The changes in soil organic matter in a forest-cultivation sequence traced by stable carbon isotopes

Soil Research ◽  
2003 ◽  
Vol 41 (7) ◽  
pp. 1317 ◽  
Author(s):  
Q. M. Liu ◽  
S. J. Wang ◽  
H. C. Piao ◽  
Z. Y. Ouyang
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Forest Soil ◽  
C3 Plants ◽  
Organic Carbon Content ◽  
Photosynthetic Pathway ◽  
Δ13c Values ◽  
Size Fractions ◽  
Density Fractions ◽  
Farmland Soil

There is an obvious difference in δ13C values between plants that assimilate carbon via the C3 photosynthetic pathway and those that do so by the C4 photosynthetic pathway. In terms of this characteristic, we analysed the organic carbon content and δ13C values of total soil and δ13C values in different size and density fractions of profile-soil samples either in farmland or in forestland near the Maolan Karst virgin forest, south-west China. This is an area where C3 plants grew previously, now replaced by C4 plants. Deforestation has accelerated the decomposition rate of soil organic matter and reduced the proportion of active components in soil organic matter and thus soil fertility. The δ13C values of different size fractions in forest soil are δ13Ccoarse sand < δ13Cfine sand < δ13Ccoarse silt < δ13Cclay < δ13Cfine silt, and the δ13C values of different size fractions in farmland soil are δ13Ccoarse sand > δ13Cfine sand > δ13Ccoarse silt > δ13Cclay > δ13Cfine silt, indicating that soil organic matter is fresh in coarse sand and oldest in fine silt. The δ13C values of different density fractions in forest soil are δ13Clight < δ13Cheavy, and the δ13C values of different density fractions in farmland soil are δ13Clight > δ13Cheavy, indicating that the soil organic matter is fresh in light fractions and old in heavy fractions.

scholarly journals Little effects on soil organic matter chemistry of density fractions after seven years of forest soil warming

2016 ◽  
Vol 103 ◽  
pp. 300-307 ◽  
Author(s):  
Jörg Schnecker ◽  
Werner Borken ◽  
Andreas Schindlbacher ◽  
Wolfgang Wanek
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Forest Soil ◽  
Soil Warming ◽  
Density Fractions

Turnover of soil organic matter and storage of corn residue carbon estimated from natural 13C abundance

1995 ◽  
Vol 75 (2) ◽  
pp. 161-167 ◽  
Author(s):  
E. G. Gregorich ◽  
C. M. Monreal ◽  
B. H. Ellert
Keyword(s):  
Particle Size ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Forest Soil ◽  
Half Life ◽  
Light Fraction ◽  
Organic C ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Corn Residue

Total organic C and natural C abundance were measured in a forest soil and a soil under corn (Zea mays L.) to assess management-induced changes in the quantity and initial source of organic matter. The total mass of organic C in the cultivated soil was 19% lower than in the forest soil. It was estimated that after 25 yr of continuous corn, 100 Mg C ha−1 was returned to the soil as residues, of which only 23 Mg ha−1 remained in the soil; 88% of the remaining corn-derived C (C4-derived C) was in the plow layer. About 30% of the soil organic C in the plow layer (0–27 cm) was derived from corn. Assuming first order kinetics, the half-life of C3-derived C in the 0- to 15-cm layer was 13 yr. The half-life of C3-derived C in the 0- to 30-cm layer, which included organic C below the plow layer, was 24 yr. Mineralization of the light fraction (LF) was faster than that of organic matter associated with particle-size fractions. More than 70% of the LF had turned over since the start of corn cropping, and 45% of organic matter in the sand fraction comprised corn residue. The half-life of C3-derived C in the LF was 8 yr. The mineralization of C from native organic matter associated with the coarse silt fraction was the slowest of all particle-size fractions. Key words: Soil organic matter, carbon storage, natural 13C abundance, light fraction, particle-size fractions, mineralization

scholarly journals Assessment of Potato Farmland Soil Nutrient Based on MDS-SQI Model in the Loess Plateau

2021 ◽  
Vol 13 (7) ◽  
pp. 3957
Author(s):  
Yingying Xing ◽  
Ning Wang ◽  
Xiaoli Niu ◽  
Wenting Jiang ◽  
Xiukang Wang
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Fertility ◽  
Soil Quality ◽  
Soil Nutrients ◽  
Organic Matter Content ◽  
Soil Nutrient ◽  
Matter Content ◽  
Soil Organic Matter Content ◽  
Farmland Soil

Soil nutrients are essential nutrients provided by soil for plant growth. Most researchers focus on the coupling effect of nutrients with potato yield and quality. There are few studies on the evaluation of soil nutrients in potato fields. The purpose of this study is to investigate the soil nutrients of potato farmland and the soil vertical nutrient distributions, and then to provide a theoretical and experimental basis for the fertilizer management practices for potatoes in Loess Plateau. Eight physical and chemical soil indexes were selected in the study area, and 810 farmland soil samples from the potato agriculture product areas were analyzed in Northern Shaanxi. The paper established the minimum data set (MDS) for the quality diagnosis of the cultivated layer for farmland by principal component analysis (PCA), respectively, and furthermore, analyzed the soil nutrient characteristics of the cultivated layer adopted soil quality index (SQI). The results showed that the MDS on soil quality diagnosis of the cultivated layer for farmland soil included such indicators as the soil organic matter content, soil available potassium content, and soil available phosphorus content. The comprehensive index value of the soil quality was between 0.064 and 0.302. The SPSS average clustering process used to classify SQI was divided into three grades: class I (36.2%) was defined as suitable soil fertility (SQI < 0.122), class II (55.6%) was defined as moderate soil fertility (0.122 < SQI < 0.18), and class III (8.2%) was defined as poor soil fertility (SQI > 0.186). The comprehensive quality of the potato farmland soils was generally low. The proportion of soil nutrients in the SQI composition ranged from large to small as the soil available potassium content = soil available phosphorus content > soil organic matter content, which became the limiting factor of the soil organic matter content in this area. This study revolves around the 0 to 60 cm soil layer; the soil fertility decreased gradually with the soil depth, and had significant differences between the respective soil layers. In order to improve the soil nutrient accumulation and potato yield in potato farmland in northern Shaanxi, it is suggested to increase the fertilization depth (20 to 40 cm) and further study the ratio of nitrogen, phosphorus, and potassium fertilizer.

scholarly journals Effect of systematic application of mineral fertilizers and long-term aftereffect of liming on the organic matter of light-grey forest soil

2020 ◽  
Vol 21 (2) ◽  
pp. 160-168
Author(s):  
N. A. Kodochilova ◽  
T. S. Buzynina ◽  
L. D. Varlamova ◽  
E. A. Katerova
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Forest Soil ◽  
Humus Content ◽  
Total Carbon ◽  
Mineral Fertilizers ◽  
Fertilized Soil ◽  
Grey Forest Soil ◽  
Nizhny Novgorod Region

The studies on assessment of changes in the content and composition of soil organic matter under the influence of the systematic use of mineral fertilizers (NPK)1, (NPK)2, (NPK)3 against the background of the aftereffect of single liming in doses of 1.0 and 2.0 h. a. (control – variants without fertilizers and lime) were conducted in the conditions of the Nizhny Novgorod region in a long – term stationary experiment on light-grey forest soil. The research was carried out upon comple-tion of the fifth rotation of the eight-field crop rotation. The results of the study showed that for 40 years (from 1978 to 2018) the humus content in the soil (0-20 cm) decreased by 0.19-0.52 abs. % in variants as compared to the original (1.60 %); though, humus mineralization was less evident against the background of long-term use of mineral fertilizers compared to non-fertilized control. The higher humus content in the topsoil was noted in the variants with minimal (NPK)1 and increased (NPK)2 doses of fertilizer – 1.41 and 1.25 %, respectively. The humus content in non-fertilized soil and when applying high (NPK)3 doses of mineral fertilizers was almost identical – 1.08-1.09 %. The predominant group in the composition of humus were humic acids, the content of which in the experiment on average was 37.8 % of the total carbon with an evident decrease from 42.6 % in the control to 31.8% when applying increased doses of mineral fertilizers. The aftereffect of liming, carried out in 1978, was unstable and did not significantly affect the content and composition of soil organic matter.

scholarly journals Thermal fractionation of soil organic matter produces fine-scale distributions of SOM age

2021 ◽  
Author(s):  
Shane Stoner ◽  
Carlos Sierra ◽  
Marion Schrumpf ◽  
Sebastian Dötterl ◽  
Susan Trumbore
Keyword(s):  
Thermal Stability ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Chemical Oxidation ◽  
Fine Scale ◽  
Mineral Association ◽  
Density Fractions ◽  
Chemical Complexity ◽  
Wide Range ◽  
Carbon Release

&lt;p&gt;Soil organic matter (SOM) is a complex collection of organic molecules of varying origin, structure, chemical activity, and mineral association. A wide array of laboratory methods exists to separate SOM based on qualitative, biological, chemical, and physical characteristics. However, all present conceptual and logistical limitations, including the requirement of a substantial amount soil material.&lt;/p&gt;&lt;p&gt;An newly applied alternative method of fractionation relies on a conceptual analogue between biochemical stability in soil and thermal stability, e.g. more persistent SOM will require higher temperatures (greater energy inputs) to decompose than less persistent SOM. This accounts for both chemical complexity and mineral association as main factors in determining SOM persistence.&lt;/p&gt;&lt;p&gt;In this method, carbon is released by heating SOM to 900&amp;#176;C at a constant rate. The peaks of carbon release are grouped into activation energy pools, CO&lt;sub&gt;2 &lt;/sub&gt;is collected, and analyzed for &lt;sup&gt;13&lt;/sup&gt;C and &lt;sup&gt;14&lt;/sup&gt;C. We seek to describe in finer detail the distribution of soil radiocarbon by adding another fractionation step following a different paradigm of SOM stability, and explore mineralogical effects on SOM quality and stability using thermal analysis, radiocarbon, and gas chromatography.&lt;/p&gt;&lt;p&gt;Here, we analyzed bulk soil and soil fractions derived from density separation and chemical oxidation, as well as mineral horizons dominated by diverse mineralogies. Density fractions contained a wide range of radiocarbon activities and that young SOM is stabilized across multiple fractions, likely due to organomineral complexation. Initial results showed that soil minerals with limited stabilization potential released C at lower temperatures than those with diverse stabilization mechanisms. High-temperature sub-fractions contained the oldest carbon across fractions and minerals, thus supporting the assumption that thermal stability can be used as a limited analogue for stability in soil. We present a fine-scale distribution of radiocarbon in SOM and discuss the potential of this method for comparison with other fractionation techniques.&lt;/p&gt;

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