- Authors:
- Chen, D.
- Walker, C.
- Pengthamkeerati, P.
- Suter, H. C.
- Source: Soil Research
- Volume: 49
- Issue: 4
- Year: 2011
- Authors:
- Kiese, R.
- Butterbach-Bahl, K.
- Reeves, S. H.
- Dalal, R. C.
- Wang, W.
- Source: Global Change Biology
- Volume: 17
- Issue: 10
- Year: 2011
- Authors:
- Altieri, M. A.
- Lana, M. A.
- Bittencourt, H. V.
- Kieling, A. S.
- Comin, J. J.
- Lovato, P. E.
- Source: Journal of Sustainable Agriculture
- Volume: 35
- Issue: 8
- Year: 2011
- Summary: In Santa Catarina, southern Brazil, family farmers modified the
conventional no-till system by flattening cover crop mixtures on
the soil surface as a strategy to reduce soil erosion and lower fluctuations in soil moisture and temperature, improve soil quality, and enhance weed suppression and crop performance. During 2007 and 2008, we conducted three experiments aimed at understanding the processes and mechanisms at play in successful
organic conservation tillage systems (OCT), especially the underpinnings of ecological weed suppression, a key advantage of OCT systems over conventional no-till systems. Our results, as well as farmers observations, suggest that cover crops can enhance weed suppression and hence crop productivity through physical interference and allelopathy and also a host of effects on soil quality, fertility, and soil moisture that we did not measure. Results from the three trials indicate that the best cover crop mixture should include a significant proportion of rye, vetch, and fodder radish as these mixtures produce large biomass, and are readily killed by rolling forming a thick mulch sufficient to provide effective weed control in the subsequent vegetable crop.
- Authors:
- Alvarez, C. R.
- Costantini, A. O.
- Bono, A.
- Taboada, M. A.
- Boem, F. H. G.
- Fernandez, P. L.
- Prystupa, P.
- Source: Revista Brasileira de Ciência do Solo
- Volume: 35
- Issue: 6
- Year: 2011
- Summary: One of the expected benefits of no-tillage systems is a higher rate of soil C sequestration. However, higher C retention in soil is not always apparent when notillage is applied, due e.g., to substantial differences in soil type and initial C content.
The main purpose of this study was to evaluate the potential of no-tillage management to increase the stock of total organic C in soils of the Pampas region in Argentina. Forty crop fields under no-tillage and conventional tillage systems and seven undisturbed soils were sampled. Total organic C, total N, their fractions and stratification ratios and the C storage capacity of the soils under different managements were assessed in samples to a depth of 30 cm, in three layers (0–5, 5– 15 and 15–30 cm). The differences between the C pools of the undisturbed and cultivated soils were significant (p < 0.05) and most pronounced in the top (0– 5 cm) soil layer, with more active C near the soil surface (undisturbed > no-tillage > conventional tillage). Based on the stratification ratio of the labile C pool(0–5/5– 15 cm), the untilled were separated from conventionally tilled areas. Much of the variation in potentially mineralizable C was explained by this active C fraction (R2 = 0.61) and by total organic C (R2 = 0.67). No-till soils did not accumulate more organic C than conventionally tilled soils in the 0–30 cm layer, but there was substantial stratification of total and active C pools at no till sites. If the C stratification ratio is really an indicator of soil quality, then the C storage potential of no-tillage would be greater than in conventional tillage, at least in the surface
layers. Particulate organic C and potentially mineralizable C may be useful to evaluate variations in topsoil organic matter.
- Authors:
- Abreu, S. L.
- Godsey, C. B.
- Edwards, J. T.
- Warren, J. G.
- Source: Soil & Tillage Research
- Volume: 117
- Year: 2011
- Summary: Intensive tillage during the last century has greatly reduced organic carbon contents of Oklahoma cropland. Increased public interest in carbon sequestration and the potential for carbon storage in no-till soils to offset CO2 emissions has brought about the need for accurate estimates of carbon sequestration in Oklahoma. Eight locations across Oklahoma were soil sampled to determine the impact of no-till farming practices on soil carbon storage. Locations consisted of side by side no-till and tilled fields sampled at four sites in each field. Samples were divided into 0–10, 10–20, 20–40, 40–70, and 70–110 cm depths and analyzed for organic carbon (OC) and total nitrogen (TN). Averaged across locations and depth, the concentration of organic carbon (OC) was 0.7 g kg−1 greater in no-till compared to tilled fields. As expected, differences between no-till and conventional till were dependent on length of time in no-till and annual precipitation. The greater the time in no-till management and the higher the annual precipitation, the greater the carbon stocks compared to conventional till fields. Despite the high degree of variation among sample locations, the mass of OC was significantly (p = 0.07), greater in the NT compared to that found in the CT fields, with the average difference being 8.6 Mg ha−1. The highest OC accumulation was observed in Miami with an average of 3.5 Mg ha−1 year−1, while at Lahoma 2 and Goodwell no accumulation of OC was observed. Eliminating tillage operations can increase OC accumulation with the presence of adequate rainfall and an extended period of time.
- Authors:
- Source: Biomass and Bioenergy
- Volume: 35
- Issue: 5
- Year: 2011
- Authors:
- Denmead,O. Tom
- Kinsela,Andrew S.
- Reynolds,Jason K.
- Melville,Michael D.
- Macdonald,Bennett C. T.
- White,Ian
- Source: Soil Research
- Volume: 49
- Issue: 6
- Year: 2011
- Authors:
- Cockfield, G.
- Maraseni, T. N.
- Source: Agricultural Systems
- Volume: 104
- Issue: 6
- Year: 2011
- Authors:
- Shelton, H. M.
- Radrizzani, A.
- Kirchhof, G.
- Dalzell, S. A.
- Source: Crop and Pasture Science
- Volume: 62
- Issue: 4
- Year: 2011
- Summary: Soil organic carbon (OC) and total nitrogen (TN) accumulation in the top 0–0.15 m of leucaena–grass pastures were compared with native pastures and with continuously cropped land. OC and TN levels were highest under long-term leucaena–grass pasture (P < 0.05). For leucaena–grass pastures that had been established for 20, 31, and 38 years, OC accumulated at rates that exceeded those of the adjacent native grass pasture by 267, 140, and 79 kg/ha.year, respectively, while TN accumulated at rates that exceeded those of the native grass pastures by 16.7, 10.8, and 14.0 kg/ha.year, respectively. At a site where 14-year-old leucaena–grass pasture was adjacent to continuously cropped land, there were benefits in OC accumulation of 762 kg/ha.year and in TN accumulation of 61.9 kg/ha.year associated with the establishment of leucaena–grass pastures. Similar C : N ratios (range 12.7–14.5) of soil OC in leucaena and grass-only pastures indicated that plant-available N limited soil OC accumulation in pure grass swards. Higher OC accumulation occurred near leucaena hedgerows than in the middle of the inter-row in most leucaena–grass pastures.
Rates of C sequestration were compared with simple models of greenhouse gas (GHG) emissions from the grazed pastures. The amount of carbon dioxide equivalent (CO2-e) accumulated in additional topsoil OC of leucaena–grass pastures ≤20 years old offset estimates of the amount of CO2-e emitted in methane and nitrous oxide from beef cattle grazing these pastures, thus giving positive GHG balances. Less productive, aging leucaena pastures >20 years old had negative GHG balances; lower additional topsoil OC accumulation rates compared with native grass pastures failed to offset animal emissions
- Authors:
- Bird, M. I.
- Beeton, R. J. S.
- Menzies, N. W.
- Witt, G. B.
- Noel, M. V.
- Source: Agriculture, Ecosystems & Environment
- Volume: 141
- Issue: 1-2
- Year: 2011
