• Authors:
    • Figueiredo, G. C.
    • Medeiros, J. C.
    • Giarola, N. F. B.
    • Fracetto, F. J. C.
    • Silva, A. P. da
    • Cerri, C. E. P.
  • Source: Plant Soil
  • Volume: 338
  • Issue: 1-2
  • Year: 2011
  • Summary: The decomposition rate of soil organic matter (SOM) is affected by soil management practices and particularly by the physical and hydraulic attributes of the soil. Previous studies have indicated that the SOM decomposition is influenced by the Least Limiting Water Range (LLWR). Therefore, the objective of this study was to relate the C-CO 2 emissions to the LLWR of the surficial layer of soil under two management systems: no-tillage (NT), conducted for 20 years, and conventional tillage (CT). Soil in NT presented greater soil organic carbon (SOC) stocks than in CT. Emissions of C-CO 2 were greater in the NT than in the CT, because of the greater carbon stocks in the soil surface layer and the greater biological activity (due to the improvement of the soil structure) in NT as compared to CT. The use of LLWR associated with the measurement of C-CO 2 emissions from the soil could help to predict the efficacy of the adopted management system for trapping carbon in the soil.
  • Authors:
    • Singh, M. R.
    • Singh, M. K.
  • Source: Indian Journal of Agronomy
  • Volume: 56
  • Issue: 2
  • Year: 2011
  • Summary: Excessive tillage and soil degradation are important factors limiting wheat [ Triticum aestivum (L) emend. Fiori & Paol.] productivity, particularly in rice ( Oryza sativa L.) - wheat cropping system. Therefore present field experiment was conducted during winter of 2007-08 and 2008-09 at Varanasi to study the effect of seed rate and weed management on weed growth and yield in late sown zero till wheat. Treatments comprised of three seed rates viz., 100, 120 and 140 kg/ha in the main plots and five weed management treatments viz., weedy, 2,4-D Na salt 625 g/ha (POE), metsulfuron methyl 4 g/ha (POE), sulfosulfuron 30 g/ha+metsulfuron methyl 2 g/ha (POE) and 2-hand weedings in sub-plots with three replications. Broad leaved weed population was found more in the experimental crop as compared to narrow leaved weeds. All the herbicidal treatments were effective in reducing weed density and dry weight in comparison to weedy check. Seed rate of 120 kg/ha recorded significantly higher grain yield in comparison to seed rate of 100 and 140 kg/ha. Amongst weed management treatments all the herbicidal weed control had significantly higher grain yield in comparison to weedy check. Sulfosulfuron 30 g/ha+metsulfuron methyl 2 g/ha had higher grain yield than alone application of 2, 4-D @ 625 g/ha and metsulfuron methyl 4 g/ha.
  • Authors:
    • Melero, S.
    • Panettieri, M.
    • Madejon, E.
    • Gomez Macpherson, H.
    • Moreno, F.
    • Murillo, J. M.
  • Source: Soil & Tillage Research
  • Volume: 112
  • Issue: 2
  • Year: 2011
  • Summary: Long-term no-till practices (NT) have a positive effect on recovery and improving soil fertility and decreasing soil erosion. Nevertheless, long term no-till practices may also cause some inconveniences, such as soil compaction, water infiltration and problems in seed germination. Thus, in the present work we assess the effects of the implementation (October 2008) of a traditional tillage (mouldboard ploughing) (TT) and reduced tillage (chiselling) (RT) on soil quality in a dryland calcareous soil (Leptic Typic Xerorthent) after 8 years of soil no-till management (NT) in SW Spain. The results were compared to those found under no-till. We hypothesised that C fractions and biological properties would be adequate indicators of soil quality changes. To test the hypothesis soil samples were collected at three depths (0-5, 5-10 and 10-25 cm) and in three sampling periods, after tillage and sowing (January 2009) after harvesting (June 2009) a vetch crop ( Vicia sativa, L) and after tillage and sowing (January 2010) of a wheat crop ( Triticum aestivum, L). Total organic carbon (TOC) and carbon labile fractions (active carbon (AC) and water soluble carbon (WSC)) were determined. Biological status was evaluated by the analysis of soil microbial biomass carbon and nitrogen (MBC and MBN) and enzymatic activities [dehydrogenase activity (DHA), and beta-glucosidase activity (Glu)]. The implementation of chiselling did not cause depletion in most of the studied soil properties compared to no-till in the first 5 cm of soil. However, the application of traditional tillage reduced 23% of TOC, 27% of WSC, 12% of AC, 19% of MBC, 44% of MBN, 37% of DHA and 51% of Glu in the upper layer of the soil (0-5 cm depth) with respect to no-till. Soil organic carbon and microbial parameter values decreased as depth increased, particularly in conservation tillage systems (RT and NT) in all sampling periods. Under our conditions, dryland Mediterranean areas, the mouldboard ploughing is not considered a suitable soil tillage system since it showed an early negative effect on soil organic fractions and biochemical quality. Although further studies would be necessary, the use of chiselling could be a solution in case of problems related to no-till.
  • Authors:
    • Wood,C. W.
    • Price,A. J.
    • Mulvaney,M. J.
  • Source: Journal of Sustainable Agriculture
  • Volume: 35
  • Issue: 3
  • Year: 2011
  • Summary: Limited input producers may adopt no-till production if sufficient weed suppression can be achieved. High-biomass producing cover crops used in conjunction with organic mulches may provide sufficient weed control in no-till vegetable production. Our objective was to quantify weed suppression from a forage soybean summer cover crop and three types of organic mulches applied after collard ( Brassica oleracea L.) planting. Forage soybean residue did not suppress weeds, but mulches were generally effective. Broadleaf and sedge weeds decreased in population size over the three-year period, but grass weed management remained problematic until three years after conversion to no-till. Grass suppression was greater when mulches were applied after the first year. Collard yield, averaging 17,863 kg ha -1, was not affected by any cover crop or mulch treatment.
  • Authors:
    • Ortega, A. L.
  • Source: Archives of Agronomy and Soil Science
  • Volume: 57
  • Issue: 6
  • Year: 2011
  • Summary: The permanent bed planting system for wheat ( Triticum aestivum L.) production has recently received additional attention. Studies using hard red spring wheat (cultivar Nahuatl F2000) were conducted at two locations in central Mexico. The studies included the installation of three furrow diking treatments, two granular N timing treatments and three foliar N rates applied at the end of anthesis. The objective was to evaluate the effect of these factors on wheat grain yield, yield components and grain N in a wheat-maize ( Zea maize L.) rotation with residues of both crops left as stubble. Results indicated that diking in alternate furrows increased both grain yield and the final number of spikes per m 2. The split application of N fertilizer enhanced the number of spikes per m 2 and grain N uptake, but the effect on grain yield was inconsistent. Similarly, grain protein increased with the foliar application of 6 kg N ha -1, depending upon the maximum temperature within the 10 days following anthesis. The normalized difference vegetative index (NDVI) readings collected at four growth stages were generally higher for the split N application than for the basal N application at planting. Grain N uptake was associated to NDVI readings collected after anthesis.
  • Authors:
    • Valboa, G.
    • Favilli, F.
    • L'Abate, G.
    • Papini, R.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 140
  • Issue: 1-2
  • Year: 2011
  • Summary: Land use strongly influences soil properties and unsuitable practices lead to degradation of soil and environmental quality. The aim of this study was to assess the impact of different land uses on some chemical properties of soils developed from Pliocene clays, within hilly environments of central and southern Italy. The areas investigated are located in Vicarello di Volterra (Pisa, Tuscany), S. Quirico d'Orcia (Siena, Tuscany) and Soveria Simeri (Catanzaro, Calabria). Within each area different land uses were compared, including a natural ecosystem (Mediterranean bush), a perennial grass or pasture and an intensive crop (wheat, as monoculture or in rotation). The soils were sampled at 0.0-0.1, 0.1-0.2 and 0.2-0.4 m depth and analysed for particle size, pH, bulk density, cation exchange capacity and exchangeable cations, total organic carbon (TOC) and humified carbon (HC) concentrations, organic carbon stock and total N. The stratification ratio of soil organic carbon was calculated to characterize soil organic carbon distribution with depth. At all sites, soil under Mediterranean bush contained the largest amounts of TOC (as both concentration and stock), HC, total N and exchangeable K, together with the highest cation exchange capacity and the lowest pH values. The decrease in soil OC stock with land use change from natural to agricultural ecosystem was 65-85% to 0.1 m depth, 55-82% to 0.2 m depth and 44-76% to 0.4 m depth, with the lowest decrements for perennial grass from S. Quirico and the highest decrement for continuous wheat from Soveria Simeri. Continuous wheat cropping, based on conventional tillage, proved to be the least sustainable land use. At Soveria Simeri, the organic carbon content under pasture was not significantly larger than under wheat cultivation, probably because of grazing mismanagement; however, organic carbon under pasture was more humified. At S. Quirico, the perennial grass resulted in a significant increase in soil organic carbon at the soil surface relative to the wheat cultivation, while at Vicarello no differences were observed between alfalfa/wheat rotation and perennial grass. Our results lead to the questioning of sustainability of intensive cereal farming and uncontrolled grazing in the considered environments, emphasizing the need for greater attention to conservative land managements.
  • Authors:
    • Parr, M.
    • Grossman, J. M.
    • Reberg-Horton, S. C.
    • Brinton, C.
    • Crozier, C.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 6
  • Year: 2011
  • Summary: Sixteen winter annual cover crop cultivars were grown in North Carolina to determine total N accumulation, biological N fixation (BNF) potential, and compatibility with a roller-crimper-terminated organic corn ( Zea mays L.) production system. Cover crops and termination dates were tested in a stripped block design. Treatments included hairy vetch ( Vicia villosa Roth), common vetch ( Vicia sativa L.), crimson clover ( Trifolium incarnatum L.), Austrian winter pea ( Pisum sativum L.), berseem clover ( Trifolium alexandrinum L.), subterranean clover ( Trifolium subterraneum L.), narrow leaf lupin ( Lupinus angustifolius L.), and Balansa clover ( Trifolium michelianum Savi.), as well as bicultures of rye ( Secale cereale L.), hairy vetch, and Austrian winter pea. Roller-crimper termination occurred in mid-April, early May, and mid-May. Total biomass, N concentration, and C/N ratios were determined for cover crops at all roll times and natural 15N abundance at the optimal kill date. Hairy vetch and crimson clover monocultures had the greatest overall biomass in 2009, and bicultures the greatest biomass in 2010. Crimson clover successfully terminated in late April, hairy vetch and Austrian winter pea in mid-May, and berseem clover and common vetch in late May. All cover crops except lupin and subterranean clover derived between 70 and 100% of their N from the atmosphere. Corn response to cover crop mulches was significantly affected by the time of rolling, with poor stands resulting from competition with insufficiently terminated mulches. Crimson, Balansa, and subterranean clover mulches resulted in poor corn yields despite relatively high levels of total N. The highest corn yields were achieved in hairy vetch and rye plus hairy vetch bicultures.
  • Authors:
    • Paudel, B. R.
    • Anderson, S. H.
    • Udawatta, R. P.
  • Source: Applied Soil Ecology
  • Volume: 48
  • Issue: 2
  • Year: 2011
  • Summary: Establishment of buffers and incorporation of trees and shrubs are believed to improve soil quality and thereby improve water quality from grazed pasture systems. Although enzyme activities and water stable aggregates have been identified as measurable soil quality parameters for early responses to changes in soil management, the literature lacks information on those parameters for grazing systems with agroforestry buffers. The objective of this study was to examine the activities of fluorescein diacetate (FDA) hydrolase, dehydrogenase, beta-glucosidase and beta-glucosaminidase, the percentage of water stable aggregates (WSA) and soil organic carbon and nitrogen as soil quality parameters for grazed pasture and row-crop systems. The study consisted of four management treatments: grazed pasture (GP), agroforestry buffer (AgB), grass buffer (GB) and row-crop (RC). The WSA was determined by wet sieving method while the enzyme activities were colorimetrically quantified using a spectrophotometer in laboratory assays. Soil organic carbon (SOC) and total nitrogen (TN) contents were also determined. Two soil depths (0-10 and 10-20 cm) were analyzed for all treatments. The row-crop treatment showed significantly lower activities compared to all other treatments for beta-glucosidase and beta-glucosaminidase enzymes along with lower WSA. The dehydrogenase activities were significantly higher in GP treatment compared to RC treatment. The FDA hydrolase activities were not significantly different among treatments. Surface soil revealed higher enzyme activities and higher WSA than the sub-surface soil. The treatment by depth interaction was significant for beta-glucosidase and beta-glucosaminidase enzymes. The soil organic carbon and total nitrogen data strongly supported the results of enzyme activities and WSA. Implications can be made that perennial vegetation enhances organic matter accumulation in the soil, has minimum disturbance to the soil and will have positive impacts on the ecosystem.
  • Authors:
    • Pes, L. Z.
    • Amado, T. J. C.
    • La Scala Jr., N.
    • Bayer, C.
    • Fiorin, J. E.
  • Source: Soil & Tillage Research
  • Volume: 117
  • Year: 2011
  • Summary: The physical protection of mineralizable carbon (C) in aggregates has been identified as the primary mechanism of soil C stabilization. Therefore, it is possible to hypothesize that the disruption of aggregate by soil tillage is a key process driving C losses during the crop-establishment period. However, these findings are based on studies performed in temperate soils. Limited information is available for studies performed in subtropical and tropical soils, especially in Oxisols, which are rich in oxides that provides chemical C stabilization. This study was performed in southern Brazil in a long-term soil-management experiment carried out in a clay Typic Haplorthox in Cruz Alta (RS). During the 22nd year of the experiment, carbon dioxide (CO2-C) emissions, temperature, and soil moisture were intensively evaluated over a 21-day summer crop-establishment period using a closed infrared CO2-flux chamber. The cropping system investigated was an intensive crop rotation following the soil input of winter-cover crops (black oat (Avena strigosa Schreb) + common vetch (Vicia sativa L) under two contrasting tillage systems, conventional tillage (CT) and no-till (NT). The apparent contributions to CO2-C losses by resident soil C associated with aggregate disruption and recent crop-residue C input were assessed in treatments with crop-residue input (+R) and with crop-residue removed (-R). An exponential-decay model was used to fit the differences in CO2-C flux between CT - R and NT - R (apparent aggregate-disruption effect) and between CT + R and CT - R (apparent recent crop-residue C input effect). As expected, the CT + R showed an increase of 72% in CO2-C losses relative to NT + R. During the three-week crop-establishment period, crop-residue C input was the primary source of CO2-C emissions under CT. The CO2-C losses under CT were equivalent to 65% of the aboveground C input by winter cover crops, whereas this value decreased to 35% in NT. Exponential-decay modeling of the data for the first week showed that approximately 20% of the CO2-C losses under CT were related to the exposure of mineralizable resident soil C due by tillage operations. The analysis showed that this value decreased to only 2% for the three-week period. The CO2-C emissions exhibited a positive linear relationship with soil temperature and soil water-filled porosity under NT, but a similar relationship was found only with soil temperature under CT. For this Oxisol during the crop-establishment period, the physical aggregate disruption induced by long-term CT played a secondary role in CO2-C losses relative to the recent crop-residue C input from tillage operations.
  • Authors:
    • Petersen, S. O.
    • Mutegi, J. K.
    • Hansen, E. M.
    • Munkholm, L. J.
  • Source: Soil Biology and Biochemistry
  • Volume: 43
  • Issue: 7
  • Year: 2011
  • Summary: Conservation tillage practices are widely used to protect against soil erosion and soil C losses, whereas winter cover crops are used mainly to protect against N losses during autumn and winter. For the greenhouse gas balance of a cropping system the effect of reduced tillage and cover crops on N2O emissions may be more important than the effect on soil C. This study monitored emissions of N2O between September 2008 and May 2009 in three tillage treatments, i.e., conventional tillage (CT), reduced tillage (RI) and direct drilling (DD), all with (+CC) or without (-CC) fodder radish as a winter cover crop. Cover crop growth, soil mineral N dynamics, and other soil characteristics were recorded. Furthermore, soil concentrations of N2O were determined eight times during the monitoring period using permanently installed needles. There was little evidence for effects of the cover crop on soil mineral N. Following spring tillage and slurry application soil mineral N was dominated by the input from slurry. Nitrous oxide emissions during autumn, winter and early spring remained low, although higher emissions from +CC treatments were indicated after freezing events. Following spring tillage and slurry application by direct injection N2O emissions were stimulated in all tillage treatments, reaching 250-400 mu g N m(-2) h(-1) except in the CT + CC treatment, where emissions peaked at 900 mu g N M-2 h(-1). Accumulated emissions ranged from 1.6 to 3.9 kg N2O ha(-1). A strong positive interaction between cover crop and tillage was observed. Soil concentration profiles of N2O showed a significant accumulation of N2O in CT relative to RI and DD treatments after spring tillage and slurry application, and a positive interaction between slurry and cover crop residues. A comparison in early May of N2O emissions with flux estimates based on soil concentration profiles indicated that much of the N2O emitted was produced near the soil surface.