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Accurate and continuous measurements of soil thermal and hydraulic propertiesare required for environmental, Earth and planetary science, and engineering applications, but they are not practicallyobtained by steady-state methods. The heat pulse (HP) method is a transient method for determinationof soil thermal properties and a wide range of other physical properties in laboratory and field conditions. The HP method is based on the line-heat source solution of the radial heat flow equation. This literature review begins with a discussion of the evolution of the HP method and related applications, followed by the principal theories, data interpretation methods and their differences. Important factors for HP probe construction are presented. The properties determined in unfrozen and frozen soilsare discussed, followed by a discussion of limitations and perspectives for the application of this method. The paper closes with a brief overview of future needs and opportunities for further development and application of the HP method.Keywords thermal properties, thermal conductivity, thermal resistivity, heat capacity, thermal diffusivity, thermal inertia, dual probe heat pulse, thermal probe, hot-wire method, fiber optics, distributed temperature sensing (DTS), thermo-time/frequency domain reflectometry (thermo-TDR, thermo-FDR), soilwater content, ice content, frozen soils, instrumentation DisciplinesAgricultural Science | Agriculture | Hydrology | Soil Science Comments This is a manuscript of an article published as He, Hailong, Miles F. Dyck, Robert Horton, Tusheng Ren, Keith L. Bristow, Jialong Lv, and Bingcheng Si. "Development and application of the heat pulse method for soil physical measurements." Reviews of Geophysics (2018) This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1029/2017RG000584 © 2018 American Geophysical Union. All rights reserved.Development and application of the heat pulse method for soil physical properties in laboratory and field conditions. The HP method is based on the line-heat source solution of the radial heat flow equation. This literature review begins with a discussion of the evolution of the HP method and related applications, followed by the principal theories, data interpretation methods and their differences. Important factors for HP probe construction are presented. The properties determined in unfrozen and frozen soilsare discussed, followed by a discussion of limitations and perspectives for the application of this method. The paper closes with a brief overview of future needs and opportunities for further development and application of the HP method.

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Dissolved organic matter (DOM) plays an essential role in many environmental processes, particularly in soil ecosystems. In the present study, ultraviolet-visible (UV-Vis) spectroscopy and parallel factor analysis (PARAFAC) of three-dimensional fluorescence excitation-emission matrices (3D-EEMs) were used to characterize DOM extracted from various agricultural soils across four climate regions of China. The maximum (86.01 mg L) and minimum (17.39 mg L) dissolved organic carbon (DOC) concentrations were found in soils from Jiangsu and Yunnan, respectively. Specific UV-Vis absorption at 254 nm (SUVA) for soil DOM from the temperate continental climate (TCC) region was higher than that of soil DOM in other climate regions. Three fluorescence components including UVC humic-like substances (excitation peak at 400 nm, emission peak at 525 nm), UVA humic-like substances (250(330)/430 nm), and tyrosine-like materials (220(275)/320 nm) were identified in soil DOM using PARAFAC analysis. However, there were no significant differences in the distributions of these three components for soil DOM from different climate regions. Positive correlations were found among the humification index (HIX), fluorescence index (FI), and autochthonous index (BIX). Our results demonstrate that EEMs-PARAFAC could be a feasible approach for characterizing DOM in agricultural soils from different crop systems and can be used to further study complex DOM in agricultural environments.

Fertilization is important to increase crop yields, but long-term application of fertilizers probably aggravated the risk of heavy metals in acidic soils. In this study, the effect of 22-year fertilization and cropping on accumulation, availability, and uptake of heavy metals in red soil was investigated. The results showed that pig manure promoted significantly cadmium (Cd) accumulation (average 1.1 mg kg(-1)), nearly three times higher than national soil standards and, thus, increased metal availability. But the enrichment of heavy metals decreased remarkably by 50.5 % under manure fertilization, compared with CK (control without fertilization). On the contrary, chemical fertilizers increased greatly lead (Pb) availability and Cd activity; in particular, exceeding 85 % of soil Cd became available to plant under N (nitrogen) treatment during 9-16 years of fertilization, which correspondingly increased their enrichment by 29.5 %. Long-term application of chemical fertilizers caused soil acidification and manure fertilization led to the increase in soil pH, soil organic matter (SOM), and available phosphorus (Olsen P), which influenced strongly metal behavior in red soil, and their effect had extended to deeper soil layer (20∼40 cm). It is advisable to increase application of manure alone with low content of heavy metals or in combination with chemical fertilizers to acidic soils in order to reduce toxic metal risk.