• Authors:
    • Cogo, N. P.
    • Paz Gonzalez, A.
    • Vidal Vazquez, E.
    • Bertol, I.
    • Luciano, R. V.
    • Fabian, E. L.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 34
  • Issue: 1
  • Year: 2010
  • Summary: Quantity and size distribution of sediments transported by runoff are influenced by soil management, cover and crop systems, and by rainfall, among other factors, representing an important aspect in soil conservation planning. The objective of this study was to quantify runoff sediments and relate them with runoff velocity, during soybean growth, in a simulated rainfall experiment initiated in 1998 on a typical Hapludox, under the following soil management systems: conventional tillage with one plowing plus two diskings (CT) and no-tillage on a never tilled soil with burned residues (NT). In these treatments, the rotation crop systems consisted of oat, soybean, vetch, corn, oats, bean, fodder radish, soybean, vetch, corn, and soybean. An additional treatment with bare soil with one plowing plus two diskings (BS) was also studied. Five simulated rainfall tests were applied to the treatments in the last soybean crop cycle, with an intensity of 63-67 mm h -1 for one hour, 24 h after a pre-wetting rainfall, with an intensity of 65 mm h -1 and long enough to initiate runoff. The sediments were quantified in runoff samples collected 10 minutes before the end of each simulated rainfall test, and were related with the runoff velocity. The sediment size in the runoff was influenced by soil management systems and the rainfall quantity. In the treatment without soil cover (BS), the quantity of coarse sediments was higher than in the treatments with cultivated soil, whereas in CT and NT treatments the quantity of fine-sized sediments was higher than in the BS treatment. More sediments tended to be transported in the runoff with the application of more rainfall events. The sediment quantity transported by runoff was related with the sediment size, fitting to a positive exponential model, while runoff velocity decreased exponentially with increased soil cover. The D 50 index was related with other variables, fitting to the potential model and increasing with runoff velocity.
  • Authors:
    • Lambrecht, S. C.
    • D'Amore, A.
  • Source: Ecological Restoration
  • Volume: 28
  • Issue: 4
  • Year: 2010
  • Summary: A study was conducted to gauge the relative efficacy of mowing twice, discing, and solarization in controlling invasive weeds. The two specific objectives were to test whether solarization could be used effectively for weed control in a cool, coastal region, and to compare this approach with other methods of weed control in terms of effectiveness, cost, and time required for implementation. The study was conducted in an area within a 1-ha fallow field in California, USA that had not been cultivated for ten years. Non-native annual grasses dominated the vegetation, primarily ryegrass ( Lolium perenne subsp. multiflorum), but also soft brome ( Bromus hordeaceus), oats ( Avena spp.), and foxtail barley ( Hordeum murinum). Mustard ( Brassica rapa) and radish ( Raphanus sativus) were also common non-native weeds. The site is about 7 km from the ocean, so it experiences a strong maritime influence. The solarization treatment was the most effective method for controlling weed cover at Triple M. All treatment areas had similar weed cover beforehand, and treatments differed in their effectiveness. Although all treatments were equally effective in reducing non-native annual grass cover, both the disking and mowing treatment areas were invaded by the annual/biennial bristly oxtongue ( Picris echioides) during the study. This species comprised 85% of the posttreatment weedy forb cover in the disked area and 98% in the mowed area, but was not found in the solar-treated area. This is the first study to demonstrate effective weed control using solarization in a cool coastal region.
  • Authors:
    • Claupein, W.
    • Mohring, J.
    • Bühler, A.
    • Gruber, S.
  • Source: European Journal of Agronomy
  • Volume: 33
  • Issue: 2
  • Year: 2010
  • Summary: Conventional tillage systems with high soil disturbance are being steadily replaced by tillage systems with low or no soil disturbance. An approach using three methodological steps (greenhouse, deliberate seed burial and field) revealed the long-term vertical distribution and losses of a soil seed bank as effects of different tillage operations. Seeds (oilseed rape; Brassica napus L.) and seed substitutes (plastic pellets) acted as models for a seed bank. (a) A pot experiment in the greenhouse showed that emergence rates were highest in soil depths of 1-5 cm. Germination and emergence was clearly reduced in depths of 0 and 7 cm, and emergence was completely inhibited at 12 cm. About 40-50% of seeds fell dormant in 0 and 12 cm depth, while almost no seeds fell dormant in 1-7 cm depth. (b) The high-dormancy variety Smart persisted to a high extent (60% of the initial seed number), but only 8% of seeds of the low-dormancy variety Express persisted over 4.5 years, after deliberate seed burial. Seed persistence was similar in all soil depths of 0-10 cm, 10-20 cm, and 20-30 cm. (c) The field experiment lasted from 2004 to 2009 and had different tillage treatments of inversion and non-inversion tillage: stubble tillage immediately after harvest combined with primary tillage by mouldboard plough (SP), chisel plough (SC), or rototiller (SRTT); primary tillage without stubble tillage by mouldboard plough (P), chisel plough (C); or no tillage (NT). The seed bank from an artificial seed rain of 20,000 seeds m -2 was significantly higher in all treatments with immediate stubble tillage, and clearly declined over time. However, seed bank depletion was slow once a seed bank had been established. The distribution of oilseed rape seeds and plastic pellets (7000 pellets m -2 broadcast) tended to equalise over the soil layers of 0-10, 10-20 and 20-30 cm over the course of five years. Since seed bank depletion was not attributable to a specific soil depth, shallow and low disturbance tillage did not generally result in a high seed persistence. More important than the depth was the timing of tillage. Though no-till systems provided conditions for seeds to fall dormant at the soil surface to a small extent, the effect lasted only for a limited time. Seed substitutes can be well used in methodological approaches to picture movement of seeds in the soil in order to optimize tillage strategies in agricultural practice.
  • Authors:
    • Caesar-TonThat, T.
    • Wright, S. F.
    • Sainju, U. M.
    • Kolberg, R.
    • West, M.
  • Source: Proceedings of the 19th World Congress of Soil Science: Soil solutions for a Changing World, Brisbane, Australia, 1-6 August 2010. Congress Symposium 2: Soil ecosystem services
  • Year: 2010
  • Summary: Lentil ( Lens culinaris Medikus CV. Indianhead) used to replace fallow in spring-wheat ( Triticum aestivum) rotation in the semi-arid Eastern Montana USA, may improve soil quality. We evaluate the 14 years influence of continuous wheat under no-tillage (WNT), fallow-wheat under conventional tillage (FCT) and no-tillage (FNT), lentil-wheat under tillage (LCT) and no-tillage (LNT) on soil formation and stability, and on the amount of immunoreactive easily-extractable glomalin (IREEG) and soil aggregating basidiomycete fungi in the 4.75-2.00, 2.00-1.00, 1.00-0.50, 0.50-0.25, and 0.25-0.00 mm aggregate-size classes, at 0-5 cm soil depth. The 4.75-2.00 mm aggregate proportion was higher in LNT than FNT and higher in LT than FT treatments and mean weight diameter (MWD) was higher when lentil was used to replace fallow under NT. No-till systems had higher glomalin and basidiomycete amount than CT in all aggregate-size classes and glomalin was higher in LNT than FNT in aggregate-size classes less than 0.50 mm. We conclude that residue input in NT systems triggers fungal populations which are involved in soil binding in aggregates, and that replacing fallow by lentil in spring wheat rotation in dryland seems to favor aggregate formation/stability under NT probably by increasing N fertility during the course of 14 years.
  • Authors:
    • Fernandes, M. F.
    • Chaer, G. M.
  • Source: Proceedings of the 19th World Congress of Soil Science: Soil solutions for a changing world
  • Year: 2010
  • Summary: Soil biological and biochemical properties have been proposed as sensitive indicators of soil degradation. Nevertheless, their potential to predict the deterioration of major soil functions related to physical stability, and water and nutrient storage and fluxes has not been validated under experimental conditions. The sensitivity of 16 biological and biochemical variables was contrasted with other eight of chemical or physical nature in a gradient of soil degradation induced by cycles of one, two, three, or four tillage events, plus a no-till control. Twenty-four variables were analysed in soil samples (0-20 cm) collected 60 d after the last cycle. Out of these, 22 were significantly affected by soil disturbance. Six biological (microbial biomass-C, -N, and -C to N ratio; qMic; FDA and urease), two physical (water stable aggregates and aggregate mean diameter) and one chemical variable (org-P) were highly sensitive to soil disturbance. Soil bulk density, invertase activity, organic C and CEC were only slightly sensitive to tillage, whereas qCO 2 and xylanase were not significantly affected by tillage frequency. Although some biological and biochemical properties were highly responsive to soil degradation, there was no general trend of superiority of these variables over those of chemical and physical natures regarding the sensitivity to soil degradation.
  • Authors:
    • Piccolo, M. de C.
    • Feigl, B. J.
    • Cerri, C. C.
    • Cerri, C. E. P.
    • Frazao, L. A.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 135
  • Issue: 3
  • Year: 2010
  • Summary: The Brazilian Cerrado soils were incorporated into the agricultural production process in the 1970s. The introduction of pastures and/or annual crops utilizing different management systems produced changes in the dynamics of soil organic matter. This study evaluated the microbial attributes of a Typic Quartzipsamment (Arenosols in FAO classification) in native vegetation, pastures, and soybean cultivation under conventional (CT) and no-till (NT) systems. The soil samples (0-5, 5-10 and 10-20 cm layers) were collected in July 2005 and February 2006 from different systems: native Cerrado (CE), CT for 4 years with soybean (CT4 S), CT for 4 years with soybean in rotation with millet (CT4 S/M), an area that has been under pasture for 22 years (PA22), and an area that remained under pasture for 13 years, followed by NT with soybean in rotation with millet for 5 years (NT5). Soil inorganic N (nitrate and ammonium), microbial C and N and basal respiration were determined. The soil metabolic quotient (qCO 2) and the C mic:C org ratios were calculated. The predominant form of inorganic N in the native Cerrado (CE) and in the pasture area (PA22) was ammonium, while the conventional system (CT4 S/M) and no-till system (NT5) areas presented higher nitrogen availability for crops in the form of nitrate. The microbial C and N concentrations increased in the wet season, and the highest values were found in the Cerrado (CE) and in pasture (PA22) areas, where the permanent soil cover and the lack of soil disturbance by agricultural practices allowed more favorable conditions for microbial development. The CT4 S area presented the highest qCO 2 index and the lowest C mic:C total ratio, indicating that the conversion of total carbon into microbial carbon is less efficient in this system. Since sandy soils are more susceptible to degradation, the use of more conservationist management systems promotes more favorable conditions to microbial development and maintenance.
  • Authors:
    • Batlle-Bayer, L.
    • Batjes, N. H.
    • Bindraban, P. S.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 137
  • Issue: 1-2
  • Year: 2010
  • Summary: This paper reviews current knowledge on changes in carbon stocks upon land use conversion in the Brazilian Cerrado. First, we briefly characterize the savanna ecosystem and summarize the main published data on C stocks under natural conditions. The effects of increased land use pressure in the Cerrado and current uncertainties of estimations of changes in land cover and land use are reviewed next. Thereafter, we focus on soil organic carbon (SOC) dynamics due to changes in land use, particularly conversion to pastures and soybean-based cropping systems, and effects of management practices such as soil fertilization, crop rotations and tillage practices. Most studies considered here suggest that more intensive agriculture, which include no-till practices and the implementation of best or recommended management practices (RMP), reduces SOC losses after land use conversion from conventional tillage-based, monocropping systems; however, these studies focussed on the first 0.3 m of soil, or less, and seldom considered full carbon accounting. To better estimate possible global warming mitigation with agriculture in the Cerrado more comprehensive studies are needed that analyse fluxes of the biogenic greenhouse gases (GHG; CO 2, N 2O and CH 4) to determine the net global warming potential (GWP). Follow up studies should include the application of an integrated modelling system, comprised of a Geographic Information System (GIS) linked to dynamic modelling tools, to analyse SOC dynamics and make projections for possible changes in net C flows in the Cerrado region upon defined changes in soil use and management.
  • Authors:
    • Halvorson, A. D.
    • Archer, D. W.
  • Source: Soil Science Society of America Journal
  • Volume: 74
  • Issue: 2
  • Year: 2010
  • Summary: Recent soil and crop management technologies have potential for mitigating greenhouse gas emissions; however, these management strategies must be profitable if they are to be adopted by producers. The economic feasibility of reducing net greenhouse gas emissions in irrigated cropping systems was evaluated for 5 yr on a Fort Collins clay loam soil (a fine-loamy, mixed, superactive, mesic Aridic Haplustalf). Cropping systems included conventional tillage continuous corn (Zea mays L.) (CT-CC), no-till continuous corn (NT-CC), and no-till corn-bean (NT-CB) including 1 yr soybean [Glycine max (L.) Merr.] and 1 yr dry bean (Phaseolus vulgaris L.). The study included six N fertilization rates ranging from 0 to 246 kg ha-1. Results showed highest average net returns for NT-CB, exceeding net returns for NT-CC and CT-CC by US$182 and US$228 ha-1, respectively, at economically optimum N fertilizer rates. Net global warming potential (GWP) generally increased with increasing N fertilizer rate with the exception of NT-CC, where net GWP initially declined and then increased at higher N rates. Combining economic and net GWP measurements showed that producers have an economic incentive to switch from CT-CC to NT-CB, increasing annual average net returns by US$228 ha-1 while reducing annual net GWP by 929 kg CO2 equivalents ha-1. The greatest GWP reductions (1463 kg CO2 equivalents ha-1) could be achieved by switching from CT-CC to NT-CC while also increasing net returns, but the presence of a more profitable NT-CB alternative means NT-CC is unlikely to be chosen without additional economic incentives.
  • Authors:
    • Pepo, P.
  • Source: 45th Croatian & 5th International Symposium on Agriculture
  • Year: 2010
  • Summary: In non-irrigated treatment the maximum yields of winter wheat were 5590 kg ha -1 in biculture (maize-wheat) and 7279 kg ha-1 in triculture (peas-wheat-maize) in 2007 year characterized by water-deficit stress. In 2008 (optimum rain amount and distribution) the maximum yields were 7065 kg ha -1 (biculture) and 8112 kg ha -1 (triculture) in non irrigated conditions. The fertilization surpluses of wheat were 2853-3698 kg ha -1 (non-irrigated) and 3164-5505 kg ha -1 (irrigated) in a dry cropyear (2007) and 884-4050 kg ha -1 (non-irrigated) and 524-3990 kg ha -1 (irrigated) in an optimum cropyear (2008). The optimum fertilizer doses varied N150-200+PK in biculture and N50-150+PK in triculture depending on cropyear and irrigation. The optimalization of agrotechnical elements provides 7,8-8,5 t ha -1 yields in dry cropyear and 7,1-8,1 t ha -1 yields of wheat in good cropyear, respectively. Our scientific results proved that in water stress cropyear (2007) the maximum yields of maize were 4316 kg ha -1 (monoculture), 7706 kg ha -1 (biculture), 7998 kg ha -1 (triculture) in non irrigated circumstances and 8586 kg ha -1, 10 970 kg ha -1, 10 679 kg ha -1 in irrigated treatment, respectively. In dry cropyear (2007) the yield-surpluses of irrigation were 4270 kg ha -1 (mono), 3264 kg ha -1 (bi), 2681 kg ha -1 (tri), respectively. In optimum water supply cropyear (2008) the maximum yields of maize were 13 729-13 787 (mono), 14 137-14 152 kg ha -1 (bi), 13 987-14 180 kg ha -1 (tri) so there was no crop-rotation effect. We obtained 8,6-11,0 t ha -1 maximum yields of maize in water stress cropyear and 13,7-14,2 t ha -1 in optimum cropyear on chernozem soil with using appropriate agrotechnical elements.
  • Authors:
    • Christie, P.
    • Streck, T.
    • Li, L.
    • Qin, Z. C.
    • Ingwersen, J.
    • Ju, X. T.
    • Qiu, S. J.
    • Zhang, F. S.
  • Source: Soil & Tillage Research
  • Volume: 107
  • Issue: 2
  • Year: 2010
  • Summary: In recent years large areas of conventional cereal production in China have been transferred to greenhouse production with huge excessive nitrogen (N) fertilizer application and massive irrigation. However, the effects of this change in land use on soil carbon and nitrogen pools remain to be explored. Here we report a comparative study in which paired soil samples were taken from four greenhouses and from adjacent conventional cereal fields. Soil organic carbon (SOC), carbonate carbon (IC), total nitrogen (TN) and mineral nitrogen (N min) to 100 cm depth and the soil active organic pools, including particulate organic matter (POM), soil microbial biomass (SMB) and dissolved organic matter (DOM), to 0-40 cm depth were determined. The natural isotopic signatures of SOC, TN and POM were also analyzed. In both production systems all of the carbon and nitrogen pools in the surface soil (0-10 cm) were greater than deeper in the soil profile except for dissolved organic nitrogen (DON) and NH 4-N. SOC and TN and dissolved organic carbon (DOC) concentrations were higher in the greenhouse system than in conventional cereal soils ( P>0.05). A similar trend was found for POM ( P0.05) and IC in the greenhouse system showed a dramatic decline. The SOC/TN ratios of different pools in the greenhouse soils were lower than in the conventional cereal system ( P>0.05). The SOC/TN ratio ranged from 8.4 to 10.0 in greenhouse soils and 8.5 to 11.7 in the cereal soils. At each depth POM content in the greenhouses (1.5-7.1 g kg -1) was significantly greater than that in the field soils (0.8-2.9 g kg -1) ( P