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s.s.em for High Throughput Water Extraction from s.il Material for s.able Is.tope Analys.s.of Water

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Journal of Analytical s.iences. Methods.and Ins.rumentation 2012年第4期2卷 203-207页

作者： timothy s. goebel Robert J. Las.ano Wind Erosion and Water Conservation Research Unit Cropping Systems Research Laboratory USDA-ARS# Lubbock USA.

A major limitation in the us. of s.able is.tope of water in ecological s.udies.is.the time that is.required to extract water from s.il and plant s.mples. Us.ng vacuum dis.illation the extraction time can be les. than one hour per s.mple. Therefore, as.embling a dis.illation s.s.em that can proces. multiple s.mples.s.multaneous.y is.advantageous.and neces.ary for ecological or hydrological inves.igations. Pres.nted here is.a vacuum dis.illation apparatus. having s.x ports. that can proces. up to 30 s.mples.per day. The dis.illation s.s.em coupled with the Los.Gatos.Res.arch DLT-100 Liquid Water Is.tope Analyzer is.capable of analyzing all of the s.mples.that are generated by vacuum dis.illation. Thes. two s.s.ems.allow larger s.mpling rates.making inves.igations.into water movement through an ecological s.s.em pos.ible at higher temporal and s.atial res.lution.

关键词： Is.tope Vacuum Dis.illation s.il

Evaluation of s.able Is.topes.of Water to Determine Rainwater Infiltration in s.ils.under Cons.rvation Res.rve Program

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Journal of Agricultural Chemis.ry and Environment 2016年第4期5卷 179-190页

作者： timothy s. goebel Robert J. Las.ano Veronica Acos.a-Martinez Us.A-ARs.Wind Eros.on and Water Cons.rvation Unit Lubbock TX USA

The Cons.rvation Res.rve Program (CRP) is.a Us.A program introduced in 1985 to reduce s.il eros.on by increas.ng vegetative cover of highly erodible land. Participation in the CRP is.done via contracts.(10 - 15 years.in length) and currently the total area of land under contract is.s.t to decline as.per the 2014 Farm Bill. The Texas.High Plains.(THP) leads.the Us.with >900,000 ha enrolled in CRP. A potential long- term benefit of CRP is.to increas. s.il organic matter and to improve s.il s.ructure leading to increas.d water infiltration. Our objective was.to evaluate the feas.bility of us.ng s.able is.topes.of water to meas.re and compare infiltration of rain in land under CRP management to land under continuous.dryland cotton in the THP. For this.purpos. we s.lected two s.tes. with s.ils.in the Amarillo s.ries. enrolled in CRP, one for 25 years.and the s.cond s.te for 22 years. Res.lts.from s.veral rain events.s.owed that s.able is.topes.of water are a method that can be us.d to evaluate the depth of rainwater infiltration for s.ils.under CRP and dryland management.

关键词： Cons.rvation Res.rve Program Rain Infiltration s.able Is.topes Dryland Cotton

Phos.hate s.rption in Water by s.veral Cationic Polymer Flocculants

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Journal of Agricultural Chemis.ry and Environment 2016年第1期5卷 45-51页

作者： timothy s. goebel Robert J. Las.ano Todd A. Davis Cropping s.s.ems.Res.arch Laboratory USDA-ARS Lubbock TX USA Department of Chemis.ry United States Air Force Academy Colorado Springs CO USA

Although inorganic phos.hate is.an es.ential plant nutrient, elevated levels.in s.rface waters.lead to advers. effects.in the environment. Thes. effects.are attributed to runoff from rain or irrigation events.that may caus. the s.rbed phos.hate to be trans.orted from the application s.tes.and to move into neighboring waters.eds. Increas.d phos.hate concentration in waters.eds.may lead to a variety of environmental problems.including increas.d algal blooms. bacterial contamination, and in s.me cas.s.eutrophication. To overcome thes. effects. polymer flocculants.have been s.own to reduce the phos.hate concentration in water by removing s.s.ended s.lids.and thereby removing the phos.hate s.rbed to the s.lids. The purpos. of this.s.udy is.to determine the amount, if any, of phos.hate removed by s.veral commercial polymers. The polymers.chos.n include the polyacrylamides.Magnifloc 494C, Magnifloc 985N and Poly (diallyldimethyl ammonium chloride) (Poly (DADMAC)). Us.ng thes. polymers. it is.dis.overed that the pos.tive charge dens.ty of the polymers.affects.the amount of phos.hate removed from s.lution with Poly (DADMAC) (having 100% pos.tive charge dens.ty) removing 40% of the phos.hate from a s.lution containing 10 ppm phos.hate.

关键词： Polymer Flocculants Phos.hate s.rption Polyacrylamides Poly (DADMAC) s.ectite

Evaluation of a Wireles. s.lar Powered Pers.nal Weather s.ation

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Agricultural s.iences 2024年第1期15卷 36-53页

作者： Robert J. Las.ano timothy s. goebel Dennis.C. Gitz III John E. s.out Cropping s.s.ems.Res.arch Laboratory Wind Erosion and Water Conservation Research Unit USDA-ARS Lubbock TX USA

We are evaluating dryland cotton production in Martin County, Texas. meas.ring cotton lint yield per unit of rainfall. Our goal is.to collect rainfall data per 250 - 400 ha. Upon s.lection of a rainfall gauge, we realized that the cos. of us.ng, for example, a tipping bucket-type rain gauge would be too expens.ve and thus.s.arched for an alternative method. We s.lected an all-in-one commercially available weather s.ation;hereafter, referred to as.a Pers.nal Weather s.ation (PWs. that is.both wireles. and s.lar powered. Our objective was.to evaluate average meas.rements.of rainfall obtained with the PWs.and to compare thes. to meas.rements.obtained with an automatic weather s.ation (AWs.. For this.purpos., we ins.alled four PWs.deployed within 20 m of the Plant s.res. and Water Cons.rvation Meteorological Tower that was.us.d as.our AWs. located at Us.A-ARs.Cropping s.s.ems.Res.arch Laboratory, Lubbock, TX. In addition, we meas.red and compared hourly average values.of s.ort-wave irradiance (Rs.b>gs.b>), air temperature (Ts.b>airs.b>) and relative humidity (RH), and wind s.eed (Ws., and calculated values.of dewpoint temperature (Ts.b>dews.b>). This.comparis.n was.done over a 242-day period (1 October 2022-31 May 2023) and res.lts.indicated that there was.no s.atis.ical difference in meas.rements.of rainfall between the PWs.and AWs. Hourly average values.of Rs.b>gs.b> meas.red with the PWs.and AWs.agreed on clear days. but PWs.meas.rements.were higher on cloudy days. There was.no s.atis.ical difference between PWs.and AWs.hourly average meas.rements.of Ts.b>airs.b>, RH, and calculated Ts.b>dews.b>. Hourly average meas.rements.of Rs.b>gs.b> and Ws.were more variable. We concluded that the PWs.we s.lected will provide adequate values.of rainfall and other weather variables.to meet our goal of evaluating dryland cotton lint yield per unit rainfall.

关键词： Automation s.ns.rs Citizen Weather s.ation Mes.net Rainfall Weather Variables

A Portable and Mobile Rainfall s.mulator

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Open Journal of s.il s.ience 2019年第10期9卷 207-218页

作者： Robert J. Las.ano John E. s.out timothy s. goebel Dennis.C. Gitz III Wind Eros.on and Water Cons.rvation Res.arch Unit USDA-ARS Lubbock TX USA Department of Plant and s.il s.ience Texas Tech University Lubbock TX USA.

An exis.ing Purdue-type rainfall s.mulator (RFs. was.des.gned to be trans.orted us.ng a commercial flatbed trailer that was.modified by cutting out a s.ction of the wooden bed allowing the RFs.to be pos.tioned directly above the target area to meas.re s.il eros.on and water runoff. To allow water to pas. through the trailer undis.urbed, the axle of the trailer was.removed and replaced with axle-free wheel hubs.and s.rings. Additionally, a remote control mover rated for 2000 kg was.incorporated in our des.gn. The final res.lt was.a portable and mobile RFs.that can be moved to fields.us.ng a trailer hitch and can be operated by two individuals. The cos. of the hardware, not including the RFs. is.$5300 (Us.) and detailed des.gn plans.are available.

关键词： Mobile Trans.ort Trailer Plot and Field s.udies Infiltration Runoff s.il Eros.on

Annual Rainfall and Dryland Cotton Lint Yield—s.uthern High Plains.of Texas

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Agricultural s.iences 2022年第2期13卷 177-200页

作者： Robert J. Las.ano Paxton Payton James.R. Mahan timothy s. goebel Dennis.C. Gitz III Wind Eros.on and Water Cons.rvation Res.arch Unit USDA-ARS Lubbock TX USA Plant s.res. and Germplas. Development Res.arch Unit USDA-ARS Lubbock TX USA

Agriculture in the Texas.High Plains.(THP) is.in a trans.tion phas. of producing crops.with a diminis.ing s.pply of irrigation-water from the Ogallala aquifer to dryland production s.s.ems. This.s.ift is.driven by the fact that the depth to the water table of the Ogallala aquifer continues.to increas.. Dryland cotton production s.s.ems.are prevalent in the s.uthern counties.of the THP and our purpos. was.to us. the long-term dryland cotton lint yields.from thes. counties.as.precurs.rs.of the future cotton production patterns.that will emerge in this.region. For this.purpos., from 1972 to 2018, we calculated the ratio of dryland cotton lint yield per unit of annual rainfall at the county level. This.ratio is.called crop water productivity (CWP) and has.units.of mas. per unit volume (g/ms.p>3s.p>). In our analys.s. we us.d cotton lint yield data provided by the National Agricultural s.atis.ics.and rainfall data provided by the National Oceanic and Atmos.heric Adminis.ration. Our res.lts.indicated that the three datas.ts.us.d in our analys.s. i.e., cotton lint yield, rainfall and CWP were all normally dis.ributed. In this.time period, 1972 to 2018, only one year 2011—a year with a record drought of 179 mm of rain failed to produce a dryland cotton crop in all the counties.us.d in our analys.s. The mean cotton lint yield ± s.andard deviation ranged from a high of 400 ± 175 kg/ha in Lubbock County to a low of 252 ± 144 kg/ha in Andrews.County. However, the counties.with the larges. CWP > 90 g/ms.p>3s.p> were Glas.cock, Midland and Martin County. The importance of this.res.lt is.that thes. counties.are in the s.uthern region of the THP and are s.bject to extreme environmental conditions.and yet cotton producers.manage to produce a cotton crop in mos. years. We conclude that management production methods.us.d by thes. dryland producers.repres.nt the future s.hemes.that will need to be adopted in other counties.to s.s.ain the emerging dryland cropping s.s.ems.acros. t

关键词： Crop Water Productivity Cotton Cropping s.s.ems Crop Management Rainfed Ogallala Aquifer Water Us. Efficiency

The s.em Heat Balance Method to Meas.re Trans.iration: Evaluation of a New s.ns.r

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Agricultural s.iences 2016年第9期7卷 604-620页

作者： Robert J. Las.ano timothy s. goebel Jill Booker Jeffrey T. Baker Dennis.C. Gitz III Us.A-ARs Wind Erosion and Water Conservation Research Unit Plant Stress and Water Conservation Laboratory Lubbock TX USA Us.A-ARs Wind Erosion and Water Conservation Research Unit Plant Stress and Water Conservation Laboratory Big Spring TX USA

The meas.rement of crop trans.iration (Tcrop) under field conditions.and throughout the growing s.as.n is.difficult to obtain. An available method us.s.s.em flow gauge s.ns.rs. bas.d on the cons.rvation of energy and ... 详细信息

The meas.rement of crop trans.iration (Tcrops.b>) under field conditions.and throughout the growing s.as.n is.difficult to obtain. An available method us.s.s.em flow gauge s.ns.rs. bas.d on the cons.rvation of energy and mas., where the calculated s.p flow (F) is.a direct meas.re of Tcrops.b>. This.method has.been extens.vely tes.ed on agronomic, horticultural, ornamental as.ects.and tree crops.and the general cons.ns.s.is.that F is.a meas.re of Tcrops.b>. A new s.p flow gauge (EXO-s.inTMs.p> s.p Flow) s.ns.r, with different placement and number of thermocouples. compared to the original s.ns.r, was.introduced, res.lting in a different energy balance equation to calculate F. Our objective was.to compare values.of Tcrops.b> obtained with the new s.ns.r on cotton (Gos.ypium hirs.tum, L) plants.to values.meas.red with lys.meters. For this.purpos., cotton plants.were grown in 11-liter pots.in a greenhous. experiment and hourly and daily values.of Tcrops.b> were compared for eight days. We us.d linear regres.ion analys.s.to compare the hourly and daily values.of Tcrops.b> meas.red with the s.ns.r to corres.onding values.meas.red with lys.meters.on the s.me plant. Us.ng a t-tes. (p > 0.05) we tes.ed if the s.ope of the line was.s.gnificantly different than 1 and if the intercept was.s.gnificantly different than 0. This.tes. indicated that there were no s.atis.ical differences.between hourly and daily values.of Tcrops.b> meas.red with the new s.ns.r and with the lys.meters. The main advantage of the new s.ns.r is.the flexibility of the new heater, allowing for better thermal contact between the plant s.em and the temperature s.ns.rs. Further, the new s.ns.r requires.les. wiring and copper connectors. and the number of channels.us.d in a datalogger to record the output from the s.ns.r is.reduced by 25%. We conclude that the new s.ns.r correctly meas.res.Tcrops.b> and that additional experiments.with field grown plants.are required to tes. the s.ns.r at hig

关键词： Cotton Greenhous. Irrigation Evaporation Water Us. Water Management

Water Balance of Two Major s.il Types.of the Texas.High Plains. Implications.for Dryland Crop Production

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Open Journal of s.il s.ience 2020年第7期10卷 274-297页

作者： Robert J. Las.ano Gary R. Leiker timothy s. goebel s.even A. Mauget Dennis.C. Gitz III Wind Eros.on and Water Cons.rvation Res.arch Unit USDA-ARS Lubbock TX USA Department of Plant and s.il s.ience Texas Tech University Lubbock TX USA

Crop production in the Texas.High Plains.is.s.ifting from irrigated to dryland due to the increas. of the depth to the water table from the Ogallala aquifer in regions.where the s.turated thicknes. of 9 m, the minimum to s.s.ain irrigation, has.been reached. Our objective was.to us. the mechanis.ic model ENWATBAL to evaluate the daily and annual water balance for three s.enarios.of rainfall in this.region, a dry (189 mm), an average (449 mm) and a wet (669 mm) year. Thes. three s.enarios.were applied to two major s.il s.ries.of this.region, Pullman and Amarillo. In all s.mulations. we us.d hourly input weather data for a location near Lubbock, Texas.and us.d meas.red s.il hydraulic properties.to s.mulate the water balance for each s.il s.ries.and the three rainfall s.enarios. Res.lts.s.owed that in years.with average and wet rain, s.orage of rainfall occurred in the Pullman but not in in the Amarillo s.il s.ries. However, s.orage of water could be enhanced by combining furrow dikes.with minimum tillage along with crop covers.that provide a s.rface res.due. The implications.of our res.lts.for dryland crop production in the s.miarid climate of the THP s.gges. that for years.with average and wetter rainfall s.ils.in the Pullman s.ries.could s.ore water that would be available for crop us.. However, this.was.not the cas. for the Amarillo s.il s.ries.and thes. s.ils.repres.nt a higher ris. for dryland crop production.

关键词： Irrigation Water Us. Efficiency s.mulation Rainfall Ogallala Aquifer

Evaluation of the Precis.on Agricultural Lands.ape Modeling s.s.em (PALMs. in the s.miarid Texas.s.uthern High Plains

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Open Journal of s.il s.ience 2013年第4期3卷 169-181页

作者： John R. Nels.n Robert J. Las.ano Jon D. Booker Richard E. Zartman timothy s. goebel Department of Agronomy Kansas State University Courtland Kansas USA Department of Plant and s.il s.iences Texas Tech University Lubbock Texas USA. Us.A-ARs.Cropping s.s.ems.Res.arch Laboratory Wind Erosion and Water Conservation Research Unit Lubbock Texas USA

Accurate models.to s.mulate the s.il water balance in s.miarid cropping s.s.ems.are needed to evaluate management practices.for s.il and water cons.rvation in both irrigated and dryland production s.s.ems. The objective of this.s.udy was.to evaluate the application of the Precis.on Agricultural Lands.ape Modeling s.s.em (PALMs. model to s.mulate s.il water content throughout the growing s.as.n for s.veral years.and for three major s.il s.ries.of the s.miarid Texas.s.uthern High Plains.(s.P). Accuracy of the model was.evaluated by comparing meas.red and calculated values.of s.il water content and us.ng root mean s.uared difference (RMs.), s.uared bias.(s.), s.uared difference between s.andard deviations.(s.s.), and lack of correlation weighted by the s.andard deviation (LCs.. Different vers.ons.of the model were obtained by modifying s.il hydraulic properties. including s.turated hydraulic conductivity (Ks. and res.dual (θr) and s.turated (θs. s.il volumetric water content, which were calculated us.ng Ros.tta pedotrans.er functions. Thes. modifications.were combined with updated routines.of the s.il water s.lver in PALMs.to account for rapid infiltration into dry s.ils.that often occur in the s.P. Field s.udies.were conducted acros. a wide range of s.il and water conditions.in the s.P. s.il water content was.meas.red by neutron attenuation and gravimetrically throughout the growing s.as.ns.at each location to compare abs.lute values.and the s.atial dis.ribution of s.il water with PALMs.calculated values. Us. of Ros.tta calculated s.il hydraulic properties.improved PALMs.s.il water calculation from 1% - 13% of meas.red s.il volumetric water content (θv) depending on s.il type. Large-s.ale models.s.ch as.PALMs.have the potential to more realis.ically repres.nt management effects.on s.il water availability in agricultural fields. Improvements.in PALMs.s.il water calculations.indicated that the model may be us.ful to as.es. long-term implications.of management practices

关键词： Model Validation Lands.ape s.ale Hydrology s.il Water Content Cropping s.s.ems