Beneficial effects of reduced tillage and green manure on soil aggregation and stabilization of organic carbon in a Mediterranean agroecosystem (original) (raw)
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Tillage and Manure Effects on Soil and Aggregate-Associated Carbon and Nitrogen
Soil Science Society of America Journal, 2004
. Golchin et al. (1994) divided SOM based on difference in position within the soil matrix and In agricultural systems, maintenance of soil organic matter (SOM) accessibility to soil organisms into (i) free particulate has long been recognized as a strategy to reduce soil degradation. organic matter (POM) and (ii) occluded POM (POM No-tillage and manure amendments are management practices that within aggregates). Mineralization studies of C and N can increase SOM content and improve soil aggregation. We investigated the effects of 10
Soil & Tillage Research, 2020
Studying the impact of different tillage systems on soil organic matter (SOM) dynamics is essential to define better strategies to improve soil fertility and soil organic carbon (SOC) sequestration. We used density fractio-nation to assess the changes in SOM in an Inceptisol following nine-years of contrasting tillage under wheat (Triticum aestivum) based cropping systems. The major objective of the study was to investigate the amount of C content within soil aggregates as influenced by tillage and residue management. For this a nine-year old experiment was conducted with two tillage practices in main plots (zero-tillage: ZT and conventional tillage: CT) and four residue management practices in sub-plots (No residue: NR, wheat residue: WR, soybean residue: SR and wheat + soybean residue: WR + SR). The results indicated that SOC content increased by ∼48, 42 and 36%, respectively, in WR + SR, SR and WR plots compared with the NR plots in the 0-5 cm soil layer. The SOC content within macroaggregates were ∼30 and 25% higher in the ZT plots than CT in the 0-5 and 5-15 cm soil depths, respectively. The intra-aggregate particulate organic matter (iPOM) inside microaggregates within macroaggregates (iPOM_mM) was ∼16% higher in the CT than the ZT plots. Tillage management had no significant effect on light fraction inside microaggregates within macroaggregates (LF_mM) and iPOM_mM SOC contents inside microaggregates within macroaggregates (mM) in the surface soil, but residue management improved LF_mM and iPOM_mM SOC contents. The WR + SR, SR and WR plots had ∼73, 40 and 35% more LF_mM SOC content, respectively, than NR plots. Within free microaggregates in the surface soil, the LF_m SOC content was significantly enhanced due to ZT operation by ∼61% than the CT plots but not by crop residue addition. The iPOM_mM and iPOM_m fraction accounted for about ∼35 and 51% of the total SOC content within macroaggregates and microaggregates, respectively. That indicates the role of iPOM fraction in SOC seques-tration within the soil aggregates in tropical Inceptisol. Plots under ZT had ∼38% more C content inside mi-croaggregates within macroaggregates (mM) than CT (2.31 Mg ha-1), indicating ZT management could be adopted for C stabilization within aggregates.
Agriculture
Tillage is a significant type of soil intervention and should be conducted based on the specific soil type. The aim of this study was to determine the influence of different tillage intensities (RT: reduced tillage; CT: conventional tillage), which are correlated with carbon sequestration, on soil properties. The study areas included fields on real farms in Eutric Fluvisol (EF), Mollic Fluvisol (MF), Haplic Chernozem (HC), Haplic Luvisol (HL), Eutric Regosol (ER), Eutric Gleysol (EG), and Stagnic Planosol (SP). The effects of tillage systems depended on the soil type and were more evident in soil aggregates of more productive soils. Agronomically, the most valuable fractions of aggregates were dominant in more productive soils (EF, MF, HC) in the CT system and less dominant in less productive soils (HL, ER, EG, SP) in the RT system. Smaller aggregates (<0.5 mm), which indicate deterioration of soil properties, were negatively correlated with clay (r = −0.364, p < 0.01), total ...
International Journal of Current Microbiology and Applied Sciences, 2019
Tillage systems can changes in soil organic carbon dynamics and soil microbial biomass by changing aggregate formation and C distribution within the aggregate. However, the effects of tillage method or straw return on soil organic C (SOC) have showed inconsistent results in different soil/climate/ cropping systems. Soil TOC and labile organic C fractions contents were significantly affected by straw returns, and were higher under straw return treatments than non-straw return at three depths. The soil organic carbon (SOC) stock in bulk soil was 40.2-51.1% higher in the 0.00-0.05 m layer and 11.3-17.0% lower in the 0.05-0.20 m layer in NT system no-tillage without straw (NT-S) and with straw (NT+S), compared to the MP system moldboard plow without straw (MP-S) and with straw (MP+S), respectively. Residue incorporation caused a significant increment of 15.65% in total water stable aggregates in surface soil (0– 15 cm) and 7.53% in sub-surface soil (15–30 cm). In surface soil, the maximum (19.2%) and minimum (8.9%) proportion of total aggregated carbon was retained with >2 mm and 0.1–0.05 mm size fractions, respectively. At 0–7 cm depth, soil MBC was significantly higher under plowing tillage than rotary tillage, but EOC was just opposite. Rotary tillage had significantly higher soil TOC than plowing tillage at 7–14 cm depth. However, at 14– 21 cm depth, TOC, DOC and MBC were significantly higher under plowing tillage than rotary tillage except for EOC. A considerable proportion of the total SOC was found to be captured by the macro-aggregates (>2–0.25 mm) under both surface (67.1%) and sub-surface layers (66.7%) leaving rest amount in micro-aggregates and „silt + clay‟ sized particles. Application of inorganic fertilizer could sustain soil organic carbon (SOC) concentrations, whereas long-term application of manure alone or combined with NPK (M and NPK + M) significantly increased SOC contents compared with the unfertilized control. Manure application significantly increased the proportion of large macro-aggregates (> 2000 μm) compared with the control, while leading to a corresponding decline in the percentage of micro-aggregates (53–250 μm). Carbon storage in the intra-aggregate particulate organic matter within micro-aggregates was enhanced from 9.8% of the total SOC stock in the control to 19.7% and 18.6% in the M and NPK + M treatments, respectively. The shift in SOC stocks towards micro-aggregates is beneficial for long-term soil C sequestration. Moreover, the differences in the micro-aggregate protected C accounted, on average, for 39.8% of the differences in total SOC stocks between the control and the manure-applied treatments. Thus, we suggest that the micro-aggregate protected C is promising for assessing the impact of conventional and conservation agriculture on SOC storage in the vertisol. Soil disturbance by tillage leads to destruction of the protective soil aggregate. This in turn exposes the labile C occluded in these aggregates to microbial breakdown. The present study found that SOC change was significantly influenced by the crop residue retention rate and the edaphic variable of initial SOC content.
The identification of sensitive soil organic carbon (SOC) fractions can be crucial for an understanding of SOC dynamics and stabilization in soil. This study was conducted during 2012-14 in fallow-wheat cropping system at loess dryland Pothwar, Pakistan to assess the effect of minimum tillage (MT), reduced tillage (RT), zero tillage (ZT) and conventional tillage (CT), with residue retuned (R +) and removed (R-) on SOC fractions and aggregate stability. The results showed that the ZT with residue returned provided the highest amount of SOC (7.80g kg-1), microbial biomass carbon (MBC, 473 µg kg-1), particulate organic carbon (POC, 2.27 g kg-1) and water stable aggregates (WSA, 36%). On the other hand, CT with residue removed gave the least amounts of SOC (5.35 g kg-1), MBC (130 µg kg-1), POC (1.25 g kg-1) and aggregate stability (24%). The trend among tillage treatments was ZT > RT > MT > CT for studied parameters. Among residue treatments, residue return (+R) had higher SOC ...
Journal of Soil and Water Conservation, 2014
Soil tillage can affect the formation and stability of soil aggregates. The disruption of soil structure weakens soil aggregates to be susceptible to the external forces of water, wind, and traffic instantaneously, and over time. The choice of tillage system or land management changes the soil physical condition and soil organic matter content, which is an essential factor in building soil aggregates. This study was conducted to investigate the effects of different tillage systems on the rate of decay of different sizes of soil aggregate fractions and other associated properties over time as subjected to a continuous wetting process. This research was conducted on a long-term tillage study, established in 2002 at the Iowa State University Agronomy Research Farm near Ames, Iowa. The soil association in this study is Clarion-Nicollet-Webster (Clarion [fine-loamy, mixed, mesic, Typic Hapluduolls], Nicollet [fine-loamy, mixed, mesic, Aquic Hapluduolls], and Webster [fine-loam, mixed, mesic, Typic Endoaquolls]). The experimental design was a randomized complete block design with four replications. Main plot treatments were five tillage systems: moldboard-plow, chisel-plow, deep-rip, strip-till, and no-till. The cropping system was corn (Zea mays L.)soybean (Glycine max L.) rotation. Wet aggregate stability was measured using the Wet Sieving Apparatus (Eijkelkamp, Agrisearch Equipment. Art no. 08.13). Soil organic carbon (SOC) and soil total nitrogen (N) were analyzed by dry combustion using CHN Analyzer (TruSpec CHN Version 2.5x). Results show no-till with the highest carbon (C) content and the highest macro-and microaggregate stability over time. The findings also show a strong relationship between the increase in SOC content and the stability of macro-and microaggregate under continuous wetting process. Furthermore, the findings suggest that aggregate stability and moisture content are highly correlated with SOC content, and the rate of decay of both aggregate sizes (macro and micro) is highly influenced by the intensity of tillage. The implication of this research is the importance of no-till not only in increasing the stability of micro-and macroaggregates and SOC storage, but also in its effect on increasing the stability of all aggregate fractions in continuous wet conditions for extended periods of time.
Applied Soil Ecology, 2001
Changes in the proportions of water-stable soil aggregates, organic C, total N and soil microbial biomass C and N, due to tillage reduction (conventional, minimum and zero tillage) and crop residue manipulation (retained or removed) conditions were studied in a tropical rice-barley dryland agroecosystem. The values of soil organic C and total N were the highest (11.1 and 1.33 g kg −1 soil, respectively) in the minimum tillage and residue retained (MT + R) treatment and the lowest (7.8 and 0.87 g kg −1 , respectively) in conventional tillage and residue removed (CT − R) treatment. Tillage reduction from conventional to minimum and zero conditions along with residue retention (MT + R, ZT + R) increased the proportion of macroaggregates in soil (21-42% over control). The greatest increase was recorded in MT + R treatment and the smallest increase in conventional tillage and residue retained (CT + R) treatment. The lowest values of organic C and total N (7.0-8.9 and 0.82-0.88 g kg −1 soil, respectively) in macro-and microaggregates were recorded in CT − R treatment. However, the highest values of organic C and total N (8.6-12.6 and 1.22-1.36 g kg −1 , respectively) were recorded in MT + R treatment. The per cent increase in the amount of organic C in macroaggregates was greater than in microaggregates. In all treatments, macroaggregates showed wider C/N ratio than in microaggregates. Soil microbial biomass C and N ranged from 235 to 427 and 23.9 to 49.7 mg kg −1 in CT − R and MT + R treatments, respectively. Soil organic C, total N, and microbial biomass C and N were strongly correlated with soil macroaggregates. Residue retention in combination with tillage reduction (MT+R) resulted in the greatest increase in microbial biomass C and N (82-104% over control). These variables showed better correlations with macroaggregates than other soil parameters. Thus, it is suggested that the organic matter addition due to residue retention along with tillage reduction accelerates the formation of macroaggregates through an increase in the microbial biomass content in soil.
Soil Science Society of America Journal, 2008
Tillage events have an important infl uence on residue incorporation into soil profi les and soil aggregate disruption, and ultimately infl uence the net C gain or loss in soils. Thus, our objective was to evaluate tillage-induced infl uences on aggregate structure, residue-derived C stabilization, and the subsequent effi ciency of C stabilization in aggregates of no-till (NT) and tillage management (TM) practices at different depth increments of the soil profi le. Uniformly 13 C-labeled wheat residues were added to incubation cores representing soils under NT and TM during a year-long in situ incubation at a dryland agriculture experiment site. Residue was added directly onto the surface of NT cores, while residues were incorporated into the 0-to 5-, 5-to 15-, and 15-to 30-cm depth increments of the TM cores. We found that residue additions did not have a signifi cant effect (P > 0.05) on aggregate dynamics in either NT or TM, but NT management did result in the greatest stabilization of residue-derived C (11.2 ± 2.4 g residue C kg −1 soil kg −1 residue C added, P < 0.05) in the macroaggregate (>250-µm) fraction of the 0-to 15-cm increment. Residue-derived C stabilization was signifi cantly greater (P < 0.05) in the 0-to 30-cm increment than in the 0-to 15-cm increment of the TM management cores. Overall, our results indicate that, within a plow depth of 15 cm, limiting the tillage-induced disruption of aggregates has a stronger infl uence on the effi ciency of C stabilization than residue incorporation into the profi le via tillage. When residues are distributed to a 30-cm depth, however, the negative impact of aggregate disruption through tillage appears counterbalanced, with similar effi ciencies of C stabilization between the NT and TM practices, possibly due to slower decomposition of residues deeper in the profi le.
Soil Use and Management, 2010
In rainfed semiarid agroecosystems, soil organic carbon (SOC) may increase with the adoption of alternative tillage systems (e.g. no-tillage, NT). This study evaluated the effect of two tillage systems (CT, conventional tillage vs. NT) on total SOC content, SOC concentration, water stable aggregate-size distribution and aggregate carbon concentration from 0 to 40 cm soil depth. Three tillage experiments were chosen, all located in northeast Spain and using contrasting tillage types but with different lengths of time since their establishment (20, 17, and 1-yr). In the two fields with mouldboard ploughing as CT, NT sequestered more SOC in the 0-5 cm layer compared to CT. However, despite there being no significant differences, SOC tended to accumulate under CT compared to NT in the 20-30 and 30-40 cm depths in the AG-17 field with 25%-50% higher SOC content in CT compared to NT. Greater amounts of large and small macroaggregates under NT compared to CT were measured at 0-5 cm depth in AG-17 and at 5-10 cm in both AG-1 and AG-17. Differences in macroaggregate C concentration between tillage treatments were only found in the AG-17 field at the soil surface with 19.5 and 11.6 g C/kg macroaggregates in NT and CT, respectively. After 17 years of experiment, CT with mouldboard ploughing resulted in a greater total SOC concentration and macroaggregate C concentration below 20 cm depth, but similar macroaggregate content compared to NT. This study emphasizes the need for adopting whole-soil profile approaches when studying the suitability of NT vs. CT for SOC sequestration and CO2 offsetting.