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Hu M.,CAS Shenyang Institute of Applied Ecology | Guan T.,CAS Shenyang Institute of Applied Ecology | He H.,CAS Shenyang Institute of Applied Ecology | Zhang X.,CAS Shenyang Institute of Applied Ecology | Zhang X.,National Field Observation and Research Station of Shenyang Agro Ecosystems
Huanjing Kexue Xuebao/Acta Scientiae Circumstantiae

The form distribution and temporal dynamics of Cu in Mollisol as well as the effect of manure applications were investigated through wheat pot experiments. The results showed that the oxidable fraction accounted for the largest proportion (40.4%~65.0%) of Cu regardless of the addition amount. With increasing Cu addition, the proportion of acid-extractable fractions increased slightly and that of reducible portion increased significantly. In contrast, that the fraction of residuals decreased significantly, suggesting the increased bioavailability of Cu with increasing Cu input. Compared with 2009, the proportion of acid-extractable fraction declined while that of residual Cu increased at all levels of Cu addition, indicating that Cu tended to be stabilized in soil and thus its bioavailability declined. The application of manure at 1% rate (based on dry matter) declined the mobility of Cu significantly compared to that at 3% rate. The proportion of reducible fraction declined to higher degree while that of residual fraction increased more significantly. The low concentration of Cu (<200 mg·kg -1) can promote the growth of wheat to increase the biomass, but the high concentration of Cu (>600 mg·kg -1) was evidently toxic. Compared with 2009, the uptake of Cu in wheat increased in 2010, thus the short-term stabilization (for one growing season) of Cu in soil did not exhibit significant influence on the Cu bioavailability in soil as well as the uptake by wheat. Source

Tian Q.,CAS Shenyang Institute of Applied Ecology | Tian Q.,University of Chinese Academy of Sciences | He H.,CAS Shenyang Institute of Applied Ecology | Cheng W.,CAS Shenyang Institute of Applied Ecology | And 3 more authors.
Soil Biology and Biochemistry

Carbon dioxide from soil respiration is a key source of atmospheric CO2 and a major component of the global carbon cycle. However, the temporal pattern of soil respiration is not well understood and even wrongly modeled. In a 360-day laboratory experiment, we investigated temporal patterns of soil respiration and microbial carbon availability using five soils taken from five altitudinal zones on a temperate Mountain. We found two distinctive patterns in soil respiration and carbon availability among the five soils: a new pulse-dynamic pattern for soils taken from middle altitudinal zones, and the commonly reported pattern of monotonic decline for other soils. Our redundancy analysis further showed that soil texture plays a major role in determining the occurrence and magnitude of the pulse-dynamic pattern. The new pulse-dynamic pattern challenges the commonly held static view of soil organic carbon mineralization, and has crucial implications for modeling soil carbon in terrestrial ecosystems. © 2013 Elsevier Ltd. Source

Cui Y.-H.,CAS Shenyang Institute of Applied Ecology | Cui Y.-H.,University of Chinese Academy of Sciences | Zhang W.,CAS Shenyang Institute of Applied Ecology | He H.-B.,CAS Shenyang Institute of Applied Ecology | And 3 more authors.
Chinese Journal of Ecology

A laboratory incubation of soil samples was conducted to study the dynamics of three kinds of microbial-derived amino sugars in forest soil after adding different amounts of nitrogen. The relative contribution of soil fungi and bacteria to soil nitrogen transformation and accumulation was also investigated by the ratio of glucosamine to muramic acid. The results showed that, dynamics of the soil amino sugar contents were closely related to the nutrient status of the soil. When nitrogen was added to the soil, the microorganisms could use the extraneous nitrogen to synthesize their own cell wall material, and the content of muramic acid in the high nitrogen treatment was higher than that in the low nitrogen treatment, while the content of glucosamine in the high nitrogen treatment was lower than that in the low nitrogen treatment. Our study indicated that increased nitrogen addition was more beneficial to the accumulation of bacteria-derived mu-ramic acid. However, high nitrogen addition was detrimental to the accumulation of fungi-derived glucosamine. The response of galactosamine to nitrogen addition was weak. When soil nutrient was deficient, the amino sugars could be decomposed with different degrees. In addition, the ratio of bacteria-derived amino sugar to fungi-derived amino sugar was changed. We found that the contribution of bacteria to soil nitrogen transformation in soil was greater than that of fungi, and the contribution of bacteria to soil nitrogen transformation was greater under high nitrogen addition. This study indicated that nitrogen addition changed the microbial transformation of amino sugar- derived soil nitrogen. © 2016, Editorial Board of Chinese Journal of Ecology. All Rights Reserved. Source

Tian Q.-X.,CAS Shenyang Institute of Applied Ecology | Tian Q.-X.,University of Chinese Academy of Sciences | Zhang B.,CAS Shenyang Institute of Applied Ecology | Zhang B.,University of Chinese Academy of Sciences | And 4 more authors.
Chinese Journal of Applied Ecology

In July 2010, soil samples were collected from five typical forests (Pinus koraiensis and broadleaved mixed forest, Picea and Abies forest, Larix and Abies forest, Betula ermanii forest, and alpine tundra) along an altitude gradient on the northern slope of Changbai Mountains to investigate the distribution and quantity of neutral sugar in the soils and related affecting factors. The origins of the neutral sugar were differentiated to probe into the biochemical accumulation mechanisms of soil organic matter. There was a significant difference in the neutral sugar content among the forest soils. The relative content of soil neutral sugar's carbon to soil organic carbon ranged in 80.55-170.63 mg C·g-1, and tended to be increased with elevated altitude. The multiple regression analysis showed that the mean temperature in growth season was the main factor affecting the relative content of soil neutral sugar, and low temperature was conducive to the accumulation of neutral sugar. The ratio of (galactose + mannose)/(arabinose + xylose) in the five soils was around 1.62-2.28, and had an increasing trend with elevated altitude, illustrating that the contribution of soil microbial neutral sugar to soil organic matter increased with elevated altitude. Soil microbial metabolic quotient declined significantly along elevated altitude, suggesting that in low temperature environment, soil microbial activity decreased but the carbon utilization efficiency enhanced. As a result, a significant portion of decomposed plant residues was transformed into microbial neutral sugar and accumulated stably in soil, and thus, increased the proportion of soil microbial neutral sugar. Source

Liu X.,CAS Shenyang Institute of Applied Ecology | Liu X.,University of Chinese Academy of Sciences | Hu G.,CAS Shenyang Institute of Applied Ecology | Hu G.,University of Chinese Academy of Sciences | And 9 more authors.
Agriculture, Ecosystems and Environment

Understanding long-term microbial immobilization of nitrogen (N) fertilizer is essential for N management in agricultural soils. Evaluating the transformation and accumulation of N fertilizer into microbial residues is critical for developing such an understanding due to the requirement of time-integrated biomarkers and a 15N-labeling technique. By tracing the dynamics of amino sugars derived from annually applied fertilizer over 8 years, we investigated the influence of continuous maize residue mulching on the temporal immobilization of fertilizer N in an agricultural soil and quantified the turnover of microbial residues in situ. We found that the amino sugar transformation rate from fertilizer N was constant over time in both fertilization-only and maize residue mulching managements, but it was significantly higher in the upper cultivation layer (0-10 cm) after maize residue mulching. Mulching with maize residue facilitated initial fertilizer N transformation, while the subsequent 7-year application maintained the increased transformation rate. Consequently, the accumulation of fertilizer-derived amino sugars increased linearly in both managements within the 8 years of our field experiment. The mean residence time (MRT) of soil amino sugar-N was estimated by using extrapolation and first-order kinetics approaches, respectively. The calculated MRT of amino sugar-N using first-order kinetics (78 and 154 years at 0-10 and 10-20 cm, respectively) was slightly shorter than that estimated by the extrapolation (89 and 165 years at 0-10 and 10-20 cm, respectively) in the fertilization-only management. Mulching with maize residue did not change the MRT of amino sugar-N because maize residue addition enhanced the immobilization of maize residue-derived N or the transformation of indigenous soil N in addition to those of fertilizer N, leading to the same proportion of new N assimilated in microbial residues. © 2016 Elsevier B.V. Source

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