ranging from 67 to 223 lbs N/ac and from 18 to 134 lbs P/ac were made on leveled terraces that were managed using either no-tillage or stubble-mulch tillage practices. The fields were planted to grain sorghum in a wheat-sorghum-fallow rotation. Standard methods of soil extraction yielded a wide range of estimates of P availability that varied from two to five-fold differences in solution concentrations. To better understand nutrient release mechanisms and optimize land loading rates will necessitate a standardization of methods and systematic classification of extracted pools of various waste forms. Model parameters will be developed to predict nutrient status for various soils, crop systems, and climatic conditions.
Thanh H. Dao, Soil Scientist, USDA-ARS
Optimized guidelines are acutely needed for applying livestock manure on crop and range lands as a function of climatic variables, soils, and hydrogeology. Studies were conducted to determine the environmental risks of surface-applied animal wastes on crop and grasslands in the design a total manure management system. Research approaches used to reduce the environmental risks of surface applications of animal wastes included modifications of nutrient availability and adjusting rates to actual nutrient requirements of the crops. Application strategies were based on plant requirements for either nitrogen or phosphorus to meet growth and development needs. Traditionally land treatments were designed toward meeting the N requirements. The imbalance between nitrogen and phosphorus that exists in animal manure ranged from 1:4 to 1:8 created a large loading of phosphorus when applications are designed to meet nitrogen demands of the crop. The aerobic composting of manure further concentrates and raises the phosphorus content of the final product. The high loading of P, primarily in the forms of phosphate and organic P, is in excess of plant needs and is susceptible to offsite losses. We are studying the effects of co-amendment with feedlot manure and composted manure to reduce soluble phosphorus, in the range of five to seven-fold, thus allowing applications of manure and compost in amounts that deliver adequate N for plant growth and minimize loss of soluble P. These treatments are being contrasted to applications based on phosphorus needs of the sorghum and wheat crops. Water and nutrient runoff measurements will demonstrate the relative efficacy of the land application strategies.
Thanh H. Dao, Soil Scientist, USDA-ARS
Manure from cattle feedlots can be a good source of nutrients for crops; however, the ratio of nutrients in the manure, especially the nitrogen to phosphorus ratio, may not be in the optimum proportions for field crops. The objectives of this research are to develop nutritional and management regimens that decrease the amounts of manure produced, improve the nutrient ratios in collected manure (ie. increase the N/P ratio), and decrease the emissions of particulates that may contribute to odor or dust concerns. Research studies range from basic studies of nutrient digestion and metabolism to applied studies on animal performance. The beef cattle research facilities, at Bushland (USDA/TAES) and at West Texas A&M University, are currently being renovated to expand this research effort. Studies currently in progress and(or) planned include the following: influence of sequential protein supplementation on nutrient excretion and balance; influence of implant strategy on phosphorus excretion and metabolism; influence of sorghum genetics, planting density and processing method on nutrient excretion and metabolism; development of internal markers that can be used to determine diet digestibility under feedlot conditions; development of lab procedures to evaluate phosphorus availability of feeds; and evaluate the effects of phytate-phosphorus on phosphorus utilization of cattle fed high concentrate diets. Studies to date indicate that alternating the dietary protein content at 2-day intervals may improve nitrogen utilization and thus reduce nitrogen excretion. Other studies indicate that implanting may improve phosphorus utilization and reduce phosphorus excretion.
N. Andy Cole, Research Animal Scientist, USDA-ARS
L. W. Greene, Beef Cattle Nutritionist, M. L. Galyean, Beef Cattle Nutritionist, N. Chirase, Research Scientist, TAES/WTAMU
and T. McCollum, Beef Cattle Specialist, TAEX
Water has been provided for years with mechanical wind pumps using multi-bladed windmills. These windmills have rotors with numerous blades (15-18 blades) that produce a high starting torque, but reach a maximum operating speed at 20 to 25 mph (8-10 m/s). The rotating motion of the rotor is converted to reciprocating motion which operates a piston pump to lift water. Flow rates from mechanical windmills 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). An 8-ft mechanical windmill cost about $5400, including the pump and pipe for a 100 ft lift.
R. Nolan Clark, Laboratory Director and Agricultural Engineer, USDA-ARS
Wind turbines that produce electricity are used with standard electric pumps and motors (submersible pumps with 3-phase motors). Flow rates vary from 13 gpm (38 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) and a wind speed of 22 mph (10 m/s). Four different wind-electric pumping systems ranging from 850 Watts to 10 kW have been tested since 1988. The average daily volume of water pumped with a 1500 W wind turbine and a 1.5 horsepower electric pump and motor is 8428 gal/day (31,900 L/day) for a 100 ft (30 m) well. The 850-W wind-electric water pumping system costs less than an 8-ft mechanical windmill and provides about the same volume of water for livestock as the mechanical windmill.
R. Nolan Clark and Brian Vick, USDA-ARS and Shitao Ling, AEI-WTAMU
Solar photovoltaic panels are used to produce DC electricity that is used directly to power electric pumps. Diaphragm 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 W). An inverter is used to convert the DC output of photovoltaic panels to AC electricity to power the submersible motors on the larger systems. For a 100 ft (30 m) pumping depth, the average daily volume of water pumped for the small system (100 W, Solarjack) was 431 gal/day (1,630 L/day) and the daily volume for the larger system (900 W, Golden Photon) was 1,406 gal/day (5,320 L/day). With the 900 W system, a 3-phase motor pumps almost twice as much water as a single-phase motor. Since single-phase and three-phase motors cost about the same, there is no increase in cost by using a three-phase motor and pumping twice as much water.
R. Nolan Clark and Brian Vick, USDA-ARS and Shitao Ling, AEI-WTAMU
Electric tools, equipment, appliances, and conveniences are desired by many people to make life easier and improve production. For remote farms and ranches, islands, or Alaskan villages, electrical power is most often supplied by diesel generators. By adding wind turbines, the renewable wind energy at the remote site is substituted for part of the diesel fuel normally consumed by the generator sets. The search for the best technique and the most economic sizes and types of equipment used in the design of such a system is ongoing. The USDA - Agricultural Research Service is researching various system configurations, control strategies, and storage schemes to find the ones that provide reliable power of acceptable quality at the least cost over the life of a system. The specific items under investigation are penetration (rated wind power/ consumer load), system configurations with and without storage, controls, bio-diesel generator fuels (soybean oil), resistive and inductive load concerns, power storage effects, and best storage methods and sizes. Additional investigation items have to do with reliability and maintainability of the system and it=s components. The test system power generators include three CAT 3304 powered diesel generator sets (one 60 kW, 1,800 rpm and two 42 kW, 1,200 rpm), an AOC 15/50 wind turbine (50 kW) and an Enertech 44/40 wind turbine (40 kW). Water pumps, lights, and a resistive load bank represent the Avillage@ load. We do this work as part of an interagency agreement with the US Department of Energy.
Eric Eggleston and Nolan Clark, USDA-ARS
Larger wind turbines with induction generators which are interconnected to the electric utility have been operated at Bushland since 1979. The electric power from these wind turbines is used to supplement electricity used for irrigation pumps. A 40-kW, three bladed wind turbine has been in operation for 15 years. During this time electricity is produced 65% of the time and the machine was "on" available to run for 97% of the time. The machine is off 1% of the time for routine service (checking the oil in gearbox, checking wiring, etc.), 1% for weather related incidents (icing, lightning outages, etc.), and 1% for failures (yaw bearing replacement, gearbox seal replacement, etc.). Our goal is to operate one of these wind turbines for 20 years and determine the mean time to failure of the main components.
R. Nolan Clark, Ron Davis, and Eric Eggleston, USDA-ARS
The 34-m Vertical-Axis Wind Turbine (VAWT) has an equatorial diameter 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. Research with this turbine has demonstrated that airfoils designed specifically for wind turbines can improve performance by 45% over airfoils used on earlier wind turbines that were adapted from aerospace technology. The turbine operates only when tests are conducted.
R. Nolan Clark and Ron Davis, USDA-ARS