Organic Matter and Water Stability of Field Aggregates Affected by Tillage in South Dakota (original) (raw)
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Particulate Organic Matter and Water-Stable Aggregation of Soil under Contrasting Management
Soil Science Society of America Journal, 2007
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. I nteractions among crop and soil management practices and soil condition are often clouded by variability within a system. Further, causal relationships between management and soil quality are diffi cult to extrapolate among regions because of differences in soil type, climate, and management norms. The quantity and quality of soil organic matter provides an important diagnostic link between management and sustainability of soil function. Generally, it is accepted that conversion to crop production practices has caused a decline in SOM compared with the original grassland levels throughout the Great Plains (Campbell and Souster, 1982; Monreal and Janzen, 1993; Allmaras et al., 2000). Tillage has caused SC losses from 28 to 77% depending on geographic location (climate) and soil type (Paustian et al., 1997). Summer fallow, a practice used to conserve soil water, has been associated with serious declines in SOM in a wheat (Triticum aestivum L.)-fallow crop sequence (Monreal and Janzen, 1993; Rasmussen and Parton, 1994; Biederbeck et al., 1984) compared with annual cropping systems. Conversely, changes in agricultural management from conventional tillage to NT and increased crop-rotation diversity can increase accumulation of SC (West and Post, 2002). Soil organic matter mediates many chemical and physical soil properties (Carter, 2002). Boyle et al. (1989) reviewed the infl uence of SOM on soil aggregation and water infi ltration and concluded that SOM had a disproportionate effect on soil physical properties. Soils high in SOM generally have greater available water-holding capacity than soils of similar texture with less SOM (Hudson, 1994), although Bauer and Black (1992) found that a decline in SOM did not change the available water-holding capacity of moderately coarse-textured soils. An increase in phytomass input to a loamy sand improved aggregate stability and water infi ltration (Bruce et al., 1992). In long-term tillage, residue management, and N-fertility plots, Pikul and Zuzel (1994) reported that an increase in SOM increased the porosity of surface crusts in a silt loam soil, while on a Naff silt loam, Mulla et al. (1992) were not able to establish a relation between SOM and physical properties of conventional and alternatively managed farms. The "alternative" farm studied by Mulla et al. (1992) used a cropping system that was more diverse than the "conventional" farm; however, tillage was used on both farms. Generally, soil compaction decreases with increasing SOM (Soane, 1990; Adams, 1973, Hudson, 1994). Maintenance of SOM thus is a key component in sustainability of the soil resource and crop productivity (Doran et al., 1998). Particulate organic matter is a labile intermediate in the SOM continuum from fresh organic materials to humifi ed
Soil and Tillage research , 2020
Agricultural management practices control soil organic carbon (SOC) content in croplands. Long-term cropping system experiments offer a great opportunity to understand the magnitude and direction of SOC change in response to management practices. Such information is very limited from the southeastern US, a region with warm and humid climatic conditions that typically favor SOC decomposition over accumulation. Therefore, this study was conducted to assess the effect of 39 years of chisel plow (CP), disc plow (DP), moldboard plow (MP), no-tillage (NT), NT with winter wheat (Triticum aestivum L.) cover crop (NTW), and NT with wheat-soybean (Glycine max L.) double crop (NTWD) on total SOC and SOC fractions including permanganate oxidizable C (POXC), water extractable C (WEC), resistant C (RC), and aggregate-associated SOC in a continuous soybean system. Additionally, aggregate size distribution, mean weight diameter (MWD), and wet aggregate stability (WAS) were determined. Results showed that NTW and NTWD significantly increased SOC and POXC compared to MP with mean SOC (g kg−1 soil) of 12.2 (NTW) ≥10.9 (NTWD) >7.2 (MP) and mean POXC (mg kg−1 soil) of 465 (NTWD) ≥418 (NTW) >252 (MP). The WEC and RC fractions did not differ among treatments. Across the treatments, the greatest aggregate-associated SOC concentration was found in microaggregates (0.053–0.25 mm) and the lowest in clay- and silt-size particles (<0.053 mm). Additionally, WAS under NT systems was significantly higher (45.5–52.3 %) than under tilled treatments (21.9–29.1 %). Total SOC correlated significantly with POXC (r = 0.68, p < 0.01), RC (r = 0.46, p < 0.05), WAS (r = 0.65, p < 0.01), and aggregate-associated SOC concentrations (r > 0.6, p < 0.01). Overall, this study revealed that NT enhanced SOC and POXC accumulation and macroaggregation compared to tilled treatments. Cover cropping and double cropping further improved SOC accumulation. In conclusion, long-term adoption of different tillage intensities can strongly alter SOC dynamics in bulk soil and aggregates under continuous soybean production systems of the southeastern US.
Soil organic matter widens the range of water contents for tillage
Soil and Tillage Research
The effects of soil organic matter on the water contents for tillage were investigated by sampling soils with a uniform texture, but a range of soil organic carbon (SOC) from two long-term field experiments at Highfield in Rothamsted Research, UK and Askov Experimental Station, Denmark. The treatments studied in Highfield were Bare fallow (BF), Continuous arable rotation (A), Ley-arable (LA) and Grass (G); and in Askov: unfertilized (UNF), ½ mineral fertilizer (½ NPK), 1 mineral fertilizer (1NPK), and 1½ animal manure (1½AM). Minimally undisturbed soil cores (100 cm3) were sampled per plot in both locations from 6-10 cm depth to generate water retention data. Soil blocks were also sampled at 6-15 cm depth to determine basic soil properties and to measure soil aggregate strength parameters. The range of soil water contents appropriate for tillage were determined using the water retention and the consistency approaches. SOC content in Highfield was in the order: G>LA=A>BF, and in Askov: 1½ AM>1NPK=½NPK>UNF. Results showed that different long-term management of the silt loam Highfield soil, and fertilization of the sandy loam Askov soil affected the mechanical properties of the soils-for Highfield soil, aggregates from the G treatment were stronger in terms of rupture energy when wet (-100 hPa matric potential) than the BF treatment. As the soil dried (-300 and-1000 hPa matric potentials), soil aggregates from the G treatment were relatively weaker and more elastic than the BF soil. Our study showed, for both Highfield and Askov soils, a strong positive linear increase in the range of water contents for tillage with increasing contents of SOC. This suggests that management practices leading to increased SOC can improve soil workability by increasing the range of water contents for tillage. We recommended using the consistency approach over the water retention approach for determining the range of water contents for tillage because it seems to give realistic estimates of the water contents for tillage.
Pedosphere, 2017
Promoting soil carbon sequestration in agricultural land is one of the viable strategies to decelerate the observed climate changes. However, soil physical disturbances have aggravated the soil degradation process by accelerating erosion. Thus, reducing the magnitude and intensity of soil physical disturbance through appropriate farming/agricultural systems is essential to management of soil carbon sink capacity of agricultural lands. Four sites of different land use types/tillage practices, i) no-till (NT) corn (Zea mays L.) (NTC), ii) conventional till (CT) corn (CTC), iii) pastureland (PL), and iv) native forest (NF), were selected at the North Appalachian Experimental Watershed Station, Ohio, USA to assess the impact of NT farming on soil aggregate indices including water-stable aggregation, mean weight diameter (MWD) and geometric mean diameter (GMD), and soil organic carbon and total nitrogen contents. The NTC plots received cow manure additions (about 15 t ha −1) every other year. The CTC plots involved disking and chisel ploughing and liquid fertilizer application (110 L ha −1). The results showed that both water-stable aggregation and MWD were greater in soil for NTC than for CTC. In the 0-10 cm soil layer, the > 4.75-mm size fraction dominated NTC and was 46% more than that for CTC, whereas the < 0.25-mm size fraction was 380% more for CTC than for NTC. The values of both MWD and GMD in soil for NTC (2.17 mm and 1.19 mm, respectively) were higher than those for CTC (1.47 and 0.72 mm, respectively) in the 0-10 cm soil layer. Macroaggregates contained 6%-42% and 13%-43% higher organic carbon and total nitrogen contents, respectively, than microaggregates in soil for all sites. Macroaggregates in soil for NTC contained 40% more organic carbon and total nitrogen over microaggregates in soil for CTC. Therefore, a higher proportion of microaggregates with lower organic carbon contents created a carbon-depleted environment for CTC. In contrast, soil for NTC had more aggregation and contained higher organic carbon content within water-stable aggregates. The soil organic carbon and total nitrogen stocks (Mg ha −1) among the different sites followed the trend of NF > PL > NTC > CTC, being 35%-46% more for NTC over CTC. The NT practice enhanced soil organic carbon content over the CT practice and thus was an important strategy of carbon sequestration in cropland soils.
Soil Organic-Matter in Water-Stable Aggregates Under Different Soil-Management Practices
Agriculture (Pol'nohospodárstvo)
An experiment of different management practices in a commercial vineyard, which was established in 2006 in the locality of Nitra-Dražovce, Slovakia on Rendzic Leptosol, was used to evaluate the dynamics of soil organic-matter parameters during the years 2008–2015. The following treatments were established: 1. G (grass without fertilisation as control), 2. T (tillage), 3. T+FYM (tillage + farmyard manure), 4. G+NPK3 (grass + 3rd intensity of fertilisation for vineyards: it means 125 kg/ha N, 50 kg/ha P, 185 kg/ha K), and 5. G+NPK1 (grass + 1st intensity of fertilisation for vineyards: it means 100 kg/ha N, 30 kg/ha P, 120 kg/ha K). The results showed that the soil-management practices in the vineyard significantly influenced the soil organic carbon in water-stable aggregates (SOC in WSA). The content of SOC in WSAma increased on average in the following order: T < G < G+NPK1 < G+NPK3 < T+FYM. Intensive soil cultivation in the T treatment resulted in a statistically signif...
Biology and Fertility of Soils, 2010
The objectives were to investigate (1) to which extent water-stable macro-and microaggregates sequester organic matter (OM) in a minimum tillage (MT) system compared to a conventional tillage (CT) system and (2) if the content of biochemically stabilized OM differs between both tillage systems, and (3) to study the temporal dynamics of the distribution of aggregate size classes and of storage of OM within aggregates in the field. Surface soils (0-5 cm) and subsoils (10-20 cm) were sampled after fallow (March 2007) and directly after tillage (November 2007) from a long-term experimental field near Göttingen, Germany. Macroaggregates (>0.25 mm) were in general less abundant after fallow than directly after tillage. In March, only 21% (CT) and 45% (MT) of C org was stored within macroaggregates in the surface soil, whereas in November, the percentages increased to 58% and 73%, respectively. CT and MT soils of both depths were incubated as bulk soil (CT bulk , MT bulk) and with macroaggregates disrupted (<0.25 mm) (CT md , MT md) for 28 days at 22°C and water content of 50% of the maximum water holding capacity. For the MT bulk and MT md surface soils, C mineralization was significantly higher compared to the CT soils. Incubation of md soils did not generally result in a significantly higher C mineralization compared to the respective bulk soils, except for the MT md subsoil. Acid hydrolysis showed that the proportion of biochemically stabilized, nonhydrolysable, C org to total C org was lower in the MT than in the CT soils. Overall, the data indicate that the effect of physical stabilization of OM stored in the macroaggregates may not be a mechanism protecting very labile C with a turnover time of weeks, but that longer preservation likely occurs after macroaggregate transformation into microaggregates, and the surplus of OM found in the surface soil of MT does not only depend on the biochemically stabilized OM. Finally, our data suggest that the temporal variability of distribution of aggregate size classes in the field is large, but spatial and operator variability also contributed to the observed differences.
Biologically Defined Soil Organic Matter Pools as Affected by Rotation and Tillage
Environmental Management, 2004
The importance of soil organic matter is well recognized; however, changes in C and N fractions are inadequately quantified. The objective of this study was to determine tillage and crop rotation effects on soil organic C and N fractions from a long-term (27-year) study in eastern Kansas. Cropping systems included continuous and rotation sequences of wheat (Triticum aestivum L.), grain sorghum (Sorghum bicolor (L.) Moench), and soybean (Glycine max (L.) Merrill) on a Muir silt loam (fine-silty, mixed, mesic Cumulic Haplustolls). Tillage included conventional (CT), reduced (RT), and no-till (NT). Total C and N (C T and N T) were determined on all treatments. Mineralizable C and N (C o and N o) and microbial biomass C and N were determined for the NT and CT soybean and sorghum rotations. Cropping systems that included wheat contained the greatest amount of C T and N T. Continuous wheat contained 2910 g C m Ϫ2 and 287 g N m Ϫ2 , compared to 2225 g C m Ϫ2 and 222 g N m Ϫ2 (0-15 cm) for continuous soybean. No-tillage contained 1128 g C m Ϫ2 and 109 g N m Ϫ2 at 0-5 cm compared to 918 g C m Ϫ2 and 87 g N m Ϫ2 for CT. Sorghum contained 51% more C o than soybean, and NT accounted for 59% more C o than CT. More crop residue was produced and retained in rotations that included sorghum. No-tillage increased C 2440 kg ha Ϫ1 , while CT increased C 340 kg ha Ϫ1 across all soybean/sorghum rotations. The highest sequestration rate (122 kg C ha Ϫ1 y Ϫ1) was observed with NT sorghum and was equivalent to ϳ3.2% of the plant material (root and shoot, less gain harvest) remaining in the soil annually.
Soil and Tillage Research, 2016
Soil organic matter affects a number of soil processes and properties. A better understanding of soilprofile distribution of organic matter components and related soil properties under long-term tillage systems is thus needed. The objective of this study was to evaluate the impacts of 33 years no-till (NT), double disk (DD), chisel (CH), and plow tillage (PT) under corn (Zea mays L.)-soybean (Glycine max L.) rotation on soil organic C (SOC), particulate organic matter (POM), pH, and wet aggregate stability to 100 cm soil depth on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudolls) in eastern NE. After 33 years, NT and DD management increased SOC by 1.2 times and mean weight diameter (MWD) of aggregates by 2 times compared with CH and PT at the 0-10 cm depth. At the 0-20 cm, NT had 1.1 times higher SOC concentration than CH and PT. When compared with data collected 24 years prior to this study, SOC at the 0-20 cm increased by 12.5% across NT, DD, and CH and by 2.7% for PT. No-till had 5 times higher total POM concentration than PT, 4.7 times higher than CH, and 2.4 times higher than DD at the 0-10 cm depth. However, at the 10-20 cm, PT had higher POM than other tillage systems, which is most probably due to mixing and burial of residues at the bottom of the plow layer. Soil pH did not differ among tillage treatments at the 0-10 cm, but it differed in this order: PT > CH > DD > NT at the 10-20 cm and PT = CH = DD > NT at the 20-40 cm depth. The lower pH under NT, DD, and CH in deeper soil depths may be due to the limited or no lime mixing in these systems compared with PT. When compared with data (pH 5) collected 33 years prior to this study, soil pH increased by 0.9 in NT, 1.4 in DD, 1.5 in CH, and 1.9 units in PT at 0-20 cm depth, probably due to surface application and incorporation of lime. Overall, 33 years of NT increased near-surface soil organic matter components and soil aggregation compared with the PT.