Search

A minimally invasive transverse beam profile monitor based on supersonic gas curtain technology and beam-induced fluorescence has been developed and demonstrated. The concept presented can be used to measure both the profile of the proton beam in the Large Hadron Collider (LHC) and the concentricity of the electron and the proton beams in the LHC hollow electron lens. In this Letter, the performance of such a monitor for a low energy electron beam is discussed, which paves the way for its wider implementation.

The mention of trade names of commercial products in this article is solely for the purpose of providing specifi c information and does not imply recommendation or endorsement by the USDA.Soil Sci. Soc. Am. J. 72:677-682doi:10.2136/sssaj2007.0122Received 30 Mar. 2007.*Corresponding author (R.Louis.Baumhardt@ars.usda.gov).© Soil Science Society of America677 S. Segoe Rd. Madison WI 53711 USAAll rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.

Successful and sustainable semiarid dryland cropping depends on effective soil water storage and erosion control, which are influenced by surface soil aggregate size and stability. We hypothesized long-term tillage and cropping system treatments affect water-stable aggregate size distribution, aggregate water stability, and dry soil aggregation. A study on a Torrertic Paleustoll from 1982 to 1994 at Bushland, TX, involved tillage methods (no-tillage, NT; stubble mulch tillage, SMT) and cropping systems for dryland winter wheat (Triticum aestivum L.) and grain sorghum [Sorghum bicolor (L.) Moench] production. In 1994, mean percentages of >4-mm water-stable aggregates at 0 to 2 cm were 3.5 with NT and 1.0 with SMT in wheat, sorghum, fallow, rotation phase, or crop comparison plots. Mean percentages of

Soil organic carbon (SOC) distribution is altered by residue management practices, but the effect on total C mass is not well understood, especially in warm regions. The objective of this study was to determine the effect of residue management practices on SOC distribution and amount across an 1100 km transect (northwest to southeast) of Texas. Long-term (>10 years) continuous cropping rotation and residue management plots located near Bushland, Temple, and Corpus Christi, Texas, were sampled incrementally with depth for SOC distribution and mass. The mass of SOC varied among locations depending on management, and climatic conditions. No-tillage management resulted in increased SOC concentration and mass in the surface 0.07 m in comparison to more intensive tillage management (e.g., sweep, chisel plow, moldboard plow). Fertilization had little effect on C sequestration at any site. Carbon sequestration decreased as mean annual temperature increased. Carbon may be sequestered in soil under Texas climatic conditions, but the amounts may be quite small.

Limited information is available regarding soil organic carbon (SOC) distribution and the total amounts that occur in dryland cropping situa­ tions in semiarid regions. We determined crop rotation, tillage, and fer­ tilizer effects on· SOC distribution and mass in the semiarid southern Great Plains. A cropping system study was conducted for 10-years at Bushland,TX, to compare no-till and stubblelTlUlch management on four dryland cropping systems: continuous wheat (CW) (Triticum aestivum L.); continuous grain sorghum (CS) (Sorghum bicolor [L.] Moench.); wheat/fal­ low/sorghum/fallow (WSF); and wheat/fallow (WF). Fertilizer (45 kg N ha- 1 ) was added at crop planting to main plots. Subplots within each tillage and cropping treatment combination received no fertilizer. Ten years after treatment initiation, soil cores were taken incrementally to a 65-cm depth and subdivided for bulk density and SOC determination. The no-till treatments resulted in significant differences in SOC distrib­ ution in the soil profile compared with stubblemulch tillage in all four crop rotations, although differences were largest in the continuous crop­ ping systems. Continuous wheat averaged 1.71% SOC in the surface 2 cm of soil compared with 1.02% SOC with stubblemulch tillage. Continuous sorghum averaged 1.54% SOC in the surface 2 crn of soil in no-till com­ pared with 0.97% SOC with stubblemulch tillage. Total SOC content in the surface 20 cm was increased 5.6 t C ha- 1 in the CW no-till treatment and 2.8 t C ha- 1 in the CS no-till treatment compared with the stub­ blemulch treatment. Differences were not significantly different between tillage treatments in the WF and WSF systems. No-till management with continuous crops sequestered carbon in comparison to stubblemulch management on the southern Great Plains. Fallow limits carbon accu­ mulation.

Increased use of agricultural chemicals with no-tillage (NT) may negatively impact the environment through chemical or nutrient loss in runoff or by leaching below the root zone. We compared environmental impacts of NT and the lower chemical input stubble mulch (SM) management methods for dryland crop production on a clay loam soil in a semiarid environment. We measured runoff volume and sediment, nutrient, and triazine concentrations in runoff for 9 yr from seven field-sized watersheds (2-5 ha each) cropped in a dryland winter wheat (Triticum aestivum L.)-grain sorghum [Sorghum bicolor (L.) Moench]-fallow sequence with SM or NT management with no N or P fertilizer added. We analyzed soil cores to a 6-m depth for NO 3 - -N and to a 3-m depth for atrazine and propazine content. Adoption of NT management reduced sediment loss by 54% compared with SM, although annual runoff was 15 mm yr -1 greater from NT. Nutrient concentrations and losses (NO 3 - -N, NH 4 + -N, TN, soluble P, biologically available P, PT) in runoff were extremely small from both tillage systems (losses

Dryland crops produce limited amounts of residue, thus the water conservation benefits of no-tillage (NT) may be reduced. We compared infiltration, runoff, and water conservation effects of NT with stubblemulch (SM) tillage at Bushland, Texas, in the semiarid southern Great Plains. From 1981 to 1992, we cropped six field-sized (2 to 4 ha) graded-terraced watersheds in a dryland, three-year, winter wheat (Triticum aestivum L.)-sorghum [Sorghum bicolor (L.) Moench]-fallow (WSF) sequence. There were three pairs of watersheds in the sequence, each with NT and SM treatments maintained on the same watersheds each year. Runoff was measured with H-flumes from each watershed beginning in 1984. Infiltration differences were measured with a rainfall simulator in 1990 and 1991. We compared soil water storage during fallow to evaluate the water conservation effectiveness of tillage treatments. 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 h of simulated rainfall was 90% greater on SM than on NT for tests conducted 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 25.5 and 40.1 mm/year for eight cycles of WSF for SM and NT treatments, respectively, with most runoff occurring during fallow periods. Despite greater surface runoff from the NT system than from the SM system, NT management resulted in improved water conservation due to reduced evaporation. Total plant available soil water storage during fallow after sorghum was 18% greater with the NT treatment and 10% greater during fallow after wheat than for soil water storage obtained with the SM treatment. More intensive cropping with less fallow appears possible on drylands by using NT management.

Bioavailable P (BAP) in agricultural runoff represents P potentially available for algal uptake and consists of soluble P (SP) and a variable portion of participate P (PP). Evaluation of the impact of agricultural management on BAP in runoff will aid assessment of the resultant biological productivity of receiving water bodies. Soluble P, PP, and bioavailable PP (BPP) (estimated by NaOH extraction) were determined over a 5-yr period in runoff from 20 unfertilized and fertilized, grassed, and cropped watersheds in the Southern Plains. Soluble P, BPP, and BAP loss in runoff was reduced by practices minimizing erosion and runoff, with respective mean annual amounts ranging from 237 to 122, 1559 to 54, and 1796 to 176 g P ha yr (for peanut-sorghum [ L.- (L.) Moench] and native grass watersheds, respectively). However, as vegetative cover improved, BAP (SP plus BPP) comprised a larger portion of total P (TP) loss (29% for peanut-sorghum and 88% for native grass). This results from an increasing contribution to BAP of SP (13% for peanut-sorghum and 69% for native grass watersheds) and BPP to PP (26% for peanut-sorghum and 69% for native grass watersheds). Clearly, P bioavailability is a dynamic function of physiochemical processes controlling erosion, particle size enrichment, P desorption-dissolution reactions, and plant residue breakdown, in addition to soil and fertilizer P management. Hence, the change in trophic state of a water body may not be adequately reflected by TP inputs only. To more reliably evaluate the biological response of a water body to agricultural P inputs, particularly from conservation tillage practices, it may be necessary to determine BAP in runoff.

(...) Sulfate-S transport in runoff was predicted using an equation describing the kinetics of SO 4 -S desorption from soil and compared with measured values. No SO 4 -S was added to any of the watersheds directly as S fertilizer or indirectly in N or P fertilizer material. No difference (at 5% level) in SO 4 -S concentration in runoff from grassed (mean annual value of 12.6 mg L −1 ) and cropped (mean annual value of 11.0 mg L −1 ) watersheds was observed. Differences in amounts (0.2-18.9 kg ha −1 yr −1 ) were a function of runoff volume as influenced by land management. (...)

Nonpoint-source pollution of surface water by the transport of sediment, N, and P in agricultural runoff is one of the nation's major water quality concerns. Consequently, concentrations and amounts of sediment, N, and P in runoff from Conventional Till (CT), Reduced Till (RT), and No Till (NT), sorghum [ (L.) Moench.] watersheds in the Southern Plains, were measured during a 5-yr period to evaluate water quality impacts of sorghum culture. Mean annual sediment and total N and P loss in runoff from NT (281, 0.76, and 0.28 kg ha yr, respectively) and RT (523, 0.99, and 0.37 kg ha yr, respectively) were lower than from CT sorghum (8877, 7.28, and 2.5 kg ha yr, respectively). In contrast, tillage effects on soluble N and P losses were generally small and less consistent, although soluble P concentrations exceeded limits associated with accelerated eutrophication (0.01 mg L). Predicted losses of soluble P and particulate N and P using desorption kinetics and enrichment ratio relationships were not significantly different from measured values for all tillage practices (ranged from 0.66 to 0.99). Overall, conservation tillage (NT and RT) reduced sediment, N, and P transport in runoff relative to CT and thereby lessened the potential impact of sorghum culture on surface water quality in the Southern Plains.

Grain sorghum grown in 38-cm (high-density) or 76-cm rows (normal-density) was steam-flaked, harvested as high-moisture grain followed by rolling and ensiling, or dry-rolled. Chemical composition, enzymatic starch availability, CP insolubility, and IVDMD in a reduced-strength buffer were evaluated. High-density planting increased (P.10) OM and starch concentration and decreased (P.0001) CP concentration but did not affect (P.10) P concentration, enzymatic starch availability, or CP insolubility. High-density planting resulted in lower (P.10) in vitro ruminal culture pH at 6, 12, and 18 h of incubation when grain sorghum was processed by steam flaking, and lower (P.10) IVDMD at 6, 12, and 18 h of digestion when grain sorghum was processed by dry rolling. Steam flaking decreased (P.10) CP concentration and solubility and increased (P.10) OM concentration. High-moisture ensiling decreased (P.10) the insolubility of CP but did not otherwise seem to alter the chemical composition of grain sorghum relative to dry rolling. Starch was more available (P.10), and DM was digested more rapidly and extensively (P.10) in vitro, in steam-flaked sorghum followed by high-moisture sorghum. Based on these data, it seems that planting density primarily affected chemical composition of grain sorghum, whereas processing primarily affected CP insolubility and rate and extent of starch fermentation.

In this study we have investigated the feasibility of multi-element analysis using a simple 1+1 photo-excitation/photo-ionization scheme. Although such schemes are usually far from ideal for optimum resonance ionization, they are the approach of choice if one wishes to maintain a simple, easy-to-operate laser set-up which is potentially suitable for routine analysis. In addition, we only made use of the second-harmonic tuning range of a single dye. While this limits the range of elements which are accessible in the 1+1 RIS scheme it further adds to the simplicity and allows for automation of sequential multi-element analysis.

A comparison is made of the techniques of secondary ion mass spectrometry (SIMS) and resonance ionization mass spectrometry (RIMS) for the detection of the neuro-toxic element aluminium in cortical tissue. Experiments were performed using a reflectron-type time-of-flight mass spectrometer (TOFMS) in conjunction with an Ar+ source for target sputtering and a pulsed tuneable dye laser system for resonance ionization. It is shown how isobaric interference of species such as CNH and C2H3 in the case of aluminium greatly affect the quantitative accuracy and the detection limit of aluminium in biological samples when analysed using SIMS. In contrast the use of RIMS virtually eliminates this problem, so allowing easier quantification and much lower detection limits to be achieved. Detection limits of approximately 3 ppm for aluminium in brain tissue homogenates were achieved using RIMS, with a spatial resolution of less than 100 microns.

Resonance effects of isotope ratio measurements using three‐photon one‐color RIMS in lead are discussed. The shape of the ionization signal is considered for the case of a non‐monochromatic laser field. The intensity of the laser radiation is adjusted to be low enough to cause saturation of the transitions. The variation of the isotope ratio as a function of laser frequency is considered. It is shown that the deviation of the measured from the expected isotope ratio, for a Lorentzian lineshape equals the ratio of the isotope shift to the laser bandwidth. Unfortunately, the background noise in the experiments makes verification difficult for the isotopes of low abundance.

Tillage is performed for the purposes of controlling weeds, insects, and diseases; improving the soil’s physical condition by destroying compacted plowpans or other dense layers; incorporating fertilizer, herbicide, and plant residues; conserving soil and water; and preparing a seedbed. Although tillage has many advantages, it also has disadvantages such as tending to destroy soil structure, burying surface residues, and increasing evaporation from the tilled zone. The latter problem is particularly important in dryland farming, which is defined as farming that requires cropping practices including adaptations to soil water deficiency during the growing season (Cannell and Dregne, 1983). Dryland tillage practices should be aimed at (1) conserving the maximum amount of water possible in the root zone during noncrop periods and (2) creating a seedbed that allows the crop to be established at the optimum time to use the limited water supply efficiently.

Grain sorghum grown in 38-cm rows (high density [HD]) or 76-cm rows (normal density [ND]) was treated as follows: steam-flaked (SF), high-moisture-harvested followed by rolling and ensiling (HM), or dry-rolled (DR). Resulting grains were evaluated using lambs in two 5 x 5 Latin square digestion trials. Treatment diets contained either SF-HD, SF-ND, HM-HD, HM-ND, or DR-ND grain sorghum in two trials; a 90 or a 60% concentrate diet was fed in each trial. High-density planting increased (P0.10) the apparent absorption of P relative to ND planting for both 60 and 90% concentrate diets. Steam flaking decreased (P0.10) the apparent absorption of P in the 90% concentrate diet and decreased (P0.10) the apparent absorption of N in both the 90 and 60% concentrate diets. Despite differences in N digestibility, steam flaking and HM ensiling resulted in similar (P0.10) N retention as a percentage of N intake in both trials. However, changes in the distribution of N between feces and urine among processing methods could affect N content of manure and alter nutrient management strategies. These results indicate that both planting density and grain processing can alter the apparent absorption of grain sorghum P by ruminants. Furthermore, it seems that grain processing can alter the route of N excretion in ruminants without changing total N retention.

Perceptual experience, John Heil scepticism, relevance, and relativity, Stewart Cohen proper knowledge, David H.Sanford Dretske on how reasons explain behaviour, Jaegwon Kim actions, reasons, and the explanatory role of content, Terence Horgan the role of mental meaning in psychological explanation, Robert Cummins ways of establishing harmony, Daniel C.Dennett causal contents, Frederick Adams belief individuation and Dretske on naturalizing content, Brian P.McLaughlin Dretske's replies.

Effects of tillage on the incidence and severity of common root rot caused by Bipolaris sorokiniana and on spore distribution were studied in continuous wheat culture at three locations in Texas. Spore populations were determined to a depth of 40 cm in 10-cm increments. The majority of spores were found in the top 10 cm of soil regardless of tillage method. Although significantly more spores were found with conventional tillage than in the no-still system, the distribution of spores in the soil profile was not significantly affected by tillage (...)

A 0.20‐ha (0.5‐acre) recharge basin was tested for conserving storm runoff that collected in a 16‐ha (40‐acre) playa in the Southern High Plains. The basin was constructed by removing 1.2 m (4 ft) of soil to expose permeable sediments. Turbid water was pumped from the playa to the basin during eight tests over a 7‐yr interval. Average recharge rate during 187 days of flooding was 0.373 m/d (1.22 ft/day). After three recharge tests during the first year, no maintenance was done to the basin bottom. Our research showed that recharge basins could be an effective technique for partially replenishing the depleted Ogallala Aquifer.

The chemical composition of rainfall, agricultural runoff, groundwater, and pond water at several rural Oklahoma and north Texas locations was determined over a number of years (1972–1985). The inputs of acid, P, Cl, and cations in rainfall are not of major agronomic importance, although inputs of N (as NO3-N and NH4-N) and S (as SO4) in rainfall can contribute a significant proportion of the uptake of these elements by grasses or crops. The mean annual pH of rainfall was consistently greater than that of pure rainfall (5.6) averaging 6.5, while the average pH of two farm ponds (7.8) was even greater than that of rainfall. If a decrease in the pH of rainfall in the Southern Plains should occur in the future, the impact of the acidity on surface water will be reduced to a certain degree by the buffering capacity of the area soils. Appreciably more acid was added annually to the agricultural soils of the area via fertilizer P and N than in rainfall. Under present conditions it would take up to 1,50...

The effectiveness of selected low-cost, water-conserving land forming systems in preventing runoff and increasing dryland grain sorghum [Sorghum bicolor (L.) Moench] yields on Pullman clay loam was evaluated for 4 years (1975-1978) at Bushland, Tex. Systems investigated were mini-bench terraces (5 m wide), conservation mini-bench terraces (9 m wide with a ratio of watershed to level bench area of 1:1), and three configurations of contour furrows. Runoff was measured from conventional graded furrows (0.25% grade) that were used for the check treatment. Total runoff for the 4 years was 258 mm, about 15% of total precipitation. All systems that retained runoff on the field produced significantly greater yields and had greater water-use efficiencies than the graded furrow system. Grain yield and water-use efficiency were significantly greater with mini-bench terraces than with any other treatment. Mean annual grain yield on mini-bench terraces was 2,380 kg/ha, compared to 1,210 kg/ha on conventional graded furrows. Minibenches, conservation mini-benches, and large contour furrows controlled erosion and retained all precipitation from a storm of 75-year expected frequency. In that storm, conventional furrows overtopped and failed to retain runoff.

In order to determine movement of farm chemicals that might accidentally contaminate underground water supplies, low concentrations of three herbicides and NaNO3 as a tracer were injected into a sand aquifer through a dual-purpose well. Herbicides used were picloram, atrazine, and trifluralin. Recharge by injection continued for 10 days at an average rate of 81.8 m3/hour. After a 10-day pause, the well was pumped for 12 days to determine if the herbicides and tracer could be recovered. Water samples were pumped from observation wells located 9, 20, and 45 m from the dual-purpose well. Herbicides were detected in the 9- and 20-m distant wells, but none of the herbicides or the tracer was detected in the 45-m distant well. Picloram and atrazine moved freely through the aquifer, but some trifluralin adsorbed to aquifer particles around the well. Although, two herbicides moved freely from the point of injection, all of the chemicals were removed from the aquifer by pumping the contaminated water. Ninety-three percent of the NO3 tracer and more than 90% of each herbicide were recovered with the pumped water. This study indicates that herbicides accidentally injected into a well in a relatively static aquifer can be recovered by pumping. Water could be utilized for irrigation of tolerant crops.

IMPROVED management practices increased infiltra-tion rates in excavated basins and more than doubled the amount of turbid playa water artificially recharged to the Ogallala aquifer. Management practices that in-creased recharge most were increased depth of flooding and partial incorporation of an organic mat (cotton gin trash) in the bottom of recharge basins. Addition of ca-tionic flocculent to playa water increased the total amount of playa water infiltrated when suspended sedi-ment content of the water was 250 to 300 mg/L but had little effect on infiltration when water contained 150 mg/L suspended soilds.

In his book, Theory of Knowledge, Roderick Chisholm distinguishes very precisely between, amongst others, what he calls acceptable, reasonable and evident propositions. A proposition is acceptable if with-holding it is not more reasonable than believing it; a proposition is reasonable if believing it is more reasonable than with-holding it; and a proposition is evident for a person provided it is reasonable for him, and there is no other proposition such that the latter is more reasonable than the former. The notion of being more reasonable is obviously pivotal, and Chisholm explains what it is for an attitude to be more reasonable than another in the following words: “If the person in question were a rational being, if his concerns were purely intellectual, and if he were to choose between the two attitudes, then he would choose the more reasonable in preference to the less reasonable”. The wording of this conditional suggests that Chisholm does not think a person is necessarily rational, so it is imperative that we ask: When is a person rational?

The effects of major water management practices on the pumping requirement from the Ogallala aquifer are discussed. Demand on the aquifer may be reduced as much as 15 percent by recycling irrigation runoff, 25 percent by recycling irrigation runoff and irrigating with water from playas, and 29 percent by recycling irrigation water in combination with irrigation from playas and artificial recharge of playa water to the aquifer. Other practices that can result in more efficient use of precipitation and groundwater are limited irrigation, land forming, soil profile modification, and improved irrigation systems, thereby reducing the pumping demand on the Ogallala. Additional water supplies can possibly be obtained by water harvesting, weather modification, and water importation. Conclusions reached were that the overdraft on the aquifer can be reduced by the application of sound water management practices on an area-wide basis.