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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. 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 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. Wheat grain yields were 680 lb/ac for continuous wheat, 300 lb/ac after fall canola, 560 lb/ac after spring canola, 500 lb/ac in rotation with sorghum, and 970 lb/ac as an opportunity crop in 1995. Triticale yield was 1570 lb/ac in 1995. Wheat and triticale yields were less than 200 lb/ac in all cases in 1996. Canola did not produce seed in 1995 and was not planted for the 1996 crop because of the drought. In 1995, sorghum grain yields were 3000 lb/ac for continuous sorghum, 2550 lb/ac in rotation with wheat, and 1790 lb/ac as an opportunity crop. Grain sorghum was not planted in 1996 because of the drought. Dry matter yields were 5750 lb/ac in 1994 and 8200 lb/ac in 1995 for forage sorghum, 7940 lb/ac in 1995 for millet, and 2180 lb/ac in 1995 for kenaf. Forage sorghum, millet, and kenaf were planted after the rains started in 1996.
Paul W. Unger, Soil Scientist, USDA-ARS
CROP AND RESIDUE MANAGEMENT SYSTEMS FOR DRYLAND GRAIN PRODUCTION
No-tillage was compared with stubblemulch (sweep) tillage for ten years with four cropping systems; continuous wheat (CW), continuous sorghum (CS), wheat- sorghum-fallow (WSF), and wheat fallow (WF). No-tillage management of wheat residues increased soil water contents and grain yields. With NT, the soil water profile 4 months after wheat harvest contained an average of 1.4 inches more plant available water than with SM tillage. NT management of sorghum residues were not as effective as NT management of wheat residues in storing water and reducing evaporation; however, in no instance were soil water profile contents with NT less than contents measured on stubblemulch. Keeping all residues on the surface reduced evaporation and improved water conservation. Cropping systems with sorghum (CS, WSF) had highest grain production, used water more efficiently and had much greater returns per acre than wheat only systems. Tillage system had at maximum, a 10% effect on grain production, whereas cropping system selection had a 400% effect on production. Average annualized grain production (SM tillage) was; CS - 44 bu/ac/yr; WSF - 27 bu/ac/yr; CW - 14.5 bu/ac/yr; and WF - 11.0 bu/ac/yr.
Reggie Jones, Soil Scientist, USDA-ARS
INCREASING CROP RESIDUES RETAINED ON THE SOIL SURFACE
Soil water storage and erosion control improve with increases in amount of crop residues retained on the soil surface. However, dryland crops such as winter wheat and grain sorghum 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' will be done in the fall of 1996. No data are available at this time.
Paul W. Unger, Soil Scientist, USDA-ARS
SHORT SEASON SORGHUM PRODUCTION
Research objectives are 1) to evaluate a short season - high planting density strategy for dryland sorghum production and 2) to evaluate short-season sorghum hybrids for adaptability to a short season, high planting density concept for dryland sorghum production. Primary criteria for hybrid evaluation are grain yield and standability. Short-season hybrids have reduced yield potential compared to longer season hybrids, but they have a higher harvest index and use water over a shorter period of time; thus, placing less reliance on growing season precipitation and more reliance on stored soil water to produce grain. Therefore with a high soil water content at planting, a short-season hybrid may avoid water stress whereas a longer season hybrid may use stored soil water for vegetative production and have a water deficit during grain filling and maturation. The short-season hybrid is planted at a higher density to overcome reduced yield potential. Since the short-season high density concept hastens maturity, it is particularly adaptable for late planting to help avoid freeze damage. Although 5 year average grain yields have been greater with short-season high density (DK28Y, 3640 lb/ac) than with a medium maturity sorghum hybrid (DK41Y, 3250 lb/ac) we do not recommend the short- season, high density-narrow row concept for early or mid-season planting dates because of severe lodging. We did identify several short-season hybrids in 1995 that appear to have high yields and good standability with high density-narrow row planting and these hybrids are being evaluated again in 1996. We do recommend the short-season, high density-narrow row concept for late planting if you have good soil water (wet at least 4-ft deep) at planting.
Grant Johnson, Biological Science Technician Soils, Reggie Jones, Soil Scientist, USDA-ARS and Tim Lust, National Grain Sorghum Producers Association
CONVERSION OF CRP LAND TO CROPLAND
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 will be planted in the fall and grain sorghum will be planted in 1997.
Paul W. Unger, Soil Scientist, USDA-ARS
TO GRAZE OR TO RE-CROP CRP LANDS IN THE POST-CONTRACT PERIOD?
As the bulk of CRP contracts will be expiring in 1996 and 1997, contract holders will have to choose a future use for their CRP lands. Many land-use and management options are available. Landowners or operators will choose whether to use CRP grasslands in livestock production or to revert to annual crop production; they will have to decide whether to remove or not remove the accumulated old litter, plow or no-till the first crop into the sod, etc ... Many management actions must be planned and taken well in advance of the day the contract expires. Our multi-agency collaborative research and demonstration project was initiated in 1993 to identify best-management practices on how to prepare for grazing or haying CRP grasslands or to revert successfully and in an environmentally-sound manner to wheat and cotton production on highly-erodible lands at two CRP sites under contract near the Oklahoma-Texas border. We evaluate the field performance and economics of the best options and work to transfer the information to the public and action agencies and help end-users determine their best course of action after the CRP.
Thanh H. Dao, Soil Scientist, USDA-ARS
USING WASTE PAPER TO INCREASE SOIL WATER STORAGE AND CROP YIELDS
Waste paper accounts for much of the material disposed of in landfills. However, landfill space 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. Because of the drought this year, differences is soil water storage were slight. The first sorghum crop was planted in 1996, but no data for sorghum are available at this time. Paper pellets were applied to a second set of plots in 1996.
Paul W. Unger, Soil Scientist -- USDA-ARS
WATER USE AND YIELD OF LIMITED IRRIGATION CORN
The Soil-Plant-Environment Research facility (SPER) features a rain shelter building and 48 lysimeters containing undisturbed soil profiles from the major cropping regions of the southern Great Plains. The soils are a clay loam (Bushland), silt loam (Garden City, KS), and sandy loam (Big Spring, TX). The rain shelter automatically covers the lysimeters during a rain event so water regime treatments can be controlled with minimal rainfall interference. This year is the third year of limited irrigation corn studies on short season corn (PIO-3737). The irrigation treatments are 110, 80, 50, and 20% of weekly crop water use. Beginning plant available water (PAW) was 10- in in each soil type. In 1994 and 1995, the crops began with either full soil profiles (1994) or similar PAW (8- in in 1995) and received about 60 and 35% of average summer rainfall as irrigation treatments. In 1994, the silt loam treatments averaged 156 bu/ac with 21-in of water use, the clay loam treatments averaged 115 bu/ac with 17-in of water use, and the sandy loam treatments averaged 127 bu/ac with 18.5-in of water use. In 1995, the silt loam treatments averaged 115 bu/ac with 17.4-in of water use, the clay loam treatments averaged 90 bu/ac with 15.6-in of water use, and the sandy loam treatments 101 bu/ac with 15.1-in of water use. Corn is able to more effectively utilize soil water from the silt loam than from the sandy loam or clay loam soils apparently due to differing rooting patterns and density affected by the calcic horizons.
J.A. Tolk, Plant Physiologist; T.A. Howell, Agricultural Engineer; S.R. Evett, Soil Scientist, USDA-ARS
CONSERVATION BENCH TERRACE (CBT) SYSTEM
The CBT system was originated by USDA scientist A. W. Zingg in the 1950s, and the system was installed at Bushland in 1955. The terraces you will observe are the original terraces--still very serviceable after 41 years. The CBT system uses leveled contour benches to capture storm runoff from watersheds that are cropped in a wheat-sorghum-fallow sequence. CBT benches are annually cropped in wheat, grain sorghum, corn, or sunflower. CBT has proven to be a highly successful system for conserving runoff water, reducing erosion, and increasing grain production.
Reggie Jones, Soil Scientist, 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) and stubblemulch (SM) tillage were measured from 1984 to 1995, on field-sized (5- to 10-ac) graded-terraced watersheds in a dryland, 3-yr, 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/yr for eight 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 from NT. Nutrient concentration and loses 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.
Reggie Jones, Soil Scientist USDA-ARS
NUTRITIONAL AND MANAGEMENT PROCEDURES TO DECREASE POLLUTION FROM CATTLE FEEDING OPERATIONS
When large numbers of animals are concentrated in a relatively small area, such as a cattle feedyard, the nutrients from the animal feeds are also concentrated in a relatively small area. This concentration of nutrients can lead to potential pollution of the atmosphere as well as surface and ground water. Studies were started in late 1995 to evaluate nutritional and management regimens that decrease the potential of pollution from cattle feedyards. Studies will concentrate in the following primary areas: 1) improving diet digestibility to decrease manure production by cattle, 2) decreasing nitrogen volatilization from feedlot surfaces via dietary modifications and (or) other management practices, 3) decreasing phosphorus, sodium and trace mineral excretion by cattle, 4) decreasing dust emissions from feedlot surfaces, and 5) developing techniques to improve the composting of feedlot manure. Cattle in the research feedlot are currently on three collaborative experiments to study various aspects of these research areas.
N. Andy Cole, Research Animal Scientist (Nutrition) - USDA-ARS
INFLUENCE OF DIETARY AGRI-HUME AND PEN SURFACING ON FECAL CHARACTERISTICS OF FEEDLOT STEERS AND HEIFERS
The value of feedlot manure directly affects the degree to which nutrients are concentrated on a farm or in a watershed. When feedlot manure is of low agronomic quality and value, it cannot be transported far from the source, resulting in a net accumulation of nutrients such as nitrogen and phosphorus within a small area surrounding the feedlot. Conversely, when the agronomic value of manure is high, demand can outstrip supply, increasing the distance manure can be economically transported and dispersing nutrients more widely. An important limiting factor for manure quality is the nitrogen-to-phosphorus ratio (N/P). Average N/P ratios of feedlot manure result in excessive application of phosphorus when manure is used to satisfy crop N requirements. A higher N/P ratio will result in greater transportability of manure and reduced phosphorus application. In these studies, we examine the N/P ratio of feedlot manure as influenced by dietary humic acid (0, 57, 142, and 284 g/hd/day) and pen surfacing (dirt surface vs. fly ash).
Norbert Chirase, Assoc. Research Scientist (TAES/TAMU), Brent Auverman, Agricultural Engineer, TAEX/TAES/WTAMU
N. Andy Cole, Research Animal Scientist (Nutrition), USDA-ARS
MICROBIOLOGY ASPECTS OF SOIL, WATER, AND WASTE MANAGEMENT
A. Soil microbial research
Animal manure is used as a soil amendment to increase the organic content of most soils and provide meeded nutrients. However, little is known of the most basic microbial population interaction of our soil resources when large amounts of manure are added. Elementary applied research needs to be done at the microbial level. Microbes are the first sentinel life forms which will be affected by our waste management procedures. Thus these microbial sentinel life forms need to be studied under various normal environmental conditions, and under conditions which may stress our land. This research may have application toward understanding why unproductive areas may exist in an otherwise productive field. We are currently comparing microbial populations of plots, overlaid with three different concentrations of the following products: commercial fertilizer, cattle manure, and compost, to those of untreated control plots. Soil core samples were taken from the treated and untreated control plots and the microbial populations were compared at different depths (1, 5, 10, and 20 cm). Preliminary information indicates that total bacterial population counts are higher on the surface treated with manure and compost. Total bacterial colony counts decrease with increasing depths. The majority of the bacteria appear to be in the Actinomycete group, however, several other groups of Gram positive bacteria have been identified. Most pathogens in the Gram negative group (Salmonella and coliforms) appear to have been killed due to drying while being stockpiled for a number of months at the feedyard and again after application to the plots. Microbial populations of mesophilic anaerobic and aerobic bacteria and thermophilic bacteria and fungi are also being compared. Mesophylic fungi were also identified at the various depths.
B. Playa lake water microbial research
Excess rainfall in the arid High Plains usually drains into playa lakes. This water remains until it evaporates. Feedyards located near playa lakes to minimize cost of waste water containment and reduce potential for ground water pollution. However, the collection of runoff offers the potential to concentrate minerals, nitrogen, and microbes. Many of these microbes are beneficial, but some are pathogenic. We have very little information on the microbial communities of normal playas and playas which are stressed with animal waste. The indigenous microbial communities may kill potential pathogens very rapidly. The normal and environmental conditions may further kill pathogens very quickly. An objective of this study is to determine the microbial populations and the movement of such populations in wet or dry and cracking soil conditions. The destruction of sentinel microbial life forms will be the first indications of potential problems in the playa ecosystems. A number of scientist have teamed up to conduct an experiment which will determine how long certain viruses, bacteria, fungi, and protozoans can survive in playa basins under normal environmental conditions.
Charles W. Purdy, Veterinary Microbiologist, USDA-ARS
FEEDLOT RENOVATION
Plans are being developed to renovate and modernize the 250 head cattle feedlot at Bushland jointly owned and operated by the Texas Agricultural Experiment Station and USDA-Agricultural Research Service. Presently, there are 12 feeding pens with fly-ash surfacing and 12 conventional soil surfaced pens on either side of a North - South feed alley. These pens are functional for animal nutrition research and several pens are equipped with individual animal feed intake recording devices connected to a computer. However, these pens have pen-to-pen drainage which is not desirable for research involving manure and wastewater management which is a new area of emphasis of the agricultural/environmental engineering, animal science, veterinary microbiology, and environmental soil science research team.
Therefore, the lower 12 pens will be replace by 18 new pens which will be built across the existing slope to allow individual pen drainage. A portion of the new pens will by fly-ash surfaced. The cattle receiving and sorting pens will be reconfigured as well to streamline and facilitate to flow of cattle into and out of the feedlot.
John M. Sweeten, Resident Director and Professor, TAES
R. Nolan Clark, Laboratory Director, USDA-ARS
WIND-MECHANICAL WATER PUMPING
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-ELECTRIC WATER PUMPING
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). 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 Watt wind turbine and a 1.5 horsepower electric pump is 3310 gal/day (12,534 L/day). The 850-W wind electric water pumping system cost less than 8-ft mechanical windmill and provide about the same volume of water for livestock.
R. Nolan Clark and Brian Vick, USDA-ARS
Shitao Ling, AEI-WTAMU
SOLAR-POWERED WATER PUMPING FOR LIVESTOCK
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 Watts). An inverter is used to convert the DC output of photovoltaic panels to AC electricity to power the submersible motors on the larger systems. Average daily volume of water pumped for the small system (0.1 kW Solarjack) was 431 gal/day (1,630 L/day) and the daily volume for the larger system (0.9 kW Golden Photon) was 1,406 gal/day (5,320 L/day).
R. Nolan Clark and Brian Vick, USDA-ARS
Shitao Ling, AEI-WTAMU
ELECTRICAL GENERATION
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 14 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
34-m VERTICAL-AXIS WIND TURBINE
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
REMOTE WIND/DIESEL ELECTRICAL POWER SYSTEM RESEARCH
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 "village" load. This work is conducted under an interagency agreement with the U.S. Department of Energy.
Eric Eggleston, USDA-ARS