• Authors:
    • Ferris, H.
    • DuPont, S. T.
    • Horn, M. van
  • Source: Applied Soil Ecology
  • Volume: 41
  • Issue: 2
  • Year: 2009
  • Summary: Soil food webs cycle nutrients and regulate parasites and pathogens, services essential for both agricultural productivity and ecosystem health. Nematodes provide useful indicators of soil food web dynamics. This study was conducted to determine if nematode soil food web indicators and crop yield can be enhanced by combinations of cover crops in a conservation tillage system. The effects of three cover crop treatments (vetch/pea, oat/wheat and oat/wheat/pea/vetch) with low, medium and high C:N and a bare fallow control were investigated in Davis, CA. Nematode fauna, soil properties and plant productivity were measured. Soil food web indices, including the Enrichment Index (EI), Structure Index (SI), Basal Index (BI), and Channel Index (CI), based on the composition of nematode assemblages, were calculated to infer soil food web condition. Cover cropped tomato/corn rotations had twice the number of enrichment opportunist bacterial feeding nematodes, active participants in nitrogen mineralization, than fallowed tomato/corn rotations (opportunist bacterial feeders=163 versus 98). In winter fallowed plots food webs were basal, common in disturbed, nutrient-poor conditions (BI=37). Total number of enrichment opportunist nematodes, soil NH 4-N levels, and inferred nitrogen mineralization, were higher in cover crop treatments with low to mid C:N ratios. Omnivore and predator nematodes were scarce, averaging less than 6 nematodes 100 g -1 in all treatments. In year one, plant productivity was highest after fallow. In contrast, in year two productivity was highest after cover crops with high nitrogen content and productivity significantly correlated with the structure of the soil fauna. Monitoring the abundance of enrichment opportunists may provide managers with a new tool to evaluate soil food web nitrogen mineralization and plant productivity.
  • Authors:
    • Eastridge, M. L.
    • Dick, R. P.
    • Barker, D. J.
    • Sulc, R. M.
    • Fae, G. S.
    • Lorenz, N.
  • Source: Agronomy Journal
  • Volume: 101
  • Issue: 5
  • Year: 2009
  • Summary: The benefits of cover crops within crop rotations are well documented, but information is limited on using cover crops for forage within midwestern United States cropping systems, especially under no-tillage management. Our objective was to evaluate plant, animal, and soil responses when integrating winter cover crop forages into no-till corn ( Zea mays L.) silage production. Three cover crop treatments were established no-till after corn silage in September 2006 and 2007 at Columbus, OH: annual ryegrass ( Lolium multiflorum L.), a mixture of winter rye ( Secale cereale L.) and oat ( Avena sativa L.), and no cover crop. Total forage yield over autumn and spring seasons was 38 to 73% greater ( P≤0.05) for oat+winter rye than for annual ryegrass. Soil penetration resistance (SPR) in May 2007 was 7 to 15% greater ( P≤0.10) in the grazed cover crops than in the nongrazed no cover crop treatment; however, subsequent silage corn yield did not differ among treatments, averaging 10.4 Mg ha -1 in August 2007. Compared with the no cover crop treatment, cover crops had three- to fivefold greater root yield, threefold greater soil microbial biomass (MB) in spring 2008, and 23% more particulate organic carbon (POC) concentrations in the 0- to 15-cm soil depth. Integration of forage cover crops into no-till corn silage production in Ohio can provide supplemental forage for animal feed without detrimental effects on subsequent corn silage productivity, with the added benefit of increasing labile soil C.
  • Authors:
    • Denardin, R. B. N.
    • Wildner, L. do P.
    • Coimbra, J. L. M.
    • Gatiboni, L. C.
  • Source: Biotemas
  • Volume: 22
  • Issue: 2
  • Year: 2009
  • Summary: The present study was carried out with the aim of monitoring the edaphic fauna modifications during the decomposition of cover crops straw. The experiment was carried out in the 2005/2006 spring-summer season in Chapeco/SC, Brazil. The treatments were: (1) Straw of black oat ( Avena strigosa Scrheb.); (2) Straw of black oat cultivated with addition of 50 kg ha -1 of nitrogen; (3) Straw of rye ( Secale cereale L.); (4) Straw of rye cultivated with addition of 50 kg ha -1 of nitrogen; (5) Uncovered soil. The cover crops were cultivated until flowering, when they were handled with a roll-knife. Ten evaluations of the edaphic fauna were made during the straw decomposition process (from 23/09/2005 to 03/02/2006) using pitfall traps. The first sampling was taken six days before the handling of cover crops, and the others were taken at 4, 18, 32, 46, 67, 83, 98, 112 and 127 days after handling. The results showed that the evaluated edaphic fauna groups were sensitive to the remaining amount of straw covering the soil under no tillage, and that the straw decomposition induced a decrease in fauna diversity because of the relative increase of the Collembola group.
  • Authors:
    • Albuquerque, J. A.
    • Reichert, J. M.
    • Reinert, D. J.
    • Genro Junior, S. A.
  • Source: CIENCIA RURAL
  • Volume: 39
  • Issue: 1
  • Year: 2009
  • Summary: A study was conducted to evaluate the effects of crop succession and rotation on the crop yields and physical properties of an oxisol (clayey Haplortox) under no-tillage system, in Rio Grande do Sul State, Brazil. The treatments included four cropping sequences, used from 1998 to 2001: (1) succession wheat/soyabean; (2) rotation corn/oat/corn + Cajanus cajan/wheat/soyabean/wheat; (3) rotation Cajanus cajan/wheat/soyabean/wheat/soybean/oat; and (4) rotation Crotalaria juncea/wheat/soyabean/oat/corn/wheat. In October 2000 and 2001, soil samples were collected to determine the physical properties, and in all years, crop yields were measured. The oxisol under no-tillage had a high degree of compaction with the greater soil bulk density and lower macroporosity than the critical limit for clay texture. The largest limitations were observed below the layer of 0-0.03 m, because in the uppermost layer, soil mobilization by successive operations of fertilizer application and sowing increased soil porosity and reduced soil density. Thus, greater volume of pores was observed between soil saturation and field capacity, responsible for soil aeration, and between field capacity and wilting point, responsible for storage of plant available water. The use of cover crops once every three years was not efficient to reduce soil compaction. The yield of the subsequent crops was positively influenced in the rotation with Crotalaria juncea, while the other cropping systems did not differ from crop succession.
  • Authors:
    • Lovato, P.
    • Lana, M.
    • Fayad, J.
    • Comin, J.
    • Kieling, A.
  • Source: Ciencia Rural
  • Volume: 39
  • Issue: 7
  • Year: 2009
  • Summary: To eliminate herbicide use in no-tillage tomato production, an experiment was carried out to evaluate the best combination of winter cover crops for weed control and tomato production at the Ituporanga Experimental Station in Santa Catarina, Brazil. Oat ( Avena strigosa [ Avena nuda]), vetch ( Vicia villosa) and fodder radish ( Raphanus sativus) were grown in monoculture and in mixes. The tomato cv. Marcia-EPAGRI was stake-trained and grown under fertigation. The highest values in above-ground dry biomass were obtained by oat+vetch and oat monoculture, followed by vetch+radish, oat+radish, and oat+vetch+radish. Treatments with oats had the best performances in controlling resident vegetation, while vetch was associated with the worst performances. There were no significant differences between the treatments for total yield and marketable fruit production.
  • Authors:
    • Cabezas, W. A. R. L.
    • Lange, A.
    • Trivelin, P. C. O.
  • Source: Revista Brasileira de Milho e Sorgo
  • Volume: 8
  • Issue: 1
  • Year: 2009
  • Summary: Strategies aiming to increase straw production by crops should be implemented in the Cerrado region in order to consolidate no-tillage cultivation. The objective of the present work was to evaluate the effect of time and splitting of supplementary nitrogen application to maize (in addition to the N-fertilization at seeding) on straw production and several yield components of black oat, a spontaneous native species. Treatments consisted of applying 70 kg ha -1 nitrogen in addition to maize fertilization at seeding, at distinct times: at black-oat seeding; 8 days before corn seeding; in covering in plants in the phases of 4-5 leaves and 6-7 leaves. At seeding, 42 kg N.ha -1 were applied in all plots. The nitrogen fertilization applied at oat seeding did not cause increase in out-of-season straw productivity. An increase in maize straw production was observed with nitrogen supply in addition to fertilization at seeding as well as the application closer to seeding resulted in an increased straw production when compared to fertilization at oat seeding.
  • Authors:
    • Ben-Hammouda, M.
    • Errouissi, F.
    • Moussa-Machraoui, S.
    • Nouira, S.
  • Source: Soil & Tillage Research
  • Volume: 106
  • Issue: 2
  • Year: 2009
  • Summary: No-tillage (NT) is becoming increasingly attractive to farmers worldwide because it clearly reduces production costs relative to conventional tillage (CT) and improves soil properties and crop yield. Currently, under semi-arid conditions in North Africa, modern no-tillage techniques are being practiced on several hectares of land. The effect of NT and CT management and crop rotation on soil properties under semi-arid Mediterranean conditions was studied, over a 4-year period at two locations in northern Tunisia. Data from a short-term (2000-2004) use of both no-tillage (NT) and conventional tillage (CT) at the ESAK (Tunisia) were used to evaluate the influence of the tillage systems on the physicochemical properties of soil at the 0-20 cm depth layers. Trial was set up in 2000, where the two tillage systems (CT and NT), and four crop types (durum wheat, barley, pea and oats) were implemented in two distinct sites close to two governorates: Kef (silt/clayey) and Siliana (sand/clay) in northwestern Tunisia. Four years after implementing the two different tillage systems, soil parameters (N, NO 32-, NH 4+ P, P 2O 5, K, K 2O, SOC, SOM and CEC) were determined and comparison between the two tillage systems was made. Our results showed that after 4 years the contents of some parameters for most crop types were greater under NT than under CT at 0-20 cm depth layers, the results varied depending on crop type and site. NT significantly improved soil content especially for K, K 2O, P 2O 5 and N. Under NT system SOM and SOC were enhanced, but without significant results. These enhancements were accompanied by the enhancement of the CEC and the decrease of the C/N ratio. Thus the mineralization process was slightly quicker under NT. Our results also indicate that residue cover combined with no-tillage appears to improve some agronomic parameters and biomass production (grain yield). Multivariate analyses indicate that the improvement of soil properties was dependant on tillage management, sites (climate and soil type) and crop succession (species and cover residue). It must be pointed out that a 4-year period was not sufficient to clearly establish some parameters used in the effects of the NT system on soil properties under semi-arid conditions in northwestern Tunisia.
  • Authors:
    • Cao, E.
    • Andrigueti, M.
    • Carvalho, P.
    • Anghinoni, I.
    • Costa, S.
    • Souza, E.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 33
  • Issue: 6
  • Year: 2009
  • Summary: The potential for adopting crop-livestock systems in southern Brazil is high, especially in untilled soybean areas with cover crops in the winter season. The long-term use of this system at different grazing intensities will result in different carbon and nitrogen stocks in the soil due to the different plant and animal residues. This research was conducted to evaluate alterations in total carbon and nitrogen pools and in organic matter fractions in a soil under different grazing intensities under no-tillage. The experiment on a Rhodic Hapludult (Oxisol) was initiated in 2001, after soybean harvest. The treatments were different cattle grazing (black oat+ryegrass) pressures (10, 20 and 40 cm sward height) and an ungrazed treatment in the winter and soybean in the summer, in a randomized block design. Soil samples were taken at the beginning of the experiment (May, 2001), after three years (May, 2004) and after six years (May, 2007) to evaluate the content and stocks of organic carbon and nitrogen. Moderate grazing intensities (20 and 40 cm plant height) resulted in an increase of total carbon and nitrogen and in the organic matter particulate fraction, similarly to the ungrazed area. However, at the most intensive grazing pressure (10 cm plant height) there were losses in the stocks of these elements and reduction in soil organic matter quality.
  • Authors:
    • Ernani, P.
    • Zanatta, J.
    • Bayer, C.
    • Vieira, F.
  • Source: Australian Journal of Soil Research
  • Volume: 47
  • Issue: 7
  • Year: 2009
  • Summary: Nitrogen-fixing crops and N fertilisation increase soil acidification, but few studies have attempted to evaluate the capacity of soil organic matter to alleviate the Al toxicity in acid no-tilled soils. This study was carried out in a 21-year-old experiment aiming to evaluate the effect of crop systems [fallow/maize ( Zea mays L.), F/M; oat ( Avena strigosa Schreb)/maize, O/M; oat+vetch ( Vigna sativa L.)/maize, O+V/M; lablab ( Dolichos lablab)+maize, L+M; and pigeon pea ( Cajanus cajan L. Millsp.)+maize, P+M] and mineral N fertilisation (0 and 149 kg/ha.year) on chemical attributes and Al speciation in the 0-0.05 and 0.05-0.10 m layers of a no-tilled Paleudult of Southern Brazil. The original soil pH (5.8) decreased in all crop systems, declining 0.37-1.52 units in 21 years without re-liming. This decrease was larger in subsoil layers and, in general, was exacerbated by legume-based crop systems and by N fertilisation. The drop in soil pH increased Al content in solid phase (range 0.07-1.85 cmol c/kg) and in soil solution (range 0.01-0.06 mmol/L), and decreased base saturation on cation exchange capacity (range 12.5-61.2%). However, the Al 3+ activity in the soil solution (1.03*10 -7-9.3*10 -8) was kept below threshold values of toxicity to maize roots, primarily due to the formation of organometallic complexes at low pH, which was estimated as up to 90% of the total Al in solution, but also due to the increased ionic strength in this no-till soil (0.0026-0.0104). Our results highlight that, although legume cover crops and N fertilisation can accelerate soil acidification, Al toxicity is offset by increased organic matter in no-till subtropical soils.
  • Authors:
    • Bernardi, A.
    • Harden, S.
    • Wilson, B.
    • Young, R.
  • Source: Australian Journal of Soil Research
  • Volume: 47
  • Issue: 3
  • Year: 2009
  • Summary: Australian agriculture contributes an estimated 16% of all national greenhouse gas emissions, and considerable attention is now focused on management approaches that reduce net emissions. One area of potential is the modification of cropping practices to increase soil carbon storage. This paper report short-medium term changes in soil carbon under zero tillage cropping systems and perennial vegetation, both in a replicated field experiment and on nearby farmers' paddocks, on carbon-depleted Black Vertosols in the upper Liverpool Plains catchment. Soil organic carbon stocks (C S ) remained unchanged under both zero tillage long fallow wheat ( Triticum aestivum)-sorghum ( Sorghum) rotations and zero tillage continuous winter cereal in a replicated field experiment from 1994 to 2000. There was some evidence of accumulation of C S under intensive (>1 crop/year) zero tillage response cropping. There was significant accumulation of C S (~0.35 tonnes/ha/year) under 3 types of perennial pasture, despite removal of aerial biomass with each harvest. Significant accumulation was detected in the 0-0.1, 0.1-0.2, and 0.2-0.4 m depth increments under lucerne and the top 2 increments under mixed pastures of lucerne and phalaris and of C3 and C4 perennial grasses. Average annual rainfall for the period of observations was 772 mm, greater than the 40-year average of 680 mm. A comparison of major attributes of cropping systems and perennial pastures showed no association between aerial biomass production and accumulation rates of C S but a positive correlation between the residence times of established plants and accumulation rates of C S . C S also remained unchanged (1998/2000-07) under zero tillage cropping on nearby farms, irrespective of paddock history before 1998/2000 (zero tillage cropping, traditional cropping, or ~10 years of sown perennial pasture). These results are consistent with previous work in Queensland and central western New South Wales suggesting that the climate (warm, semi-arid temperate, semi-arid subtropical) of much of the inland cropping country in eastern Australia is not conducive to accumulation of soil carbon under continuous cropping, although they do suggest that C S may accumulate under several years of healthy perennial pastures in rotation with zero tillage cropping.