• Authors:
    • Evans, R. G.
    • Stevens, W. B.
    • Sainju, U. M.
    • Iversen, W. M.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 77
  • Issue: 4
  • Year: 2013
  • Summary: Irrigation and tillage systems may affect surface residue and soil C and N fractions by influencing crop biomass yield, residue placement, and movement of water soluble C and N in the soil. We studied the effects of irrigation (mid-elevation spray application [MESA] and low energy precision application [LEPA ]) and tillage (conventional [CT] and strip-tillage [ST]) systems on crop biomass (stems and leaves) yield, surface residue, and soil C and N fractions at the 0- to 20-cm depth from 2004 to 2007 in a Savage clay loam (fine, smectitic, frigid Vertic Argiustolls) in Sidney, MT. Soil C and N fractions were soil organic carbon (SOC) and total nitrogen (STN), particulate organic carbon and nitrogen (POC and PON), microbial biomass carbon and nitrogen (MBC and MBN), potential carbon and nitrogen mineralization (PCM and PNM), NH4-N, and NO3-N. While crop biomass across treatments increased from 2004 to 2007, surface residue was greater with ST than with CT from 2005 to 2007. The NH4-N and NO3-N contents at 5 to 10 and 10 to 20 cm in 2005 and STN at 0 to 5 cm in 2007 were greater with ST than with CT, but SOC at 5 to 10 and 10 to 20 cm, POC and MBN at 5 to 10 cm, and PNM at 0 to 5 cm in 2007 were greater with CT than with ST. The MBC at 0 to 5 cm and MBN at 10 to 20 cm were greater in LEPA than in MESA. The PCM at 10 to 20 cm was greater with CT than with ST in LEPA . While ST increased surface soil residue and N storage, residue incorporation to a greater depth in CT increased soil C storage, microbial activity, and N mineralization. Slow rate of water application near the soil surface increased microbial biomass in LEPA.
  • Authors:
    • Blanco-Canqui, H.
  • Source: BioEnergy Research
  • Volume: 6
  • Issue: 1
  • Year: 2013
  • Summary: Crop residue removal for bioenergy can deplete soil organic carbon (SOC) pools. Management strategies to counteract the adverse effects of residue removal on SOC pools have not been, however, widely discussed. This paper reviews potential practices that can be used to offset the SOC lost with residue removal. Literature indicates that practices including no-till cover crops, manure and compost application, and return of biofuel co-products increase SOC pools and may thus be used to offset some SOC loss. No-till rotations that include semi-perennial grasses or legumes also offer a promise to promote soil-profile C sequestration and improve soil resilience after residue removal. No-till cover crops can sequester between 0.10 and 1 Mg ha(-1) per year of SOC relative to no-till without cover crops, depending on cover crop species, soil type, and precipitation input. Animal manure and compost contain about 15 % of C and thus their addition to soil can enhance SOC pools and boost soil biological activity. Similarly, application of biofuel co-products such as biochar, which contain between 45 % and 85 % of C depending on the feedstock source and processing method, can enhance long-term C sequestration. These mitigation strategies may maintain SOC pools under partial residue removal in no-till soils but are unlikely to replace all the SOC lost if residue is removed at excessive rates. More field research and modeling efforts are needed to assess the magnitude at which the different mitigation strategies can overcome SOC loss with crop residue removal.
  • Authors:
    • Gerik, T. J.
    • Williams, J. R.
    • Blumenthal, J. M.
    • Potter, S. R.
    • Kemanian, A. R.
    • Meki, M. N.
  • Source: Agricultural Systems
  • Volume: 117
  • Year: 2013
  • Summary: There is an increased demand on agricultural systems in the United States and the world to provide food, fiber, and feedstock for the emerging bioenergy industry. The agricultural intensification that this requires could have positive and negative feedbacks in productivity and the environment. In this paper we used the simulation model EPIC to evaluate the impact of alternative tillage and management systems on grain sorghum (Sorghum bicolor L. Moench) production in central and south Texas and to provide long-term insights into the sustainability of the proposed systems as avenues to increase agricultural output. Three tillage systems were tested: conventional (CT), reduced (RT), and no-tillage (NT). These tillage systems were tested on irrigated and rainfed conditions, and in soils with varying levels of structural erosion control practices (no practice, contour tillage, and contours + terraces). Grain yield differed only slightly across the three tillage systems with an average grain yield of 5.7 Mg ha(-1). Over the course of 100-year simulations, NT and RT systems had higher soil organic carbon (SOC) storage (100 and 91 Mg ha(-1), respectively) than CT (85 Mg ha(-1)), with most of the difference originating in the first 25 years of the simulations. As a result, NT and RT systems showed lower net global warming potentials (GWPs) (0.20 and 0.50 Mg C ha(-1) year(-1)) than CT (0.60 Mg C ha(-1) year(-1)). Irrigated systems had 26% higher grain yields than rainfed systems; yet the high energy needed to pump irrigation water (0.10 Mg C ha(-1) year(-1)) resulted in a higher net GWP for irrigated systems (0.50 vs. 0.40 Mg C ha(-1) year(-1)). Contours and contours + terraces had minimal impact on grain yields, SOC storage and GWP. No-till was the single technology with the largest positive impact on GWP and preservation or enhancement of SOC. Overall, the impact of individual tillage cropping systems on GWP seems to be decoupled from the productivity of a given location as determined by weather or soil type. When expressed per unit of output, high yield locations have a much lower GWP than low yield locations and would be therefore prime targets for production intensification. Published by Elsevier Ltd.
  • Authors:
    • Smith,Lydia J.
    • Torn,Margaret S.
  • Source: Climatic Change
  • Volume: 118
  • Issue: 1
  • Year: 2013
  • Summary: Terrestrial biological atmospheric carbon dioxide removal (BCDR) through bioenergy with carbon capture and storage (BECS), afforestation/reforestation, and forest and soil management is a family of proposed climate change mitigation strategies. Very high sequestration potentials for these strategies have been reported, but there has been no systematic analysis of the potential ecological limits to and environmental impacts of implementation at the scale relevant to climate change mitigation. In this analysis, we identified site-specific aspects of land, water, nutrients, and habitat that will affect local project-scale carbon sequestration and ecological impacts. Using this framework, we estimated global-scale land and resource requirements for BCDR, implemented at a rate of 1 Pg C y(-1). We estimate that removing 1 Pg C y(-1) via tropical afforestation would require at least 7 x 10(6) ha y(-1) of land, 0.09 Tg y(-1) of nitrogen, and 0.2 Tg y(-1) of phosphorous, and would increase evapotranspiration from those lands by almost 50 %. Switchgrass BECS would require at least 2 x 10(8) ha of land (20 times U.S. area currently under bioethanol production) and 20 Tg y(-1) of nitrogen (20 % of global fertilizer nitrogen production), consuming 4 x 10(12) m(3) y(-1) of water. While BCDR promises some direct (climate) and ancillary (restoration, habitat protection) benefits, Pg C-scale implementation may be constrained by ecological factors, and may compromise the ultimate goals of climate change mitigation.
  • Authors:
    • da Silva, P. B.
    • Wendling, B.
    • Cardoso, M. M.
    • Kondo, M. K.
    • Brant Albuquerque, C. J.
  • Source: Bioscience Journal
  • Volume: 28
  • Issue: 1
  • Year: 2012
  • Summary: The objective of this work was evaluated the physical attributes of soil and the main agronomic characteristics of sorghum for grain in no-tillage under different vegetation cover. The experiment was conducted during two growing seasons. In the first years were sown seven grass species in intercropping with sorghum for pasture establishment and the sorghum single defining the eight treatments. In the second season, when direct sowing of sorghum, forages available in the trial were previously desiccated for no-till sorghum. The areas representing the tillage had been barred again. In relation to soil physical properties, experiments were conducted under a randomized block design in factorial 8 (treatments) x 3 (depths) with four replications. Data related to the agronomic characteristics of the sorghum experiment was conducted in a randomized block design with four replications. It concluded with the work that the various forages used in the formation of vegetation for no-tillage affects both soil physical properties such as grain yield of sorghum.
  • Authors:
    • Martins, M. dos R.
    • Angers, D. A.
    • Cora, J. E.
  • Source: Soil Science Society of America Journal
  • Volume: 76
  • Issue: 2
  • Year: 2012
  • Summary: In no-till systems, plants play a substantial role in soil physical conditioning because physical management is otherwise confined to sowing operations. We performed a study to determine the effect of 28 different crop sequences on soil water-stable aggregation, soil organic C (SOC), and the neutral carbohydrate composition of the surface layer (0-5-cm depth) of an Oxisol under no-till. Summer crop sequences with corn ( Zea mays L.) on a continuous basis or in rotation with soybean [ Glycine max (L.) Merr.] showed a higher mean weight diameter (MWD) of water-stable aggregates than those with a rice ( Oryza sativa L.)-bean ( Phaseolus vulgaris L.)-cotton ( Gossypium hirsutum L.) rotation. Among winter crops, pearl millet [ Pennisetum americanum (L.) Leeke] or grain sorghum [ Sorghum bicolor (L.) Moench] were associated with a higher MWD than oilseed radish ( Raphanus sativus L. var. oleiformis Pers.). Plant tissues of Poaceae species (corn, pearl millet, and sorghum) were enriched in pentoses relative to other plant species. A principal component analysis showed a close positive relationship of the soil aggregate MWD with the soil xylose content, but not with other soil monosaccharide and SOC contents, and a positive relationship with the amount of pentose input to the soil, notably from aboveground plant materials. A possible explanation is that pentosans are used as an energy source by filamentous microorganisms, which play a well-known role in stabilizing soil aggregates. Our results suggest that plant-derived carbohydrates mediate crop species effects on soil structure under no-till conditions, and this effect appears to be independent of changes in total SOC.
  • Authors:
    • Presley, D. R.
    • Sindelar, A. J.
    • Buckley, M. E.
    • Mengel, D. B.
  • Source: Agronomy Journal
  • Volume: 104
  • Issue: 3
  • Year: 2012
  • Summary: Grain sorghum [ Sorghum bicolor (L.) Moench] is an important grain crop grown in both highly productive and marginal areas in the central Great Plains because of the crop's ability to use the erratic precipitation observed in this region. More effective capture and storage of this limited rainfall is needed to improve the productivity and profitability of dryland agriculture. The objective of this study was to determine the effects of long-term tillage and N fertilization on soil physical and hydraulic properties after long-term continuous grain sorghum production. Variables included conventional tillage (CT) and no-till (NT) and four rates of N fertilizer. Selected soil quality indicators included soil organic carbon (SOC), bulk density (BD), wet aggregate stability (WAS), and ponded infiltration. No-till accumulated more SOC in the surface 0 to 5 cm, and was less dense at all depths than CT. When tillage was compared across all N rates, NT contained 30% greater SOC than CT at the 0 to 5 cm. Mean weight diameter (MWD) was larger with increasing N fertilization and eliminating tillage. Ponded infiltration rates were greatest for the high N fertilization rate under NT, and lowest for the 0 kg N ha -1 rate under CT. In this long-term grain sorghum system, increasing N fertilization rate and NT both positively affected soil physical properties. These improvements in hydraulic properties will aid in more effectively capturing unpredictable precipitation, and further underscore the utility of NT management practices for the central Great Plains region.
  • Authors:
    • Ugarte, D. G. de la T.
    • English, B. C.
    • Roberts, R. K.
    • Larson, J. A.
    • Toliver, D. K.
    • West, T. O.
  • Source: Agronomy Journal
  • Volume: 104
  • Issue: 2
  • Year: 2012
  • Summary: This research evaluated differences in yields and associated downside risk from using no-till and tillage practices. Yields from 442 paired tillage experiments across the United States were evaluated with respect to six crops and environmental factors including geographic location, annual precipitation, soil texture, and time since conversion from tillage to no-till. Results indicated that mean yields for sorghum [ Sorghum bicolor (L.) Moench] and wheat ( Triticum aestivum L.) with no-till were greater than with tillage. In addition, no-till tended to produce similar or greater mean yields than tillage for crops grown on loamy soils in the Southern Seaboard and Mississippi Portal regions. A warmer and more humid climate and warmer soils in these regions relative to the Heartland, Basin and Range, and Fruitful Rim regions appear to favor no-till on loamy soils. With the exception of corn ( Zea mays L.) and cotton ( Gossypium hirsutum L.) in the Southern Seaboard region, no-till performed poorly on sandy soils. Crops grown in the Southern Seaboard were less likely to have lower no-till yields than tillage yields on loamy soils and thus had lower downside yield risk than other farm resource regions. Consistent with mean yield results, soybean [ Glycine max (L.) Merr.] and wheat grown on sandy soils in the Southern Seaboard region using no-till had larger downside yield risks than when produced with no-till on loamy soils. The key findings of this study support the hypothesis that soil and climate factors impact no-till yields relative to tillage yields and may be an important factor influencing risk and expected return and the adoption of the practice by farmers.
  • Authors:
    • Valaci, F.
    • Andrade, L.
    • Fonseca, G.
    • Andrade, M.
    • Carvalho, G.
    • Carvalho, W.
    • Oliveira, D.
  • Source: Revista Brasileira de Biociencias
  • Volume: 10
  • Issue: 1
  • Year: 2012
  • Summary: This study aimed at evaluating the allelopathic effect of species used as cover crops in no-tillage system on common bean crop. It was conducted in the greenhouse and at the Seed Analysis Laboratory in the Agricultural Department of the Federal University of Lavras, Brazil. The cover crop species used in the experiment were sunn hemp, jack bean, pigeon pea, black oat, sorghum and millet, with and without intercropping, with their straws collected at the early grain filling stage. The aqueous extracts of 5% and 10% (w/v) obtained from those straws were placed in plastic boxes (Gerbox-type) containing common bean seeds. The straws were also laid on the substrate surface sown with common bean in plastic pots and installed in the greenhouse for chemical and physical effects evaluation of the cover crops. Considering most of the variables studied, it was not verified any damage by either using of mulch or by applying allelopathic extracts. When used as mulch or when applied as aqueous extracts, residues from the intercropping between sunn hemp and sorghum positively affected the common bean plant, benefiting its initial growth.
  • Authors:
    • Handoo, Z. A.
    • Cram, M. M.
    • Fraedrich, S. W.
    • Zarnoch, S. J.
  • Source: Nematology
  • Volume: 14
  • Issue: 4
  • Year: 2012
  • Summary: Tylenchorhynchus ewingi, a stunt nematode, causes severe injury to slash pine seedlings and has been recently associated with stunting and chlorosis of loblolly pine seedlings at some forest tree nurseries in southern USA. Experiments confirmed that loblolly pine is a host for T. ewingi, and that the nematode is capable of causing severe damage to root systems. Initial population densities as low as 60 nematodes (100 cm 3 soil) -1 were sufficient to damage the root systems of loblolly pine seedlings. Populations of T. ewingi increased on pine from two- to 16-fold, depending on the initial population density. Evaluations of various cover crops used in southern forest tree nurseries indicated that legumes, rye and several varieties of sorghum were excellent hosts for T. ewingi. Other small grains such as ryegrass, oats and wheat were poorer hosts. A cultivar of pearl millet was a non-host for T. ewingi, and a cultivar of brown top millet appeared to be either a very poor host or a non-host. Nurseries that have seedling production losses caused by T. ewingi should consider rotating with non-host cover crops such as pearl millet or leaving fields fallow as part of their pest management programme.