Fate of N in soil amended with 15N-labelled residues of winter cereals combined with an organic N fertiliser

Soil Research ◽  
2016 ◽  
Vol 54 (2) ◽  
pp. 182 ◽  
Author(s):  
Paola Gioacchini ◽  
Daniela Montecchio ◽  
Emanuela Gnudi ◽  
Valeria Terzi ◽  
Antonio Michele Stanca ◽  
...  
Keyword(s):  
Cover Crops ◽  
Crop Residues ◽  
Soil Aggregates ◽  
Aggregate Size ◽  
Soil Aggregate ◽  
Organic N ◽  
Initial Amount ◽  
Winter Cereals ◽  
One Year ◽  
Wet Sieving

In organic farming winter cereals, as cover crops, provide nutrients, when they return to soil as crop residues. The fate of N deriving from two decomposing 15N-labelled winter cereals, with or without the supply of an organic N fertiliser, was studied in a field experiment. The stabilisation of residues N in soil aggregates and the portion lost from the system were also evaluated. Barley or triticale residues were incubated alone or with hydrolysed leather (L) in mesocosms over one year. The residues derived N was measured in soil and in soil aggregate size fractions >250 μm (macroaggregates, macro); 53–250 μm (microaggregates, micro); <53 μm (silt and clay, s+c) obtained by wet sieving. Barley degradation (77% of the initial amount) was faster than triticale degradation (55%). The L slowed down the barley degradation (72%) and speeded that of triticale (64%). Greater amount of residues N was in macro and micro than in s+c. The presence of L reduced the residues N stabilised in the finest fractions. The losses of barley N were reduced by the L addition, those from triticale were increased. The fate of residues N was affected by the L application that influenced the residues mineralisation, the stabilisation and the losses of their derived N.

Aggregate size distribution and stability of an oxisol under legume-based and pure grass pastures in the eastern Colombian savannas

Soil Research ◽  
1995 ◽  
Vol 33 (1) ◽  
pp. 153 ◽  
Author(s):  
AJ Gijsman ◽  
RJ Thomas
Keyword(s):  
Size Distribution ◽  
Soil Aggregates ◽  
Aggregate Stability ◽  
Aggregate Size ◽  
Soil Aggregate ◽  
Hot Water ◽  
Aggregate Size Distribution ◽  
Carbohydrate Concentration ◽  
Stability Measurement ◽  
Water Extractable

This study evaluated soil aggregate size distribution and stability of an Oxisol under improved grass-only or grass-legume pastures, established in previously native savanna. Three grass-legume combinations were included at various stocking rates. In all treatments and soil layers, soils were well aggregated, having more than 90% of their weight in macroaggregates (>250 �m). The addition of legumes to pastures did not affect the soil aggregate size distribution, although aggregates showed somewhat more stability against slaking. An increase in stocking rate negatively affected both average aggregate size and aggregate stability. Aggregates showed little or no dispersion of clay particles in any treatment. A positive correlation was found between wet aggregate stability and hot-water extractable carbohydrate concentration, supporting the hypothesis that these carbohydrates equate with plant-derived or microbial polysaccharides which glue soil aggregates together. It is suggested that determination of hot-water extractable carbohydrates may serve as a useful indicator of small differences in aggregate stability, even when these differences are not evident in the stability measurement itself.

scholarly journals Factors Determining Soil Water Repellency in Two Coniferous Plantations on a Hillslope

Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 730 ◽  
Author(s):  
Moein Farahnak ◽  
Keiji Mitsuyasu ◽  
Kyoichi Otsuki ◽  
Kuniyoshi Shimizu ◽  
Atsushi Kume
Keyword(s):  
Soil Water ◽  
Overland Flow ◽  
Soil Aggregates ◽  
Aggregate Size ◽  
Water Repellency ◽  
Soil Aggregate ◽  
Water Infiltration ◽  
Soil Water Repellency ◽  
Tree Cutting ◽  
Coniferous Plantations

Soil water repellency (SWR) is a cause of low water infiltration, overland flow and soil erosion in mountainous coniferous plantations in Japan. The factors determining SWR intensity were investigated in two coniferous plantations of Chamaecyparis obtusa (Siebold et Zucc.) Endl. and Cryptomeria japonica (L.f.) D. Don, using intact tree plots and cut tree plots on the same hillslope. The SWR of Ch. obtusa plots was stronger than that of Cr. japonica plots. SWR intensity decreased after tree cutting. There were no significant differences in SWR upslope and downslope of individual trees/stumps for both tree species, though areas downslope of individual Ch. obtusa trees had higher SWR intensity than those upslope. SWR intensity and soil aggregate stability were positively correlated in the Ch. obtusa intact tree plot (r = 0.88, p < 0.01), whereas in the cut tree plot, this correlation was weak with no significance (r = 0.29, p = 0.41). Soil aggregate size had a non-significant influence on SWR intensity. These findings suggest that SWR intensity was not related to the soil aggregate size, but SWR intensity seemed have a role in soil aggregation in the Ch. obtusa intact tree plot. Destruction of soil aggregates could occur after tree cutting because of physical disturbances or increased input of different types of organic matter from other vegetation into soil. The presence of Ch. obtusa introduces a source of SWR, although uncertainty remains about how water repellency is distributed around soil aggregates. The distribution pattern of soil water content and soil hydraulic conductivity around Cr. japonica was related to other factors such as the litter layer and non-water-repellant soil.

Stabilization of Soil Aggregates in Relation to Soil Redistribution by Intensive Tillage on a Steep Hillslope

2014 ◽  
Vol 955-959 ◽  
pp. 3566-3571 ◽  
Author(s):  
Yong Wang ◽  
Zhuang Xiong ◽  
Wu Xian Yan ◽  
Yue Qun Qiu
Keyword(s):  
Soil Aggregates ◽  
Geometric Mean ◽  
Aggregate Stability ◽  
Aggregate Size ◽  
Soil Aggregate ◽  
Soil Aggregate Stability ◽  
Mean Weight Diameter ◽  
Tillage Operation ◽  
Sloping Land ◽  
The Impact

The objective of this study was to investigate soil aggregate stability within landscape on hillslopes by intensive tillage. Traditional tillage by consecutive hoeing was performed 5 and 20 times on steeply sloping land of the Sichuan Basin, China, by using the methods of simulated tillage to analyze the impact of long-term tillage on soil aggregates at different slope positions. The dry-sieved method was used to determine distribution of aggregate size in the different landscape positions, and mean weight diameter (MWD) and geometric mean diameter (GMD) as indices of soil aggregate stability. The different times of tillage resulted in different soil aggregate distributions. The results showed that the MWD and GMD values of aggregates were significantly decreased (p< 0.05) after 20-tillage operation, compared with pre-tillage operation. The differences in distributions of MWD and GMD demonstrate that the choice of the tillage times can be an important factor in changing soil aggregate stability and productivity in steeply sloping fields.

scholarly journals THE EFFECT OF SOILAGGREGATE SIZE AND P DOSAGE ON AMF SPORES NUMBER IN SHORGUM (Sorghum bicolor L.)

2018 ◽  
Vol 4 (1) ◽  
pp. 20
Author(s):  
Samsu Samsu ◽  
Henry N Barus ◽  
Uswah Hasanah
Keyword(s):  
Agricultural Land ◽  
Soil Aggregates ◽  
Block Design ◽  
Aggregate Size ◽  
Arbuscular Mycorrhizal ◽  
Dry Weight ◽  
Soil Aggregate ◽  
Experimental Unit ◽  
Randomized Block Design ◽  
Infected Root

Mycorrhiza is a biological agent to help fertility of soil and plants. Application of mycorrhiza on the land in the form of inoculum is often used in agricultural land in the name of quality of inoculum that also influenced by the content of existing spores. One of them is growing medium. This study aimed to study the effect of soil aggregate size and P dosage on the number of mycorrhizal spores in sorghum plants. The research design used was Randomized Block Design consisting of 2 factors. First factor was soil aggregate size(μm) which consisted of 4 treatments: U1 = < 2000, U2 = 500 - 1000, U3 = 200 - 500, U4 = < 200, and second factor was P dosage: 100 mg/kg and 300mg/kg. Each treatment combination was repeated 3 times so that there were 24 units of experimental unit. Observation parameters included the percentage of the infected root, number of spores, plant height and dry weight of the plant. The research was conducted in Greenhouse and Agronomy Laboratory of Agricultural Faculty of Tadulako University Palu. The various sizes of soil aggregates do not affect the amount of arbuscular mycorrhizal spores in sorghum plants. P 100 mg/kg or f P 300 mg/kg dosage used do not address the effect of the mycorrhizal spores. There is no interaction between soil aggregate size and P dosage to the amount of mycorrhizal spores in sorghum plants.

Soil aggregate size affects C sequestration and microorganisms inside aggregate under straw addition

2020 ◽  
Author(s):  
Jinjing Lu ◽  
Sheng ping Li ◽  
Xueping Wu ◽  
Aurore Degre
Keyword(s):  
Large Scale ◽  
Soil Aggregates ◽  
Aggregate Size ◽  
C Sequestration ◽  
Soil Aggregate ◽  
Basic Unit ◽  
Size Fractions ◽  
Soil Microbial ◽  
Relationship Of ◽  
The Relationship

&lt;p&gt;As the basic unit of soil, aggregates are considered as a stable soil organic ( SOC ) pool. Changes in organic subtract due to straw addition induce variations in soil microbial community or activity, which may effect the C sequestration in aggregates. Most of the previous studies on soil microorganisms assessment was done at large scale i.e. larger quantities of soil, however, few studies on SOC is known in aggregate size fractions. This study investigated the effects of soil aggregate size on the distribution of microorganism and SOC, and the relationship of microorganism and C sequestration inside aggregate size fractions with &lt;sup&gt;13&lt;/sup&gt;C-labelled straw addition. Soil samples were collected from 0-15 cm and classified into 5 aggregates sizes classes ( &amp;#65310;5 mm, 2-5 mm, 1-2 mm, 0.25-1 mm and &amp;#65308;0.25 mm ), and the graded aggregates were incubated for 180 days at 20&amp;#160;&amp;#176;C, with or without&amp;#160;&lt;sup&gt;13&lt;/sup&gt;C-labelled straw residue. The incorporation of &lt;sup&gt;13&lt;/sup&gt;C into the five aggregate size fractions was analyzed.&lt;/p&gt;&lt;p&gt;After incubation, the SOC, DOC and ROC contents were increased more rapidly and significantly in aggregate ( &amp;#65310;5 mm ) than that in aggregate ( &amp;#65308;5 mm ) under straw addition, with the same trend of new carbon derived from straw. The total PLFAs was increased most significantly in aggregate ( &amp;#65310;5 mm ), especially fungi and negative bacteria ( G- ), while the positive bacteria ( G+ ) increased slightly in aggregate ( &amp;#65308;0.25 mm ), with no significant change in total PLFAs. The proportion of bacteria in total microorganism increased gradually, as the aggregate size increased in straw treatment. The results imply that aggregate ( &amp;#65310;5 mm ) have more space for C sequestration and greater contribution to new carbon turnovering in soil than other small aggregates, and it gradually tended to be bacterial with the enrichment of carbon. In addition, the SOC contents were strongly related to the amount of fungi and G- in aggregate ( &amp;#65308;5 mm ), while related to G+ in aggregate ( &amp;#65308;0.25 mm ) under straw addition.&lt;/p&gt;

scholarly journals Impact of Cover Crop Monocultures and Mixtures on Organic Carbon Contents of Soil Aggregates

Soil Systems ◽  
2021 ◽  
Vol 5 (3) ◽  
pp. 43
Author(s):  
Daphne Topps ◽  
Md Imam ul Khabir ◽  
Hagir Abdelmagid ◽  
Todd Jackson ◽  
Javed Iqbal ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Cover Crop ◽  
Soil Aggregates ◽  
Aggregate Size ◽  
Soil Aggregate ◽  
Control Treatment ◽  
Hairy Vetch ◽  
Vicia Villosa ◽  
Size Classes ◽  
Oilseed Radish

Cover crops are considered an integral component of agroecosystems because of their positive impacts on biotic and abiotic indicators of soil health. At present, we know little about the impact of cover crop types and diversity on the organic carbon (OC) contents of different soil aggregate-size classes. In this study, we investigated the effect of cover plant diversity on OC contents of different soil aggregates, such as macro- (<2000–500 μm), meso- (<500–250 μm), and micro-aggregates (<250 μm). Our experiment included a total of 12 experimental treatments in triplicate; six different monoculture treatments such as chickling vetch (Vicia villosa), crimson clover (Trifolium incarnatum), hairy vetch (Vicia villosa), field peas (Pisum sativum), oilseed radish (Raphanus sativus), and mighty mustard (Brassica juncea), and their three- and six-species mixture treatments, including one unplanted control treatment. We performed this experiment usingdeep pots that contained soil collected from a corn-soybean rotation field. At vegetative maturity of cover plants (about 70 days), we took soil samples, and the soil aggregate-size classes were separated by the dry sieving. We hypothesized that cover crop type and diversity will improve OC contents of different soil aggregate-size classes. We found that cover plant species richness weakly positively increased OC contents of soil macro-aggregates (p = 0.056), whereas other aggregate-size classes did not respond to cover crop diversity gradient. Similarly, the OC contents of macroaggregates varied significantly (p = 0.013) under cover crop treatments, though neither monoculture nor mixture treatments showed significantly higher OC contents than the control treatment in this short-term experiment. Interestingly, the inclusion of hairy vetch and oilseed radish increased and decreased the OC contents of macro- and micro-aggregates, respectively. Moreover, we found a positive correlation between shoot biomass and OC contents of macroaggregates. Overall, our results suggest that species-rich rather than -poor communities may improve OC contents of soil macroaggregates, which constitute a major portion of soil systems, and are also considered as important indicators of soil functions.

Elevated carbon dioxide and temperature alters aggregate specific methane consumption in a tropical vertisol

2017 ◽  
Vol 155 (8) ◽  
pp. 1191-1202 ◽  
Author(s):  
B. KOLLAH ◽  
U. AHIRWAR ◽  
S. R. MOHANTY
Keyword(s):  
Carbon Dioxide ◽  
Principal Component Analysis ◽  
Soil Aggregates ◽  
Aggregate Size ◽  
Principal Component ◽  
Elevated Carbon Dioxide ◽  
Component Analysis ◽  
Soil Aggregate ◽  
Methane Consumption ◽  
Microbial Numbers

SUMMARYExperiments were carried out to determine methane (CH4) consumption in different soil (vertisol) aggregates under elevated carbon dioxide (eCO2) and temperature. Soil aggregates of <0·25 mm diameter (microaggregates), 0·25–1 mm diameter (mesoaggregates) and 1–2 mm diameter (macroaggregates) were incubated under different CO2(400, 800 and 1200 µm/mor ppm CO2) and temperature (25, 35 and 45 °C) conditions. Methane consumption was high in mesoaggregates and low in microaggregates under ambient CO2and temperature (25 °C). However, eCO2and temperature significantly inhibited CH4consumption and decreased culturable microbial numbers. Methane consumption in mesoaggregates was inhibited by 21–66% at 800–1200 ppm of CO2. Principal component analysis designated soil aggregate size as the most important component of variation, followed by temperature and CO2. Ordination biplot indicated eCO2and temperature impacted negatively on CH4consumption and culturable methanotrophs. Results highlighted that mesoaggregates of 0·25–1·00 mm are hotspots for CH4consumption and that rising atmospheric CO2and temperature may inhibit CH4consumption significantly in a tropical vertisol.

Evaluation of selected factors influencing aggregate fragmentation using fractal theory

1992 ◽  
Vol 72 (2) ◽  
pp. 97-106 ◽  
Author(s):  
V. Rasiah ◽  
B. D. Kay ◽  
E. Perfect
Keyword(s):  
Fractal Dimension ◽  
Probability Model ◽  
Soil Aggregates ◽  
Fractal Theory ◽  
Aggregate Stability ◽  
Aggregate Size ◽  
Red Clover ◽  
Probability Of Failure ◽  
Continuous Corn ◽  
Wet Sieving

Two fractal parameters, probability of failure (P) and fractal dimension (D), were used to evaluate the influence of cropping and wetting treatments, and aggregate size on fragmentation of soil aggregates during wet sieving. Five different sizes of aggregates (4–10, 2–4, 1–2, 0.5–1 and 0.25–0.5 mm) from five cropping treatments [conventionally cultivated continuous corn (CCC), CCC underseeded to red clover (CCR), minimally tilled continuous corn underseeded to red clover (CCRM), alfalfa (AL), and bromegrass (BR)] were subjected to two wetting treatments (rapid and slow) before being wet sieved. P increased nonlinearly with increasing aggregate size. The P of the slowly wetted agggregates was always less than that of the rapidly wetted aggregates. The P of larger aggregates, 2–4 and 4–10 mm, increased in the following order of cropping: BR = AL < CCRM < CCR = CCC. The D for the size distribution of 4- to 10-mm aggregates increased in the same order of cropping as that given previously. The D for the rapidly wetted aggregates was higher than that of the slowly wetted aggregates for all cropping treatments except CCC. The values of P predicted from a fractal probability model correlated well with the observed values. The results show that P and D of soil aggregates are strongly influenced by cropping and wetting treatments and aggregate size. Key words: Probability of failure, fractal dimension, wet sieving, wet aggregate stability, prewetting

scholarly journals Modeling the impact of soil aggregate size on selenium immobilization

2013 ◽  
Vol 10 (3) ◽  
pp. 1323-1336 ◽  
Author(s):  
M. F. Kausch ◽  
C. E. Pallud
Keyword(s):  
Reactive Transport ◽  
Temporal Dynamics ◽  
Transport Model ◽  
Soil Aggregates ◽  
Aggregate Size ◽  
Soil Aggregate ◽  
Drainage Water ◽  
Rate Equations ◽  
Advective Transport ◽  
The Impact

Abstract. Soil aggregates are mm- to cm-sized microporous structures separated by macropores. Whereas fast advective transport prevails in macropores, advection is inhibited by the low permeability of intra-aggregate micropores. This can lead to mass transfer limitations and the formation of aggregate scale concentration gradients affecting the distribution and transport of redox sensitive elements. Selenium (Se) mobilized through irrigation of seleniferous soils has emerged as a major aquatic contaminant. In the absence of oxygen, the bioavailable oxyanions selenate, Se(VI), and selenite, Se(IV), can be microbially reduced to solid, elemental Se, Se(0), and anoxic microzones within soil aggregates are thought to promote this process in otherwise well-aerated soils. To evaluate the impact of soil aggregate size on selenium retention, we developed a dynamic 2-D reactive transport model of selenium cycling in a single idealized aggregate surrounded by a macropore. The model was developed based on flow-through-reactor experiments involving artificial soil aggregates (diameter: 2.5 cm) made of sand and containing Enterobacter cloacae SLD1a-1 that reduces Se(VI) via Se(IV) to Se(0). Aggregates were surrounded by a constant flow providing Se(VI) and pyruvate under oxic or anoxic conditions. In the model, reactions were implemented with double-Monod rate equations coupled to the transport of pyruvate, O2, and Se species. The spatial and temporal dynamics of the model were validated with data from experiments, and predictive simulations were performed covering aggregate sizes 1–2.5 cm in diameter. Simulations predict that selenium retention scales with aggregate size. Depending on O2, Se(VI), and pyruvate concentrations, selenium retention was 4–23 times higher in 2.5 cm aggregates compared to 1 cm aggregates. Under oxic conditions, aggregate size and pyruvate concentrations were found to have a positive synergistic effect on selenium retention. Promoting soil aggregation on seleniferous agricultural soils, through organic matter amendments and conservation tillage, may thus help decrease the impacts of selenium contaminated drainage water on downstream aquatic ecosystems.

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