Effects of fallow management and cropping history on aggregate breakdown under rainfall wetting for a range of Queensland soils

Soil Research ◽  
1994 ◽  
Vol 32 (5) ◽  
pp. 1125 ◽  
Author(s):  
RJ Loch

This paper reports changes in stability of soils to wetting under a range of fallow management/cropping treatments for eight experiment sites in Queensland. Because of its greater relevance to dryland soils, and its better correlation with field soil behaviour, wetting with high energy rain (HER) was used to wet samples and cause aggregate breakdown. The water-stable size fraction considered was that <0.125 mm, with the proportion of particles <0.125 mm referred to as P125. To study interactions between wetting method and tillage management, several other wetting methods were applied to some or all of the eight soils. These other methods were immersion (IMM), wetting by rainfall of low energy (LER) or under tension (TENS). Where fallow management treatments significantly reduced P125 under HER wetting, those reductions were generally small, and likely to increase steady infiltration rates of high energy rain into bare soil by only 2-6 mm h-1. In contrast, steady infiltration rates could be increased by 15-42 mm h-1 if those same soil surfaces were completely covered by stubble so that they received low energy rain. At least under Queensland conditions, retention of crop residues to protect soils from drop impact is therefore likely to be of much greater importance in improving water storage during fallows than any improvement in soil aggregation under 'improved' fallow management practices. Effects of fallow management and cropping history on P125 under HER varied across the sites. Three out of four virgin soils were more stable than corresponding cropped soils; stubble retention improved stability to HER wetting on three out of four sites where it was tested, and direct drill or reductions in tillage frequency improved stability at two out of eight sites. IMM showed responses to treatments that, for some soils, differed greatly from those obtained using HER. Neither LER nor TENS appeared useful, as LER gave occasional inconsistent results, and TENS caused little aggregate breakdown for most soils.

Soil Research ◽  
1994 ◽  
Vol 32 (4) ◽  
pp. 701 ◽  
Author(s):  
RJ Loch ◽  
JL Foley

This paper reports comparisons between aggregate breakdown on wetting by rainfall with breakdown measured by a range of alternative methods. It also reports correlations between measured breakdown and steady infiltration rates of simulated rain of high and low energy, and hydraulic conductivities of surface seal layers formed under high energy rain. A wide range of soils in eastern Australia were studied. Highly significant correlations were found between measurements of aggregate breakdown to < 125 �m caused by rainfall wetting and both steady infiltration rates and hydraulic conductivities. Significant, but poorer correlations were found between steady infiltration rates and breakdown resulting from immersion wetting. Deletion of swelling soils from the data set greatly improved correlations between steady infiltration rates of high energy rain and breakdown measured by both immersion and tension wetting, showing that these methods of wetting ace particularly inappropriate for swelling soils. No correlation was found between infiltration rates and measured clay dispersion. Different relationships between the proportion of particles (%) < 125 �m at the soil surface (P125) and steady infiltration rates of low and high energy rain indicated that compaction of the soil surface layer, rather than increased aggregate breakdown, is a major cause of surface sealing by raindrop impacts. Measurements of fall cone penetration confirmed that drop impacts had compacted the surface layer. Suctions across the surface seal were related to P125 in that layer, and the relationship obtained was used in calculating hydraulic conductivities. The results confirm that measurement of aggregate breakdown under rainfall wetting produces results of much greater relevance to soil behaviour under field conditions than do tests based on immersion and tension wetting.


2001 ◽  
Vol 28 (1) ◽  
pp. 37-40 ◽  
Author(s):  
Gabriele Carannante ◽  
A. Laviano ◽  
D. Ruberti ◽  
Lucia Simone ◽  
G. Sirna ◽  
...  

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 495d-495
Author(s):  
J. Farias-Larios ◽  
A. Michel-Rosales

In Western Mexico, melon production depends on high-input systems to maximize yield and product quality. Tillage, plasticulture, fumigation with methyl bromide, and fertigation, are the principal management practices in these systems. However, at present several problems has been found: pests as sweetpotato whitefly (Bemisia tabaci Gennadius), aphids (Myzus and Aphis), leafminer (Liryomiza sativae); diseases as Fusarium, Verticilium, and Pseudoperenospora, and weeds demand high pesticide utilization and labor. There is a growing demand for alternative cultural practices, with an emphasis on reducing off-farm input labor and chemicals. Our research is based on use of organic mulches, such as: rice straw, mature maize leaves, banana leaves, sugarcane bagasse, coconut leaves, and living mulches with annual legume cover crop in melons with crop rotation, such as: Canavalia, Stilozobium, Crotalaria, and Clitoria species. Also, inoculations with mycorrhizal arbuscular fungi for honeydew and cantaloupe melon seedlings production are been assayed in greenhouse conditions for a transplant system. The use of life barriers with sorghum, marigold, and other aromatic native plants in conjunction with a colored yellow systems traps for monitoring pests is being studied as well. While that the pest control is based in commercial formulations of Beauveria bassiana for biological control. The first results of this research show that the Glomus intraradices, G. fasciculatum, G. etunicatum, and G. mosseae reached 38.5%, 33.5%, 27.0%, and 31.0% of root infection levels, respectively. Honeydew melons production with rice and corn straw mulches shows an beneficial effect with 113.30 and 111.20 kg/plot of 10 m2 compared with bare soil with 100.20 kg. The proposed system likely also lowers production cost and is applicable to small- and large-scale melon production.


Author(s):  
Peter Rez

Transportation efficiency can be measured in terms of the energy needed to move a person or a tonne of freight over a given distance. For passengers, journey time is important, so an equally useful measure is the product of the energy used and the time taken for the journey. Transportation requires storage of energy. Rechargeable systems such as batteries have very low energy densities as compared to fossil fuels. The highest energy densities come from nuclear fuels, although, because of shielding requirements, these are not practical for most forms of transportation. Liquid hydrocarbons represent a nice compromise between high energy density and ease of use.


2021 ◽  
Vol 22 (15) ◽  
pp. 7879
Author(s):  
Yingxia Gao ◽  
Yi Zheng ◽  
Léon Sanche

The complex physical and chemical reactions between the large number of low-energy (0–30 eV) electrons (LEEs) released by high energy radiation interacting with genetic material can lead to the formation of various DNA lesions such as crosslinks, single strand breaks, base modifications, and cleavage, as well as double strand breaks and other cluster damages. When crosslinks and cluster damages cannot be repaired by the cell, they can cause genetic loss of information, mutations, apoptosis, and promote genomic instability. Through the efforts of many research groups in the past two decades, the study of the interaction between LEEs and DNA under different experimental conditions has unveiled some of the main mechanisms responsible for these damages. In the present review, we focus on experimental investigations in the condensed phase that range from fundamental DNA constituents to oligonucleotides, synthetic duplex DNA, and bacterial (i.e., plasmid) DNA. These targets were irradiated either with LEEs from a monoenergetic-electron or photoelectron source, as sub-monolayer, monolayer, or multilayer films and within clusters or water solutions. Each type of experiment is briefly described, and the observed DNA damages are reported, along with the proposed mechanisms. Defining the role of LEEs within the sequence of events leading to radiobiological lesions contributes to our understanding of the action of radiation on living organisms, over a wide range of initial radiation energies. Applications of the interaction of LEEs with DNA to radiotherapy are briefly summarized.


2021 ◽  
Author(s):  
Quang Hieu Tran ◽  
Thuy Thanh Ho ◽  
Tu Thanh Nguyen

A comprehensive study from Curcuma longa to powder nano curcuminoids has been carried out. Combining of both low energy method (Phase Inversion Temperature) and high-energy method (Ultrasonication), a series of...


2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Martin Bauer ◽  
Matthias Neubert ◽  
Sophie Renner ◽  
Marvin Schnubel ◽  
Andrea Thamm

Abstract Axions and axion-like particles (ALPs) are well-motivated low-energy relics of high-energy extensions of the Standard Model, which interact with the known particles through higher-dimensional operators suppressed by the mass scale Λ of the new-physics sector. Starting from the most general dimension-5 interactions, we discuss in detail the evolution of the ALP couplings from the new-physics scale to energies at and below the scale of electroweak symmetry breaking. We derive the relevant anomalous dimensions at two-loop order in gauge couplings and one-loop order in Yukawa interactions, carefully considering the treatment of a redundant operator involving an ALP coupling to the Higgs current. We account for one-loop (and partially two-loop) matching contributions at the weak scale, including in particular flavor-changing effects. The relations between different equivalent forms of the effective Lagrangian are discussed in detail. We also construct the effective chiral Lagrangian for an ALP interacting with photons and light pseudoscalar mesons, pointing out important differences with the corresponding Lagrangian for the QCD axion.


2021 ◽  
Vol 11 (10) ◽  
pp. 4349
Author(s):  
Tianzhong Xiong ◽  
Wenhua Ye ◽  
Xiang Xu

As an important part of pretreatment before recycling, sorting has a great impact on the quality, efficiency, cost and difficulty of recycling. In this paper, dual-energy X-ray transmission (DE-XRT) combined with variable gas-ejection is used to improve the quality and efficiency of in-line automatic sorting of waste non-ferrous metals. A method was proposed to judge the sorting ability, identify the types, and calculate the mass and center-of-gravity coordinates according to the shading of low-energy, the line scan direction coordinate and transparency natural logarithm ratio of low energy to high energy (R_value). The material identification was satisfied by the nearest neighbor algorithm of effective points in the material range to the R_value calibration surface. The flow-process of identification was also presented. Based on the thickness of the calibration surface, the material mass and center-of-gravity coordinates were calculated. The feasibility of controlling material falling points by variable gas-ejection was analyzed. The experimental verification of self-made materials showed that identification accuracy by count basis was 85%, mass and center-of-gravity coordinates calculation errors were both below 5%. The method proposed features high accuracy, high efficiency, and low operation cost and is of great application value even to other solid waste sorting, such as plastics, glass and ceramics.


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