• Authors:
    • DEFRA
  • Year: 2007
  • Authors:
    • Sherlock, R. R.
    • Cameron, K. C.
    • Di, H. J.
  • Source: Soil Use and Management
  • Volume: 23
  • Issue: 1
  • Year: 2007
  • Summary: Nitrous oxide (N2O) is a potent greenhouse gas and, in New Zealand, about one-third of the total greenhouse gas emissions from the agricultural sector are of N2O, mostly derived from animal excreta in grazed pasture soils. The aim of this study was to determine the effectiveness of a nitrification inhibitor, dicyandiamide (DCD), in reducing N2O emissions from animal urine patches in four different soils located in different regions of New Zealand with different soil, climatic and management conditions. The four soils are Templeton fine sandy loam and Lismore stony silt loam in Canterbury in the South Island, Horotiu silt loam in the Waikato region and Taupo pumice sand near Lake Taupo, both in the North Island. Results showed that the application of a fine-particle suspension nitrification inhibitor, DCD, to grazed pasture soils was very effective in reducing N2O emissions in all four different soils. Total N2O emissions (over 69-137 days) from animal urine patches ranged from 1 to 20.9 kg N2O-N ha-1 without DCD. These were reduced to 0.31-5.7 kg N2O-N ha-1 by the use of DCD, representing 61-73% reductions (with an average of 70% reduction). The N2O-N emission factor from animal urine N, EF3, was reduced from an average of 0.9 to 0.3% by the use of DCD. These results demonstrate the potential of using nitrification inhibitors to mitigate N2O emissions in a wide range of grazed pasture soils under different climatic and management conditions.
  • Authors:
    • Tourdonnet, S. D.
    • Carof, M.
    • Coquet, Y.
    • Hallaire, V.
    • Roger-Estrade, J.
  • Source: Soil Use and Management
  • Volume: 23
  • Issue: 3
  • Year: 2007
  • Summary: We studied soil hydraulic conductivity (K) and porosity in five combinations of soil tillage and cover crop management systems. Treatments were winter wheat (Triticum aestivum L.) grown on a conventionally tilled soil (CT), on a no-till soil (NT), and on an NT with three different cover crops: red fescue (Festuca rubra L.; Fr), bird's-foot-trefoil (Lotus corniculatus L.; Lc) and alfalfa (Medicago sativa L.; Ms). Measurements were made on a loamy soil in Grignon, France, in November 2004, May 2005 and October 2005. K and mean size of hydraulically active pores were measured in situ at three water potentials (22120.6, 22120.2 and 22120.05 kPa) at the soil surface and at 10 cm depth. In November 2004 and May 2005, pore space was described using 2D image analysis of pores on undisturbed soil samples in the 0201310 cm layer and in the 10201320 cm layer. The major differences were caused by soil tillage that created two heterogeneous soil layers and increased K in the 0201310 cm layer relative to NT. The effects of cover crop on K and porosity were not affected by the root type: there were no major differences between the grass cover crop (fibrous-root type) and the leguminous ones (tap-root type). However, we recorded larger functional pores and more tubules in the no-till treatments with a cover crop, compared with the no-till treatment without cover crop; this was probably the result of root activity. Although these changes generally did not result in larger values of K, they participated in the maintenance of soil structure and K over time.
  • Authors:
    • Sherlock, R. R.
    • Kelliher, F. M.
    • Buckthought, L. E.
    • Clough, T. J.
  • Source: Global Change Biology
  • Volume: 13
  • Year: 2007
  • Summary: There is uncertainty in the estimates of indirect nitrous oxide (N2O) emissions as defined by the Intergovernmental Panel on Climate Change (IPCC). The uncertainty is due to the challenge and dearth of in situ measurements. Recent work in a subtropical stream system has shown the potential for diurnal variability to influence the downstream N transfer, N form, and estimates of in-stream N2O production. Studies in temperate stream systems have also shown diurnal changes in stream chemistry. The objectives of this study were to measure N2O fluxes and dissolved N2O concentrations from a spring-fed temperate river to determine if diurnal cycles were occurring. The study was performed during a 72 h period, over a 180m reach, using headspace chamber methodology. Significant diurnal cycles were observed in radiation, river temperature and chemistry including dissolved N2O-N concentrations. These data were used to further assess the IPCC methodology and experimental methodology used. River NO3-N and N2O-N concentrations averaged 3.0mg L-1 and 1.6 lgL-1, respectively, with N2O saturation reaching a maximum of 664%. The N2O-N fluxes, measured using chamber methodology, ranged from 52 to 140 lgm-2 h-1 while fluxes predicted using the dissolved N2O concentration ranged from 13 to 25 lgm-2 h-1. The headspace chamber methodology may have enhanced the measured N2O flux and this is discussed. Diurnal cycles in N2O% saturation were not large enough to influence downstream N transfer or N form with variability in measured N2O fluxes greater and more significant than diurnal variability in N2O% saturation. The measured N2O fluxes, extrapolated over the study reach area, represented only 6104 % of the NO3-N that passed through the study reach over a 72 h period. This is only 0.1% of the IPCC calculated flux.
  • Authors:
    • Hedley, M. J.
    • Bolan, N. S.
    • Saggar, S.
    • Bhandral, R.
  • Source: Soil & Tillage Research
  • Volume: 94
  • Issue: 2
  • Year: 2007
  • Summary: Animal trampling is one of the main factors responsible for soil compaction under grazed pastures. Soil compaction is known to change the physical properties of the soil thereby affecting the transformation of nitrogen (N) and the subsequent of release of N as nitrous oxide (N2O). The form of N source added to these compacted soils further affects N emissions. Here we determine the interactive effects of soil compaction and form of N sources (cattle urine and ammonium, nitrate and urea fertilizers) on the loss of N through N2O emission from grassland soil. Overall, soil compaction caused a seven-fold increase in the N2O flux, the total N2O fluxes for the entire experimental period ranged from 2.62 to 61.74 kg N2O-N ha-1 for the compacted soil and 1.12 to 4.37 kg N2O-N ha-1 for the uncompacted soil. Among the N sources, the highest emissions were measured with nitrate application, emissions being 10 times more than those from other N sources for compacted soil, suggesting that the choice of N fertilizer can go a long way in mitigating N2O emissions in compacted grasslands.
  • Authors:
    • Molgaard, J. P.
    • Rasmussen, J.
    • Henriksen, C. B.
  • Source: Soil & Tillage Research
  • Volume: 94
  • Issue: 1
  • Year: 2007
  • Summary: Field experiments were conducted on sand and sandy loam from 2000 to 2002 to determine how timing of ridging affects potato tuber yield and quality depending on soil texture and the use of catch crops. On sand, ridging in winter increased soil N availability in the 0-50 cm soil layer in spring from 5.7 to 6.8 mg N kg(-1) soil (19%) compared with ridging in autumn (P
  • Authors:
    • Pals, A.
    • De Baets, S.
    • Galindo-Morales, P.
    • Poesen, J.
    • Knapen, A.
  • Source: Earth Surface Processes and Landforms
  • Volume: 32
  • Issue: 12
  • Year: 2007
  • Summary: Several studies illustrate the wind and water erosion-reducing potential of semi-permanent microbiotic soil crusts in arid and semi-arid desert environments. In contrast, little is hitherto known on these biological crusts on cropland soils in temperate environments where they are annually destroyed by tillage and quickly regenerate thereafter. This study attempts to fill the research gap through (a) a field survey assessing the occurrence of biological soil crusts on loess-derived soils in central Belgium in space and time and (b) laboratory flume (2 m long) experiments simulating concentrated runoff on undisturbed topsoil samples (0.4 x 0.1 m(2)) quantifying the microbiotic crust effect on soil erosion rates. Three stages of microbiotic crust development on cropland soils are distinguished: (1) development of a non-biological surface seal by raindrop impact, (2) colonization of the soil by algae and gradual development of a continuous algal mat and (3) establishment of a well-developed microbiotic crust with moss plants as the dominant life-form. As the silt loam soils in the study area seal quickly after tillage, microbiotic soil crusts are more or less present during a large part of the year under maize, sugar beet and wheat, representing the main cropland area. On average, the early-successional algae-dominated crusts of stage 2 reduce soil detachment rates by 37%, whereas the well-developed moss mat of stage 3 causes an average reduction of 79%. Relative soil detachment rates of soil surfaces with microbiotic crusts compared with bare sealed soil surfaces are shown to decrease exponentially with increasing microbiotic cover (b = 0 center dot 024 for moss-dominated and b = 0 center dot 006 for algae-dominated crusts). In addition to ground surface cover by vegetation and crop residues, microbiotic crust occurrence can therefore not be neglected when modelling small-scale spatial and temporal variations in soil loss by concentrated flow erosion on cropland soils in temperate environments. Copyright (C) 2007 John Wiley & Sons, Ltd.
  • 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:
    • Varma, M.
    • Rawat, S.
  • Source: International Journal of Agricultural Sciences
  • Volume: 2
  • Issue: 1
  • Year: 2006
  • Summary: A performance evaluation of zero-till-ferti-seed drill with conventional and reduced tillage method by sowing of wheat ( Triticum aestivum) was conducted, and was compared with the conventional system in terms of economics and energy consumption. The Pantnagar zero-till ferti-seed drill was developed by the G. B. Pant University of Agriculture and Technology, Pantnagar, Uttaranchal, India, and was made of mild steel angle iron 68.0*68.0*8 mm with square cross-section. Spacing between two furrow openers was 22.5 cm having 9 furrows. The treatments were: (T1) disc harrowing *2 + cultivation with planking *1 + planking *1 + seeding by seed-cum-ferti-drill; (T2) disc harrowing *1 + cultivating with planking *1 + planking *1 + seeding by seed-cum-ferti-drill; and (T3) zero-till-ferti-seed-drill. The initial moisture content and bulk density were maximum in T3. The field capacity of zero-till-ferti-seed-drill was found slightly higher than other treatments, but field efficiency was less due to presence of crop residue and no seedbed preparation. Fuel consumption in tillage and seeding system was very less i.e. 5.88 l/ha in T3 system in comparison to other treatments which indicates much saving of fuel in zero-till-ferti-seed-drill system. Wheat crop can be grown 10-15 days early that will result in timing sowing of wheat wheat crop and increases in yield. Another advantages of zero tillage is that it reduces cost of irrigation which was more economical in comparison to conventional method of sowing.