C and N stocks and the role of molecular recalcitrance and organomineral interaction in stabilizing soil organic matter in a subtropical Acrisol managed under no-tillage

Geoderma ◽  
2006 ◽  
Vol 133 (3-4) ◽  
pp. 258-268 ◽  
Author(s):  
Cimélio Bayer ◽  
Ladislau Martin-Neto ◽  
João Mielniczuk ◽  
Jeferson Dieckow ◽  
Telmo J.C. Amado
2020 ◽  
Author(s):  
◽  
Kamilla Skaalsveen

No-tillage is a non-inversion farming practice that is becoming more widely used in farming and often considered to enhance soil functions, by increasing soil organic matter levels and thereby improving soil structure. Knowledge about the effects of different management practices on separate soil functions is important to understand potential trade-offs between them. Studies have shown that no-tillage affects soil functions of water purification and water retention and can reduce erosion rates and inputs from agriculture to water bodies, however evidence from north western European countries is still limited. Alongside this gap in evidence about the physical impacts of no-tillage, knowledge about how farmers share knowledge about no-tillage, a knowledge intensive practice, and the role of farmer networks is still growing. This paper presents results from interdisciplinary (PhD) research which measured the effect of no-tillage on water related soil functions in a UK case study and analysed the distribution of no-tillage knowledge through farmer networks. The field-scale monitoring compares two neighbouring farms (one using conventional ploughing and the other no-tillage) with similar soil and topographic characteristics to assess spatial and temporal changes in soil and water variables. The 2-year monitoring included nutrient analysis of surface and sub-surface soil samples, bulk density, soil moisture, infiltration capacity, surface runoff and analysis of Dissolved Reactive Phosphorous (DRP), Total Phosphorous (TP) and Suspended Solids (SS) in downstream waters. Farmers’ networks were mapped using Social Network Analysis (SNA) to reveal the nature and extent of their knowledge exchange about no-tillage. This was complemented by semi-structured interviews with farmers to understand their reasons for implementing no-tillage. This paper presents findings from both aspects of this research. The soil and water data show varying impacts of no-tillage on soil functions and water quality with different soil types and climate. The no-tillage fields had higher bulk density and soil organic matter content and thereby increasing the soil moisture levels, but the free-draining porous limestone was providing greater benefits under no-tillage in this study compared with the limerich loamy soil with high silt and clay content. The SNA suggests that farmers’ networks expanded with the conversion to no-tillage and that their main influencers were other more experienced no-tillage farmers. In this respect I question the role of external organisations in supporting no-tillage adoption. The research offers a significant new contribution to the field as it assesses the effects of no-tillage on water purification and retention functions of the soil, and at the same time contributes to understanding the dynamics of farmer networks and the link to implementation.


Author(s):  
Xiaomeng Wei ◽  
Tida Ge ◽  
Chuanfa Wu ◽  
Shuang Wang ◽  
Kyle Mason-Jones ◽  
...  

2021 ◽  
Author(s):  
Arminda Moreira de Carvalho ◽  
Luana Ramos Passos Ribeiro ◽  
Robélio Leandro Marchão ◽  
Alexsandra Duarte de Oliveira ◽  
Karina Pulrolnik ◽  
...  

2012 ◽  
Vol 42 (11) ◽  
pp. 1953-1964 ◽  
Author(s):  
Irene Fernandez ◽  
Juan Gabriel Álvarez-González ◽  
Beatríz Carrasco ◽  
Ana Daría Ruíz-González ◽  
Ana Cabaneiro

Forest ecosystems can act as C sinks, thus absorbing a high percentage of atmospheric CO2. Appropriate silvicultural regimes can therefore be applied as useful tools in climate change mitigation strategies. The present study analyzed the temporal changes in the effects of thinning on soil organic matter (SOM) dynamics and on soil CO2 emissions in radiata pine ( Pinus radiata D. Don) forests. Soil C effluxes were monitored over a period of 2 years in thinned and unthinned plots. In addition, soil samples from the plots were analyzed by solid-state 13C-NMR to determine the post-thinning SOM composition and fresh soil samples were incubated under laboratory conditions to determine their biodegradability. The results indicate that the potential soil C mineralization largely depends on the proportion of alkyl-C and N-alkyl-C functional groups in the SOM and on the microbial accessibility of the recalcitrant organic pool. Soil CO2 effluxes varied widely between seasons and increased exponentially with soil heating. Thinning led to decreased soil respiration and attenuation of the seasonal fluctuations. These effects were observed for up to 20 months after thinning, although they disappeared thereafter. Thus, moderate thinning caused enduring changes to the SOM composition and appeared to have temporary effects on the C storage capacity of forest soils, which is a critical aspect under the current climatic change scenario.


1999 ◽  
Vol 79 (1) ◽  
pp. 103-109 ◽  
Author(s):  
F. Courchesne ◽  
J.-F. Laberge ◽  
A. Dufresne

The role of soil organic matter (OM) on SO4 retention was investigated by comparing OM content, SO4 retention, and the distribution of Fe, Al and Si compounds in OM-poor (Grands-Jardins, PGJ) and OM-rich (Hermine, HER) Podzols from Québec, Canada. At both sites, four pedons were sampled by horizon; soil pH in H2O, organic C, phosphate-extractable SO4 and, sodium pyrophosphate, acid ammonium oxalate and dithionite-citrate-bicarbonate (DCB) extractable Fe, Al and Si were measured for each mineral horizon. The mineralogy of the clay (<2 µm) and fine silt (2–20 µm) fractions of selected horizons was determined by X-ray diffraction (XRD) and infrared spectroscopy (IR). Weighted mean organic C and pyrophosphate extractable Fe and Al contents were significantly higher in the HER than in the PGJ sola, while the PGJ soils were richer in amorphous inorganic Al. No trends were observed for inorganic Fe compounds. Chemical dissolution and IR allowed the identification of short-range ordered aluminosilicates, probably allophane, in the OM-poor and slightly acidic to neutral PGJ soils. These materials were absent from the OM-rich and acidic HER soils. Phosphate extractions showed that the weighted mean native SO4 content was five times higher in the PGJ than in the HER soil. Finally, native SO4 was strongly related to inorganic Fe, Al and Si (associated with allophane) at PGJ but only to inorganic Fe at HER. These results indicate that OM indirectly affects SO4 sorption through the influence organic substances exerts on the nature and distribution of pedogenic Fe, Al and Si compounds, such as allophane, in Podzolic profiles. Key words: Organic matter, sulfate, imogolite, allophane, silica, Podzol


2021 ◽  
Author(s):  
Moritz Mohrlok ◽  
Victoria Martin ◽  
Alberto Canarini ◽  
Wolfgang Wanek ◽  
Michael Bahn ◽  
...  

&lt;p&gt;Soil organic matter (SOM) is composed of many pools with different properties (e.g. turnover times) which are generally used in biogeochemical models to predict carbon (C) dynamics. Physical fractionation methods are applied to isolate soil fractions that correspond to these pools. This allows the characterisation of chemical composition and C content of these fractions. There is still a lack of knowledge on how these individual fractions are affected by different climate change drivers, and therefore the fate of SOM remains elusive. We sampled soils from a multifactorial climate change experiment in a managed grassland in Austria four years after starting the experiment to investigate the response of SOM in physical soil fractions to temperature (eT: ambient and elevated by +3&amp;#176;C), atmospheric CO&lt;sub&gt;2&lt;/sub&gt;-concentration (eCO&lt;sub&gt;2&lt;/sub&gt;: ambient and elevated by +300 ppm) and to a future climate treatment (eT x eCO&lt;sub&gt;2&lt;/sub&gt;: +3&amp;#176;C and + 300 ppm). A combination of slaking and wet sieving was used to obtain three size classes: macro-aggregates (maA, &gt; 250 &amp;#181;m), micro-aggregates (miA, 63 &amp;#181;m &amp;#8211; 250 &amp;#181;m) and free silt &amp; clay (sc, &lt; 63 &amp;#181;m). In both maA and miA, four different physical OM fractions were then isolated by density fractionation (using sodium polytungstate of &amp;#961; = 1.6 g*cm&lt;sup&gt;-3&lt;/sup&gt;, ultrasonication and sieving): Free POM (fPOM), intra-aggregate POM (iPOM), silt &amp; clay associated OM (SCaOM) and sand-associated OM (SaOM). We measured C and N contents and isotopic composition by EA-IRMS in all fractions and size classes and used a Pyrolysis-GC/MS approach to assess their chemical composition. For eCO&lt;sub&gt;2&lt;/sub&gt; and eT x eCO&lt;sub&gt;2 &lt;/sub&gt;plots, an isotope mixing-model was used to calculate the proportion of recent C derived from the elevated CO&lt;sub&gt;2 &lt;/sub&gt;treatment. Total soil C and N did not significantly change with treatments.&amp;#160; eCO&lt;sub&gt;2&lt;/sub&gt; decreased the relative proportion of maA-mineral-associated C and increased C in fPOM and iPOM. About 20% of bulk soil C was represented by the recent C derived from the CO&lt;sub&gt;2&lt;/sub&gt; fumigation treatment. This significantly differed between size classes and density fractions (p &lt; 0.001), which indicates inherent differences in OM age and turnover. Warming reduced the amount of new C incorporated into size classes. We found that each size class and fraction possessed a unique chemical fingerprint, but this was not significantly changed by the treatments. Overall, our results show that while climate change effects on total soil C were not significant after 4 years, soil fractions showed specific effects. Chemical composition differed significantly between size classes and fractions but was unaffected by simulated climate change. This highlights the importance to separate SOM into differing pools, while including changes to the molecular composition might not be necessary for improving model predictions.&amp;#160;&amp;#160;&amp;#160;&amp;#160;&lt;/p&gt;


Perspektif ◽  
2016 ◽  
Vol 14 (1) ◽  
pp. 61
Author(s):  
Djajadi Djajadi

<p class="Default">ABSTRACT</p><p class="Default">Organik matter has an important role in determining soil health of sugarcane, i.e. soil capacity to support sugarcane to produce sustainable high yield. Soil organic matter influences soil physical, chemical, and biological properties, so that a consequence of declining soil organic matter is poorer soil fertility and lower yield. This paper has an objective to elucidate the important role of organic matter on sustainable farming of sugarcane. The important role of organic matter in soil fertility has been known for a long time before Green Revolution concept was introduced. With more intensity in sugarcane farming and more increasing of sugar demand, application of organic fertilizer started to be substituted by chemical fertilizer. Using green manure and/or biofertilizer has a chance to be spread out to the farmers due to more practical and more efficient than solid organik fertilizer, such as dung manure or compost. Future research should be focusing on the efectivity of green manure and or biofertilzer sources in improving soil fertility and cane yield, minimizing soil pathogen, reducing soil erosion of sugar cane land monoculture, and improving awareness of farmers about soil degradation as consequences of sugarcane monoculture planting for years.</p><p class="Default">Keywords: Organic matter, sugarcane, soil health sustainable farming</p><p class="Default"> </p><p class="Default"><strong>Bahan Organik: Peranannya dalam Budidaya Tebu Berkelanjutan</strong></p><p class="Default">ABSTRAK</p><p class="Default">Bahan organik tanah berperan penting dalam menentukan kesehatan tanah tebu, yaitu kapasitas tanah yang dapat mendukung produksi tebu yang tinggi secara berkelanjutan. Kadar bahan organik tanah mempengaruhi sifat fisik, kimia dan biologi tanah. Paper ini bertujuan untuk menguraikan tentang peranan bahan organik dalam memperbaiki sifat fisik, kimia dan biologi tanah pertanaman tebu. Pentingnya peran bahan oganik tersebut sudah disadari dari dulu, sehingga sebelum revolusi hijau penggunaan pupuk organik sudah umum dilakukan petani. Dengan semakin intensifnya budidaya tebu dan semakin meningkatnya kebutuhan gula, pemanfaatan pupuk organik sudah jarang dilakukan. Diperlukan usaha untuk meningkatkan dan mempertahankan kadar bahan organik pada lahan tebu, antara lain berupa gerakan masal dalam bentuk gerakan nasional melalui program aplikasi bahan organik. Pemanfaatan pupuk hijau dan/atau pupuk hayati berpeluang untuk diterapkan karena lebih praktis dan efisien daripada penambahan pupuk organik padat. Penelitian ke depan perlu difokuskan untuk mengkaji jenis-jenis pupuk organik dan pupuk hayati yang efektif memperbaiki kesuburan, dalam menekan serangan penyakit, meminimalkan erosi pada lahan-lahan tebu monokultur, dan meningkatkan kesadaran petani tebu tentang terjadinya degradasi lahan akibat penanaman tebu yang terus menerus.</p><p class="Default">Kata kunci: Bahan organik, tebu, kesehatan tanah, budidaya berkelanjutan</p><p class="Default"> </p>


2018 ◽  
Vol 10 (8) ◽  
pp. 341
Author(s):  
Rodrigo Santos Moreira ◽  
Marcio Koiti Chiba ◽  
Isabella Clerici De Maria ◽  
Caio César Zito Siqueira ◽  
Aildson Pereira Duarte ◽  
...  

Soil organic matter is considered a key attribute for a sustainable agricultural production and is influenced by the quantity and quality of the crop residue deposited on the soil surface. Therefore, different crop rotations could change the soil organic matter pools. The objectives of this study were to evaluate the soil carbon pools obtained by chemical and physical fractionation methods and the humification index under different crop rotations in a no-till system. We test the following hypothesis: a) the distribution of C and N among the soil organic matter fractions depends on plant species rotation schemes and; b) labile fractions are more sensitive to the input of crop residues and therefore, more suitable for evaluating the impact of different crop rotations in the soil organic matter quality. We evaluated four crop sequences (corn/corn/corn; corn/wheat/corn; soybean/wheat/corn and soybean/corn/corn) in a no-till system. A five-year reforested area was used as reference. We determined the total C and N contents, the mineral-associated C and N, the light fraction of C and N, the labile carbon extracted with KMnO4 and the soil organic matter humification index. We found narrow differences between the crop rotation systems in the total C and N levels, the mineral-associated C and N fractions and the labile C extracted with KMnO4. The diversification of the agricultural system with soybean in crop rotation favored the accumulation of light fraction C and N in the soil that were more efficient to provide information about the changes in the soil organic matter quality.


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