• Authors:
    • Leary, M.
    • Roberti, D. A.
    • Medina, J.
    • Eaton, D.
    • Paparian, M.
    • Jones, S. R.
    • Moulton-Patterson, L.
  • Year: 2002
  • Summary: from exec summary: "This project sought to quantify the effect of compost feedstocks (green waste and poultry manure), compost maturity, and soil texture on vegetable crops. All of the field work was conducted in cooperation with commercial vegetable growers in Santa Cruz, Santa Clara, and San Benito Counties. Initially, the intent was to work equally with conventionally and organically farmed crops. However, in the end, the majority of the field trials occurred on conventional farms. Efforts to match similar crops to trials performed on different soil textures (conventional and organic) were largely unsuccessful due to the inevitable complications inherent in on-farm studies."
  • Authors:
    • Jellum, E. J.
    • Kuo, S.
  • Source: Agronomy Journal
  • Volume: 94
  • Issue: 3
  • Year: 2002
  • Summary: Removing cover crop top growth in the spring for forage or to prevent incorporation problems is one management option. The effects of this residue management on soil quality and productivity need to be determined. This study, conducted from 1994 to 1998 at Puyallup, WA, determined effects of various winter cover crops and residue management on soil N availability, soil C and N, and corn (Zea mays L.) yield. Included in the study were monocultures of rye (Secale cereale L.), ryegrass (Lolium multiflorum Lam), and vetch (Vicia villosa Roth subsp. villosa) and biculture of vetch and rye or ryegrass. Each year, the cover crops were seeded in the fall and incorporated into, or removed from, the soil in the spring. Average top-growth biomass was higher for the bicultures than for the monocultures. Total N accumulation was generally greatest under vetch, followed by the bicultures, and lowest for the monocultured rye or ryegrass. Whereas removing top growth of monocultured vetch or bicultures depressed presidedress soil NO3-N (Ni), the effect was generally not found for monocultured rye or ryegrass. Corn yields were affected by amounts of Ni and N fertilizer applied (r2 > 0.789), irrespective of cover crop species and residue management. Removing top growth of the cover crops limited residue C input and reduced soil organic C and N after 5 yr. Soil organic C and N accumulation, as well as increasing soil C sequestration to reduce CO2 release into atmosphere, should be considered when deciding which residue management option to choose.
  • Authors:
    • Follett, R. F.
    • Paustian, K.
    • Sperow, M.
    • Eve, M. D.
  • Source: Environmental Pollution
  • Volume: 116
  • Issue: 3
  • Year: 2002
  • Summary: Average annual net change in soil carbon stocks under past and current management is needed as part of national reporting of greenhouse gas emissions and to evaluate the potential for soils as sinks to mitigate increasing atmospheric CO2. We estimated net soil C stock changes for US agricultural soils during the period from 1982 to 1997 using the IPCC (Intergovernmental Panel on Climate Change) method for greenhouse gas inventories. Land use data from the NRI (National Resources Inventory; USDA-NRCS) were used as input along with ancillary data sets on climate, soils, and agricultural management. Our results show that, overall, changes in land use and agricultural management have resulted in a net gain of 21.2 MMT C year-1 in US agricultural soils during this period. Cropped lands account for 15.1 MMT C year-1, while grazing land soil C increased 6.1 MMT C year-1. The land use and management changes that have contributed the most to increasing soil C during this period are (1) adoption of conservation tillage practices on cropland, (2) enrollment of cropland in the Conservation Reserve Program, and (3) cropping intensification that has resulted in reduced use of bare fallow.
  • Authors:
    • Aroca, J. A.
    • Guerrero-Campo, J.
    • Bienes, R.
    • Nicolau, J. M.
    • Gomez, B.
    • Espigares, T.
  • Source: Man and soil at the Third Millennium. Proceedings International Congress of the European Society for Soil Conservation, Valencia, Spain, 28 March-1 April, 2000. Volume 2 2002
  • Year: 2002
  • Summary: The desertion of large agricultural lands in Mediterranean areas has important consequences on soil erosion. The aim of this study was to quantify runoff and water soil erosion evolution during the period 1994-97. Runoff and erosion were measured in erosion plots (20* 4 m). Four different treatments were applied, namely bare soil maintained with herbicide, no-tilled barley crop, spontaneous vegetation and leguminous sowing before desertion. These trials were carried out in four areas with different types of soils. The areas are located in the centre of Spain, under a Mediterranean-continental climate. In bare soils, annual runoff coefficient was higher than 10%, increasing through the time because of the soil compaction. These plots showed high soil erosion rates, between 1.3 and 28 t ha/year. Spontaneous vegetation plots produced the lowest erosion rates (from 0.0002 to 0.15 t ha/year). Annual runoff coefficient in no-tilled barley plots increased lightly through the four years, because the minimum ploughing favoured a light soil compaction. Soil erosion rate was low, ~0.3 t ha/year, showing the efficiency of this crop on erosion control. Runoff coefficient in abandoned plots (with spontaneous vegetation) and plots with leguminous sowing before desertion, decreased through the time. The lowest erosion rates were recorded when plant cover was higher than 50%, that is, from 6 months to 2.5 years after crops desertion. It is shown that in these environments soil erosion is not a continuous process, because the main water erosion measured during the four years period were produced only in two or three big storms.
  • Authors:
    • Petersen,SO
    • Frohne,PS
    • Kennedy,AC
  • Source: Soil Science Society of America Journal
  • Volume: 66
  • Issue: 3
  • Year: 2002
  • Summary: In arable systems, seasonal fluctuations of microbiological properties can be significant. We hypothesized that adaptation to soil environmental conditions may contribute to the variation observed, and this was examined by characterization of different microbial community attributes under a range of soil conditions. Soil was sampled from no-till and chisel-tilled fields within a long-term experiment in eastern Washington during growth of spring wheat (Triticum aestivum). The range of soil environmental conditions covered was extended by amendment of crop residues. Soil samples were characterized with respect to biomass N and biomass P, substrate utilization dynamics, phospholipid fatty acid (PLFA) profiles and whole-soil fatty acid (MIDI-FA) profiles, and with respect to soil environmental variables (bulk density, soil organic C [SOC], temperature, moisture, and inorganic N and P). Bacterial and fungal lipid biomarkers were negatively correlated (P < 0.001), confirming that these subsets of fatty acids are associated with contrasting components of the microbial biomass. Biomass N was closely associated with soil conditions, notably N availability. The proportion of substrates used with no apparent lag phase decreased during summer and was negatively correlated with lipid stress indicators. Cyclopropyl fatty acids accounted for more than 60% of the variation in bacteria] PLFA. These observations suggest that adaptation to environmental stresses was partly responsible for the microbial dynamics observed. Tillage practice had little effect on the relationships between soil conditions and microbiological properties. The results showed that MIDI-FA included a significant background of nonmicrobial material and was less sensitive to soil environmental conditions than PLFA.
  • Authors:
    • Mrabet, R.
  • Source: Conservation Agriculture, a Worldwide Challenge
  • Volume: 2
  • Year: 2001
  • Summary: This paper discusses the benefits of changing from actual agricultural systems to no-tillage for Moroccan dry farming. Recent findings showed that no-tillage cropping systems are the best ways to manage risk and improve efficiency and accordingly present two major agronomic advantages: (i) sustain or maintain crop productivity vis-a-vis variations in climate while reducing costs and natural resource degradation; and (ii) diverse crops and intensify the rotation to meet farmer's needs while maintaining a protective residue cover to curb erosion and evaporation and enhance water and nutrient use efficiency. Technological developments in machinery will increase adaptation to adverse soil and climate conditions. Improvements in no-till drill design, which focus on proper seed and fertilizer placement, are needed and national no-till drill industry should be favoured.
  • Authors:
    • Wuest, S. B.
  • Source: Applied Soil Ecology
  • Volume: 18
  • Issue: 2
  • Year: 2001
  • Summary: Dryland fanning in the Mediterranean climate of the Pacific Northwest, USA supports extremely low earthworm populations under conventional tillage. Increases in earthworm populations are being observed in fields under no-till cropping systems. A 30+ year experiment with four tillage levels in a pea (Pisum sativum L.)-winter wheat (Triticum aestivum L.) rotation was evaluated for earthworm populations and ponded infiltration rates. Where tillage has been limited to 2.5 cm depth, Apporectodea trapezoides (Duges) mean population was 25 m(-2). Plots subject to tillage by plow (25 cm depth) or chisel (35 cm depth) averaged less than 4 earthworms m-2. The shallow tillage treatment also had the highest average infiltration rate of 70 mm h(-1) compared to 36 for chisel, 27 for spring plow, and 19 mm h(-1) for fall plow treatments. The highly variable nature of earthworm counts and infiltration measurements prevented conclusive correlation between the two, but increases in both can be attributed to minimum tillage.
  • Authors:
    • Barrett, D. J.
    • Galbally, I. E.
    • Graetz, R. D.
  • Source: Global Change Biology
  • Volume: 7
  • Issue: 8
  • Year: 2001
  • Authors:
    • Lal, R.
    • Kimble, J. M.
    • Follett, R. F.
  • Year: 2001
  • Summary: Grazing lands represent the largest and most diverse land resource-taking up over half the earth's land surface. The large area grazing land occupies, its diversity of climates and soils, and the potential to improve its use and productivity all contribute to its importance for sequestering C and mitigating the greenhouse effect and other conditions brought about by climate change. The Potential of U.S. Grazing Lands to Sequester Carbon and Mitigate the Greenhouse Effect gives you an in-depth look at this possibility.
  • Authors:
    • Morse, R. D.
    • Miyao, E. M.
    • Temple, S. R.
    • Lanini, W. T.
    • Mitchell, J. P.
    • Herrero, E. V.
    • Campiglia, E.
  • Source: California Agriculture
  • Volume: 55
  • Issue: 1
  • Year: 2001
  • Summary: The efficacy of no-till systems in conserving soil moisture and improving water infiltration under furrow irrigation was evaluated during 1997 and 1998 in California, USA. Two grass/legume mixtures, i.e. triticale/lana woolypod vetch (* Triticosecale/ Vicia dasycarpa [ V. villosa]) and rye/lana woolypod vetch ( Secale cereale/ V. dasycarpa), were used as cover cop mulches in no-till treatments, and compared with a winter fallow treatment with pre-plant herbicide (fallow +h) and a fallow control treatment with no herbicide (fallow -h). Tomato cv. Halley 3155 plants were transplanted in April 1997 and 1998, sprinkle irrigated during the first 6 weeks after transplanting, and furrow irrigated thereafter until 3 weeks before harvest. During 1997, soil water content between 0 and 78 inches did not differ among treatments, while soil water content during the 1997/98 winter was higher under the fallow +h than the cover crop treatments until cover crop termination. Soil water content of cover crop treatments in shallower soil layers (18 and 42 inches) was significantly lower than fallow treatments at the end of the winter. During the 1998 tomato crop season, soil water content between 0 and 90 inches was greater under the triticale and rye mulches than the fallow +h, beginning the 3rd week after furrow irrigations were started. Soil moisture in the shallower layers was also affected by cover crop mulches. In the 42-inch depth increment, there was significantly higher water content under the cover crops than under the fallow +h from about 1 month after the first furrow irrigation until 2 weeks before the last irrigation. Changes in soil water content during furrow irrigation under the fallow +h treatment appeared to be more pronounced than under the triticale or rye surface mulches. Soil compaction in the fallow +h treatment was higher than under the cover crop mulches for most of the 0.6-inch intervals, especially below 1 foot, but differences were significantly higher only for the 3, 3.6, 4.2, 17, 18, and 24-inch depth, but lower from the surface to 2.4 inches. Soil carbon was significantly higher (by 14 and 18%) under triticale and rye, respectively, compared with the fallow +h treatment. The number of earthworms was also higher in no-till (2.1 earthworms per square foot) than in the fallow treatments (0.6 earthworms). Tomato canopy growth did not reach 100% cover in either 1997 or 1998, while tomato plant growth, assessed by measuring the photosynthetically active radiation intercepted by the canopy, did not differ in the triticale, rye, and fallow +h system in either 1997 or 1998. Results showed that the no-till mulch system enhanced water infiltration and soil water conservation.