Effects of Ecological Projects on Grassland Soil Physicochemical Properties in Three-River Headwater

2013 ◽  
Vol 807-809 ◽  
pp. 843-847
Author(s):  
Xu Dong Zhao ◽  
De Gang Zhang ◽  
Li Na Shi ◽  
Yong Shun Yang
Keyword(s):  
Organic Matter ◽  
Physicochemical Properties ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Available Phosphorus ◽  
Soil Physicochemical Properties ◽  
Total N ◽  
Effective Measure ◽  
Artificial Grassland

The depth variations of soil physicochemical properties in the degraded native grasslands and the artificially restored grasslands were studied in the Three-river headwater areas of Qinghai-Tibetan plateau, China. The results showed: (1) With the increase of the gradient of restoration years, soil water content, total chemical properties, total potassium, phosphorus, available phosphorus and potassium were increased thereafter in the artificial grasslands. (2) With the increase of grassland degradation gradient, soil water content was gradually reduced, and the total N, K, the organic matter didnt gradually reduced also. (3) Both restoration years and degradation degree didnt influence the nutrient distribution in soil. (4) The organic matter, total N and K of degraded grassland were increased by artificial grassland construction. Therefore, artificial grassland construction canbe used as an effective measure of ecological projects in the Three-river headwater area.

scholarly journals Biochar and Rhizobacteria Amendments Improve Several Soil Properties and Bacterial Diversity

2020 ◽  
Vol 8 (4) ◽  
pp. 502
Author(s):  
Han Ren ◽  
Baoling Huang ◽  
Víctor Fernández-García ◽  
Jessica Miesel ◽  
Li Yan ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Physicochemical Properties ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Community Composition ◽  
Soil Conditions ◽  
Microbial Composition ◽  
Total N ◽  
Total P

In the current context, there is a growing interest in reducing the use of chemical fertilizers and pesticides to promote ecological agriculture. The use of biochar and plant growth-promoting rhizobacteria (PGPR) is an environmentally friendly alternative that can improve soil conditions and increase ecosystem productivity. However, the effects of biochar and PGPR amendments on forest plantations are not well known. The aim of this study is to investigate the effects of biochar and PGPR applications on soil nutrients and bacterial community. To achieve this goal, we applied amendments of (i) biochar at 20 t hm−2, (ii) PGPR at 5 × 1010 CFU mL−1, and (iii) biochar at 20 t hm−2 + PGPR at 5 × 1010 CFU mL−1 in a eucalyptus seedling plantation in Guangxi, China. Three months after applying the amendments, we collected six soil samples from each treatment and from control plots. From each soil sample, we analyzed several physicochemical properties (pH, electrical conductivity, total N, inorganic N, NO3−-N, NH4+-N, total P, total K, and soil water content), and we determined the bacterial community composition by sequencing the ribosomal 16S rRNA. Results indicated that co-application of biochar and PGPR amendments significantly decreased concentrations of soil total P and NH4+-N, whereas they increased NO3-N, total K, and soil water content. Biochar and PGPR treatments increased the richness and diversity of soil bacteria and the relative abundance of specific bacterial taxa such as Actinobacteria, Gemmatimonadetes, and Cyanobacteria. In general, the microbial composition was similar in the two treatments with PGPR. We also found that soil physicochemical properties had no significant influence on the soil composition of bacterial phyla, but soil NH4+-N was significantly related to the soil community composition of dominant bacterial genus. Thus, our findings suggest that biochar and PGPR amendments could be useful to maintain soil sustainability in eucalyptus plantations.

Distribution of carbon and nutrients and fluxes of mineral nitrogen after clear-felling a Pinusradiata plantation

1990 ◽  
Vol 20 (9) ◽  
pp. 1490-1497 ◽  
Author(s):  
P. J. Smethurst ◽  
E. K. S. Nambiar
Keyword(s):  
Organic Matter ◽  
Soil Temperature ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
N Mineralization ◽  
Soil Depth ◽  
Mineral N ◽  
Southeastern Australia ◽  
Nutrients Fluxes

The effects of clear-felling and slash removal on the distribution of organic matter and nutrients, fluxes of mineral N, and soil water and temperature were studied in a 37-year-old Pinusradiata D. Don plantation, on a sandy Podzol in southeastern Australia. Slash, litter, and the top 30 cm of soil combined contained 1957 kg N•ha−1, of which slash and litter contained 12 and 25%, respectively. Therefore, loss of slash and litter due to burning or other intensive site preparation practices would substantially reduce the N capital at the site. During the first 18 months after clear-felling, soil water content in the clear-felled area was up to 50% higher than in the uncut plantation, but there were only minor differences in soil temperature. Slash removal decreased the water content of litter, but had little effect on the water content or temperature of the soil. In the uncut plantation, N mineralized in litter and soil was completely taken up by the trees. Following clear-felling, rates of N mineralization increased in litter after 4 months, and in soil after 12 months, but changes were less pronounced with slash removal. After clear-felling, increased mineralization and the absence of trees (no uptake) led to increased concentrations of mineral N in both litter and soil, 64–76% of which was leached below the 30 cm soil depth prior to replanting. Despite leaching, concentrations of mineral N after clear-felling remained higher than those in the uncut plantation for at least 3 years.

scholarly journals Evaluation of Improved Model to Accurately Monitor Soil Water Content

Water ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 3441
Author(s):  
Jingyu Ji ◽  
Junzeng Xu ◽  
Yixin Xiao ◽  
Yajun Luan
Keyword(s):  
Organic Matter ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Texture ◽  
Irrigation Management ◽  
Clay Fraction ◽  
Organic Matter Content ◽  
Matter Content ◽  
Improved Model

The accurate monitoring of soil water content during the growth of crops is of great importance to improve agricultural water use efficiency. The Campbell model is one of the most widely used models for monitoring soil moisture content from soil thermal conductivities in farmland, which always needs to be calibrated due to the lack of adequate original data and the limitation of measurement methods. To precisely predict the water content of complex soils using the Campbell model, this model was evaluated by investigating several factors, including soil texture, bulk density and organic matter. The comparison of the R2 and the reduced Chi-Sqr values, which were calculated by Origin, was conducted to calibrate the Campbell model calculated. In addition, combining factors of parameters, a new parameter named m related to soil texture and the organic matter was firstly introduced and the original fitting parameter, E, was improved to an expression related to clay fraction and the organic matter content in the improved model. The soil data collected from both the laboratory and the previous literature were used to assess the revised model. The results show that most of the R2 values of the improved model are >0.95, and the reduced Chi-Sqr values are <0.01, which presents a better matching performance compared to the original. It is concluded that the improved model provides more accurate monitoring of soil water content for water irrigation management.

scholarly journals Long-Term Soil Water Content and Exchangeable Ca Interact to Stabilize Organic Matter

2020 ◽  
Author(s):  
Itamar Shabtai ◽  
Srabani Das ◽  
Thiago Inagaki ◽  
Johannes Lehmann
Keyword(s):  
Organic Matter ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Exchangeable Ca

Long-term soil water content and exchangeable Ca interact to stabilize organic matter

2020 ◽  
Author(s):  
Itamar Shabtai ◽  
Srabani Das ◽  
Thiago Inagaki ◽  
Ingrid Kogel-Knabner ◽  
Johannes Lehmann
Keyword(s):  
Organic Matter ◽  
Soil Moisture ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Microbial Respiration ◽  
Plant Litter ◽  
Exchangeable Ca

&lt;p&gt;Organo-mineral interactions stabilize soil organic matter (SOM) by protecting from microbial enzymatic attack. Soil water content affects aggregation, mineral weathering, and microbial respiration, thus influencing the relative importance of SOM stabilization mechanisms. While the response of microbial respiration to momentary changes in water content is well established, it is unclear how microbial activity will impact stabilization mechanisms under different long-term moisture contents.&lt;/p&gt;&lt;p&gt;To understand how long-term soil moisture affects SOM stabilization mechanisms we studied fallow soils from upstate New York situated on a naturally occurring water content gradient. Wetter (but not saturated) soils contained more exchangeable Ca and had more strongly stabilized SOM, resulting in SOM accumulation. But it was not clear whether Ca-driven surface interactions or occlusion in micro-aggregates was more important, and if interactions with Fe and Al played a role in the Ca-poor soils. Also, the role of biotic drivers in SOM stabilization at different water contents was unknown.&lt;/p&gt;&lt;p&gt;We tested which mechanisms governed SOM stabilization by determining C and N contents and natural isotope abundances in particulate and mineral-associated organic matter fractions. We also extracted the C bound to Ca and to reactive Fe+Al phases. Wetter, Ca-rich soils had higher oPOM content, and in the heavy mineral fraction, higher relative concentrations of Ca-bound C, lower C:N values, and more oxidized C forms. In addition, wetter soils had greater microbial biomass. Together, these results showed that high long-term soil moisture increased microbial SOM cycling, and that processed SOM was better stabilized, in agreement with the recent notion that stable SOM consists of processed labile C. Additionally, higher soil moisture augmented the role of Ca in SOM stabilization over that of Al+Fe phases. We then manipulated the exchangeable Ca content and incubated soils with &lt;sup&gt;13&lt;/sup&gt;C&lt;sup&gt;15&lt;/sup&gt;N labeled plant litter. Ca-amended soils emitted less CO&lt;sub&gt;2 &lt;/sub&gt;while incubated with litter, confirming that Ca is instrumental in SOM stabilization. Tracing the labeled isotopes in the gaseous phase and soil fractions will allow us to gain a clearer understanding of how water content and soil Ca interact to stabilize SOM.&amp;#160;&amp;#160;&lt;/p&gt;

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