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

<p>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.</p><p>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.</p><p>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 <sup>13</sup>C<sup>15</sup>N labeled plant litter. Ca-amended soils emitted less CO<sub>2 </sub>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.  </p>

Soil water dynamics and growth of perennial pasture species for dryland salinity control

2000 ◽  
Vol 40 (1) ◽  
pp. 37 ◽  
Author(s):  
S. J. Lolicato
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Lotus Corniculatus ◽  
Growth Patterns ◽  
Water Dynamics ◽  
Seasonal Growth ◽  
Long Term Effects ◽  
Soil Water Dynamics

Fortnightly soil water content measurements to a depth of 2.1 m under 4 cocksfoot cultivars, 2 phalaris cultivars, 2 lucerne cultivars and 1 Lotus corniculatus cultivar were used to compare soil profile drying and to define seasonal patterns of plant water use of the species over a 3-year period, on a duplex soil. Cultivars were also selected, within species groups, for varying seasonal growth patterns to assess this influence on soil water dynamics and growth. Over the 3-year period, treatments with the highest and lowest measures of profile soil water content were used to derive and compare values of maximum plant extractable water. Plots were maintained for a further 3 years, after which soil water content measurements in autumn were used to assess long-term effects of the treatments. The effect of seasonal growth patterns within a species was negligible; however, there were significant differences between species. Twenty-one months after pasture establishment, lucerne alone had a drying effect at 2.0 m depth and subsequently it consistently showed profiles with the lowest soil water content. Maximum plant extractable water was greatest for lucerne (230 mm), followed by phalaris (210 mm), Lotus corniculatus (200 mm) and cocksfoot (170 mm). Profiles with the lowest soil water content were associated with greater herbage growth and greater depths of water extraction. The soil water deficits developed by the treatments in autumn of the fourth year were similar to those measured in autumn of the seventh year, implying that a species-dependant equilibrium had been reached. Long-term rainfall data is used to calculate the probabilities of recharge occurring when rainfall exceeds maximum potential deficits for the different pasture species.

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.

Simulating maize (Zea mays L.) growth and yield, soil nitrogen concentration, and soil water content for a long-term cropping experiment in Ontario, Canada

2014 ◽  
Vol 94 (3) ◽  
pp. 435-452 ◽  
Author(s):  
S. Liu ◽  
J. Y. Yang ◽  
C. F. Drury ◽  
H. L. Liu ◽  
W. D. Reynolds
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Inorganic Nitrogen ◽  
Nitrogen Concentration ◽  
Growth And Yield ◽  
Model Data ◽  
Soil Inorganic Nitrogen ◽  
Soil Inorganic

Liu, S., Yang, J. Y., Drury, C. F., Liu, H. L. and Reynolds, W. D. 2014. Simulating maize (Zea mays L.) growth and yield, soil nitrogen concentration, and soil water content for a long-term cropping experiment in Ontario, Canada. Can. J. Soil Sci. 94: 435–452. A performance assessment of the Decision Support Systems for Agrotechnology Transfer (DSSAT) model (v4.5) including the CERES-Maize and CENTURY modules was conducted for continuous maize production under annual synthetic fertilization (CC-F) and no fertilization (CC-NF) using field data from a long-term (53-yr) cropping experiment in Ontario, Canada. The assessment was based on the accuracy with which DSSAT could simulate measured grain yield, above-ground biomass, leaf area index (LAI), soil inorganic nitrogen concentration, and soil water content. Model calibration for maize cultivar was achieved using grain yield measurements from CC-F between 2007 and 2012, and model evaluation was achieved using soil and crop measurements from both CC-F and CC-NF for the same 6-yr period. Good model–data agreement for CC-F grain yields was achieved for calibration (index of agreement, d=0.99), while moderate agreement for CC-NF grain yields was achieved for evaluation (d=0.79). Model–data agreement for above-ground biomass was good (d=0.83–1.00), but the model consistently underestimated for CC-F and overestimated for CC-NF. DSSAT achieved good model–data agreement for LAI in CC-F (d=0.82–0.99), but moderate to poor agreement in CC-NF (d=0.46–0.64). The CENTURY module of DSSAT simulated soil inorganic nitrogen concentrations with moderate to good model–data agreement in CC-F (d=0.74–0.88), but poor agreement in CC-NF (d=0.40–0.50). The model–data agreement for soil water content was moderate in 2007 and 2008 for both treatments (d=0.60–0.76), but poor in 2009 (d=0.46–0.53). It was concluded that the DSSAT cropping system model provided generally good to moderate simulations of continuous maize production (yield, biomass, LAI) for a long-term cropping experiment in Ontario, Canada, but generally moderate to poor simulations of soil inorganic nitrogen concentration and soil water content.

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 Long-Term Soil Water Content Database, Reynolds Creek Experimental Watershed, Idaho, United States

2001 ◽  
Vol 37 (11) ◽  
pp. 2847-2851 ◽  
Author(s):  
M. S. Seyfried ◽  
M. D. Murdock ◽  
C. L. Hanson ◽  
G. N. Flerchinger ◽  
S. Van Vactor
Keyword(s):  
United States ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Reynolds Creek

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 Dynamics of Soil Water Content Across Different Landscapes in a Typical Desert-Oasis Ecotone

2020 ◽  
Vol 8 ◽  
Author(s):  
Guohua Wang ◽  
Qianqian Gou ◽  
Yulian Hao ◽  
Huimin Zhao ◽  
Xiafang Zhang
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Groundwater Resources ◽  
Time Lag ◽  
Northwest China ◽  
Deep Soil ◽  
Deep Layers ◽  
Desert Oasis

An understanding of soil water content dynamics is important for vegetation restoration in an arid desert-oasis ecotone under different landscapes. In this study, the dynamics of soil water content under three typical landscapes (i.e., desert, sand-binding shrubland, and farmland shelter woodland) were investigated in the Hexi Corridor, northwest China, during the growing season from 2002 to 2013. The results showed that the soil water content in the deep layers decreased from 20–30% to a stable low level of 3–5% in the desert and shrubland. For the farmland shelter woodland, the soil water content at the deep layers also decreased, but the decrease rate was much smaller than the desert and shrubland. The decrease of soil water content in the deep soil layers among desert–shrubland–woodland was strongly associated with the increase of groundwater depths. The greatest increase of groundwater depths mainly occurred during 2008–2011, while the largest decrease of soil water content took place during the years 2009–2011, with a time-lag in response to increase in groundwater depths. This study provides new insight into the long-term dynamics of soil water content in a typical desert oasis ecotone under different landscape components from the influence of overexploiting groundwater that cannot be inferred from a short-term study. The findings demonstrate that the sharp increase of groundwater depths could be the main reason behind the reduction of soil water content in the clay interlayers, and sustainable development of groundwater resources exploitation is very important for the management of desert-oasis ecotone from a long-term perspective.

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