• Authors:
    • Govaerts, B.
    • Verhulst, N.
    • Dendooven, L.
    • Guerrero, A.
    • De Leon, F.
    • Etchevers, J.
    • Hidalgo, C.
    • Fuentes, M.
  • Source: PLANT AND SOIL Volume: 355 Issue: 1-2 Pages:
  • Volume: 355
  • Issue: 1-2
  • Year: 2012
  • Summary: Conservation agriculture, the combination of minimal soil movement (zero or reduced tillage), crop residue retention and crop rotation, might have the potential to increase soil organic C content and reduce emissions of CO2. Three management factors were analyzed: (1) tillage (zero tillage (ZT) or conventional tillage (CT)), (2) crop rotation (wheat monoculture (W), maize monoculture (M) and maize-wheat rotation (R)), and (3) residue management (with (+r), or without (-r) crop residues). Samples were taken from the 0-5 and 5-10 cm soil layers and separated in micro-aggregates (< 0.25 mm), small macro-aggregates (0.25 to 1 mm) and large macro-aggregates (1 to 8 mm). The carbon content of each aggregate fraction was determined. Zero tillage combined with crop rotation and crop residues retention resulted in a higher proportion of macro-aggregates. In the 0-5 cm layer, plots with a crop rotation and monoculture of maize and wheat in ZT+r had the greatest proportion of large stable macro-aggregates (40%) and highest mean weighted diameter (MWD) (1.7 mm). The plots with CT had the largest proportion of micro-aggregates (27%). In the 5-10 cm layer, plots with residue retention in both CT and ZT (maize 1 mm and wheat 1.5 mm) or with monoculture of wheat in plots under ZT without residues (1.4 mm) had the greatest MWD. The 0-10 cm soil layer had a greater proportion of small macroaggregates compared to large macro-aggregates and micro-aggregates. In the 0-10 cm layer of soil with residues retention and maize or wheat, the greatest C content was found in the small and large macro-aggregates. The small macro-aggregates contributed most C to the organic C of the sample. For soil cultivated with maize, the CT treatments had significantly higher CO2 emissions than the ZT treatments. For soil cultivated with wheat, CTR-r had significantly higher CO2 emissions than all other treatments. Reduction in soil disturbance combined with residue retention increased the C retained in the small and large macro-aggregates of the top soil due to greater aggregate stability and reduced the emissions of CO2 compared with conventional tillage without residues retention and maize monoculture (a cultivation system normally used in the central highlands of Mexico).
  • Authors:
    • González-Prieto, S. J.
    • Couto-Vázquez, A.
    • Gómez-Rey, M. X.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 124
  • Year: 2012
  • Summary: The effect of 14-years of plough and conservation tillage on macro- and micro-nutrient availability and on N transformation rates was evaluated in a temperate humid region soil (0-5 and 5-15cm) under an annual Italian ryegrass-maize forage rotation. Nutrients were extracted with an NH 4Ac-DTPA solution. Gross N mineralization (m), nitrification (n) and immobilization (i) rates were calculated by 15N isotope dilution technique (experiment with 15NH 4, 48-h incubation) with the FLUAZ model. Our results demonstrate that long-term conservation tillage increases organic C in the upper soil layer and the availability of most of studied nutrients (Co, Fe, Mg, Mn, Na, P and Zn) compared with plough tillage. On the contrary, conservation tillage resulted in lower contents of NO 3 --N, and extractable K and Mn in the 5-15cm soil layer. Extractable Al, Ca and Cu were unaffected by tillage system or soil depth. No significant effect of tillage practices on gross and net N transformation rates was observed. Soil C contents was not related to gross and net N fluxes, while positive relationships were found between: (1) m and soil available NH 4 +-N; (2) n and soil available K and d 15N; (3) i and soil available K, Mn, Mg, total N and NO 3 --N; and (4) net m and n with soil available NO 3 --N and K. The negative relationships of n and d 15N with soil Co content suggested that Co availability could affect the nitrifying activity. Results suggest that tillage practices had a limited effect on N transformation rates in this soil and that NO 3 --N leaching could decrease under conservation tillage. For N fluxes in these agricultural soils, K was a more important factor than the other nutrients, suggesting close relationships between N and K availability; however, some micro-nutrients could also play a relevant role on soil N cycle and, therefore, they must be considered in future studies on gross N fluxes. © 2012 Elsevier B.V.
  • Authors:
    • Wang, J. P.
    • Zhang, Z. S.
    • Kou, Z. K.
    • Yue, L. X.
    • Li, C. F.
    • Cao, C. G.
  • Source: SOIL & TILLAGE RESEARCH Volume: 119 Pages: DOI:
  • Volume: 119
  • Year: 2012
  • Summary: Conservation management practices, such as no-tillage (NT) or crop residue mulch, alter soil organic carbon (C) lability, thus affecting soil quality. However, inconsistent effects of conservation management practices on soil labile organic C have been commonly reported. We hypothesized, however, that conservation management practices can improve soil labile organic C fractions and then C management index (CMI) and soil quality. Thus, our objective was to quantify labile organic C contents on a clay loam soil (Anthrosols, World Reference Base for Soil Resources) 3 years after implementing four tillage/crop residue management treatments under a rice Liangyoupeijiu (Oryza sativa L.)-rape Huayouzaliuhao (Brassica napus) rotation in Wuxue City of central China. The experiment included four treatments: (1) single conventional tillage (CT) without crop residue (rape with NT-rice with CT); (2) double CT without crop residue (rape with CT-rice with CT); (3) double NT without crop residue (rape with NT-rice with NT); and (4) double NT plus crop residue (rape with NT. +. rice residue mulch-rice with NT. +. rape residue mulch). Five soil organic C fractions were determined from 0 to 30. cm layer in October 2009 (3 years after a rape-rice double crop rotation). Total organic C, microbial biomass C, dissolved organic C, particulate organic C, easily oxidizable C, and water stable aggregation were measured. A CMI was also calculated. The concentrations of total organic C, microbial organic C, dissolved organic C, and particulate organic C under the double NT plus crop residue treatment were 1.07-1.17, 1.20-1.26, 1.08-1.30 and 1.17-1.76 times higher than those under the other three treatments. The total organic C and labile organic C contents under the double NT with or without crop residue treatment were generally higher at 0-5. cm than at greater sampling depths. The proportions of 0.5-2. mm water-stable aggregates at the 0-5. cm depth under the double NT with or without crop residue treatment were significantly greater (P< 0.05) than those under the single or double CT without crop residue treatment, but lower (P< 0.05) at the 5-30. cm depth. Soil labile organic C fractions were positively correlated with each other. The greater C pool index (CPI) at the 0-5. cm depth observed under double NT with or without crop residue treatment compared to single or double CT without crop residue treatment led to greater CMI at the same depth. However, CMI at the 5-30. cm depth was lower for the double NT with or without crop residue treatment compared to the single or double CT without crop residue treatment. Thus, our results indicated that soil labile organic C fractions were only sensitive to changes in management practices in the upper soil profile, and that short-term effects of continuous NT or NT with crop residue mulch in a rape-rice rotation system appeared to only improve soil quality in the upper soil profile. Based on these results, we suggested that greater quantities of labile organic C can be concentrated in the 0-30. cm soil layer of a soil under rape-rice rotation by more sustainable practices than those currently being used in central China. © 2011 Elsevier B.V.
  • Authors:
    • Ogle, S. M.
    • Masanet, E.
    • Torn, M. S.
    • Mishra, U.
  • Source: GEODERMA
  • Volume: 189
  • Year: 2012
  • Summary: Regional assessments of change in soil organic carbon (SOC) stocks due to land-use change are essential for supporting policy and management decisions related to greenhouse gas emissions and mitigation through carbon sequestration in soils. We have developed an improved approach by integrating geostatistical techniques with the Intergovernmental Panel on Climate Change (IPCC) carbon inventory approach to assess the impact of no-till management and crop-residue retention on SOC changes at a regional scale. Specifically, the improved approach utilizes regression kriging (RK) to estimate reference carbon stocks for the IPCC method. In our case study, we compared the results from the RI( method with a simple averaging (SA) method to derive the reference stocks as implemented in the Tier 2 IPCC approach, for a seven state area of the Midwestern United States. Using this improved method, we predict that eliminating tillage and retaining crop residues on all croplands of the study area would result in 11,735 Gg C yr(-1) sequestration for 20 years in the top 30 cm of the soil profile. Most cropland area would sequester 02-0.75 Mg C ha(-1) yr(-1). However, at a few places, the predicted rate of sequestration was more than 0.75 Mg C ha(-1) yr(-1), with an upper limit of 1.1 Mg C ha(-1) yr(-1). The highest rates of carbon accumulation were associated with favorable environmental conditions, such as lower slope positions and cold, temperate, moist climates. Validating predicted SOC change at 18 sites with varying soil types and environmental conditions showed that the RK approach to estimate reference carbon stocks decreased global prediction errors by 45% relative to the default reference values. The increase in prediction accuracy was due to using spatially varying SOC stocks rather than simple data averaging to derive reference SOC values. The uncertainty analysis demonstrated that there was more precision in the results from the RK approach in comparison to the results from the SA approach. These results suggest that improved geostatistical approach is a promising technique for improving soil carbon inventories that utilize the IPCC method, and will provide more precise results for informing public policy and management decisions while retaining ease of application.
  • Authors:
    • McLaughlin, N. B.
    • Reynolds, W. D.
    • Drury, C. F.
    • Yang, X. M.
    • Shi, X. H.
    • Zhang, X. P.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 120
  • Year: 2012
  • Summary: Ridge tillage (RT) creates a distinctly different soil environment relative to no-tillage (NT) and mouldboard plow tillage (MP), which may in turn affect soil properties. In this study, the impacts of long-term (29 years) RT on soil organic carbon (SOC), water content, bulk density and penetration resistance were compared with NT and MP tillage on a clay loam soil under a corn (Zea mays L.)-soybean (Glycine max L. Merr.) rotation. The ridges in RT were formed at 76-cm spacing and corn was planted in the center of the ridges whereas soybean was planted in the shoulders of the ridges at 38-cm spacing. Soil samples were collected from the ridge crest (i.e. corn row), from the two ridge shoulder positions and from the interrow (furrow) positions of the ridges to evaluate both the spatial and profile distributions of the selected soil properties under RT relative to NT and MP. Ridge tillage produced low SOC in the interrows, high SOC in the crests and medium SOC in the shoulders relative to MP and NT. Soil water content was higher in the interrows than in the crests of the ridges, while soil penetration resistance followed the reverse trend. No-tillage resulted in a distinct SOC stratification with significantly higher SOC in surface soil and slightly lower SOC in subsurface soil while a uniform distribution of SOC was observed in the plow layer of MP soil. Hence, RT produced different SOC, water content, bulk density and penetration resistance distributions than NT and MP. Twenty-nine years of RT management resulted in improved soil physical conditions in the plow layer for crop root growth relative to NT and greater SOC stocks within the plow layer compared to MP.
  • Authors:
    • Bosch, D. D.
    • Franklin, D. H.
    • Truman, C. C.
    • Potter, T. L.
    • Strickland, T. C.
    • Hawkins, G. L.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 122
  • Year: 2012
  • Summary: Assessment of erosion impact on soil carbon and nitrogen loss and redistribution within landscapes is needed to develop estimates of soil carbon sequestration potential, soil quality management plans, and to evaluate potential for transport of sediment bound agrochemicals. We used variable intensity rainfall simulations to quantify the effects of tillage, conventional and strip, and antecedent soil water content on sediment-bound carbon and nitrogen loss from a Tifton loamy sand located in the southeastern Atlantic Coastal Plain (USA). Carbon and nitrogen loss via erosion of silt. +. clay sized versus sand sized sediment particles were quantified. Antecedent water content had no effect on mean sediment loss within tillage treatments, but losses from conventional till treatments were significantly greater than from strip till. Sediment lost as silt. +. clay was from 58 to 78% of the total under conventional and from 30 to 39% under strip tillage. The fraction of sediment lost as silt. +. clay versus sand was greater under conventional tillage than under strip tillage. Within-event sediment carbon enrichment compared to the top 2. cm of soil was 0.9-7.2 for conventional and 0.6-3.7 for strip tillage. The strip till silt. +. clay fraction had significantly higher carbon content than the strip till sand fraction and the conventional till silt. +. clay fraction. Carbon loss from treatments was directly proportional to sediment loss. However, the conventional till treatments lost 4.6-6 times more carbon from the silt. +. clay sized fraction and 1.9-4.8 times more carbon from the sand sized fraction than strip till treatments. Results suggest that the higher proportion of silt. +. clay fraction sediment loss from conventional till may deplete nitrogen enriched organic matter while decreased erosion from strip till may serve to increase retention of organic nitrogen. Findings also indicate that an approach that adjusts loss estimates of organic carbon and nitrogen by using wet-sieved subsamples for analysis followed by standardization against total bulk sediment loss accounts for introduced errors from both sub-sampling efficiency and disturbance.
  • Authors:
    • Filley, T. R.
    • Yang, X.
    • Zhang, X.
    • Zhang, X.
    • Ding, X.
    • He, H.
    • Zhang, B.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 124
  • Year: 2012
  • Summary: Tillage practices affect soil microorganisms, which in turn influence many processes essential to the function and sustainability of soil. In this study, the changes in soil microbial biomass and community composition in response to conventional tillage (CT, moldboard plowing and post-harvest residue removal) and no-tillage (NT) practices were examined during a maize (Zea mays L.) growing season in a clay loam soil (Typic Hapludoll) in northeastern China. Soil samples were taken in May, June, July, August, and September of 2008 at 0-5, 5-10, and 10-20. cm depths. Microbial communities were characterized by phospholipid fatty acid (PLFA) analysis. While microbial biomass increased at the beginning then decreased toward the end of the growing season in CT soils, it showed the opposite trend in NT soils. Microbial community structure showed better distinction among sampling months than between tillage practices. These results suggest that seasonal variations in soil microbial communities could be greater than changes associated with tillage treatments. However, microbial biomass accumulation was tillage dependent. On average, NT treatment resulted in 21% higher microbial biomass in 0-5. cm depth than CT treatment (P<0.05). Higher fungi to bacteria ratio was also observed under NT than CT treatment at both the 0-5 and 5-10. cm sampling depths. These data demonstrate that examining the effect of management practices on soil quality based on soil microbial communities should consider seasonal changes in the environmental properties. It is strongly recommended that NT practice should be adopted as an effective component of an overall strategy to improve soil quality and sustainability in northeastern China.
  • Authors:
    • van Ranst, E.
    • Fadlaoui, A.
    • Moussadek, R.
    • Mrabet, R.
  • Source: Field Crops Research
  • Volume: 132
  • Year: 2012
  • Summary: Moroccan agriculture is characterized by the co-existence of both modern and smallholder traditional agriculture. Both types of agriculture are under degradative processes due to mis-use of tillage implements, mis-management of crop residues and inappropriate links between grain and livestock productions. From the research conducted over the last three decades, the vast majority of beneficial tillage effects are transient. Conversely, the harmful effects of conventional tillage (CT) systems are long-lasting, if not permanent. The present paper aims at evaluating major achievements in conservation or no-tillage agriculture (CA or NT) research conducted in dry areas of Morocco and presenting important ways to implement these achievements within the Moroccan rural society. CA has been introduced in response to issues of soil conservation, drought mitigation and soil quality management. NT systems have resulted in reduced soil erosion, greater soil water conservation, improved soil quality and stable and higher crop yields. Changes in crop production practices due to shifting to NT or CA systems and retention of crop residues at or near the surface produced progressive qualitative and quantitative variations in soil organic matter. This can allow agriculture to contribute to country's efforts to reduce and control greenhouse gas emissions. These effects benefited both farmers and society in terms of higher returns and efficiencies. Under NT, benefits from improved agriculture's environmental performance must be added to remunerations of reducing costs of production and improving well-being of farmers. The other strong benefits that CA brings come from the opportunity for early sowing and savings in time, machinery and fuel. Even though, many agronomic, socio-economic and environmental benefits accrue from NT and increasing crop diversity; lack of incentives from the government and social factors encourage the continued use of CT systems. CA systems were sufficiently tested in research stations but found limited adoption in farm communities. The shift in the late nineties to more on-farm research did not result in the envisaged breakthroughs, mainly due to poor research-extension linkages and several social and technical barriers. Consequently, in order to realize durable agricultural growth, there is a huge challenge to out- and up-scale CA in Morocco through linkage of all stakeholders (farmers, developers, researchers, industrials and policy makers). This paper fulfills information gaps and presents a thorough discussion on constraints to CA adoption as well. (C) 2011 Elsevier B.V. All rights reserved.
  • Authors:
    • Torbert, H.
    • Watts, D.
    • Way, T.
    • Mays, D.
    • Nyakatawa, E.
    • Smith, D.
  • Source: Journal of Sustainable Agriculture
  • Volume: 36
  • Issue: 8
  • Year: 2012
  • Summary: Soil management practices can alter the natural balance at the soil-plant-atmosphere ecosystem interface, which can significantly affect the environment. This study compared CO2 fluxes in conventional tillage (CT) and no-tillage (NT) corn (Zea mays L.) production systems receiving poultry litter (PL) and ammonium nitrate (AN) fertilizers on a Decatur silt loam soil in the Tennessee Valley region of North Alabama from Spring 2008 to Fall 2009. Soil CO2 flux in CT plots (9.5 kg CO2 ha(-1) day(-1)) was significantly greater than that in NT plots (4.9 kg CO2 ha(-1) day(-1) in summer. Soil CO2 fluxes were lowest in fall where CT plots had a mean soil CO2 emission of 0.8 kg CO2 ha(-1) day(-1), while plots under NT and grass fallow system were sinks of CO2 with fluxes -0.6 and -1.0 kg CO2 ha(-1) day(-1), respectively. Mean soil CO2 flux averaged over seasons in NT plots was 36% lower than that in CT plots. Grass fallow plots were net sinks of CO2 with a mean CO2 flux of -0.4 kg CO2 ha(-1) day(-1). Our study showed that application of PL or AN fertilizer in NT systems can significantly reduce soil CO2 emissions compared to CT systems in corn production.
  • Authors:
    • Paustian, K.
    • Swan, A.
    • Ogle, S.
  • Source: Agriculture Ecosystems & Environment
  • Volume: 149
  • Year: 2012
  • Summary: The efficacy of no-till agriculture for increasing C in soils has been questioned in recent studies. This is a serious issue after many publications and reports during the last two decades have recommended no-till as a practice to mitigate greenhouse gas emissions through soil C sequestration. Our objective was to investigate the possibility that the lack of C increase in some no-till systems may be due to changes in crop productivity and subsequent C input to soils. A meta-analysis of 74 published studies was conducted to determine if crop production varies between no-till and full tillage management. The results were used to estimate the change in C input due to no-till adoption and the influence on soil organic C stocks at steady-state using the Century model. We found that crop productivity can be reduced with adoption of no-till, particularly in cooler and/or wetter climatic conditions. The influence varies, however, and crop productivity can even increase in some regions following adoption of no-till. In cases where crop production and C inputs decreased due to no-till, the potential reduction in soil organic C stocks was offset by a decrease in soil C decomposition rates, except in cases where C inputs declined by 15% or more. Challenges still remain for understanding the full impact of no-till adoption on soil organic C stocks, such as changes on C inputs in deeper subsurface horizons, the influence of variation in NT seeding methods on soil disturbance, and changes in SOM stabilization due to saturation limits in mineral soil fractions, which may further modify net C storage in soils. (C) 2011 Elsevier B.V. All rights reserved.