• Authors:
    • Tolbert, V. R.
    • Mays, D. A.
    • Nyakatawa, E. Z.
    • Green, T. H.
    • Bingham, L.
  • Source: Biomass and Bioenergy
  • Volume: 30
  • Issue: 7
  • Year: 2006
  • Summary: Renewable energy sources such as bioenergy crops have significant potential as alternatives to fossil fuels. Potential environmental problems arising from soil sediment and nutrient losses in runoff water from bioenergy crops need to be evaluated in order to determine the sustainability and overall feasibility of implementing bioenergy development strategies. This paper discusses runoff, sediment, N, and total P losses from agricultural land (continuous cotton (Gossypium hirsutum L.)) converted to short-rotation sweetgum (Liquidamber styraciflua L.) plantations with and without fescue (Festuca elatior L.) and switchgrass (Panicum virgatum L.) bioenergy crops, compared to corn (Zea mays L.), on a Decatur silt loam soil in north Alabama, from 1995 to 1999. Runoff volume was significantly correlated to total rainfall and sediment yield in each year, but treatment differences were not significant. Sweetgum plots produced the highest mean sediment yield of up to 800 kg ha(-1) compared to corn and switchgrass plots, which averaged less than 200 kg ha(-1). Runoff NH4+ N losses averaged over treatments and years for spring season (3.1 kg ha(-1)) were three to five times those for summer, fall, and winter seasons. Runoff NO3- N for no-till corn and switchgrass plots in spring and summer were five to ten times that for sweetgum plots. No-till corn and switchgrass treatments had 2.4 and 2.1 kg ha(-1) average runoff total P, respectively, which were two to three times that for sweetgum treatments. Growing sweetgum with a fescue cover crop provides significantly lower risk of water pollution from sediment, runoff NH4+ N, and NO3- N. (c) 2006 Published by Elsevier Ltd.
  • Authors:
    • Lohr, L.
    • Paudel, K. P.
    • Cabrera, M.
  • Source: Renewable Agriculture and Food Systems
  • Volume: 21
  • Issue: 2
  • Year: 2006
  • Summary: Cotton production is the number one crop enterprise in Georgia in terms of revenue generation. However, due to continuous deterioration of soil quality with conventional tillage and chemical fertilizer application, the economic viability and sustainability of cotton production in Georgia are questionable. Residue management systems (RMSs) comprising winter cover crops were analyzed as an alternative to the existing system, which consists of conventional tillage and chemical fertilizer using yield benefit, net revenue, carbon sequestration, and yield efficiency criteria. Four different RMSs were examined for profitability and input efficiency. Four RMSs encompassing tillage versus no-till and chemical versus organic sources of plant nutrients were compared for their yield and net return differences. No-till and poultry litter with a cover crop was the only system with a positive return and crop yield based on the results from experimental data. Limited results from the experimental field were reinforced using a simulation study. When cotton yield is simulated with an alternative level of organic matter and nitrogen application, production function shows efficiency in input application at the higher level of organic matter. Regression results based on an erosion productivity impact calculator/environmental policy integrated climate (EPIC) simulation indicated that, in the long term, a no-till and poultry litter system may have promise in the region. The results from simulation confirm the results from the experimental study. This study reflected a need to change the cotton management system from the 200-year-old practice of employing intensively cultivated conventional tillage and chemical fertilizers to a new renewable resource-based system where residue management and organic sources of nutrients would be the key components.
  • Authors:
    • Whitehead, W. F.
    • Singh, B. P.
    • Sainju, U. M.
    • Wang, S.
  • Source: Journal of Environmental Quality
  • Volume: 35
  • Issue: 4
  • Year: 2006
  • Summary: Soil carbon (C) sequestration in tilled and nontilled areas can be influenced by crop management practices due to differences in plant C inputs and their rate of mineralization. We examined the influence of four cover crops (legume [hairy vetch (Vicia villosa Roth)], non-legume [rye (Secale cereale L.)], biculture of legume and nonlegume (vetch and rye), and no cover crops (or winter weeds)) and three nitrogen (N) fertilization rates (0, 60 to 65, and 120 to 130 kg N ha(-1)) on C inputs from cover crops, cotton (Gossypium hirsutum L.), and sorghum [Sorghum bicolor (L.) Moench)], and soil organic carbon (SOC) at the 0- to 120-cm depth in tilled and nontilled areas. A field experiment was conducted on Dothan sandy loam (fine-loamy, siliceous, thermic Plinthic Paleudults) from 1999 to 2002 in central Georgia. Total C inputs to the soil from cover crops, cotton, and sorghum from 2000 to 2002 ranged from 6.8 to 22.8 Mg ha(-1). The SOC at 0 to 10 cm fluctuated with C input from October 1999 to November 2002 and was greater from cover crops than from weeds in no-tilled plots. In contrast, SOC values at 10 to 30 em in no-tilled and at 0 to 60 cm in chisel-tilled plots were greater for biculture than for weeds. As a result, C at 0 to 30 cm was sequestered at rates of 267, 33, -133, and -967 kg C ha(-1) yr(-1) for biculture, rye, vetch, and weeds, respectively, in the no-tilled plot. In strip-tilled and chisel-tilled plots, SOC at 0 to 30 cm decreased at rates of 233 to 1233 kg C ha(-1) yr(-1). The SOC at 0 to 30 cm increased more in cover crops with 120 to 130 kg N ha(-1) yr(-1) than in weeds with 0 kg N ha(-1) yr(-1) regardless of tillage. In the subtropical humid region of the southeastern United States, cover crops and N fertilization can increase the amount of C input and storage in tilled and nontilled soils, and hairy vetch and rye biculture was more effective in sequestering C than monocultures or no cover crop.
  • Authors:
    • Garbuio, F. J.
    • Barth, G.
    • Caires, E. F.
  • Source: Soil & Tillage Research
  • Volume: 89
  • Issue: 1
  • Year: 2006
  • Summary: Brazil has extensive pasturelands that could be used, in part, for grain production. A no-till system was established on pastureland to obtain a suitable method for liming upon conversion from pasture to a no-till cropping system. The study was conducted during the period from 1998 to 2003, in Parana State (Brazil), on a clayey, kaolinitic, thermic Rhodic Hapludox. Soil chemical properties and grain production were evaluated after application of dolomitic lime. The experimental treatments were: control (no lime), split application of lime on the surface (three yearly applications of 1.5 t ha -1), surface lime (4.5 t ha -1), and incorporated lime (4.5 t ha -1). The lime rate was calculated to raise the base saturation in the topsoil (0-0.20 m) to 70%. The cropping sequence was: soyabean ( Glycine max L. Merril), barley ( Hordeum distichum L.), soyabean, wheat ( Triticum aestivum L.), soyabean, corn ( Zea mays L.), and soyabean. When surface-applied, liming neutralized acidity and increased exchangeable Ca 2++Mg 2+ to a depth of 0.10 m, and to a depth of 0.20 m, when incorporated. Split application of lime on the surface resulted in a slower neutralization reaction only in the first year after liming. Soil pH increased with liming and resulted in a decline of exchangeable Al 3+ and an increase in base saturation. At 0-0.05 m depth, lime incorporation resulted in lower levels of soil organic matter than surface application. It took 4-5 years after lime incorporation for soil organic matter to return to its baseline value. Liming increased grain yield in only one crop of soyabean, and only when lime was surface-applied at the full rate. However, cumulative grain yield was higher with liming than in the control treatment (no lime), regardless of the application method. Surface application of lime, at either full or split rates, was the best alternative to neutralize soil acidity when establishing a no-till system on pastureland because, in addition to conserving soil structure, it provided a greater economic return.
  • Authors:
    • Volk, L. B. D.
    • Cogo, N. P.
    • Castro, L. G.
  • Source: Revista Brasileira de Ciência do Solo
  • Volume: 30
  • Issue: 2
  • Year: 2006
  • Summary: Although being temporary, the presence of tillage-induced surface roughness in the soil is an important requirement in conservation tillage systems. The reason is that surface roughness increases both surface retention and surface infiltration of water in the soil, reduces runoff velocity and volume, and traps eroded sediments, thus reducing water erosion damages. With this in mind, this study was developed with the objective of evaluating modifications in soil surface roughness by tillage and rainfall actions related to water erosion, in the absence and presence of mulch cover. The experiment was carried out in the field, at the Agriculture Experimental Station of the Federal University of Rio Grande do Sul (EEA/UFRGS), in Eldorado do Sul County, Rio Grande do Sul State, Brazil, in 1996 and 1997, using simulated rainfalls on a sand), clay loam Paleudult with 0.07 m m(-1) slope steepness. The tillage types evaluated in the study included plowing, plowing plus double-disking and no-till, all them in the absence and presence of 60% soil cover (oat residue), submitted to four simulated rainfall tests. The first test consisted of a rainfall segmented in four portions, lasting for 20, 20, 30, and 30 min, separated 30 to 40 min front each other, applied immediately after tillage. The remaining tests consisted of uninterrupted rains of 90-min duration, applied 1, 20, and 35 days after the first rain. These rainfalls were applied with the rotating-boom rainfall simulator at a constant intensity of 64.0 mm h(-1). Tillage caused greater changes in the soil surface roughness titan rainfall. Soil surface roughness was most reduced by rain action in the very first event in recently-tilled soil, in the pre-runoff period. Soil surface roughness impeded or delayed runoff ill treatments with soil Mobilization in the rainfall segments with short duration applied soon after tillage, impeding or reducing water and soil losses in that period, regardless of soil cover. In the continuous, subsequent long rains, surface roughness did not influence water loss in the studied treatments without cover, where it was high throughout the experimental period, but it did reduced water loss in the presence of cover. Water loss in no-till was high for such rains throughout the experiment. Under the same rain type, soil loss reduction as influenced by roughness was more evident in the absence of cover, whereas it was substantially obscured in its presence. Mulch of crop residue added to the soil surface did not preserve the initially high surface roughness created by tillage in the degraded soil used in the study. Nevertheless, by the end of the experiment more than half of the theoretical initial water and sediment retention capacity still remained in the microdepressions formed by roughness. The obtained data were consistent with theories and concepts used in soil erosion mechanics studies.
  • Authors:
    • Franzluebbers, A. J.
    • Causarano, H. J.
    • Reeves, D. W.
    • Shaw, J. N.
  • Source: Journal of Environmental Quality
  • Volume: 35
  • Issue: 4
  • Year: 2006
  • Summary: Past agricultural management practices have contributed to the loss of soil organic carbon (SOC) and emission of greenhouse gases (e.g., carbon dioxide and nitrous oxide). Fortunately, however, conservation-oriented agricultural management systems can be, and have been, developed to sequester SOC, improve soil quality, and increase crop productivity. Our objectives were to (i) review literature related to SOC sequestration in cotton (Gossypium hirsutum L.) production systems, (ii) recommend best management practices to sequester SOC, and (iii) outline the current political scenario and future probabilities for cotton producers to benefit from SOC sequestration. From a review of 20 studies in the region, SOC increased with no tillage compared with conventional tillage by 0.48 +/- 0.56 Mg C ha(-1) yr(-1) (H(0): no change,p
  • Authors:
    • Cavigelli, M. A.
    • Szlavecz, K.
    • Clark, S.
    • Purrington, F.
  • Source: Environmental Entomology
  • Volume: 35
  • Issue: 5
  • Year: 2006
  • Summary: Ground beetle assemblages were compared in organic, no-till, and chisel-till cropping systems of the USDA Farming Systems Project in Maryland. The cropping systems consisted of 3-yr rotations of corn ( Zea mays L.), soybean ( Glycine max L. Merr.), and wheat ( Triticum aestivum L.) that were planted to corn and soybean during the 2 yr of field sampling (2001-2002). Each year, ground beetles were sampled using pitfall traps during three 9- to 14-d periods corresponding to spring, summer, and fall. A total of 2,313 specimens, representing 31 species, were collected over the 2 yr of sampling. The eight most common species represented 87% of the total specimens collected and included Scarites quadriceps Chaudoir, Elaphropus anceps (LeConte), Bembidion rapidum (LeConte), Harpalus pensylvanicus (DeGeer), Poecilus chalcites (Say), Clivina impressefrons LeConte, Agonum punctiforme (Say), and Amara aenea (DeGeer). Canonical variates analysis based on the 10 most abundant species showed that the carabid assemblages in the three cropping systems were distinguishable from each other. The organic system was found to be more different from the no-till and chisel-till systems than these two systems were from each other. In 2002, ground beetle relative abundance, measured species richness, and species diversity were greater in the organic than in the chisel-till system. Similar trends were found in 2001, but no significant differences were found in these measurements. Relatively few differences were found between the no-till and chisel-till systems. The estimated species richness of ground beetles based on several common estimators did not show differences among the three cropping systems. The potential use of ground beetles as ecological indicators is discussed.
  • Authors:
    • Hons, F.
    • Wright, A.
  • Source: Biology and Fertility of Soils
  • Volume: 41
  • Issue: 2
  • Year: 2005
  • Summary: Management practices, such as no tillage (NT) and intensive cropping, have potential to increase C and N sequestration in agricultural soils. The objectives of this study were to investigate the impacts of conventional tillage (CT), NT, and cropping intensity on soil organic C (SOC) and N (SON) sequestration and on distribution within aggregate-size fractions in a central Texas soil after 20 years of treatment imposition. Tillage regime and cropping sequence significantly impacted both SOC and SON sequestration. At 0-5 cm, NT increased SOC storage compared to CT by 33% and 97% and SON storage by 25% and 117% for a sorghum/wheat/soybean (SWS) rotation and a continuous sorghum monoculture, respectively. Total SOC and SON storage at both 0-5 and 5-15 cm was greater for SWS than continuous sorghum regardless of tillage regime. The majority of SOC and SON storage at 0-5 cm was observed in 250-m to 2-mm aggregates, and at 5-15 cm, in the >2-mm and 250-m to 2-mm fractions. Averaged across cropping sequences at 0-5 cm, NT increased SOC storage compared to CT by 212%, 96%, 0%, and 31%, and SON storage by 122%, 92%, 0%, and 37% in >2-mm, 250-m to 2-mm, 53- to 250-m, and
  • Authors:
    • Hons, F.
    • Wright, A.
  • Source: Soil Science Society of America Journal
  • Volume: 69
  • Issue: 1
  • Year: 2005
  • Summary: No-tillage (NT) has the potential to enhance C and N sequestration in agricultural soils of the southern USA, but results may vary with crop species. The objectives of this study were to investigate the impacts of NT, conventional tillage (CT), and crop species on soil organic carbon (SOC) and nitrogen (SON) sequestration and distribution within aggregate-size fractions in a central Texas soil after 20 yr of management. No-tillage increased SOC over CT at the 0- to 5-cm depth by 97, 47, and 72%, and SON by 117, 56, and 44% for continuous grain sorghum [ Sorghum bicolor (L.) Moench], wheat ( Triticum aestivum L.), and soyabean [ Glycine max (L.) Merr.], respectively. Crop species had significant impacts on SOC and SON sequestration. On average, the wheat monoculture had greater SOC (9.23 Mg C ha -1) at the 0- to 5-cm depth than sorghum (6.75 Mg C ha -1) and soyabean (7.05 Mg C ha -1). No-tillage increased the proportion of >2-mm and 250-m to 2-mm macroaggregate fractions in soil compared with CT. At the 0- to 5-cm depth, NT increased SOC compared with CT by 158% in macroaggregate fractions, but only 40% in 2-mm, 250-m to 2-mm, 53- to 250-m, and
  • Authors:
    • Hons, F.
    • Wright, A.
  • Source: Soil & Tillage Research
  • Volume: 84
  • Issue: 1
  • Year: 2005
  • Summary: No tillage (NT) and increased cropping intensity have potential for enhanced C and N sequestration in agricultural soils. The objectives of this study were to investigate the impacts of conventional tillage (CT), NT, and multiple cropping sequences on soil organic C (SOC) and N (SON) sequestration and on distribution within aggregate-size fractions in a southcentral Texas soil at the end of 20 years of treatment imposition. Soil organic C and SON sequestration were significantly greater under NT than CT for a grain sorghum [ Sorghum bicolor (L.) Moench]/wheat ( Triticum aestivum L.)/soybean [ Glycine max (L.) Merr.] rotation (SWS), a wheat/soybean doublecrop (WS), and a continuous wheat monoculture (CW) at 0-5 cm and for the SWS rotation at 5-15 cm. At 0-5 cm, NT increased SOC storage compared to CT by 62, 41, and 47% and SON storage by 77, 57, and 56%, respectively, for SWS, WS, and CW cropping sequences. Increased cropping intensity failed to enhance SOC or SON sequestration at either soil depth compared to the CW monoculture. No-tillage increased the proportion of macroaggregates (>2 mm) at 0-5 cm but not at 5-15 cm. The majority of SOC and SON storage under both CT and NT was observed in the largest aggregate-size fractions (>2 mm, 250 m to 2 mm). The use of NT significantly improved soil aggregation and SOC and SON sequestration in surface but not subsurface soils.