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Copyright of Applied Mathematics & Mechanics (1000-0887) is the property of Applied Mathematics & Mechanics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Potato Journal is the property of Northeast Agricultural University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Slope farmland is the main type of farmland in the black soil region of northeastern China, accounting for about 60% in total. Currently, long-term high intensity utilization and irrational farming have led to the deterioration of soil physical properties, particularly on the gentle and long slope. However, it is still unclear on the effect of different tillage on the soil physical properties of slope positions. In this study, a 4-year field experiment was conducted at the Xiangyang experimental base of Northeast Agricultural University, in order to clarify the impact of farming modes on the vertical distribution of maize roots, and the soil physical properties in the slope farmland of thin black soil in Northeast of China. Two farming treatments were set as no-tillage (NT) and conventional tillage (CT). The slopes were divided longitudinally into three positions from high to low according to the altitude: upper, middle, and lower layer. Each treatment was repeated three times. The particle size distribution of soil water-stable aggregates was obtained at different slope positions. The indicators were measured, including the stability of water-stable aggregates, soil bulk density, soil porosity, soil penetration resistance, and the distribution of vertical depth in root systems. The results showed that: 1) Compared with NT, the CT significantly increased the soil porosity of 0-20 cm soil layer, and the main distribution depth of maize roots, the vertical direction (P<0.05), while significantly reduced the soil layer of 0-20 cm soil bulk density, and soil penetration resistance of 10-20 cm soil layer (P<0.05). 2) Compared with NT, the CT significantly reduced the content of water-stable aggregates larger than 5 mm (P<0.05), with an average reduction of 59.1%, and the average weight diameter of soil water-stable aggregates led to the deterioration of soil structure, but increased the content of water-stable aggregates of 1~2 mm. 3) In the CT treatment, the middle and lower slope were better than the upper slope, according to the evaluation on the influence of slope position on the soil porosity, the content of water-stable aggregates larger than 5 mm, and the average weight diameter. The NT effectively increased the content of water-stable aggregates stability larger than 5 mm in the upper slope soil, and the structural stability in the upper slope soil, thereby to improve the physical properties of the soil. 4) Correlation and regression analysis showed that the plowing can contribute to increase the content of 1-2 mm water-stable aggregates, soil porosity, and the vertical distribution depth of roots, while reduce the soil penetration resistance, the grain size greater than 5 mm the water-stable aggregate content, and the stability of soil structures. The results of the study demonstrated that the plowing can effectively improve the soil compaction and the rooting systems, while lead to the deterioration of soil structure on the slope. Therefore, it is recommended to take conservation measures of water and soil on the upper slope, in order to reduce the soil erosion of slope farmland in the thin black soil area of the Northeast China. [ABSTRACT FROM AUTHOR]

Soil aggregates and organic carbon content are important soil quality evaluation indices. They play important roles in guiding agriculture and ensuring food production safety. In order to solve the problem of deterioration of soil structural properties and decrease of organic carbon content caused by irrational farming in the black soil area of Northeast China, an experiment was carried out in Xiangyang experimental base of Northeast Agricultural University in Harbin since 2015. To study effects of no tillage and straw returning on soil aggregate stability, soil organic carbon content and the soil organic carbon content of the aggregates in 0-10 and 10-20 cm soil layers in the Northeast thin black soil area, four treatments including straw returning with no-tillage (NTS), no-tillage(NT), straw returning with conventional tillage(CTS) and conventional tilliage(CT) were designed. Soil samples were collected in 2018 and 2019. The impact of conservation tillage on the physical and chemical properties of soil was analyzed. The results showed that the percentage content of water-stable aggregates larger than 5 mm and Mean Weight Diameter (MWD) of NTS treatment were significantly higher than those in the other three treatments of 0-10 and 10-20 cm soil layers in 2018 and 2019. Compared with 2018, the percentage content of water-stable aggregates larger than 5 mm of NTS and NT treatments increased to varying degrees in 2019. In 2018, the MWD values of 0-10 cm soil layer ordered from high to low were NTS, NT, CTS and CT. In 2019, the NTS treatment was significantly higher than NT treatment (P<0.05), and no significant difference was found between CTS treatment and CT treatment. In 2018 and 2019, the MWD values of 10-20 cm soil layer ordered from high to low were NTS, NT, CT and CTS, and the difference was significant between treatments (P<0.05). The organic carbon content of soil and organic carbon content in aggregates decreased with the increase of soil depth generally. In 2018, the soil organic carbon content of NTS and NT treatments in 0-10 and 10-20 cm soil layers were significantly higher than those in CTS and CT treatments (P < 0.05). In 2019, no significant difference in 0-10 cm soil layer was found between CT treatment and CTS treatment. In 10-20 cm soil layer of 2019, the contents of soil organic carbon of NTS and NT treatments were not significantly different, and CTS treatment was significantly higher than CT treatment (P < 0.05). In 2018 and 2019, the peak value of organic carbon content of water stable aggregates in 0-10 and 10-20 cm soil layers appeared at 1-2 mm, the organic carbon content of water-stable aggregates smaller than 0.25 mm was the lowest. In 0-10 and 10-20 cm soil layers of 2018 and 2019, the organic carbon contribution rates of water-stable aggregates of >5, 2-5 and 1-2 mm of NTS and NT treatments were higher than those in CTS and CT treatments generally, and those of water stable aggregate smaller than 0.25 mm was smaller than those of CTS and CT treatments. The research showed that no tillage and straw returning were beneficial to stability of soil aggregates and accumulation of organic carbon in different aggregates at sloping farmland of thin black soil. The treatments of no-tillage combined with straw returning had the best effect compared with treatments of no-tillage, conventional tillage and conventional tillage combined with straw returning. [ABSTRACT FROM AUTHOR]

Copyright of Rare Metal Materials & Engineering is the property of Northwest Institute for Nonferrous Metal Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)