• Authors:
    • Sainju, U. M.
    • Caesar-TonThat, T.
    • Lenssen, A. W.
    • Evans, R. G.
    • Kolberg, R.
  • Source: Soil Science Society of America Journal
  • Volume: 71
  • Issue: 6
  • Year: 2007
  • Summary: Long-term management practices are needed to increase dryland C storage and improve soil quality. We evaluated the 21-yr effects of combinations of tillage and cropping sequences on dryland crop biomass (stems + leaves) returned to the soil, residue C, and soil C fractions at the 0- to 20-cm depth in a Dooley sandy loam (fine-loamy, mixed, frigid, Typic Argiborolls) in eastern Montana. Treatments were no-till continuous spring wheat (Triticum aestivum L.) (NTCW), spring-tilled continuous spring wheat (STCW), fall- and spring-tilled continuous spring wheat (FSTCW), fall- and spring-tilled spring wheat-barley (Hordeum vulgare L.) (1984-1999) followed by spring wheat-pea (Pisum sativum L.) (2000-2004) (FSTW-B/P), and spring-tilled spring wheat-fallow (STW-F). Carbon fractions were soil organic C (SOC), soil inorganic C (SIC), particulate organic C (POC), microbial biomass C (MBC), and potential C mineralization (PCM). Mean crop biomass was 53 to 66% greater in NTCW, STCW, FSTCW, and FSTW-B/P than in STW-F. Soil surface residue amount and C content in 2004 were 46 to 60% greater in NTCW and FSTCW than in STW-F As a result, soil C fractions at 0 to 20 cm were 23 to 141 % greater in all other treatments than in STW-F due to increased C input. At 0 to 5 cm, SOC, SIC, POC, and PCM were greater in NTCW than in FSTW-B/P. At 5 to 20 cm, POC was greater in NTCW than in FSTW-B/P and PCM was greater in STCW than in FSTCW. Long-term reduced tillage with continuous nonlegume cropping increased dryland crop biomass, residue and soil C storage, and soil quality by increasing microbial biomass and activities compared with a conventional system such as STW-F.
  • Authors:
    • Lenssen, A.
    • Caesar-Thonthat, T.
    • Waddell, J.
    • Sainju, U. M.
  • Source: Soil & Tillage Research
  • Volume: 93
  • Issue: 2
  • Year: 2007
  • Summary: Soil and crop management practices may alter the quantity, quality, and placement of plant residues that influence soil C and N fractions. We examined the effects of two tillage practices [conventional till (CT) and no-till (NT)] and five crop rotations [continuous spring wheat (Triticum aestivum L.) (CW), spring wheat-fallow (W-F), spring wheat-lentil (L-ens culinaris Medic.) (W-L), spring wheat-spring wheat-fallow (W-W-F), and spring wheat-pea (Pisum sativum L.)-fallow (W-P-F)] on transient land previously under 10 years of Conservation Reserve Program (CRP) planting on the amount of plant biomass (stems + leaves) returned to the soil from 1998 to 2003 and soil C and N fractions within the surface 20 cm in March 2004. A continued CRP planting was also included as another treatment for comparing soil C and N fractions. The C and N fractions included soil organic C (SOC), soil total N (STN), microbial biomass C and N (MBC and MBN), potential C and N mineralization (PCM and PNM), and NH4-N and NO3-N contents. A field experiment was conducted in a mixture of Scobey clay loam (fine-loamy, mixed, Aridic Argiborolls) and Kevin clay loam (fine, montmorillonitic, Aridic Argiborolls) in Havre, MT, USA. Plant biomass yield varied by crop rotation and year and mean annualized biomass was 45-50% higher in CW and W-F than in W-L. The SOC and PCM were not influenced by treatments. The MBC at 0-5 cm was 26% higher in W-W-F than in W-F. The STN and NO3-N at 5-20 cm and PNM at 0-5 cm were 17-1206% higher in CT with W-L than in other treatments. Similarly, MBN at 0-5 cm was higher in CT with W-L than in other treatments, except in CT with W-F and W-P-F. Reduction in the length of fallow period increased MBC and MBN but the presence of legumes, such as lentil and pea, in the crop rotation increased soil N fractions. Six years of tillage and crop rotation had minor influence on soil C and N storage between croplands and CRP planting but large differences in active soil C and N fractions.
  • Authors:
    • Agenbag, G. A.
    • Louw, P. J. E.
    • Fourie, J. C.
  • Source: South African Journal of Enology and Viticulture
  • Volume: 28
  • Issue: 2
  • Year: 2007
  • Summary: The trial was conducted over a period of ten years (1993/94 to 2002/03) on a sandy soil in a Sauvignon blanc/Ramsey vineyard near Lutzville (31degrees35′S, 18degrees52′E), situated in the semi-arid Olifants River Valley of the Western Cape. Fourteen treatments, consisting of three grain species and four legumes, managed according to two cover crop management practices, were included. One management practice consisted of cover crops which were sown annually and full surface, post-emergence chemical control which was applied before bud break and when the berries reached pea size (BB). The second management practice consisted of cover crops which were sown biennially. Post-emergence chemical control was applied to the vine row before bud break and full surface when the berries reached pea size (AB). From 1999/2000 to 2002/03 the cover crops were sown annually, while the full surface post-emergence control applied at the end of November was advanced to mid-October. Two treatments in which Avena sativa L. v. Saia ('Saia' oats) and Vicia dasycarpa Ten. (grazing vetch) were sown annually, controlled mechanically in the work row and chemically in the vine row from bud break to harvest (MC), were also applied. These treatments were compared to a control, in which no cover crop was sown and MC was applied. A treatment in which no cover crop was sown and BB was applied (weedchem), was also included. During the third growing season of the vines (1994/95), the grapevine shoot mass of the BB treatments of grazing vetch and Medicago truncatula Gaertn. v. Paraggio ('Paraggio' medic) was significantly more than that of the AB and MC treatments, with the exception of Secale cereale L. v. Henog (AB) and grazing vetch (MC). The first harvest (1994/95) from the grapevines in the BB treatments was significantly higher than that of weedchem and the MC treatments. The grape yield of the BB treatments, grazing vetch (AB) and Ornithopus sativus L. v. Emena (pink Seradella) (AB) was significantly more than that of weedchem and the control during the 1997/98 season. The NO 3-N concentration in the leaf petioles in all the cover crop treatments was, with the exception of the AB treatments of rye, M. truncatula Gaertn. v. Parabinga ('Parabinga' medic) and grazing vetch, significantly higher than that in weedchem and the control, as measured during the 1994/95 season. The NO 3-N concentration in the leaf petioles of the BB and AB treatment of a species differed significantly. The N concentration in the juice of the cover crop treatments during the 1995/96 season was, with the exception of 'Saia' oats (MC) and 'Parabinga' medic (AB), significantly higher than that of weedchem and the control. During the 1998/99 season, the N concentration of the juice in the BB and AB treatments of grazing vetch and pink Seradella was significantly higher than that of the MC treatments, two rye treatments, weedchem and the AB treatments of the other cover crops. The concentration of Ca in the juice of the cover crop treatments was, with the exception of the pink Seradella treatments, significantly higher than that of weedchem and the control. Wine quality did not differ between treatments.
  • Authors:
    • Souza, R. A.
    • Crispino, C. C.
    • Franchini, J. C.
    • Torres, E.
    • Hungria, M.
  • Source: Soil & Tillage Research
  • Volume: 92
  • Issue: 1/2
  • Year: 2007
  • Summary: The objective of this work was to identify soil parameters potentially useful to monitor soil quality under different soil management and crop rotation systems. Microbiological and chemical parameters were evaluated in a field experiment in the State of Parana, southern Brazil, in response to soil management [no-tillage (NT) and conventional tillage (CT)] and crop rotation [including grain (soybean, S; maize, M; wheat, W) and legume (lupin, L.) and non-legume (oat, O) covers] systems. Three crop rotation systems were evaluated: (1) (O/M/O/S/W/S/L/M/O/S), (2) (O/S/L/M/O/S/W/S/L/M), and (3) (O/S/W/S/L/M/O/M/W/M), and soil parameters were monitored after the fifth year. Before ploughing, CO 2-emission rates were similar in NT and CT soils, but plough increased it by an average of 57%. Carbon dioxide emission was 13% higher with lupin residues than with wheat straw; decomposition rates were rapid with both soil management systems. Amounts of microbial biomass carbon and nitrogen (MB-C and MB-N, respectively) were 80 and 104% higher in NT than in CT, respectively; however, in general these parameters were not affected by crop rotation. Efficiency of the microbial community was significantly higher in NT: metabolic quotient ( qCO 2) was 55% lower than in CT. Soluble C and N levels were 37 and 24% greater in NT than in CT, respectively, with no effects of crop rotation. Furthermore, ratios of soluble C and N contents to MB-C and MB-N were consistently lower in NT, indicating higher immobilization of C and N per unit of MB. The decrease in qCO 2 and the increase in MB-C under NT allowed enhancements in soil C stocks, such that in the 0-40 cm profile, a gain of 2500 kg of C ha -1 was observed in relation to CT. Carbon stocks also varied with crop rotation, with net changes at 0-40 cm of 726, 1167 and -394 kg C ha -1 year, in rotations 1, 2 and 3, respectively. Similar results were obtained for the N stocks, with 410 kg N ha -1 gained in NT, while crop rotations 1, 2 and 3 accumulated 71, 137 and 37 kg of N ha -1 year -1, respectively. On average, microbial biomass corresponded to 2.4 and 1.7% of the total soil C, and 5.2 and 3.2% of the N in NT and CT systems, respectively. Soil management was the main factor affecting soil C and N levels, but enhancement also resulted from the ratios of legumes and non-legumes in the rotations. The results emphasize the importance of microorganisms as reservoirs of C and N in tropical soils. Furthermore, the parameters associated with microbiological activity were more responsive to soil management and crop rotation effects than were total stocks of C and N, demonstrating their usefulness as indicators of soil quality in the tropics.
  • Authors:
    • Pedersen, J. B.
  • Source: Oversigt over Landsfors<o>gene 2007. Fors<o>g og unders<o>gelser i de land<o>konomiske foreninger
  • Year: 2007
  • Summary: Work conducted by Landsforsgene, a collaborative body that undertakes field trials and experiments on crop plants in Denmark, is reported. A general introduction gives details of conditions in the 2007 growing season (warmer in spring and wetter than usual in summer), and their effects on factors such as the efficacy of fertilizer application and the harvest. The aim is to give growers a basis for future planning, taking account of environmental conditions and profitable plant production. Most of the report is devoted to separate sections covering individual crops: winter barley, winter rye, triticale, winter wheat, spring barley, oats, spring wheat, field peas, grass seeds, rape, hemp, spinach, strawberries, potatoes, sugar beet, pasture plants (grasses and clovers), and maize. Within these sections details of varieties, fertilizers, weeds, and diseases are provided in the text and in numerous tables and photographs. Other small sections deal with topics including organic production, fertilizers, plant breeding, statistical methods, policies, and names and addresses of suppliers. The report concludes with a list of the 23 authors of sections, and a comprehensive index.
  • Authors:
    • Mielniczuk, J.
    • Dieckow, J.
    • Zanatta, J.
    • Bayer, C.
    • Vieira, F.
    • He, Z.
  • Source: Soil & Tillage Research
  • Volume: 96
  • Issue: 1/2
  • Year: 2007
  • Summary: The carbon management index (CMI) is derived from the total soil organic C pool and C lability and is useful to evaluate the capacity of management systems to promote soil quality. However, the CMI has not been commonly used for this purpose, possible due to some limitations of the 333 mM KMnO 4-chemical oxidation method conventionally employed to determine the labile C fraction. We hypothesized, however, that physical fractionation of organic matter is an alternative approach to determine the labile C. The objectives of this study were (i) to assess the physical fractionation with density (NaI 1.8 Mg m -3) and particle-size separation (53 m mesh) as alternative methods to the KMnO 4-chemical oxidation (60 and 333 mM) in determining the labile C and thus the CMI, and (ii) to evaluate the capacity of long-term (19 years) no-till cropping systems (oat/maize: O/M, oat + vetch/maize: O + V/M, oat + vetch/maize + cowpea: O + V/M + C, and pigeon pea + maize: P + M) and N fertilization (0 and 180 kg N ha -1) to promote the soil quality of a Southern Brazilian Acrisol, using the CMI as the main assessment parameter. Soil samples were collected from 0 to 12.5 cm layer, and the soil of an adjacent native grassland was taken as reference. The mean annual C input of the cropping systems varied from 3.4 to 6.0 Mg ha -1 and the highest amounts occurred in legume-based cropping systems and N fertilized treatments. The C pool index was positively related to the annual C input ( r2=0.93, P
  • Authors:
    • Lares, M. T.
    • Liebig, M. A.
    • Tanaka, D. L.
    • Merrill, S. D.
    • Krupinsky, J. M.
    • Hanson, J. D.
  • Source: Agronomy Journal
  • Volume: 99
  • Issue: 4
  • Year: 2007
  • Summary: Field research was conducted to determine the influence of crop and crop sequencing on crop residue coverage of soil with 10 crops [buckwheat (Fagopyrum esculentum Moench), canola (Brassica napus L.), chickpea (Cicer arietinum L.), corn (Zea mays L.), dry pea (Pisum sativum L.), grain sorghum [Sorghum bicolor (L.) Moench], lentil (Lens culinaris Medik.), oil seed sunflower (Helianthus annuus L.), proso millet (Panicum miliaceum L.), and hard red spring wheat (Triticum aestivum L.)]. Crop residue production was obtained. Crop residue coverage of the soil surface was measured with a transect technique at the time of seeding spring wheat. Crop residue coverage varied and was more clearly associated with the second-year crop than with the first-year crop of a 2-yr crop sequence. Crop sequences composed of spring wheat, proso millet, and grain sorghum had higher crop residue coverage compared with sequences composed of the other crops. When these three crops and three crops that provide lower crop residue coverage of soil the subsequent year (lentil, chickpea, and sunflower) were analyzed as a subset to compare various sequences of crops providing a range of residue coverage, for example, lower (first yr)/lower (second yr), the surface residue coverage ranged from 65% for the lower/lower combination to 93% for the higher/higher combination in 2004 and from 56 to 94% in 2005, respectively. A producer operating on more fragile soil and concerned about reducing soil erosion hazards would be advised to grow crops that provide higher residue coverage in the year before crops that provide lower residue coverage.
  • Authors:
    • Lares, M. T.
    • Liebig, M. A.
    • Merrill, S. D.
    • Tanaka, D. L.
    • Krupinsky, J. M.
    • Hanson, J. D.
  • Source: Agronomy Journal
  • Volume: 99
  • Issue: 4
  • Year: 2007
  • Summary: Crop sequence is an important management practice that may lower the risk for leaf spot diseases of spring wheat ( Triticum aestivum L.). Field research was conducted near Mandan, ND, to determine the impact of crop sequences on leaf spot diseases of hard red spring wheat early in the growing season. Spring wheat was evaluated for disease severity following crop sequence combinations of 10 crops [buckwheat ( Fagopyrum esculentum Moench)], canola ( Brassica napus L.), chickpea ( Cicer arietinum L.), corn ( Zea mays L.), dry pea ( Pisum sativum L.), grain sorghum [ Sorghum bicolor (L.) Moench], lentil ( Lens culinaris Medik.), oil seed sunflower ( Helianthus annuus L.), proso millet ( Panicum miliaceum L.), and hard red spring wheat. Spring wheat leaves with distinct lesions were collected for determination of lesion number and percentage necrosis data, which were used to estimate leaf spot disease severity. Pyrenophora tritici-repentis (Died.) Drechs., the cause of tan spot, and Phaeosphaeria nodorum (E. Muller) Hedjaroude, the cause of Stagonospora nodorum blotch, were the major leaf spot diseases and consistently present throughout the growing season. The frequency of isolation following alternative crops was generally lower compared with spring wheat following wheat. Leaf spot diseases on spring wheat were impacted by crop sequencing. Spring wheat following crop sequences with alternative crops for 1 or 2 yr had lower levels of disease severity compared with a continuous spring wheat treatment early in the growing season. Disease severity was apparently not related to the percentage of crop residue coverage on the soil surface associated with various crop sequence combinations. New alternative crops preceding spring wheat reduce levels of leaf spot diseases.
  • Authors:
    • White, R. E.
    • Chapman, D. F.
    • Eckard, R. J.
  • Source: Australian Journal of Agricultural Research
  • Volume: 58
  • Issue: 12
  • Year: 2007
  • Authors:
    • Apan, A.
    • Maraseni, T. N.
    • Cockfield, G.
  • Source: Journal of Environmental Science and Health, Part A: Toxic/Hazardous Substances and Environmental Engineering
  • Volume: 42
  • Issue: 1
  • Year: 2007