• Authors:
    • Lenssen, A. W.
    • Johnson, G. D.
    • Carlson, G. R.
  • Source: Field Crops Research
  • Volume: 100
  • Issue: 1
  • Year: 2007
  • Summary: Available water is typically the biggest constraint to spring wheat production in the northern Great Plains of the USA. The most common rotation for spring wheat is with summer fallow, which is used to accrue additional soil moisture. Tillage during fallow periods controls weeds, which otherwise would use substantial amounts of water, decreasing the efficiency of fallow. Chemical fallow and zero tillage systems improve soil water conservation, allowing for increased cropping intensity. We conducted a field trial from 1998 through 2003 comparing productivity and water use of crops in nine rotations under two tillage systems, conventional and no-till. All rotations included spring wheat, two rotations included field pea, while lentil, chickpea, yellow mustard, sunflower, and safflower were present in single rotations with wheat. Growing season precipitation was below average most years, resulting in substantial drought stress to crops not following fallow. Preplant soil water, water use, and spring wheat yields were generally greater following summer fallow than wheat recropped after wheat or alternate crops. Water use and yield of wheat following summer fallow was greater than for chickpea or yellow mustard, the only other crops in the trial that followed summer fallow. Field pea performed best of all alternate crops, providing yields comparable to those of recropped spring wheat. Chickpea, lentil, yellow mustard, safflower, and sunflower did not perform well and were not adapted to this region, at least during periods of below average precipitation. Following summer fallow, and despite drought conditions, zero tillage often provided greater amounts of soil water at planting compared to conventional tillage.
  • Authors:
    • Montemurro, F.
    • Maiorana, M.
    • Convertini, G.
    • Ferri, D.
  • Source: Agronomy for Sustainable Development
  • Volume: 27
  • Issue: 2
  • Year: 2007
  • Summary: The application of conventional agricultural practices, e. g. deep soil tillage and repeated, plentiful mineral fertilisation, can lead to a progressive deterioration of soil fertility, especially in Mediterranean environments characterised by scanty rains and high summer temperatures. As a consequence, to maintain high levels of both crop productivity and soil organic matter and to improve some soil properties, a reduction of agricultural inputs and a greater supply of organic material are needed. In the light of these considerations, we carried out a two-year field experiment in Southern Italy to determine the effects of reduced soil tillage and municipal solid waste compost application on growth parameters, production and quality of sugar beet crops, and on both soil chemical characteristics and mineral nitrogen deficit. Two soil tillage depths were compared: conventional tillage, till 40-45 cm and shallow tillage, at 15-20 cm. Within each soil tillage, the following N-fertilising strategies were tested: (1) mineral fertilisation, with 100 kg N ha(-1); (2) organic fertilisation with municipal solid waste compost at 100 kg N ha(-1); (3) mixed fertilisation, with 50% of organic N as municipal solid waste compost, and 50% of mineral N; and (4) slow-release organic-mineral N fertiliser, at 100 kg N ha(-1). All these treatments were compared with a lower level of mineral fertiliser at 50 kg N ha(-1), and with an unfertilised control. Our findings show first the absence of a significant difference in root and sucrose yields between reduced tillage and deep tillage; as shown by roots (36.02 t ha(-1)) and sucrose (3.41 t ha(-1)) yields for reduced tillage and 35.76 and 3.51 t ha(-1), respectively, for the deepest tillage. Secondly, among the N treatments, the mixed organic-mineral N fertilisation gave productions statistically not diffierent from mineral N fertilisation; as shown by root yields (36.38 versus 36.40 tha(-1)) and sucrose yields ( 3.56 versus 3.65 t ha(-1)). Third, the mixed organic-mineral N induced a reduction of 13.2% in a-amino N content by comparison with the mineral treatment of 100 kg N ha-1. Fourth, our results showed that the applications of the municipal solid waste compost increased the extracted and the humified organic carbon by +27.7 and +25.4%, compared with the mineral fertiliser, and did not raise the content of heavy metals. These findings highlighted that in Southern Italy it is sustainable to adopt alternative sugar beet production, safeguarding crops' quantitative and qualitative performance, decreasing the production costs and using the natural resources better.
  • Authors:
    • Radford, B. J.
    • Yule, D. F.
    • McGarry, D.
    • Playford, C.
  • Source: Soil & Tillage Research
  • Volume: 97
  • Issue: 2
  • Year: 2007
  • Summary: Heavy wheel traffic causes soil compaction, which adversely affects crop production and may persist for several years. We applied known compaction forces to entire plots annually for 5 years, and then determined the duration of the adverse effects on the properties of a Vertisol and the performance of maize and sorghum crops under no-till dryland cropping with residue retention. For up to 5 years after a final treatment with a 10 Mg axle load on wet soil, soil shear strength at 70-100 mm and cone index at 180-360 mm were significantly ( P<0.05) higher than in a control treatment, and soil water storage and grain yield were lower. We conclude that compaction effects persisted because (1) there were insufficient wet-dry cycles to swell and shrink the entire compacted layer, (2) soil loosening by tillage was absent and (3) there were fewer earthworms in the compacted soil. Compaction of dry soil with 6 Mg had little effect at any time, indicating that by using wheel traffic only when the soil is dry, problems can be avoided. Unfortunately such a restriction is not always possible because sowing, tillage and harvest operations often need to be done when the soil is wet. A more generally applicable solution, which also ensures timely operations, is the permanent separation of wheel zones and crop zones in the field-the practice known as controlled traffic farming. Where a compacted layer already exists, even on a clay soil, management options to hasten repair should be considered, e.g. tillage, deep ripping, sowing a ley pasture or sowing crop species more effective at repairing compacted soil.
  • 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:
    • Babu, K. S.
    • Sharma, R. K.
    • Kumar, K.
    • Sharma, A. K.
  • Source: Crop Protection
  • Volume: 26
  • Issue: 6
  • Year: 2007
  • Summary: A study was conducted to evaluate the influence of tillage systems on the incidence of Tilletia indica (Karnal bunt) in a rice-wheat system that is the most popular and prevalent crop rotation in the Indo-Gangetic Plains of India. A total of 906 samples, were drawn from the farmers' fields during the month of April during the 3 years study period. The samples collected were 365, 171, and 370 from the zero tillage (ZT), furrow irrigated raise bed system (FIRBS), and conventional till (CT) sown fields, respectively. The disease incidence, incidence index and percent-infected samples were calculated and statistically analyzed. Results showed that ZT fields had the lowest mean incidence of Karnal bunt, i.e. 9.00% infected samples in comparison to 18.10% and 16.20% under FIRBS and CT, respectively. Similarly, the average infection in infected samples was equal in FIRBS and CT, but the samples from ZT were statistically lower. KB incidence index showed a similar trend. ZT has shown a reduced incidence of KB in comparison to the raised bed (FIRBS) and CT systems. If ZT is followed for a period of a few years, it may help in reducing the effective soil inoculum and reducing the disease incidence over time.
  • Authors:
    • Pereira, J.
    • Prior, M.
    • Uribe-Opazo, M.
    • Nobrega, L.
    • Lopes, R.
  • Source: Acta Scientiarum Agronomy
  • Volume: 29
  • Issue: Suplemento Espec
  • Year: 2007
  • Summary: This study evaluated alterations in the physical properties water content, soil density and porosity in areas under no tillage and tillage systems in the cultures of soybean and maize in three agricultural years. The experiment was carried out at the Experimental Nucleus of Agricultural Engineering of Unioeste (Cascavel, state of Parana). Soybean culture occurred in the first two years and in the third year maize, as summer crop, black oats and forage turnip as winter cover crops. During these three years the study observed reduction of water content and soil density and increase of porosity. The variations as regards the physical properties of the soil showed direct proportional relation between water content and soil density and was in inverse proportion for soil porosity. The soil presented improvements on its physical conditions for the porosity increase and density reduction with the black oats and forage turnip crops and maize. The soybean/maize management in rotation with black oats and forage turnip showed more adequate in the improvement of the physical conditions of the soil as compared with the management systems, since neither of the systems had a major impact in the improvements of the physical properties evaluated throughout this whole period.
  • Authors:
    • Silva, P.
    • Ernani, P.
    • Sangoi, L.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 31
  • Issue: 3
  • Year: 2007
  • Summary: No-tillage systems, associated with black oat as preceding cover crop, have been increasingly adopted. This has motivated anticipated maize nitrogen fertilizer application, transferring it from the side-dress system at the stage when plants have 5-6 expanded leaves to when the preceding cover crop is eliminated or to maize sowing. This study was conducted to evaluate the effects of soil tillage system and timing of N fertilizer application on maize grain yield and agronomic efficiency of N applied to a soil with high organic matter content. A three-year field experiment was conducted in Lages, state of Santa Catarina, Brazil, from 1999 onwards. Two soil tillage systems were tested in the main plots: conventional tillage (CT) and no-tillage (NT). Six N management systems were assessed in the split-plots: S1, control (without N application); S2, all N (100 kg ha -1) applied at oat desiccation; S3, all N applied at maize sowing; S4, all N side-dressed when maize had five expanded leaves (V5 growth stage); S5, 1/3 of N rate applied at maize sowing and 2/3 at V5; and S6, 2/3 of nitrogen rate applied at maize sowing and 1/3 at V5. Maize response to the time and form of splitting N was not affected by the soil tillage system. Grain yield ranged from 6.0 to 11.8 t ha -1. The anticipation of N application (S2 and S3) decreased grain yield in two of three years. In the rainiest early spring season (2000/2001) of the experiment, S4 promoted an yield advantage of 2.2 t ha -1 over S2 and S3. Application of total N rate before or at sowing decreased the number of kernels produced per ear in 2000/01 and 2001/02 and the number of ears produced per area in 2001/02, resulting in reduced grain yield. The agronomic efficiency of applied N (kg grain increase/kg of N applied) ranged from 13.9 to 38.8 and was always higher in the S4 than in the S2 and S3 N systems. Short-term N immobilization did not reduce grain yield when no N was applied before or at maize sowing in a soil with high organic matter content, regardless of the soil tillage system.
  • Authors:
    • Hons, F.
    • Dou, F.
    • Wright, A.
  • Source: Soil Science
  • Volume: 172
  • Issue: 2
  • Year: 2007
  • Summary: Crop species and conservation tillage may enhance carbon (C) and nitrogen (N) sequestration potential in subsurface soils. The objectives of this study were to determine the effects of crop species and tillage on soil organic C (SOC) and total N distribution in six soil depth intervals from 0 to 105 cm after 20 years of treatment imposition. Tillage had the most influence on soil C and N at 0 to 5 cm, and impacts extended to the 15- to 30-cm depth for wheat and sorghum. Overall, SOC and total N for wheat were 18 and 15% higher than sorghum and soybean. Dissolved organic C (DOC) depth distribution was similar to SOC and total N. The proportion of SOC as DOC ranged from 1.3 to 3.3% and increased with soil depth. The highest soil C and N levels occurred for wheat under no tillage. The depth of soil impacted by crop species was shallower for conventional tillage than no tillage, and the depth distribution exhibited a logarithmic pattern. Soil organic C, total N, and DOC decreased 404, 507, and 205%, respectively from 0-5 to 80-105 cm. The maximum depth interval below which no further decreases in SOC and total N occurred was 30 to 55 cm for soybean, 55 to 80 cm for wheat, and 80 to 105 cm for sorghum, demonstrating the importance of subsurface soils for C sequestration. Crop management impacts below the depth of tillage demonstrate the importance of crop rooting and belowground biomass, or translocation of dissolved organic matter, to subsoil C sequestration.
  • Authors:
    • Six, J.
    • West, T. O.
  • Source: Climatic Change
  • Volume: 80
  • Issue: 1
  • Year: 2007
  • Summary: Rates of soil C sequestration have previously been estimated for a number of different land management activities, and these estimates continue to improve as more data become available. The time over which active sequestration occurs may be referred to as the sequestration duration. Integrating soil C sequestration rates with durations provides estimates of potential change in soil C capacity and more accurate estimates of the potential to sequester C. In agronomic systems, changing from conventional plow tillage to no-till can increase soil C by an estimated 16 ± 3%, whereas increasing rotation intensity can increase soil C by an estimated 6 ± 3%. The increase in soil C following a change in rotation intensity, however, may occur over a slightly longer period (26 yr) than that for tillage cessation (21 yr). Sequestration strategies for grasslands have, on average, longer sequestration durations (33 yr) than for croplands. Estimates for sequestration rates and durations are mean values and can differ greatly between individual sites and management practices. As the annual sequestration rate declines over the sequestration duration period, soil C approaches a new steady state. Sequestration duration is synonymous with the time to which soil C steady state is reached. However, soils could potentially sequester additional C following additional changes in management until the maximum soil C capacity, or soil C saturation, is achieved. Carbon saturation of the soil mineral fraction is not well understood, nor is it readily evident. We provide evidence of soil C saturation and we discuss how the steady state C level and the level of soil C saturation together influence the rate and duration of C sequestration associated with changes in land management.