• Authors:
    • Cue, R. I.
    • Rochette, P.
    • Gregorich, E. G.
    • Whalen, J. K.
    • Sey, B. K.
  • Source: Soil Science Society of America Journal
  • Volume: 72
  • Issue: 4
  • Year: 2008
  • Summary: Agricultural practices affect the production and emission of CO2 and N2O from soil. The purpose of this 2-yr field study was to determine the effects of tillage (conventionally tilled [CT] and no-till [NT]) and fertilizer source (composted cattle manure and inorganic N-P-K fertilizer) on the CO2 and N2O content in soil profiles under corn (Zea mays L.) and soybean [Glycine max (L.) Merr.]. The mean CO2 and N2O gas contents (i.e., mass of gas per unit soil volume) in the soil profile were determined periodically during two field seasons by sampling the soil atmosphere using plastic tubes installed at three depths (10, 20, and 30 cm) within the crop row. The soil CO2 content was greater in CT than NT soil and in manure-amended than inorganically fertilized plots during 1 yr of the study. The soil N2O content was not affected by tillage practices or fertilizer sources. A significant autocorrelation between sampling dates in both years suggested that the CO2 and N2O contents in the soil profile were not erratic or random, but temporally dependent on site-specific factors. The peak CO2 and N2O levels were measured within 50 d after seeding, probably because soil moisture conditions slowed diffusive gas flux but were favorable for microbial activity. Fluctuations in soil CO2 and N2O contents were not related to the seasonal variation in soil temperature. At most sampling dates, there was a significant (P < 0.05) positive correlation between the CO2 and N2O content in the soil profile, suggesting similarity in the rate of gas accumulation and diffusive flux for CO2 and N2O in soils. The CO2 and N2O content in the soil profile appeared to be controlled more by soil moisture than soil temperature or agricultural practices.
  • Authors:
    • Smith, R. F.
    • Koike, S. T.
    • Yokota, R.
    • Murphree, L.
    • Jackson, L. E.
    • Smukler, S. M.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 126
  • Issue: 3-4
  • Year: 2008
  • Summary: Studying the management strategies suited to large-scale organic production, particularly during the mandated 3-year transition period from conventional management, is a unique research challenge. Organic production traditionally relies on small, diverse plantings and complex management responses to cope with soil fertility and pest pressures, so research should represent decision-making options of an organic grower at the farm scale. This study analyzes crop, soil, pest and management changes during the organic transition period on two ranches (40 and 47 ha) in the Salinas Valley, California in cooperation with a large conventional vegetable producer, Tanimura and Antle, Inc. Permanent transects were established across the two ranches at the onset of adoption of organic practices, and soil and plants were sampled at harvest of almost all crops, while all management operations were recorded by the co-operator. The similar to 10 ha blocks were divided into many small plantings, and 17 different cash crop and cover crop species were planted during the transition period. Management inputs consisted of a range of organic fertilizers and amendments, sprinkler and drip irrigation, cultivation and hand-hoeing, and several types of organic pesticides. Results from the 3-year period followed these general trends: increase in soil biological indicators (microbial biomass and arbuscular mycorrhizae), low soil nitrate pools, adequate crop nutrients, minor disease and weed problems, and sporadic mild insect damage. Multivariate statistical analyses indicated that some crops and cultivars consistently produced higher yields than others, relative to the maximum yield for a given crop. Multi-factor contingency tables showed clear differences in insect and disease damage between crop taxa. Although Tanimura and Antle, Inc. used some of the principles of organic farming (e.g., crop diversity, crop rotation, and organic matter (OM) management), they also relied on substitution-based management, such as fertigation with soluble nutrients, initially heavy applications of organic pesticides, and use of inputs derived from off-farm sources. Their initial production of a large number of crop taxa in small plantings at staggered intervals proved to be an effective strategy for avoiding risks from low yields or crop failure and allowed them to move towards a smaller number of select, successful crops towards the end of the transition. This study demonstrates the feasibility of large-scale producers to transition to organic practices in a manner that was conducive to both production goals and environmental quality, i.e., increased soil C pools, low soil nitrate, and absence of synthetic pesticides. (C) 2008 Elsevier B.V. All rights reserved.
  • Authors:
    • Hepperly, P.
    • LaSalle, T. J.
  • Year: 2008
  • Authors:
    • Reule, C. A.
    • Del Grosso, S. J.
    • Halvorson, A. D.
  • Source: Journal of Environmental Quality
  • Volume: 37
  • Issue: 4
  • Year: 2008
  • Summary: We evaluated the effects of irrigated crop management practices on nitrous oxide (N2O) emissions from soil. Emissions were monitored from several irrigated cropping systems receiving N fertilizer rates ranging from 0 to 246 kg N ha-1 during the 2005 and 2006 growing seasons. Cropping systems included conventional-till (CT) continuous corn (Zea mays L.), no-till (NT) continuous corn, NT corn-dry bean (Phaseolus vulgaris L.) (NT-CDb), and NT corn-barley (Hordeum distichon L.) (NT-CB). In 2005, half the N was subsurface band applied as urea-ammonium nitrate (UAN) at planting to all corn plots, with the rest of the N applied surface broadcast as a polymer-coated urea (PCU) in mid-June. The entire N rate was applied as UAN at barley and dry bean planting in the NT-CB and NT-CDb plots in 2005. All plots were in corn in 2006, with PCU being applied at half the N rate at corn emergence and a second N application as dry urea in mid-June followed by irrigation, both banded on the soil surface in the corn row. Nitrous oxide fluxes were measured during the growing season using static, vented chambers (1-3 times wk-1) and a gas chromatograph analyzer. Linear increases in N2O emissions were observed with increasing N-fertilizer rate, but emission amounts varied with growing season. Growing season N2O emissions were greater from the NT-CDb system during the corn phase of the rotation than from the other cropping systems. Crop rotation and N rate had more effect than tillage system on N2O emissions. Nitrous oxide emissions from N application ranged from 0.30 to 0.75% of N applied. Spikes in N2O emissions after N fertilizer application were greater with UAN and urea than with PCU fertilizer. The PCU showed potential for reducing N2O emissions from irrigated cropping systems.
  • Authors:
    • Fabian, E.
    • Pegoraro, R.
    • Bertol, I.
    • Zoldan Junior, W.
    • Zavaschi, E.
    • Vazquez, E.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 32
  • Issue: 1
  • Year: 2008
  • Summary: Surface soil roughness is affected by many factors, such as the residual effect of the soil management, tillage and rainfall erosivity and, together with the soil cover of crop residues, influences water erosion. The objective of this study was to determine the effects of a chiselling operation, together with rainfall erosivity, on soil surface roughness, from June 2005 to March 2006, in an aluminic Typical Hapludox, under the following soil management systems: bare soil under conventional tillage (BCT), cultivated soil under conventional tillage (CCT), no-tillage in a never-tilled soil with burnt plant residues (BNT), and traditional no-tillage (TNT). The crop sequence in the treatments CCT, BNT and TNT was black oat, soyabean, common vetch, maize, black oat, common bean, fodder radish, soyabean, common vetch, maize and black oat. Five simulated rain tests were applied, with a constant intensity of 64 mm h -1 and durations of 20, 30, 40, 50, and 60 min each. Natural rains during the experimental period accounted for 57 mm, between the 2nd and 3rd rainfall test; 21 mm, between the 3rd and 4th test; and, 30 mm, between the 4th and 5th test. The surface roughness was determined immediately before and immediately after the chiseling tillage, and immediately after each test of rain simulation. The original and linear soil surface roughness was not influenced by the management, unlike random roughness, at the end of a six-month fallow period. The original, linear and random roughness in different soil management systems was affected by a six-month fallow period, when the soil was subjected to chiselling. Random roughness was less influenced by soil slope than by tillage marks, which decreased with the increasing rainfall erosivity. The coefficient of decay of this kind of soil roughness was similar in the studied soil management systems under no tillage and conventional tillage.
  • Authors:
    • Reddy, K. C.
    • Tazisong, I. A.
    • Nyakatawa, E. Z.
    • Senwo, Z. N.
    • Sainju, U. M.
  • Source: Journal of Environmental Quality
  • Volume: 37
  • Issue: 3
  • Year: 2008
  • Summary: Quantification of soil carbon (C) cycling as influenced by management practices is needed for C sequestration and soil quality improvement. We evaluated the 10-yr effects of tillage, cropping system, and N source on crop residue and soil C fractions at 0-to 20-cm depth in Decatur silt loam (clayey, kaolinitic, thermic, Typic Paleudults) in northern Alabama, USA. Treatments were incomplete factorial combinations of three tillage practices (no-till [NT], mulch till [MT], and conventional till [CT]), two cropping systems (cotton [Gossypium hirsutum L.]-cotton-corn [Zea mays L.] and rye [Secale cereale L.]/cotton-rye/cotton-corn), and two N fertilization sources and rates (0 and 100 kg N ha(-1) from NH4NO3 and 100 and 200 kg N ha(-1) from poultry litter). Carbon fractions weresoil organic C (SOC), particulate organic C (POC), microbial biomass C (MBC), and potential C mineralization (PCM). Crop residue varied among treatments and years and total residue from 1997 to 2005 was greater in rye/cottoil-rye/cotton-corn than in cotton-cotton-corn and greater with NH4NO3 than with poultry litter at 100 kg N ha(-1). The SOC content at 0 to 20 cm, after 10 yr was greater with poultry litter than with NH4NO3 in NT and CT, resulting in a C sequestration rate of 510 kg C ha(-1) yr(-1) with poultry litter compared with -120 to 147 kg C ha(-1) yr(-1) with NH4NO3. Poultry litter also increased PCM and MBC compared with NH4NO3. Cropping increased SOC, POC, and PCM compared with fallow in NT Long-term poultry litter application or continuous cropping increased soil C storage and microbial biomass and activity compared with inorganic N fertilization or fallow, indicating that these management practices can sequester C, offset atmospheric CO2 levels, and improve soil and environmental quality.
  • Authors:
    • Suzuki, L. G. A. S.
    • Alves, M. C.
    • Suzuki, L. E. A. S.
    • Rodrigues, R. A. F.
  • Source: Científica, Jaboticabal
  • Volume: 36
  • Issue: 2
  • Year: 2008
  • Summary: The objective of this study was to verify the biomass yield potential of different cover crops in a Cerrado region, in Selviria, Mato Grosso do Sul, Brazil. The work was conducted in the Experimental University Farm of the Paulista State University (UNESP). The experimental design was the randomized complete blocks in strips with splitsplit plot: the plots were the cover crops Mucuna aterrima, Pennisetum americanum, Crotalaria juncea, Cajanus cajan and a fallow area; the split plots were the no-tillage and the conventional tillage, and the splitsplit plots were corn ( Zea mays L.), soybean ( Glycine max (L.) Merrill), and cotton ( Gossypium hirsutum L.) crops. In the winter irrigated Phaseolus vulgaris L. was the crop. In the spring/summer season the cover crop with the greatest biomass yield was Pennisetum americanum. Crotalaria juncea and the fallow area showed medium results while Mucuna aterrima and Cajanus cajan were those with the least yields. Pennisetum americanum was the crop cover with the biggest production potential of dry biomass. The cultivation systems did not influence the dry biomass of the cover crops. Only Pennisetum americanum production was influenced by crop sequence.
  • Authors:
    • Anderson, R. L.
  • Source: Weed Technology
  • Volume: 22
  • Issue: 1
  • Year: 2008
  • Summary: Producers are interested in tactics for managing crop residues when growing maize after spring wheat. We compared five systems of managing spring wheat residues: conventional tillage, no-till, strip-till, cover crop (hairy vetch) with no-till, and cover crop with strip-till following spring wheat. Conventional tillage consisted of chisel ploughing and discing, whereas strip-till consisted of tilling a 15-cm band centred on maize rows, which were spaced 76 cm apart. Plots were split into weed-free and weed-infested subplots. Grain yield in weed-free conditions did not differ among treatments. However, weed-free yield was nearly 40% greater than weed-infested maize in conventional tillage. In contrast, weeds reduced yield only 15% with strip-till. Weed density and biomass was two-fold greater with conventional tillage compared with the no-till and strip-till treatments. Weed seedlings also emerged earlier with conventional tillage. Increased weed tolerance with strip-till may be related to fertilizer placement. Maize growth and tolerance to weeds in no-till systems may be improved if a starter fertilizer is placed in the seed furrow.
  • Authors:
    • Correia, M. E. F.
    • Mercante, F. M.
    • Silva, R. F. da
    • Aquino, A. M. de
    • Guimaraes, M. de F.
    • Lavelle, P.
  • Source: European Journal of Soil Biology
  • Volume: 44
  • Issue: 2
  • Year: 2008
  • Summary: This work was aimed at evaluating the invertebrate macrofauna community in the soil, by means of its abundance and richness of groups under different plant covers in the no-till system. Evaluations were performed at the experimental field of Embrapa Agropecuaria Oeste, in the municipal district of Dourados-MS, on a Typic Hapludox under conventional, no-till, and natural systems. Samplings were performed in December 2000, June 2001, January 2002, and June 2002. Five soil monoliths measuring 0.25*0.25 m width and 0.30 m depth were sampled along a transect. Turnip residues before a corn crop (turnip/corn) and soybean residues before wheat and turnip crops (soybean/wheat and soybean/turnip) provided positive effects on the density and diversity of the edaphic macrofauna community.
  • Authors:
    • Buschiazzo, D. E.
    • Alvarez, R.
    • Bono, A.
    • Cantet, R. J. C.
  • Source: Soil Science Society of America Journal
  • Volume: 72
  • Issue: 4
  • Year: 2008
  • Summary: Tillage systems may affect soil C sequestration, with a potential impact on crop productivity or organic matter mineralization. We evaluated crop yield, C inputs to the soil, and in situ CO 2-C fluxes under no-till and conventional tillage (disc tillage) during the 3- to 6-year period from the installation of an experiment in an Entic Haplustoll of the Semiarid Pampean Region of Argentina to elucidate the mechanisms responsible for possible management-induced soil organic matter changes. Yield and biomass production were greater under no-till than disc tillage for all the crops included in the rotation (oat + hairy vetch ( Vicia villosa ssp. villosa), maize, wheat and oat). This result was attributed to the higher soil water content under no-till. Carbon inputs to the soil averaged 4 Mg C ha -1 year -1 under no-till and 3 Mg C ha -1 year -1 under disc tillage. Soil temperature was similar between tillage systems and CO 2-C emission was approximately 4 Mg C ha -1 year -1, with significant but small differences between treatments (~0.2 Mg C ha -1 year -1). Carbon balance of the soil was nearly equilibrated under no-till; meanwhile, greater C losses as CO 2 than inputs in crop residues were measured under conventional tillage. Organic C in the soil was 5.4 Mg ha -1 higher under no-till than the disc tillage treatment 6 years after initiation of the experiment. Results showed that in our semiarid environment, C sequestration occurred under no-till but not conventional tillage. The sequestration process was attributed to the effect of the tillage system on crop productivity rather than on the mineralization intensity of soil organic pools.