• Authors:
    • Lafond, G. P.
    • Zentner, R. P.
    • Biederbeck, V. O.
    • Campbell, C. A.
  • Source: Canadian Journal of Soil Science
  • Volume: 71
  • Issue: 3
  • Year: 1991
  • Summary: The effects of crop rotations and various cultural practices on soil organic matter quantity and quality in a Rego, Black Chernozem with a thin A horizon were determined in a long-term study at Indian Head, Saskatchewan. Variables examined included: fertilization, cropping frequency, green manuring, and inclusion of grass Jegume hay crop in predominantly spring wheat (Triticum aestiyum L.) production systems. Generally, fertilizer increased soil organic C and microbial biomass in continuous wheat cropping but not in fallow-wheat or fallow-wheat-wheat rotations. Soil organic C, C mineralization (respiration) and microbial biomass C and N increased (especially in the 7.5- to l5-cm depth) with increasing frequency of cropping and with the inclusion of legumes as green manure or hay crop in the rotation. The influence of treatments on soil microbial biomass C (BC) was less pronounced than on microbial biomass N. Carbon mineralization was a good index for delineating treatment effects. Analysis of the microbial biomass C/N ratio indicated that the microbial suite may have been modified by the treatments that increased soil organic matter significantly. The treatments had no effect on specific respiratory activity (CO2-C/BC). However, it appeared that the microbial activity, in terms of respiration, was greater for systems with smaller microbial biomass. Changes in amount and quality of the soil organic matter were associated with estimated amount and C and N content of plant residues returned to the soil.
  • Authors:
    • Duffy, M.
    • Chase, C.
  • Source: American Journal of Alternative Agriculture
  • Volume: 6
  • Issue: 04
  • Year: 1991
  • Summary: Labor requirements, production costs, yields, and economic returns were evaluated for conventional and reduced-chemical cropping systems in northeast Iowa from 1978 to 1989. Continuous corn (C-C) and corn-soybean (C-Sb) rotations represented the conventional system; a corn-oat-meadow (C-O-M) rotation represented the reducedchemical system. The C-C and C-Sb rotations used both commercial pesticides and fertilizers. The C-O-M rotation used manure for fertilization and applied pesticides only in emergencies. Operations for all systems were implemented by one farm manager. The C-Sb rotation had the highest corn yield over the 12-year period, and the C-O-M rotation the lowest. The corn within the C-O-M rotation, however, produced the second highest average return to land, labor, and management. With costs of production substantially lower than the conventional systems, the C-O-M corn crop had competitive returns despite lower yield. The C-Sb average return to land, labor, and management was significantly higher than for the other systems. Hourly labor charges of $4, $10, $20, and $50 had little effect on the rankings of economic returns. Because of unusually high alfalfa reseeding costs and low average oat yields, returns to the C-O-M rotation were significantly lower than C-Sb but comparable to C-C. With better alfalfa establishment and higher average oat yields, the reduced-chemical system might have been competitive with the C-Sb conventional system.
  • Authors:
    • Ojima, D. S.
    • Cole, C. V.
    • Schimel, D. S.
    • Parton, W. J.
  • Source: Soil Science Society of America Journal
  • Volume: 51
  • Issue: 5
  • Year: 1987
  • Summary: We analyzed climatic and textural controls of soil organic C and N for soils of the U.S. Great Plains. We used a model of soil organic matter (SOM) quantity and composition to simulate steady-state organic matter levels for 24 grassland locations in the Great Plains. The model was able to simulate the effects of climatic gradients on SOM and productivity. Soil texture was also a major control over organic matter dynamics. The model adequately predicted aboveground plant production and soil C and N levels across soil textures (sandy, medium, and fine); however, the model tended to overestimate soil C and N levels for fine textured soil by 10 to 15%. The impact of grazing on the system was simulated and showed that steady-state soil C and N levels were sensitive to the grazing intensity, with soil C and N levels decreasing with increased grazing rates. Regional trends in SOM can be predicted using four site-specific variables, temperature, moisture, soil texture, and plant lignin content. Nitrogen inputs must also be known. Grazing intensity during soil development is also a significant control over steady-state levels of SOM, and since few data are available on presettlement grazing, some uncertainty is inherent in the model predictions.
  • Authors:
    • Sommerfeldt, T. G.
    • Freeze, B. S.
  • Source: Canadian Journal of Soil Science
  • Volume: 65
  • Issue: 4
  • Year: 1985
  • Summary: The economics of hauling manure as a substitute for commercial fertilizer in the production of cultivated crops was investigated using a computer model that accommodates variables such as hauling distance, machinery complement, hauling speed, labor use, spreading time, and crop response. Machinery complement and labor requirements were defined and budgeted for three farm-feedlot scenarios, namely: a very large farm-feedlot (> 1000 head capacity), a large farm-feedlot (500–1000 head capacity), and a small farm-feedlot (< 500 head capacity). Results indicate that manure, valued for its N and P2O5 nutrient content, is generally an economical substitute for commercial fertilizer when hauled up to 15 km from feedlot sources. Large farm-feedlots, hauling manure less frequently and employing a farm tractor with front-end loader and single axle truck with a manure box, can haul manure up to 15 km and recover all costs. Small farm-feedlots employing a farm tractor with front-end loader and pull-type manure spreader can economically haul manure up to 15 km if non-cash costs and labor charges are disregarded. Alternatively, custom corral cleaners can be hired to haul manure up to 18 km in competition with commercial fertilizer on an N and P2O5 nutrient value basis. The yield benefits of manure increased the breakeven hauling distances dramatically for some crops. A need for more research to determine economic optimum manure application rates for various crops is identified. Key words: Fertilizer, feedlot manure, fertilizer economics, animal wastes
  • Authors:
    • Doran, J. W.
    • Linn, D. M.
  • Source: Soil Science Society of America Journal
  • Volume: 48
  • Issue: 4
  • Year: 1984
  • Summary: Surface soils from long-term tillage comparison experiments at six U.S. locations were characterized for aerobic and anaerobic microbial populations and denitrification potential using an in situ acetylene blockage technique. Measurements of soil water content, bulk density, and relative differences in pH, NO-3-N, water-soluble C, and total C and N contents between tillage treatments were also determined at the time of sampling. Numbers of aerobic and anaerobic microorganisms in surface (0-75 mm) no-till soils averaged 1.35 to 1.41 and 1.27 to 1.31 times greater, respectively, than in surface-plowed soils. Bulk density, volumetric water content, water-filled pore space, and water-soluble C and organic C and N values were similarly greater for surface no-till soils compared to conventionally tilled soils. Deeper in the soil (75-300 mm), however, aerobic microbial populations were significantly greater in conventionally tilled soils. In contrast, below 150 mm, the numbers of anaerobic microorganisms differed little between tillage treatments. In no-till soils, however, these organisms were found to comprise a greater proportion of the total bacterial population than in conventionally tilled soils. Measurements of the denitrification potential from soils at three locations generally followed the observed differences in anaerobic microbial populations. Denitrifying activity, after irrigation with 15 mm of water, was substantially greater in surface 0- to 75-mm no-till soils than in conventionally tilled soils at all locations. At the 75- to 150-mm soil depth, however, the denitrification potential in conventionally tilled soils was the same or higher than that of no-till soils. In surface no-till soils, increased numbers of anaerobic microorganisms and a substantially greater denitrification potential, following irrigation, indicate the presence of less-aerobic conditions in comparison to conventionally tilled soils. This condition appears to result from greater soil bulk densities and/or water contents of no-till soils, which act to increase water-filled porosity and the potential for water to act as a barrier to the diffusion of oxygen through the soil profile.
  • Authors:
    • Blackmer, A. M.
    • Breitenbeck, G. A.
    • Bremner, J. M.
  • Source: Journal of Environmental Quality
  • Volume: 10
  • Issue: 1
  • Year: 1981
  • Summary: A simple method was developed for accurate injection of anhydrous ammonia in field studies to assess the effects of this fertilizer on emissions of nitrous oxide (N2O) from soils. Use of this method and of a chamber technique for measurement of N2O emissions showed that fertilization of three Iowa soils with anhydrous ammonia (250 kg N/ha) led to a very marked increase in emission of N2O. Emissions of N2O-N from the fertilized soils in 139 days ranged from 12.1 to 19.6 kg/ha and averaged 15.6 kg/ha. The corresponding emissions from the unfertilized soils ranged from 1.7 to 2.5 kg/ha and averaged 2.0 kg/ha. Most of the N2O evolved from the fertilized soils was produced within 42 days after fertilization, and N2O emissions from these soils 96 days after fertilization were not appreciably greater than those from the corresponding unfertilized soils. The fertilizer-induced emissions of N2O-N observed after application of anhydrous ammonia greatly exceeded those detected in similar field studies using other N fertilizers and represented 4.0-6.8% of the fertilizer N applied.
  • Authors:
    • Moore, R. A.
    • Krueger, C. R.
    • White, E. M.
  • Source: Agronomy Journal
  • Volume: 68
  • Issue: 4
  • Year: 1976
  • Summary: Cultivated Williams loam (Typic Argiboroll, fine-loamy, mixed) soils in north-central South Dakota were sampled after pastures were established and 8 years later so that the effect of the pastures on soils could be studied from analysis in the laboratory. Pastures were seeded to Russian wildrye (Elymus junceus Fisch.), crested wheatgrass (Agropyron desertorum (Fisch.) Schult.), or a mixture smooth bromegrass (Bromus inermis Leyss.), intermediate wheatgrass (Agropyron intermedium (Host) Beauv.), a pasture alfalfa (Medicago sativa L.). Soil N and bulk densities increased as available P decreased in the 8 years. The soil organic matter increased under all pastures, but it was small. The increases in organic matter, decreases in available P, and increases in saturated-clod bulk densities were different in the various pastures. Total N and organic matter increased about 0.001 and 0.02% per year, respectively, which is slower than the rate of decrease caused by cultivating the original grassland soils.
  • Authors:
    • Fetter, J. C.
    • Brown, R. N.
    • Gorres, J. H.
    • Lee, C.
    • Amador, J. A.
  • Source: Water, Air, & Soil Po9llution
  • Volume: 223
  • Issue: 4
  • Year: 0201
  • Summary: Consumer demand for cleaned squid generates a substantial amount of waste that must be properly disposed of, creating an economic burden on processors. A potential solution to this problem involves converting squid by-products into an organic fertilizer, for which there is growing demand. Because fertilizer application to lawns can increase the risk of nutrient contamination of groundwater, we quantified leaching of NO 3-N and PO 4-P from perennial ryegrass turf ( Lolium perenne L.) amended with two types of fertilizer: squid-based (SQ) and synthetic (SY). Field plots were established on an Enfield silt loam, and liquid (L) and granular (G) fertilizer formulations of squid and synthetic fertilizers were applied at 0, 48, 146, and 292 kg Nha -1 year -1. Levels of NO 3-N and PO 4-P in soil pore water from a depth of 60 cm were determined periodically during the growing season in 2008 and 2009. Pore water NO 3-N levels were not significantly different among fertilizer type or formulation within an application rate throughout the course of the study. The concentration of NO 3-N remained below the maximum contaminant level (MCL) of 10 mg L -1 until midSeptember 2009, when values above the MCL were observed for SQG at all application rates, and for SYL at the high application rate. Annual mass losses of NO 3-N were below the estimated inputs (10 kg Nha -1 year -1) from atmospheric deposition except for the SQG and SYL treatments applied at 292 kg Nha -1 year -1, which had losses of 13.2 and 14.9 kg Nha -1 year -1, respectively. Pore water PO 4-P levels ranged from 0 to 1.5 mg PL -1 and were not significantly different among fertilizer type or formulation within an application rate. Our results indicate that N and P losses from turf amended with squid-based fertilizer do not differ from those amended with synthetic fertilizers or unfertilized turf. Although organic in nature, squid-based fertilizer does not appear to be more-or less-environmentally benign than synthetic fertilizers.