• Authors:
    • Blanco-Canqui, H.
    • Mikha, M. M.
    • Presley, D. R.
    • Claassen, M. M.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 4
  • Year: 2011
  • Summary: Inclusion of cover crops (CCs) may be a potential strategy to boost no-till performance by improving soil physical properties. To assess this potential, we utilized a winter wheat ( Triticum aestivum L.)-grain sorghum [ Sorghum bicolor (L.) Moench] rotation, four N rates, and a hairy vetch (HV; Vicia villosa Roth) CC after wheat during the first rotation cycles, which was replaced in subsequent cycles with sunn hemp (SH; Crotalaria juncea L.) and late-maturing soybean [LMS; Glycine max (L.) Merr.] CCs in no-till on a silt loam. At the end of 15 yr, we studied the cumulative impacts of CCs on soil physical properties and assessed relationships between soil properties and soil organic C (SOC) concentration. Across N rates, SH reduced near-surface bulk density (rho b) by 4% and increased cumulative infiltration by three times relative to no-CC plots. Without N application, SH and LMS reduced Proctor maximum rho b, a parameter of soil compactibility, by 5%, indicating that soils under CCs may be less susceptible to compaction. Cover crops also increased mean weight diameter of aggregates (MWDA) by 80% in the 0- to 7.5-cm depth. The SOC concentration was 30% greater for SH and 20% greater for LMS than for no-CC plots in the 0- to 7.5-cm depth. The CC-induced increase in SOC concentration was negatively correlated with Proctor maximum rho b and positively with MWDA and cumulative infiltration. Overall, addition of CCs to no-till systems improved soil physical properties, and the CC-induced change in SOC concentration was correlated with soil physical properties.
  • Authors:
    • Blanco-Canqui, H.
    • Schlegel, A. J.
    • Heer, W. F.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 144
  • Issue: 1
  • Year: 2011
  • Summary: No-till (NT) farming is considered as a potential strategy for sequestering C in the soil. Data on soil-profile distribution of C and related soil properties are, however, limited, particularly for semiarid regions. We assessed soil C pool and soil structural properties such as aggregate stability and strength to 1 m soil depth across three long-term (≥21 year) NT and conventional till (CT) experiments along a precipitation gradient in the central Great Plains of the USA. Tillage systems were in continuous winter wheat ( Triticum aestivum L.) on a loam at Hutchinson and winter wheat-sorghum [ Sorghum bicolor (L.) Moench]-fallow on silt loams at Hays and Tribune, Kansas. Mean annual precipitation was 889 mm for Hutchinson, 580 mm for Hays, and 440 mm for Tribune. Changes in profile distribution of soil properties were affected by differences in precipitations input among the three sites. At Hutchinson, NT had 1.8 times greater SOC pool than CT in the 0-2.5-cm depth, but CT had 1.5 times greater SOC pool in the 5-20-cm. At Hays, NT had 1.4 times greater SOC pool than CT in the 0-2.5-cm depth. Differences in summed SOC pool for the whole soil profile (0-1 m depth) between NT and CT were not significant at any site. The summed SOC pool with depth between NT and CT were only significant above the 5 cm depth at Hutchinson and 2.5 cm depth at Hays. At Hutchinson, NT stored 3.4 Mg ha -1 more SOC than CT above 5 cm depth. At Hays, NT stored 1.35 Mg ha -1 more SOC than CT above 2.5 cm depth. Moreover, NT management increased mean weight diameter of aggregates (MWDA) by 3 to 4 times for the 0-5-cm depth at Hutchinson and by 1.8 times for the 0-2.5-cm depth at Hays. It also reduced air-dry aggregate tensile strength (TS) for the 0-5-cm depth at Hutchinson and Hays and for the 0-2.5-cm depth at Tribune. The TS ( r=-0.73) and MWDA ( r=0.81) near the soil surface were more strongly correlated with SOC concentration at Hutchinson than at Hays and Tribune attributed to differences in precipitation input. Results suggested NT impacts on increasing SOC pool and improving soil structural properties decreased with a decrease in precipitation input. Changes in soil properties were larger at Hutchinson (880 mm of precipitation) than at Hays and Tribune (≤580 mm). While NT management did not increase SOC pool over CT for the whole soil profile, the greater near-surface accumulation of SOC in NT than in CT was critical to the improvement in soil structural properties. Overall, differences in precipitation input among soils appeared to be the dominant factor influencing NT impacts on soil-profile distribution of SOC and soil structural properties in this region.
  • Authors:
    • Brar, A. S.
    • Mahal, S. S.
    • Buttar, G. S.
    • Deol, J. S.
  • Source: Indian Journal of Agronomy
  • Volume: 56
  • Issue: 4
  • Year: 2011
  • Summary: A field experiment was conducted to work out the water productivity, economics and energetics of basmati rice ( Oryza sativa L.)-wheat [ Triticum aestivum (L.) emend. Fiori & Paol] sequence under different methods of crop establishment during 2005-06 and 2006-07. The treatments included combinations of two crop establishment methods of basmati rice (direct seeded and transplanted) and three seeding techniques of succeeding wheat (conventional, bed planting and zero tillage). Productivity of basmati rice-wheat sequence was significantly higher with transplanted basmati rice (TPBR) than direct seeded basmati rice (DSBR) irrespective of seeding technique of succeeding wheat. However, crop establishment methods of wheat did not show any significant impact on total productivity of basmati rice-wheat sequence during both the years. Total water use was 9.5 and 8.2 per cent higher in TPBR-wheat sequence than DSBR-wheat sequence during 2005-06 and 2006-07, respectively. In this sequence the highest net return was obtained from TPBR-zero till sown wheat sequence, which was closely followed by TPBR-conventionally sown wheat sequence but both gave more net returns than DSBR-zero till sown wheat sequence. The highest energy output was recorded in TPBR-conventionally sown wheat, while energy use efficiency was maximum in TPBR-zero till sown wheat, during both the years because of lowest energy input in zero till sown wheat than conventional and bed planting.
  • Authors:
    • Janzen, H. H.
    • Ellert, B. H.
    • McKenzie, R. H.
    • Bremer, E.
  • Source: Soil Science Society of America Journal
  • Volume: 75
  • Issue: 4
  • Year: 2011
  • Summary: Agroecosystems provide a range of benefits that are strongly influenced by cropping practice. Crop productivity and C, N, and greenhouse gas (GHG) balances were evaluated in an 18-yr cropping system study on an Aridic Haplustoll in the northern Great Plains. Application of synthetic fertilizers consistently increased crop yield and soil organic carbon (SOC), with greatest impact in perennial grass and continuous wheat ( Triticum aestivum L.) rotations and least impact in rotations with fallow or annual legumes. Based on N balance, N inputs other than fertilizer were 16 to 30 kg N ha -1 yr -1 in rotations without legumes and 62 kg N ha -1 yr -1 in a legume-wheat (LW) rotation, while losses of synthetic fertilizer N were 32% in annual crop rotations and 3% in perennial grass. Due to large gains in SOC, perennial grass reduced atmospheric GHG by 20 to 29 Mg CO 2 equivalent (eq.) ha -1 during the 18 yr of this study. For annual crop rotations, seed yield ranged from 1.2 to 2.5 Mg ha -1 yr -1, protein yield from 0.20 to 0.41 Mg ha -1 yr -1, and GHG intensity from 0 to 0.5 Mg CO 2 eq. Mg -1 seed. Fertilized continuous wheat had the highest crop productivity and lowest net GHG intensity, while an annual LW rotation had the highest protein productivity and among the lowest GHG intensities (0.2 Mg CO 2 eq. Mg -1 seed). Further evaluation at broader temporal and spatial scales is necessary to account for future changes in SOC and differences in use of crop products.
  • Authors:
    • Brito, I.
    • Carvalho, M. de
    • Goss, M. J.
  • Source: Soil Use and Management
  • Volume: 27
  • Issue: 3
  • Year: 2011
  • Summary: The potential to manage arbuscular mycorrhizal colonization within Mediterranean agricultural systems depends on the summer survival of extraradical mycelium. To investigate this further a three-stage experiment was undertaken. The first stage was the creation of two contrasting levels of extraradical mycelium development, achieved by two contrasting levels of soil disturbance (typifying full tillage and no-till). In the second stage, this differential mycelial inoculum was subjected to Mediterranean summer temperature and soil water regimes representing the post-harvest fallow. During the third stage, corresponding to the next growing season, survival was evaluated without further soil disturbance (typifying no-till conditions) using wheat as host crop. The results clearly indicate that the extraradical mycelium survived the prevailing summer conditions. The knowledge that extraradical mycelium can survive the Mediterranean summer encourages the use of tillage systems that minimize mechanical disturbance of the soil, such as no-till. The results from this study suggest that by making the appropriate choice of crops to establish a mycorrhizal-supportive rotation there can be opportunities for agro-ecosystem management to benefit from the symbiotic relationship.
  • Authors:
    • Caesar-TonThat, T.
    • Sainju, U. M.
    • Wright, S. F.
    • Shelver, W. L.
    • Kolberg, R. L.
    • West, M.
  • Source: Biology and Fertility of Soils
  • Volume: 47
  • Issue: 2
  • Year: 2011
  • Summary: Little is known about the long-term tillage and cropping management effects on the microbiologically derived factors that influence macroaggregates in semi-arid soil. We tested the hypothesis that differences in macro-aggregation are due to changes in soil structure related to management treatment-induced microbiological changes. In an experiment, microbiological factors consisting of aggregate stability, glomalin, russuloid basidiomycete fungi, uronic acids, total organic C (TOC), and total N (TN) were quantified in macroaggregate-size classes ranging from 4.75 to 0.25 mm, collected at 0-5 cm depth for the following treatments: (1) 12th year of fallow phase after 11 years of conventional- and no-tilled spring wheat-fallow (CTF and NTF), (2) 12th year of lentil phase after 11 years of conventional- and no-tilled spring wheat-lentil (CTL and NTL), (3) 12 years no-tilled continuous spring wheat (NTCW), and (4) 16 years uncultivated pasture (P) used as a baseline treatment. Immunoreactive easily extractable glomalin concentration was five to six times greater under P, NTCW, or NTL in the 2.00-1.00- and 1.00-0.50-mm macroaggregate-size classes than the other treatments and these results corroborated well with the results from aggregate stability assays. Russuloid basidiomycetes were highest in all NTCW macroaggregate-size classes, suggesting that annual input of lignin-containing wheat residues may influence the growth and survival of these fungi. Uronic acid amounts were highest in P but did not differ among the other treatments. In all macroaggregate-size classes, TOC content was greater in NTCW compared to CTF, and TN was about three times higher in NTL than NTF or CTF. In conclusion, 12 years of NTCW management in semi-arid soil has resulted in higher macroaggregate stability, glomalin concentration, russuloid basidiomycete populations, and TOC in macroaggregates compared to alternate-year fallow. Lentil can be used to replace fallow in dryland wheat rotation under no-till to enhance TN content and improve soil macro-aggregation.
  • Authors:
    • Caires, E. F.
    • Garbuio, F. J.
    • Churka, S.
    • Joris, H. A. W.
  • Source: Agronomy Journal
  • Volume: 103
  • Issue: 6
  • Year: 2011
  • Summary: Gypsum has been used in tropical and subtropical agriculture when subsoil acidity is an important yield-limiting factor. However, the conditions that promote increased crop yield as a result of gypsum addition in no-till (NT) systems still remain unclear. A field trial examined the effects of newly and previously surface-applied gypsum in a long-term NT system on the soil chemical properties and nutrition and yield of corn ( Zea mays L.), wheat ( Triticum aestivum L.), and soybean [ Glycine max (L.) Merr.] on a clayey Rhodic Hapludox in Parana State, Brazil. Gypsum was surface-applied at 0 and 6 Mg ha -1 in 2004 on plots that had received gypsum previously at 0, 3, 6, and 9 Mg ha -1 in 1998. Surface-applied gypsum newly and previously improved exchangeable Ca and SO 4-S availability throughout the soil profile, and increased the cumulative grain yield of the crops. Exchangeable K losses through leaching caused by gypsum application were low, and a larger mobility of exchangeable Mg as compared with exchangeable K in soil was found as a result of gypsum addition. An increase in Ca content in the corn, wheat, and soybean leaves, and in S content in the corn and wheat leaves occurred following the gypsum application. The use of gypsum showed economic viability to maximize crop grain production in a long-term NT soil with a sufficient level of exchangeable Ca (≥8 mmol c dm -3) and low levels of exchangeable Al (≤4 mmol c dm -3) and Al saturation (≤15%) in the subsoil layers (20-60 cm).
  • Authors:
    • VandenBygaart, A. J.
    • Zentner, R. P.
    • Lemke, R.
    • May, W. E.
    • Holzapfel, C. B.
    • Campbell, C. A.
    • Lafond, G. P.
  • Source: Canadian Journal of Plant Science
  • Volume: 91
  • Issue: 3
  • Year: 2011
  • Summary: We analyzed the agronomic data from a 50-yr crop rotation experiment being conducted on a fine-textured, thin Black Chernozem at Indian Head, Saskatchewan in Canada. Our objective was to determine how a change from conventional-till to no-till, together with an increase in N fertilizer rates recommended by the Saskatchewan Soil Testing Laboratory has affected wheat yields and N and P balance in the systems over the past 20 yr. The treatments assessed were fertilized (N-P) and unfertilized fallow-wheat ( Triticum aestivum L.) (F-W), F-W-W, and continuous wheat (ContW), and unfertilized legume green manure (LGM)-W-W and F-W-W-brome ( Bromus inermis Leyss.)/alfalfa ( Medicago sativa L.) hay (H)-H-H. On average, N applied to wheat grown on fallow was 6 kg ha -1 yr -1 from 1957 to 1989 and 57 kg ha -1 yr -1 from 1990 to 2007; for wheat grown on stubble, the N rates were 21 kg ha -1 yr -1 from 1957 to 1977 and 85 kg ha -1 yr -1 thereafter. Crops received P at 10 kg ha -1 yr -1. On average, fertilizer increased wheat yield of fallow-wheat by 31%; the hay system increased fallow-wheat yield by 26% compared with unfertilized fallow-wheat in F-W-W, and the LGM system increased it by 14%. Effects were greater on stubble crop than on fallow crop, with fertilizer increasing the yield of wheat grown on stubble in the monoculture system by 114%, the hay system increasing it by 83% and the LGM system increasing it by 37%. The legume-containing rotations increased yields by increasing the N supplying capacity of the soil with the hay system being more effective than the LGM because legumes occurred more frequently in the hay rotation (3 in 6 yr vs. 2 in 6 yr). The benefit of the legume-containing systems on wheat yield may have been restricted because this unfertilized system steadily depleted available soil P. Average annualized wheat production in F-W, F-W-W and ContW rotations was unaffected by cropping frequency for the unfertilized systems, but it was directly proportional to cropping frequency for the fertilized systems. Annualized wheat production for the LGM-W-W rotation was 18% greater than for unfertilized F-W-W, but 41% less than for the fertilized F-W-W. Annualized wheat production in the hay-containing rotation was 32% less than in the unfertilized F-W-W rotation because of the less frequent presence of wheat in the hay system. Greater rates of N fertilizer in the later years increased yields and grain N content; this resulted in less residual NO 3-N in the soil compared with previous years with lower fertilizer N. Thus, we expect there will be less likelihood of NO 3 leaching under fallow-containing systems under no-till when updated fertilizer recommendations are used compared with previous results under conventional tillage with lower rates of N applications.
  • Authors:
    • Cheng, L.
    • Booker, F. L.
    • Burkey, K. O.
    • Tu, C.
    • Shew, H. D.
    • Rufty, T. W.
    • Fiscus, E. L.
    • Deforest, J. L.
    • Hu, S. J.
  • Source: PLOS ONE
  • Volume: 6
  • Issue: 6
  • Year: 2011
  • Summary: Climate change factors such as elevated atmospheric carbon dioxide (CO 2) and ozone (O 3) can exert significant impacts on soil microbes and the ecosystem level processes they mediate. However, the underlying mechanisms by which soil microbes respond to these environmental changes remain poorly understood. The prevailing hypothesis, which states that CO 2- or O 3-induced changes in carbon (C) availability dominate microbial responses, is primarily based on results from nitrogen (N)-limiting forests and grasslands. It remains largely unexplored how soil microbes respond to elevated CO 2 and O 3 in N-rich or N-aggrading systems, which severely hinders our ability to predict the long-term soil C dynamics in agroecosystems. Using a long-term field study conducted in a no-till wheat-soybean rotation system with open-top chambers, we showed that elevated CO 2 but not O 3 had a potent influence on soil microbes. Elevated CO 2 (1.5 * ambient) significantly increased, while O 3 (1.4 * ambient) reduced, aboveground (and presumably belowground) plant residue C and N inputs to soil. However, only elevated CO 2 significantly affected soil microbial biomass, activities (namely heterotrophic respiration) and community composition. The enhancement of microbial biomass and activities by elevated CO 2 largely occurred in the third and fourth years of the experiment and coincided with increased soil N availability, likely due to CO 2-stimulation of symbiotic N 2 fixation in soybean. Fungal biomass and the fungi:bacteria ratio decreased under both ambient and elevated CO 2 by the third year and also coincided with increased soil N availability; but they were significantly higher under elevated than ambient CO 2. These results suggest that more attention should be directed towards assessing the impact of N availability on microbial activities and decomposition in projections of soil organic C balance in N-rich systems under future CO 2 scenarios.
  • Authors:
    • Hannachi, A.
    • Touahria, O.
    • Fellahi, Z. E. A.
    • Makhlouf, M.
    • Bouzerzour, H.
    • Chennafi, H.
  • Source: Advances in Environmental Biology
  • Volume: 5
  • Issue: 10
  • Year: 2011
  • Summary: A field study was conducted during two cropping seasons (2009/10 and 2010/11) at the Institute of Field Crop-Agricultural Research Station of Setif (eastern Algeria) to compared the effect of tillage (no till and conventional tillage) and residue management (0, 30 and 60% soil cover) on the growth and grain yield of durum wheat. The cumulative growing season precipitations were 427.7 and 312.1 mm. Soil water storage to a depth of 0.4 m was higher under CT in the first year and no significant differences existed between NT and CT during the second year. Above-ground biomass was higher under CT, while grain yield, spikes m -2 and number of kernels m -2 were higher under NT. Residue rate affected positively all measured traits, suggesting the necessity to maintain residue cover to avoid reducing yield under NT management system. Averaged over residue rates, Transpiration was higher under CT than under NT, in 2009/10, but not significant difference was noted in 2010/11. The opposite was noted for evaporation. Transpiration increased as residue rates increased during both seasons. CT showed higher WUE BIO and WUE GY in the first year, while during the second year, NT expressed higher WUE BIO and WUE GY. WUE BIO and WUE GY increased as residue rate increased, during both cropping seasons. The results of the present study indicated that with adequate residue cover, no-till did not decreased grain yield, which suggested that durum wheat can be grown under NT with the expectation that gain yield will be higher or at least equal to CT grain yield.