• Authors:
    • Krutz, L.
    • Park, S.
    • Sij, J.
    • DeLaune, P.
  • Source: Agronomy Journal
  • Volume: 104
  • Issue: 4
  • Year: 2012
  • Summary: Identifying management practices that conserve and protect water resources are very important to a wide variety of stakeholders within semiarid environments. The objective of this study was to develop water management strategies for transitioning tillage systems in cotton (Gossypium hirsutum L.) production within the Texas Rolling Plains when in a subsurface drip irrigation (SDI) system. Five irrigation regimes (0, 33, 66, 100, and 133% evapotranspiration [ET] replacement) and four tillage systems (conventional till, reduced till, no-till, and no-till with a terminated cover crop) were evaluated. The study was conducted for 3 yr and treatments were replicated three times in a randomized complete block design. Lint yields were not affected by the main effects of tillage or the interaction of tillage and ET replacement. In contrast ET replacement was a significant factor for lint yields, irrigation water use efficiency, and net returns. Greatest lint yields and net returns were achieved at 100% ET replacement. Fitted models indicated that optimum lint yields and net returns were achieved at 104.5% ET and 102% ET, respectively. Irrigation at 83% ET was within the 95% confidence interval for lint yield. Net returns were significantly higher for no-till systems compared with conventional till. Thus, adoption of conservation tillage systems should not negatively affect lint yield or net returns in deficit irrigated SDI cotton systems within the Texas Rolling Plains, particularly during the transition from intensively tilled systems to conservation tilled systems.
  • Authors:
    • O'Donovan, J. T.
    • Blackshaw, R. E.
    • Hao, X. Y.
    • Li. C. L.
    • Harker, K. N.
    • Clayton, G. W.
  • Source: Soil & Tillage Research
  • Volume: 118
  • Year: 2012
  • Summary: Environmentally Smart Nitrogen (ESN), a type of polymer-coated urea, synchronizes N release with crop demand to increase N use efficiency and potentially reduce N 2O emissions. This study investigated the effects of ESN and weed management on N 2O emissions from soil under a canola ( Brassica napus L.) no-till cropping system. The experiment was conducted from 2005 to 2008 at three sites: Lethbridge, Lacombe, and Beaverlodge, located in southern, central and northern Alberta, Canada. Treatments included a hybrid and an open-pollinated canola cultivar, with ESN and urea applied at 1 and 1.5 times (*) the recommended rate, and herbicide at 50 and 100% of registered in-crop application rates. Canola was grown in rotation with barley ( Hordeum vulgare L.) and both phases of crop rotation were present each year. The N 2O fluxes from soil were measured using vented static chambers at 2-week intervals during the growing season from 2006 to 2008. Except for a few occasions with higher fluxes from urea than ESN earlier in the growing season and higher fluxes from ESN than urea later on, N 2O fluxes were similar among all treatments for all three years and three sites. The N 2O fluxes also varied over the growing season, and peak flux occurred in response to rainfall events. Similarly, cumulative N 2O emissions, expressed as either per land area or per canola seed yield, over the three growing seasons were low (0.15-2.97 kg N ha -1 yr -1 or 0.05-1.19 g N kg -1 seed) for all treatments and sites, and unaffected by weed management or crop variety ( P>0.05). The N 2O emission across the three sites from ESN averaged 20% lower ( P=0.040) than from urea although the differences between fertilizer types or application rates were not significant ( P>0.05) at each site. Elevated N 2O emissions (72% higher; P=0.028) from 1.5 * ESN (0.83 kg N ha -1 yr -1 or 0.33 g N kg -1 seed) relative to 1 * ESN (0.26 kg N ha -1 yr -1 or 0.16 g N kg -1 seed) were only observed at Beaverlodge while emissions were similar ( P>0.05) at the other two sites. The higher N 2O emissions at 1.5 * ESN at Beaverlodge were due to excess N accumulation in soil caused by unfavourable weather conditions that reduced canola N uptake and yield. Our results suggest that ESN fertilizer could reduce N 2O emissions in Alberta, Canada, but reductions will depend on rainfall events and canola N utilization.
  • Authors:
    • Shen, X. J.
    • Zhang, J. P.
    • Zhang, J. Y.
    • Sun, J. S.
    • Liu, H.
  • Source: Ying Yong Sheng Tai Xue Bao
  • Volume: 23
  • Issue: 2
  • Year: 2012
  • Summary: To develop a suitable tillage mode and irrigation schedule of transplanted cotton following wheat harvest under sprinkler irrigation, a field experiment was conducted to study the effects of different tillage modes (conventional tillage and no-tillage) and different irrigation schedules (45 and 22.5 mm of irrigating water quota) on the water consumption, seed yield, water use efficiency, and fiber quality of cotton. Comparing with conventional tillage, no-tillage decreased the soil evaporation among cotton plants by 20.3%. Whether with conventional tillage or with no-tillage, deficit irrigation (22.5 mm of irrigating water quota) did not affect seed yield and fiber quality, while decreased the water consumption and improved the water use efficiency. No-tillage with 22.5 mm of irrigating water quota under sprinkler irrigation not only decreased the soil evaporation effectively, but also achieved water-saving, high quality and high yield of transplanted cotton following wheat harvest.
  • Authors:
    • Assis, C. P.
    • Jucksch, I.
    • Mendonça, E. S.
    • Neves, J. C. L.
    • Silva, L. H. M.
    • Wendling, B.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 43
  • Issue: 5
  • Year: 2012
  • Summary: The objective of this study was to evaluate changes in distribution and quality of organic matter in light and heavy fractions of a medium-texture Red Latosol under different uses and management practices in Capinopolis, Brazil. Soil samples were collected from different layers in the profile (0-5, 5-10, and 10-20 cm). The following treatments were evaluated: NTs, no till (no tillage) for 4 years with maize (silage)/soybean in succession; NTg, no till for 4 years with maize/maize/maize/soybean in succession; NTtf, no till for 3 years with tifton (hay) and soybeans in the last year; CS, about 30 years with conventional cultivation system (maize/soybean) with only soybean in the past 4 years; and NF, native forest. The heavy fraction contributed 75-98% of total carbon and 94-99% of total nitrogen, indicating that most carbon and nitrogen in the soil are associated with the mineral fraction, which is fundamental for the maintenance of their stocks. Tifton grass in no tillage was efficient in increasing the amounts of light fraction (free and occluded). Increases of occluded light fraction in no-till systems were greater than in conventional cultivation system. The light fraction was shown to be sensitive to soil cultivation and can be considered indicative of soil degradation. Light-fraction analysis by Fourier transform infrared spectroscopy (FTIR) allowed the study of changes in the chemical structure of these fractions under different uses and management practices. Occluded light fraction was shown to be more recalcitrant and condensed than the free light fraction. The surface layer in the conventional cultivation system has a more aromatic and condensed free light fraction than in no-tillage system. In general, the upper layers were less aromatic than the deepest ones.
  • Authors:
    • Antle, J. M.
    • Ogle, S. M.
  • Source: Climatic Change
  • Volume: 111
  • Issue: 3/4
  • Year: 2012
  • Summary: Previous research has demonstrated that soil carbon sequestration through adoption of conservation tillage can be economically profitable depending on the value of a carbon offset in a greenhouse gas (GHG) emissions market. However adoption of conservation tillage also influences two other potentially important factors, changes in soil N2O emissions and CO2 emissions attributed to changes in fuel use. In this article we evaluate the supply of GHG offsets associated with conservation tillage adoption for corn-soy-hay and wheat-pasture systems of the central United States, taking into account not only the amount of carbon sequestration but also the changes in soil N2O emission and CO2 emissions from fuel use in tillage operations. The changes in N2O emissions are derived from a meta-analysis of published studies, and changes in fuel use are based on USDA data. These are used to estimate changes in global warming potential (GWP) associated with adoption of no-till practices, and the changes in GWP are then used in an economic analysis of the potential supply of GHG offsets from the region. Simulation results demonstrate that taking N2O emissions into account could result in substantial underestimation of the potential for GHG mitigation in the central U.S. wheat pasture systems, and large over-estimation in the corn-soy-hay systems. Fuel use also has quantitatively important effects, although generally smaller than N2O. These findings suggest that it is important to incorporate these two effects in estimates of GHG offset potential from agricultural lands, as well as in the design of GHG offset contracts for more complete accounting of the effect that no-till adoption will have on greenhouse gas emissions.
  • Authors:
    • Gibson,Lance R.
    • Singer,Jeremy W.
    • Blaser,Brock C.
  • Source: Crop Science
  • Volume: 52
  • Issue: 1
  • Year: 2012
  • Summary: Frost-seeding red clover (Trifolium pratense L.) into winter cereals is an efficient establishment method, although performance under contrasting soil management practices remains unclear. Wheat and intercropped red clover productivity were evaluated in intensive tillage (IT), moderate tillage (MT), and no tillage (NT) with and without compost amendment in a corn (Zea mays L.)-soybean [Glycine max (L.) Merr.]-winter wheat (Triticum aestivum L.) and red clover rotation between 2005 and 2010. Wheat yields were not affected by tillage system and averaged 3.80 Mg ha(-1) but were 10% higher in compost amended soil compared to no compost. Red clover plant density and dry matter (DM) at cereal grain harvest averaged 127 plants m(-2) and 32 g m(-2) and were not affected by tillage or amendment treatments. Maximum wheat canopy light interception was attained in late May to early June and ranged from 84 to 91% and typically exceeded 77% light interception for at least 22 d. Red clover root DM increased on average 378% between wheat harvest and 40 d after harvest compared with a 64% average increase in red clover root length. Red clover shoot: root averaged 8.5 at wheat harvest compared with 11.2 40 d after wheat harvest. Producers using this wheat and red clover intercrop should expect no difference in wheat yield or red clover productivity when using IT, MT, or NT.
  • Authors:
    • Briedis, C.
    • Sa, J. C. de M.
    • Caires, E. F.
    • Navarro, J. de F.
    • Inagaki, T. M.
    • Boer, A.
    • Ferreira, A. de O.
    • Quadros Neto, C.
    • Canalli, L. B.
    • Santos, J. B. dos
  • Source: Soil Science Society of America Journal
  • Volume: 76
  • Issue: 1
  • Year: 2012
  • Summary: In a no-till system (NTS) on naturally acidic soils, surface liming is essential to neutralize soil acidity and increases crop productivity. As a result, the soil organic matter (SOM) pools of the soil surface layers may change, reflecting increased C inputs by crop residues. The objective of this study was to quantify changes in SOM pools and the rate of C sequestration that occur in response to surface liming in a long-term NTS experiment. The experiment was conducted in an Oxisol in southern Brazil. The treatments consisted of the application of 0 or 6 Mg ha -1 of dolomitic lime on the soil surface in 1993 and a reapplication of 0 or 3 Mg ha -1 of dolomitic lime in 2000 to plots with or without the previous lime application. Liming caused total organic C (TOC) accumulation, especially in the 0- to 2.5-cm layer. The amount of TOC stored in the 20-cm layer was 49.9, 52.9, 52.7, and 57.5 Mg ha -1 in the control, 6+0, 0+3, and 6+3 Mg ha -1 treatments, respectively. The levels of particulate organic C (POC) and mineral-associated organic C (MAOC) in the SOM were also enhanced by liming. The increase in POC was directly related ( R2=0.99, P=0.002) to the accumulation of C from crop residues, which was greater in the plots receiving lime treatment. There were positive correlations between TOC and C extractable with hot water, total polysaccharides, and labile polysaccharides. The correlation analysis also demonstrated that TOC was more tightly correlated with POC than with MAOC, indicating a greater influence of the labile fraction on the increase in TOC with surface liming.
  • Authors:
    • Santos,J. B. dos
    • Canalli,L. B.
    • Ferreira,A. de O.
    • Quadros Neto,C.
    • Boer,A.
    • Inagaki,T. M.
    • Navarro,J. de F.
    • Caires,E. F.
    • Sa,J. C. de M.
    • Briedis,C.
  • Source: Geoderma
  • Volume: 170
  • Year: 2012
  • Summary: The stabilisation of soil organic matter (SOM) is the result of the simultaneous action of three mechanisms: chemical stabilisation, biochemical stabilisation and physical protection. The objectives of this study were (i) to evaluate carbon-protection mechanisms in different SOM pools in soil aggregates and (ii) to identify the association of Ca 2+ with total organic carbon (TOC) under the influence of surface liming in a medium-textured Oxisol in a long-term experiment under no-till system (NTS) in southern Brazil (25 degrees 10′S, 50 degrees 05′W). The treatments consisted of application of zero or 6 tons ha -1 of dolomitic lime on the soil surface in 1993 and a reapplication of zero or 3 tons ha -1 of dolomitic lime in 2000 to plots with or without previous lime application. Soil samples collected at depths of 0-2.5, 2.5-5, 5-10 and 10-20 cm were separated into seven aggregate classes. In each of these classes, TOC, particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) were analysed. The 8-19 mm sized aggregates from the 0-2.5 cm layer were assessed by energy-dispersive X-ray spectroscopy (EDS) for the elemental analysis of carbon (C) and calcium (Ca). The liming caused an accumulation of TOC in the aggregates, mainly at a depth of 0-2.5 cm. The aggregates from soils treated with lime had a higher mean weight diameter (MWD) that resulted in the accumulation of TOC, especially in the 8-19 mm aggregate class, that was linear and closely related with C input (R 2=0.99). The proportion of large aggregates in the treatments with lime was closely correlated with the TOC content of the whole sample. The largest dose of lime (9 tons ha -1) resulted in higher TOC, POC and MAOC values, mainly in the 8-19 mm aggregate class. The elemental analyses for C and Ca revealed similar spectra between them for the surface-liming treatments in the clay fraction found in the centres of the 8-19 mm aggregates. The surface application of lime to NT fields provided greater stability and protection of the intra-aggregate C, presumably due to Ca 2+ acting as a cationic bridge between OC and the kaolinite in the clay fraction.
  • Authors:
    • Carr, P. M.
    • Anderson, R. L.
    • Lawley, Y. E.
    • Miller, P. R.
    • Zwinger, S. F.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 27
  • Issue: Special Issue 01
  • Year: 2012
  • Summary: The use of killed cover crop mulch for weed suppression, soil erosion prevention and many other soil and crop benefits has been demonstrated in organic no-till or zero-till farming systems in eastern US regions and in Canada. Implements have been developed to make this system possible by terminating cover crops mechanically with little, if any, soil disturbance. Ongoing research in the US northern Great Plains is being conducted to identify cover crop species and termination methods for use in organic zero-till (OZ) systems that are adapted to the crop rotations and climate of this semi-arid region. Current termination strategies must be improved so that cover crop species are killed consistently and early enough in the growing season so that subsequent cash crops can be grown and harvested successfully. Delaying termination until advanced growth stages improves killing efficacy of cover crops and may provide weed-suppressive mulch for the remainder of the growing season, allowing no-till spring seeding of cash crops during the next growing season. Excessive water use by cover crops, inability of legume cover crops to supply adequate amounts of N for subsequent cash crops and failure of cover crops to suppress perennial weeds are additional obstacles that must be overcome before the use of killed cover crop mulch can be promoted as a weed control alternative to tillage in the US northern Great Plains. Use of vegetative mulch produced by killed cover crops will not be a panacea for the weed control challenges faced by organic growers, but rather one tool along with crop rotation, novel grazing strategies, the judicious use of high-residue cultivation equipment, such as the blade plow, and the use of approved herbicides with systemic activity in some instances, to provide organic farmers with new opportunities to incorporate OZ practices into their cropping systems. Emerging crop rotation designs for organic no-till systems may provide for more efficient use of nutrient and water resources, opportunities for livestock grazing before, during or after cash crop phases and improved integrated weed management strategies on organic farms.
  • Authors:
    • Djigal, D.
    • Saj, S.
    • Rabary, B.
    • Blanchart, E.
    • Villenave, C.
  • Source: Soil & Tillage Research
  • Volume: 118
  • Year: 2012
  • Summary: Conservation agriculture (CA) is rapidly developing in Madagascar but little is known about its effects on local soil functioning. To assess some of those effects, we investigated the effects of three CA systems and two levels of fertilization on soil functioning using nematofauna as indicator. The systems consisted in (i) soybean (Glycine max L.)-maize (Zea mays L) rotation with mulch of residues, CA-R; (ii) bean (Phaseolus vulgaris L.)-soybean rotation with living mulch of Pennisetum clandestinum, CA-K; (iii) continuous maize with living mulch of Desmodium uncinatum, CA-D and were compared with soybean-maize under conventional tillage (CT) and natural fallow (NF). The fertilization levels consisted in ( i) farmyard manure, FYM; and (ii) farmyard manure + mineral fertilizers, FYM + NPK. Located in the Highlands of Madagascar, the experiment was setup in 1991 and andic Dystrustept soil had been sampled in 2005-2007. We measured nematode abundances and ecological indices as well as the abundance and biomass of soil macrofauna, soil water and organic C and N contents and plant yields. We hypothesized that (1) CA including maize in monoculture would lead to higher abundance of plant-parasitic nematodes; (2) both dead-residue mulch and inorganic fertilization would lead to a more basal nematode community structure; and (3) that the combination of system effects on soil nematode community would be able to forecast differential crop yields for the CA systems. Our results show that CA systems tested were able to support better/comparable maize and soybean yields compared with CT, provided that crop rotation is correctly managed. Supporting our first hypothesis, abundance of plant parasitic nematodes was (40-150 times) higher under maize monoculture. Abundance of soil nematofauna and trophic groups (excepted carnivores and omnivores) was stable during the three years. Inorganic fertilization increases carnivorous and omnivorous nematodes to 122% and 140%, respectively. Ecological indices showed that soil functioning of CA systems was intermediate between that NF and CT. CA systems were characterized by a highly structured soil food-web compared with CT. Yet, soil processes intensity revealed to be lower in CA with dead mulch compared with CA with living mulch, contrasting with our second hypothesis. The characterization of nematofauna discriminated well the different systems and supports our third hypothesis. Nematode structure and enrichment indices were significantly correlated to soil organic C and N content as well as grain yields. They proved to be powerful bio-indicators of soil functioning in the CA systems studied.