• Authors:
    • Hao,X.
    • Kravchenko,A. N.
  • Source: Agronomy Journal
  • Volume: 99
  • Issue: 1
  • Year: 2007
  • Summary: Management practice and soil texture are known to affect soil C. Relatively little information exists, however, on interactions between textural and management effects. The objective of this study was to evaluate management effects on soil total C along a textural gradient in well-drained Typic Hapludalfs in southwest Michigan. Three management practices considered in this study were conventional tillage (CT) and no-till (NT) both with conventional chemical inputs, and conventional tillage with leguminous cover crops and no chemical inputs (CT-cover). Four replicate plots were sampled for each practice, with approximately 100 soil samples taken at the 0- to 5-cm depth in each plot. In all management practices, the relationships of total C and N with clay + silt varied depending on the range of clay + silt values, with regression slopes at clay + silt 570 g kg-1. Total C in the CT-cover and NT treatments was higher than that in the CT treatment across the whole range of studied textures; however, a greater difference in total C between NT and CT occurred at greater clay + silt contents. Total C in the CT-cover and NT treatments were not different when clay + silt was 600 g kg-1. The results indicate that the potential for C accumulation in surface soils via NT treatment depends on soil texture.
  • Authors:
    • Burmester, C.
    • Reeves, D. W.
    • Motta, A. C. V.
    • Feng, Y.
  • Source: Communications in Soil Science and Plant Analysis
  • Volume: 38
  • Issue: 19-20
  • Year: 2007
  • Summary: The impact of conservation tillage, crop rotation, and cover cropping on soil-quality indicators was evaluated in a long-term experiment for cotton. Compared to conventional-tillage cotton, other treatments had 3.4 to 7.7 Mg ha(-1) more carbon (C) over all soil depths. The particulate organic matter C (POMc) accounts for 29 to 48 and 16 to 22% of soil organic C (SOC) for the 0- to 3- and 3- to 6-cm depths, respectively. Tillage had a strongth influence on POMc within the 0- to 3-cm depth, but cropping intensity and cover crop did not affect POW A large stratification for microbial biomass was observed varing from 221 to 434 and 63 to 110 mg kg(-1) within depth of 0-3 and 12-24 cm respectively. The microbial biomass is a more sensitive indicator (compared to SOC) of management impacts, showing clear effect of tillage, rotation, and cropping intensity. The no-tillage cotton double-cropped wheat/soybean system that combined high cropping intensity and crop rotation provided the best soil quality.
  • Authors:
    • Labreuche, J.
    • Thiébeau, P.
    • Mary, B.
    • Laurent, F.
    • Oorts, K.
    • Nicolardot, B.
  • Source: Soil & Tillage Research
  • Volume: 94
  • Issue: 2
  • Year: 2007
  • Summary: Soil N mineralization was quantified in two long-term experiments in northern France, in which no-till (NT) and conventional tillage (CT) had been differentiated for 33 years (Site 1) and 12 years (Site 2). Both sites had the same soil type but differed in crop rotation. N mineralization kinetics were assessed in situ in bare soil in both systems for 254 days (Site 1) and 555 days (Site 2) by taking frequent measurements of water and nitrate contents from soil layers and using the LIXIM calculation model. The N mineralization potential was also determined in soil samples incubated under controlled laboratory conditions. Small or non-significant differences in water and nitrate contents between NT and CT were apparent within the soil profiles on both sites. Net mineralization did not differ significantly between sites or tillage treatments. The amount of N mineralized from August 2003 to April 2004 was 6710 kg N ha -1 on Site 1 and 745 kg N ha -1 on Site 2, and 1616 kg N ha -1 from August 2003 to February 2005 on Site 2. The kinetics of N mineralization versus normalized time (equivalent time at constant temperature of 15degreesC and water content at field capacity) were linear during the shorter period (254 days corresponding to 120 normalized days). The slope (N mineralization rate) did not differ significantly between treatments and sites, and the average rate was 0.570.05 kg N ha -1 nd -1. The kinetics were non-linear on Site 2 over the longer period (555 days corresponding to 350 normalized days). They could be fitted to an exponential model with a slope at the origin of 0.62 kg N ha -1 nd -1. The N mineralization kinetics obtained in laboratory incubations for 120-150 normalized days were also almost linear with no significant differences between treatments. Assuming that mineralization took place in the ploughed layer (in CT) or over the same soil mass (in NT) they were in good agreement with the kinetics determined in situ on both sites. The calculated water drainage below the sampled profile was slightly greater in NT due to lower evaporation. The calculated leached N was slightly higher in NT than CT on Site 1, but did not differ between treatments on Site 2. It is concluded that N mineralization and leaching in NT and CT were similar, despite large differences in N distribution within the soil profile and a slight difference in organic N stock.
  • Authors:
    • Labreuche, J.
    • Gréhan, E.
    • Merckx, R.
    • Oorts, K.
    • Nicolardot, B.
  • Source: Soil & Tillage Research
  • Volume: 95
  • Issue: 1/2
  • Year: 2007
  • Summary: The greenhouse gases CO 2 and N 2O emissions were quantified in a long-term experiment in northern France, in which no-till (NT) and conventional tillage (CT) had been differentiated during 32 years in plots under a maize-wheat rotation. Continuous CO 2 and periodical N 2O soil emission measurements were performed during two periods: under maize cultivation (April 2003-July 2003) and during the fallow period after wheat harvest (August 2003-March 2004). In order to document the dynamics and importance of these emissions, soil organic C and mineral N, residue decomposition, soil potential for CO 2 emission and climatic data were measured. CO 2 emissions were significantly larger in NT on 53% and in CT on 6% of the days. From April to July 2003 and from November 2003 to March 2004, the cumulated CO 2 emissions did not differ significantly between CT and NT. However, the cumulated CO 2 emissions from August to November 2003 were considerably larger for NT than for CT. Over the entire 331 days of measurement, CT and NT emitted 3160269 and 4064138 kg CO 2-C ha -1, respectively. The differences in CO 2 emissions in the two tillage systems resulted from the soil climatic conditions and the amounts and location of crop residues and SOM. A large proportion of the CO 2 emissions in NT over the entire measurement period was probably due to the decomposition of old weathered residues. NT tended to emit more N 2O than CT over the entire measurement period. However differences were statistically significant in only half of the cases due to important variability. N 2O emissions were generally less than 5 g N ha -1 day -1, except for a few dates where emission increased up to 21 g N ha -1 day -1. These N 2O fluxes represented 0.800.15 and 1.320.52 kg N 2O-N ha -1 year -1 for CT and NT, respectively. Depending on the periods, a large part of the N 2O emissions occurred was probably induced by nitrification, since soil conditions were not favorable for denitrification. Finally, for the period of measurement after 32 years of tillage treatments, the NT system emitted more greenhouses gases (CO 2 and N 2O) to the atmosphere on an annual basis than the CT system.
  • Authors:
    • Osborne, S. L.
    • Riedell, W. E.
    • Pikul, J. L. Jr.
  • Source: Recent Research Developments in Soil Science
  • Volume: 2
  • Year: 2007
  • Summary: Maize (Zea mays L.) grown in rotation with high residue crops generally has lower grain yield under no-till than under tilled soil management in the northern US maize belt. Hence, the research objectives were to further characterize soil physical properties, maize grain yield, and seed composition under tilled and no-till soil management following soybean ( Glycine max L.) or winter wheat ( Triticum aestivum L). The two year field study was conducted on a Barnes sandy clay loam soil (fine-loamy, mixed, superactive, frigid Calcic Hapludoll) in eastern South Dakota USA. Research plots were managed under no-till starting in 1996. Tillage treatments (fall chisel plow prior to winter wheat, fall chisel plow plus spring disk-harrow prior to maize and soybean, or no-till) were started in 2001. Tillage and previous crop treatments were arranged in a completely randomized block design with 4 replications. Soil temperatures (30 cm depth) in tilled plots after winter wheat were warmer than no-till plots in June and again in August of the 2004 growing season. In 2003, soil temperatures were very similar across tillage treatments. Soil bulk density (0 to 10 cm depth) and soil penetration resistance (0 to 7 cm depth) were much greater under no-till soil management than under tilled conditions when measured in mid-June (V6 leaf development stage). While tillage treatment affected maize seed oil concentration (4.0% in tilled, 4.3% in no-till), there were no significant previous crop or interaction effects on seed oil or protein concentration. In the warmer and drier year (2003), maize grain yield under tilled conditions was 8.2 Mg ha -1 compared with 8.7 Mg ha -1 under no-till. In the cooler and wetter year (2004), yields were 9.4 Mg ha -1 under tilled soil management and 7.4 Mg ha -1 under no-till. The no-till soil management treatment following winter wheat had 27% lower maize grain yield than the tilled treatments and the no-till following soybeans. We conclude that greater bulk density and penetration resistance levels under no-till soil management, along with cool soil conditions that typically occur in the spring in the northern US maize belt, reduced maize yield under no-till management in soils with moderately low to low internal drainage.
  • Authors:
    • Kahlown, M. A.
    • Azam, M.
    • Kemper, W. D.
  • Source: Journal of Soil and Water Conservation
  • Volume: 61
  • Issue: 1
  • Year: 2006
  • Summary: Conventional management practices for the rice-wheat rotation in Pakistan's Punjab have failed to improve crop yield, increase water and fertilizer use efficiencies, and decrease production costs enough to meet an ever-increasing food demand. New technologies such as no-till, laser leveling, and bed and furrow irrigation are being rapidly adopted by the farming community, but without adequate scientific information. Therefore, those practices were evaluated on 71 farms within four representative sites. Land preparation/sowing costs, water savings, use of fertilizers, soil salinity, and crop yield were evaluated. Land preparation and sowing cost on no-till fields was significantly less than on tilled fields. Highest yields were obtained on laser-leveled fields, followed by no-till, bed and furrow fields. Water and nitrogen use efficiencies were much higher on fields with bed and furrow irrigation as compared to the conventional fields. Although the new technologies were economically feasible, we conclude that no-till was the best option for the farmers.
  • Authors:
    • Cassman, K. G.
    • Hergert, G. W.
    • Payero, J. O.
    • Tarkalson, D. D.
  • Source: Plant and Soil
  • Volume: 283
  • Issue: 1-2
  • Year: 2006
  • Summary: Soil pH is decreasing in many soils in the semiarid Great Plains of the United States under dry land no-till (NT) cropping systems. This study was conducted to determine the rate of acidification and the causes of the acidification of a soil cropped to a winter wheat (Triticum aestivum L.)-grain sorghum [Sorghum bicolor (L.) Moench]/corn (Zea mays L.)-fallow rotation (W-S/C-F) under NT. The study was conducted from 1989 to 2003 on soil with a long-term history of either continuous NT management [NT(LT)] (1962-2003) or conventional tillage (CT) (1962-1988) then converted to NT [NT(C)] (1989-2003). Nitrogen was applied as ammonium nitrate (AN) at a rate of 23 kg N ha(-1)supercript stop in 1989 and as urea ammonium nitrate (UAN) at an average annual rate of 50 kg N ha(-1) from 1990 to 2003 for both NT treatments. Soil samples were collected at depth increments of 0-5, 5-10, 10-15, and 15-30 cm in the spring of 1989 and 2003. Acidification rates for the NT(LT) and NT(C) treatments were 1.13 and 1.48 kmol H+ ha(-1) yr(-1) in the 0-30 cm depth, respectively. The amount of CaCO3 needed to neutralize the acidification is 57 and 74 kg ha(-1) yr(-1) for the NT(LT) and NT(C) treatments, respectively. A proton budget estimated by the Helyar and Porter [1989, Soil Acidity and Plant Growth, Academic Press] method indicated that NO3- leaching from the 30 cm depth was a primary cause of long-term acidification in this soil. Nitrate leaching accounted for 59 and 66% of the H+ from the acid causing factors for NT(LT) and NT(C) treatments, respectively. The addition of crop residues to the soil neutralized 62 and 47% of the acidity produced from the leaching of NO3-, and 37 and 31% of the acid resulting from NO3- leaching and the other acid-causing constituents for the NT(LT) and NT(C) treatments, respectively. These results document that surface soils in dry land W-S/C-F rotations under NT are acidifying under current management practices. Improved management to increase nitrogen uptake efficiency from applied fertilizer would help reduce the rate of acidification. The addition of lime materials to prevent negative impacts on grain yields may be necessary in the future under current management practices.
  • Authors:
    • Bona, F. D. de
    • Bayer, C.
    • Bergamaschi, H.
    • Dieckow, J.
  • Source: REVISTA BRASILEIRA DE CIENCIA DO SOLO
  • Volume: 30
  • Issue: 5
  • Year: 2006
  • Summary: The effect of irrigation on soil C stocks is a result of the balance between the effect of this practice on C input through crop residues and of C losses through microbial decomposition of soil organic matter (SOM). This study assessed the influence of sprinkler irrigation on SOM dynamics and on the total C stocks in a subtropical Acrisol under no-tillage (NT) and conventional tillage (CT) in a long-term experiment (8 years) in Universidade Federal do Rio Grande do Sul, RS, Brazil. Irrigation increased the C addition (about 8 kg C ha -1 yr -1 per mm precipitation) in both tillage systems, but this was not enough to increase the soil C stocks (0-20.0 cm) because irrigation also increased the decomposition rate of SOM by 19% in the CT soil and by 15% in NT soil. In the top layers (0-2.5 and 2.5-5.0 cm), the C concentration was higher in the NT than in CT soil, while the opposite trend was observed in the deepest layer (10.0-20.0 cm). Thus, the total C stocks in the whole 0-20.0 cm layer did not differ between tillage systems. The oat residue decomposition rate in NT soil increased with irrigation, which corroborates the higher SOM decomposition rates estimated for the irrigated soil. Based on these results, it becomes clear that the establishment of a high input cropping system able to counterbalance the higher SOM decomposition rates is a crucial point in the maintenance or improvement of soil C stocks in irrigated tropical and subtropical croplands.
  • Authors:
    • Kaspar, T. C.
    • Parkin, T. B.
  • Source: Journal of Environmental Quality
  • Volume: 35
  • Issue: 4
  • Year: 2006
  • Summary: Soil N2O emissions from three corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] systems in central Iowa were measured from the spring of 2003 through February 2005. The three managements systems evaluated were full-width tillage (fall chisel plow, spring disk), no-till, and no-till with a rye (Secale cereale L. Rymin') winter cover crop. Four replicate plots of each treatment were established within each crop of the rotation and both crops were present in each of the two growing seasons. Nitrous oxide fluxes were measured weekly during the periods of April through October, biweekly during March and November, and monthly in December, January, and February. Two polyvinyl chloride rings (30-cm diameter) were installed in each plot (in and between plant rows) and were used to support soil chambers during the gas flux measurements. Flux measurements were performed by placing vented chambers on the rings and collecting gas samples 0, 15, 30, and 45 min following chamber deployment. Nitrous oxide fluxes were computed from the change in N2O concentration with time, after accounting for diffusional constraints. We observed no significant tillage or cover crop effects on N2O flux in either year. In 2003 mean N2O fluxes were 2.7, 2.2, and 2.3 kg N2O-N ha-1 yr-1 from the soybean plots under chisel plow, no-till, and no-till + cover crop, respectively. Emissions from the chisel plow, no-till, and no-till + cover crop plots planted to corn averaged 10.2, 7.9, and 7.6 kg N2O-N ha-1 yr-1, respectively. In 2004 fluxes from both crops were higher than in 2003, but fluxes did not differ among the management systems. Fluxes from the corn plots were significantly higher than from the soybean plots in both years. Comparison of our results with estimates calculated using the Intergovernmental Panel on Climate Change default emission factor of 0.0125 indicate that the estimated fluxes underestimate measured emissions by a factor of 3 at our sites.
  • Authors:
    • Varvel, G. E.
  • Source: Soil Science Society of America Journal
  • Volume: 70
  • Issue: 2
  • Year: 2006
  • Summary: Sequestration and storage of carbon (C) by agricultural soils has been cited as one potential part of the solution to soil degradation and global climate change. However, C sequestration in soils is a slow and dynamic process. The objective of this study was to evaluate the effects of crop rotation and N fertilizer management on soil organic C (SOC) levels at several points in time during 18 yr of a long-term study in the Western Corn Belt. Seven cropping systems (three monoculture, two 2-yr, and two 4-yr rotations) with three levels of N fertilizer were compared. Soil samples were taken in the spring in 1984, 1992, 1998, and 2002 to a depth of 30 cm in 0- to 7.5-, 7.5- to 15-, and 15- to 30-cm increments. No differences were obtained in SOC levels in 1984 at the beginning of the study. After 8 yr, rotation significantly increased SOC 449 kg ha-1 across all cropping systems. From 1992 to 2002, SOC levels in the 0- to 7.5-cm depth decreased by 516 kg ha-1 across all cropping systems. Soil organic C levels in the 7.5- to 15-cm depths in 1992 and 2002 demonstrated similar rotation effects to those in the surface 0- to 7.5-cm, being not significantly affected from 1984 to 1992 but being significantly decreased from 1992 to 2002 (568 kg SOC ha-1 across all cropping systems). Many of the SOC gains in the surface 30 cm measured during the first 8 yr of the study were lost during the next 10 yr in all but the 4-yr cropping systems after 18 yr. The loss of SOC in this latter period occurred when depth of tillage was increased by using a tandem disk with larger-diameter disks. These results demonstrate that more than one point-in-time measurement from long-term experiments is necessary to monitor SOC changes when several management variables, such as cropping system and N fertilizer, are being used. They also indicate that apparent small changes in cultural practices, such as in depth of tillage in this experiment, can significantly change SOC dynamics in the soil. Subtle changes in cultural practices (e.g., tillage depth) can have significant long-term results, but long-term experiments are required to quantify their impact under variable climatic conditions.