- Authors:
- Urquiaga, S.
- Alves, B. J. R.
- Giacomini, S. J.
- Aita, C.
- Denardin, J. E.
- Dos Santos, H. P.
- Dieckow, J.
- Mielniczuk, J.
- Bayer, C.
- Zanatta, J. A.
- Conceição, P. C.
- Jantalia, C. P.
- Boddey, R. M.
- Source: Global Change Biology
- Volume: 16
- Issue: 2
- Year: 2010
- Summary: Conservation agriculture can provide a low-cost competitive option to mitigate global warming with reduction or elimination of soil tillage and increase soil organic carbon (SOC). Most studies have evaluated the impact of zero till (ZT) only on surface soil layers (down to 30 cm), and few studies have been performed on the potential for C accumulation in deeper layers (0-100 cm) of tropical and subtropical soils. In order to determine whether the change from conventional tillage (CT) to ZT has induced a net gain in SOC, three long-term experiments (15-26 years) on free-draining Ferralsols in the subtropical region of South Brazil were sampled and the SOC stocks to 30 and 100 cm calculated on an equivalent soil mass basis. In rotations containing intercropped or cover-crop legumes, there were significant accumulations of SOC in ZT soils varying from 5 to 8 Mg ha-1 in comparison with CT management, equivalent to annual soil C accumulation rates of between 0.04 and 0.88 Mg ha-1. However, the potential for soil C accumulation was considerably increased (varying from 0.48 to 1.53 Mg ha-1 yr-1) when considering the soil profile down to 100 cm depth. On average the estimate of soil C accumulation to 100 cm depth was 59% greater than that for soil C accumulated to 30 cm. These findings suggest that increasing sampling depth from 30 cm (as presently recommended by the IPCC) to 100 cm, may increase substantially the estimates of potential CO2 mitigation induced by the change from CT to ZT on the free-draining Ferralsols of the tropics and subtropics. It was evident that that legumes which contributed a net input of biologically fixed N played an important role in promoting soil C accumulation in these soils under ZT, perhaps due to a slow-release of N from decaying surface residues/roots which favored maize root growth.
- Authors:
- Vieira, F.
- Bayer, C.
- Zanatta, J.
- Source: Proceedings of the 19th World Congress of Soil Science: Soil solutions for a changing world, Brisbane, Australia, 1-6 August 2010. Congress Symposium 4: Greenhouse gases from soils
- Year: 2010
- Summary: Emissions of N 2O were measured following cover crops management (oat - O and vetch - V) under tillage (CT) and no tillage (NT) in a silt loam Acrisol in South Brazil. Effects of tillage systems and residue management on N 2O emissions were examined over 55 days in 2007 and 54 days in 2008. Larger emissions were measured in 2008 compared to 2007. N 2O emissions increased in the presence of crops residues and were further increased in NT V/M in 2007 (19384 g N/m 2/ha) and in CT V/M in 2008 (431138 g N/m 2/ha) and they are related to high water content and available soil nitrogen. Smallest fluxes of N 2O were measured from the NT O/M treatments, which 28861 g N/m 2/ha in 2007 and 27419 g N/m 2/ha in 2008.
- Authors:
- Chen, C.
- Xu, Z.
- Wu, H.
- Zhou, X.
- Source: Proceedings of the 19th World Congress of Soil Science: Soil solutions for a changing world, Brisbane, Australia, 1-6 August 2010. Working Group 3.5 Paddy soils and water scarcity
- Year: 2010
- Summary: Winter cover crops are not only one of effective agricultural management practices to control weeds but also can improve soil fertility, resulting in increasing crop productions. Up to now, however, little is known about information on how much of soil soluble organic carbon (C) incorporates into the soils applied with winter cover crops, which is a prerequisite to design strategies that improve C sequestration in agricultural ecosystems. The aims of this study were to: (1) assess the effects of winter cover crops on soluble organic carbon (SOC) pools using different extraction methods (KCl extractable organic C; microbial biomass) and microbial community functional diversity, and (2) quantify how much of the potentially mineralizable organic C pools (C 0) incorporates into the soils and associated half-life of SOC remaining under seven cover crops and nil-crop control (CK) in temperate agricultural soils of southern Australia. Cover crop treatments are cereal rye, wheat, saia oats, vetch, field peas, mustard and the mixture of cereal rye and vetch. Results showed that the CK treatment had higher soil moisture content and lower soluble organic nitrogen (SON) compared to the cover crop treatments. Among the cover crop treatments, there was significantly higher SON in the wheat, oats and vetch treatments than in the other treatments. The oats treatment had the highest amount of cumulative CO 2-C than any other treatments over one-month incubation experiment. An exponential regression approach for C mineralization was used to estimate C o and soil samples under the cover crops can be divided into four groups depending on C o. The principal component analysis of the MicroResp TM profiles showed that the CK treatment was significantly different from the cover crop treatments. The cover crop treatments with wheat, vetch and peas as well as mustard form a cluster which was significantly different from the other clusters. In addition, the vetch, field peas and mustard treatments showed higher Shannon diversity H and Evenness (E) and Simpson diversity H compared to the other cover crop treatments with the lowest Shannon H and E at CK. In conclusion, overall, the vetch and field peas as well as wheat winter cover crop may be better management practices for agricultural ecosystems in southern Australia.
- Authors:
- Source: PESQUISA AGROPECUARIA BRASILEIRA
- Volume: 45
- Issue: 12
- Year: 2010
- Summary: The objective of this work was to evaluate the influence of fall-winter and spring crops, cultivated under no-tillage system, on the aggregates and organic matter of a Rhodic Ferralsol. The experiment was performed in the 2006/2007, 2007/2008 and 2008/2009 growing seasons. Congo signal grass ( Urochloa ruziziensis), grain sorghum ( Sorghum bicolor) and sorghum mixed with brachiaria were cropped in the fall-winter to consist the main plots. In the spring, millet ( Pennisetum glaucum), 'Cober Crop' ( Sorghum bicolor * Sorghum sudanense) and Indian hemp ( Crotalaria juncea) were cultivated as subplots as well as a fallow treatment. Soybean was cropped in the summer, totaling 12 treatments. Cover crop dry matter and root growth were evaluated in 2006 and 2008. Soil samples were taken from 0-5 and 5-10 cm depths, after spring cover crops managing, in the first and third years. The mean weight diameter, geometric mean diameter, aggregate stability index, aggregates larger than 2 mm, organic matter and total organic carbon levels were evaluated in the samples of the third year. Millet and 'Cober Crop' showed higher dry matter production and root growth. The soil aggregation was improved by cover crop rotations before the summer growing season. The cultivation of 'Cober Crop' and millet influenced the macroaggregate formation in the superficial layers.
- Authors:
- Sundermeier, A.
- Diedrick, K. A.
- Dygert, C. E.
- Mullen, R. W.
- Henry, D. C.
- Source: Agronomy Journal
- Volume: 102
- Issue: 1
- Year: 2010
- Summary: Inclusion of a winter legume cover crop into a crop rotation has been suggested as a method to provide a substantial portion of the N requirement of the following crop. While the benefits of winter cover crops such as reduced soil erosion, increased soil organic matter, and increased mulch cover have been well documented, the N contribution to the subsequent crop has shown to be variable. The objective of this study was to determine the N contribution from a red clover (Trifolium pratense L.) cover crop following wheat (Triticum aestivum L.) to a subsequent corn (Zea mays L.) crop. The experiment was conducted at two western Ohio locations over 3 yr. At both locations, red clover was either interseeded into wheat or seeded after harvest, the red clover cover crop was eliminated with tillage or herbicide application, and corn was planted with three N rates (0, 90, and 180 kg N ha(-1)). The data revealed that for three of the four site years (when the cover crop was successfully established) there was no N contribution attributable to the presence of red clover. The one site that did show a N contribution revealed that the amount of N contributed was less than 90 kg N ha(-1). However, even when no N benefit was found, yields were improved by non-N-related rotational effects. Significant reductions in N fertilization rates following a red clover cover crop are likely to result in lost corn yield opportunities in western Ohio.
- Authors:
- Inomoto, M. M.
- Asmus, G. L.
- Source: Plant disease: an international journal of applied plant pathology
- Volume: 94
- Issue: 8
- Year: 2010
- Summary: Taking into account that information about the host status of cover crops for Pratylenchus brachyurus is scarce or contradictory, this study was undertaken to assess the host status of selected graminaceous cover crops by estimating nematode reproduction and their ability to decrease the nematode density in glasshouse conditions. Furthermore, the reproductive fitness of three P. brachyurus populations was assessed for Brachiaria grasses. Silage and forage sorghum proved to be good hosts for P. brachyurus; consequently, they should be avoided in fields infested with this lesion nematode, mainly before susceptible crop such as soybean, common bean, cowpea, and cotton. Dictyoneura grass, the pearl millet cv. ADR 300, and black oat were poor hosts for P. brachyurus but may increase densities of this nematode over time. Consequently, these cover crops might be used in infested fields for only short periods, because they could increase the P. brachyurus population density slowly but progressively.
- Authors:
- Varrelmann, M.
- Buhre, C.
- Kluth, C.
- Source: Plant Pathology
- Volume: 59
- Issue: 4
- Year: 2010
- Summary: The susceptibility of intercrop species (Raphanus sativus, Brassica juncea, B. rapa, Sinapis alba and Phacelia tanacetifolia) to the sugar beet pathogen Rhizoctonia solani was investigated in vitro, in the greenhouse and in the field with artificial inoculation. Disease severity in subsequently cultivated sugar beet was monitored in the field. Differences in susceptibility between species were found to be consistent in all experimental systems. All intercrop species were susceptible to R. solani. Brassica rapa and R. sativus were less susceptible than P. tanacetifolia. Compared to fallow, the cultivation of B. rapa and R. sativus reduced disease severity in subsequently grown sugar beet (median ratings of up to 3.0 and 3.5, respectively, depending on environmental conditions). This resulted in higher white sugar yield compared to fallow (up to 210% and 157% for B. rapa and R. sativus, respectively). This study demonstrates that in vitro and greenhouse resistance tests are suitable systems to predict the effects of intercrop species susceptibility in the field on disease severity and white sugar yield in subsequently grown sugar beet. Intercrop breeding programmes might profit from fast and efficient screening tests to provide Rhizoctonia-resistant intercrops as an additional control measure against R. solani in sugar beet.
- Authors:
- Source: Journal of Environmental Quality
- Volume: 39
- Issue: 3
- Year: 2010
- Summary: The management of winter cover crops is likely to influence their performance in reducing runoff and erosion during the intercropping period that precedes spring crops but also during the subsequent spring crop This study investigated the impact of two dates of destruction and burial of a rye (Secale cereale L.) and ryegrass (Lolium multifloruni Lint) cover crop on runoff and erosion, focusing on a continuous silage maize (Zea mays L) cropping system Thirty erosion plots with various intercrop management options were monitored for 3 yr at two sues. During the intercropping period. cover crops reduced runoff and erosion by more than 94% compared with muffled, post-maize harvest plots Rough tillage after maize harvest proved equally effective as a late sown cover crop There was no effect of cover crop destruction and burial dates on runoff and erosion during the intercropping period. probably because rough tillage for cover crop burial compensates for the lack of soil cover During two of the monitored maize seasons. it was observed that plots that had been covered during the previous intercropping period lost 40 to 90% less soil compared with maize plots that had been left bare during the intercropping period The burial of an aboveground cover crop biomass in excess of 1 5 t ha (1) was a necessary, yet not always sufficient. condition to induce a residual effect. Because of the possible beneficial residual effect of cover crop burial on erosion reduction, the sowing of a cover crop should be preferred over rough tillage after maize harvest
- Authors:
- da Rocha, M. R.
- Reinert, D. J.
- Carneiro Amado, T. J.
- Nicoloso, R. da S.
- Foletto Eltz, F. L.
- Lanzanova, M. E.
- Source: Revista Brasileira de Ciência do Solo
- Volume: 34
- Issue: 4
- Year: 2010
- Summary: No-tillage associated to cover crops may maintain soil quality, improving or preserving favorable soil physical conditions for plant growth. This study assessed soil bulk density, porosity, penetration resistance, and water infiltration of a PALEUDALF, in the Experimental Area of the Soil Science Department of the Federal University of Santa Maria, in Santa Maria, RS, Brazil, in an experiment started in 1991, with the following crop successions and rotations: (1) Corn/Soybean - Jackbean - MFP; (2) Bare soil - SDES; (3) Corn/Soybean - Fallow - POU; (4) Corn / Soybean - Ryegrass + Vetch - AZEV; (5) Corn / Soybean - Mucuna - MUG; (7) Natural Grass - CNA; (6) Corn/Soybean - Oilseed radish - NFO. Soil bulk density was affected in the 0-0.10 in layer; values were highest in the SDES. Total soil porosity and soil macroporosity were closely correlated to a depth of 0.10 m. Major restriction to root penetration occurred in the surface layer (0-0.03 m) in the SDES treatment, and NFO had greatest values at 0.16-0.18 m depth. The water infiltration rate was lowest in SDES and CNA treatments in all evaluations, while in the others infiltration was constant and statistically equal. Constantly uncovered soil induces degradation in soil physical properties. The studied cropping systems confirmed significant benefits in soil density, porosity, resistance, and water infiltration rate under long term no-tillage.
