【Objective】Based on the long-term fertilization experiment station, in aims to study the influences on the soil fertility by long-term application of chemical fertilizer and manure, the characteristics of water stable aggregates and structure of organic carbon was analyzed under different fertilizer application conditions.【Method】0-20 cm soil samples were collected from the 37-year long-term field experiment, including six treatments: CK (no fertilizer), NPK (chemical fertilizer alone), M2 (normal manure application), M2NPK (the chemical fertilizer combined with normal manure rate), M4 (high quantity manure application), and M4NPK (the chemical fertilizer combined with high quantity manure rate). Stability of water stable aggregates and distribution of organic carbon in aggregates were analyzed by wet sieve method.【Result】The proportion of large aggregates was reduced,while the proportion of micro aggregates was increased significantly under long-term application of organic and chemical fertilizer and high amount of organic fertilizer conditions. There was not significant change for the distribution of aggregates under long-term application of chemical fertilizer and constant organic fertilizer conditions. Compared with CK, the proportions in macro-aggregate of M2NPK, M4NPK and M4 were reduced by 32.7%, 45.8% and 55.4%, respectively, and the proportion of that in micro-aggregate were increased by 73.2%, 102.5% and 123.9%, respectively. The stability of surface soil water stable aggregates was reduced significantly under long-term organic combined chemical fertilizer and high amount of organic fertilizer conditions. The soil organic carbon content was increased significantly by 1.12-2.06 times as much as CK under long-term fertilization condition, and the increase of organic carbon content was more significantly in organic fertilizer and organic combined with chemical fertilizer. The content of organic carbon in soil water stable aggregates of each size was increased under long-term organic fertilizer application, while the increase of organic carbon content in each treatment was gradually decreased with the decrease of particle size. Organic carbon content in the water stable macro-aggregate was significantly higher than that in the micro-aggregate, indicating that the organic carbon was mainly distributed in the macro-aggregate. The contribution rate of organic carbon in macro-aggregate was reduced significantly, and the contribution rate of organic carbon was increased significantly in micro-aggregate under long-term application of high amount of organic and combined with chemical fertilizer. The contribution rate of organic carbon in other treatments was higher in macro-aggregates than in micro-aggregates.【Conclusion】There were no significant effect for distribution and organic carbon content in aggregates under long-term chemical fertilization. The proportion of macro-aggregates and the stability of soil aggregates were reduced significantly under high amount of organic fertilizer and combination of organic and chemical fertilizer. The content of organic carbon in the aggregates was increased significantly under long-term application of organic fertilizer. The contribution rate of organic carbon in macro-aggregates was reduced significantly under high amount of organic fertilizer and combined with chemical fertilizer. The micro-aggregate was the dominant aggregate size of the organic carbon contribution rate.
【Objective】The objectives of this study were to assess the in?uence of long-term fertilization on the soil dissolved organic carbon (DOC) as well as soil dissolved organic nitrogen (DON) under various use types, cropping systems and soil pH, to give management guidance on how to increase soil carbon and nitrogen in Chinese Cropland. 【Method】In current study, 72 literatures including effects of long-term fertilization on the contents of DOC and DON in Chinese Cropland from 2000 to 2019 were selected (510 dataset for DOC and 208 dataset for DON). The meta-analysis was used to investigate how the magnitude of the DOC and DON contents response to mineral fertilizer and manure application at three aspects: use types, cropping systems and soil pH.【Result】At national scale, the contents of DOC and DON in the fertilized soils were significantly higher than those in the no fertilized soils (CK). The increments of DOC and DON contents in manure applied soils (60%和93%) were 4.6 and 3.2 times higher than those in the soils with mineral fertilizers (13% and 29%). Under different use types, fertilizer application can significantly increase the contents of DOC and DON in upland soil, and the increments of DOC and DON contents improved by manure in upland soil were higher than those in upland-paddy soil. Furthermore, manure application could increase the content of DOC in mono-cropping (85%) compared with no fertilizer (CK), which was significantly higher than that in double-cropping (38%). For the alkaline soils (pH>7.5), the increments of DOC and DON contents in the treatment with manure amendment (85% and 162%) were higher than those in the neutral (6.5＜pH＜7.5, 48% and 70%) and acidic soils (pH＜6.5, 32% and 61%) compared with no fertilizer (CK), respectively. 【Conclusion】In summary, the application of manure (only manure or combined with mineral fertilizer) could significantly increase the contents of DOC and DON, but the effects varied greatly across various use types, cropping systems, soil pH. Therefore, the appropriate conditions of soil and environment should be taken into account when applying manure.
【Objective】The purpose of this study was to identify the effect of no-tillage with manure on soil enzyme activities and soil organic carbon content, clarify scientific application of fertilizers under no-tillage system, enhance soil biological activity, and promote soil quality.【Method】Based on the long-term field experiment in Yuncheng, Shanxi, we selected no-tillage (NT) treatment and no-tillage with manure (NTM) to measure soil enzyme activity (β-Glucosidase, β-Xylanase, cellobiohydrolase, and α-1,4-Glucosidase) relating to carbon transformation, soil temperature, soil water content and soil respiration rate in growth stages of winter wheat and soil total organic carbon and soil active organic carbon content (dissolved organic carbon - DOC; Easily oxidized organic carbon - EOC; Microbial biomass carbon -MBC) in productive growth stages of winter wheat.【Result】(1) There were significant seasonal differences in soil enzyme activities among the growth stages of winter wheat. The activities of β-Xylanase and α-1,4-Glucosidase increased in jointing stage and filling stage, while the activity of β-Glucosidase and cellobiohydrolase showed a small fluctuation. The changes of soil respiration at different growth stages were basically consistent with the activities of β-Xylanase and α-1,4-Glucosidase. Besides, the results of principal component analysis showed that the soil enzyme activities were mainly affected by soil water content and soil respiration rate. (2) No-tillage with manure significantly increased β-Xylanase activity at different growth stages (over-wintering stage: 17.6%, heading stage: 8.5%, filling stage: 14.1%, and mature stage: 10.0%). The activity of α-1, 4-Glucosidase increased by 16.7% and 10.2% respectively at the overwintering stage and jointing stage. The results of principal component analysis showed that the enzyme activities were mainly affected by soil temperature and soil respiration rate. (3) No-tillage with manure significantly increased the content of TOC, DOC, EOC and MBC in winter wheat growing season (TOC: 16.9%, DOC: 27.7%, EOC: 38.4% and MBC: 50.7%). (4) The correlation analysis of soil biological indicators were higher between β-Xylanase, α-1, 4-Glucosidase activities and total organic carbon, organic carbon active components in winter wheat growth stages (correlation index were greater than 0.85).【Conclusion】No-tillage with manure increased β-Xylanase and α-1,4-Glucosidase activities by influencing soil water content and soil temperature. Meanwhile, the addition of manure increased the content of total organic carbon and active organic carbon components on the basis of straw returning to the field, which was beneficial to the improvement in biological activities such as soil enzyme and soil quality.
【Objective】This study was aimed to explore the characteristics of the labile organic matter (LOM) and carbon pool management index (CPMI) under different fertilization in different soil layers in red soil, so as to provide a theoretical basis for carbon pool management in red soil. 【Method】Based on the long-term experiment site located at Jinxian, Jiangxi province, four typical treatments were chosen as: (1) no fertilization (CK); (2) mineral nitrogen, phosphorus, potassium (NPK); (3) NPK combined with pig manure and straw (NPKSM); (4) NPK combined with straw (NPKS). The highly LOM (HLOM), moderately LOM (MLOM), lowly LOM (LLOM), non-LOM (NLOM) and CPMI in four soil depths (i.e. 0-10 cm, 10-20 cm, 20-40 cm and 40-60 cm) were measured and analyzed. 【Result】The results showed that the soil organic matter (SOM) content under each treatment was decreased with increasing of soil depths. Compared with CK treatment, the SOM was increased under the fertilization treatments. In 0-20 cm, the SOM content was ordered as NPKSM >NPKS >NPK >CK, with the highest value as 43.47 g·kg -1(10-20 cm) and 45.09 g·kg -1(0-10 cm) under NPKSM treatment. In 20-60 cm, the SOM content under NPKSM and NPKS was significantly higher than that under CK, while there was no different between NPKSM and NPKS. The dissolved organic carbon (DOC) content was decreased with soil depth under all treatments except NPK. The DOC content under NPKSM and NPKS was significantly higher than that under NPK and CK, and the highest value was 35.93 mg·kg -1under NPKSM treatment. The HLOM, MLOM, and LLOM content were increased under fertilization treatments compared with CK treatment. The LOM content was ordered as LLOM> MLOM> HLOM under the same treatment in same soil layer. All the LOM components content was significantly higher under NPKSM and NPKS treatments in all soil layers. The HLOM and MLOM content under all treatments were trended as first increased and then decreased with increasing of soil depth. The HLOM content was reached to peak in 20-40 cm under NPKSM (5.31 g·kg -1) and NPKS (5.49 g·kg -1). The highest MLOM content appeared in 10-20 cm under NPKSM treatment with 10.62 g·kg -1. The LLOM content under all treatments was decreased with soil depth. In 0-20 cm, the LLOM content was highest under NPKSM treatment with 18.52 g·kg -1(0-10 cm) and 15.93 g·kg -1(10-20 cm), respectively. The proportion of different LOM components and CPMI were increased under the fertilizer treatments. In 0-10 cm, compared with CK, the LOM content under NPKS and NPKSM was increased by 27.9%and 29.48%, respectively, MLOM proportion was increased by 7.21% and 7.72%, respectively, HLOM proportion was increased by 5.10% and 4.96%, respectively. The CPMI under fertilization treatment was higher than 100, and which was obviously higher under NPKSM and NPKS. In 0-20 cm, the different LOM components were extremely significantly positive correlation(P≤0.01), and they were significantly positive correlated with total SOM, total nitrogen, dissolved SOM and rice yield (P≤0.05). 【Conclusion】The SOM and LLOM content under all treatments were decreased with the increasing of soil depth. The SOM and all LOM components were significantly improved under NPKSM treatment, and HLOM and CPMI under NPKSM were the highest, followed by NPKS in 0-20 cm, while, which was the highest under NPKS in 20-60 cm.
【Objective】The change characteristics of water soluble organic carbon (WSOC) content and components in black soil with the addition of different organic materials were explored to provide a scientific basis for soil fertility improvement methods in black soil area.【Method】This study was based on experimental plots of returning organic materials to the field in Keshan County, Heilongjiang Province, and the experiment has lasted for seven years. The content and structure of WSOC treated with organic fertilizer, biochar, straw and single fertilizer treatment (CK) was analyzed by routine determination and fluorescence analysis.【Result】Compared with the single application of chemical fertilizer, the content of soil water-soluble organic carbon increased by 9.65%-20.30% and soil organic carbon increased by 6.63%-14.86% under the application of organic materials. The contents of tyrosine-like protein and tryptophan-like protein in WSOC decreased under the treatment of organic materials. The application of organic fertilizer increased the contents of metabolites of soluble microorganisms in WSOC, increased the contents of fulvic acid and humic acid in WSOC, and simplified their structures. Straw and biochar simplified the structure of fulvic acids and biochar complicates the structure of humic acids in WSOC.【Conclusion】Organic fertilizer, biochar and straw improved the content of soil water-soluble organic carbon, enhanced the decomposition and metabolism of soil microorganisms, increased the content and simplified the structure of fulvic acid component in water-soluble organic carbon. Organic fertilizer had the best effect.
