Francis J. Larney

The role of organic amendments in soil reclamation: A review

Larney, F. J. and Angers, D. A. 2012. The role of organic amendments in soil reclamation: A review. Can. J. Soil Sci. 92: 19-38. A basic tenet of sustainable soil management is that current human activities are not detrimental to future generations. Soils are degraded by natural events (erosion) or industrial activity. A prevalent feature of degraded or disturbed soils is lack of organic matter compared with adjacent undisturbed areas. Organic amendments, such as livestock manure, biosolids, pulp and paper mill by-products, wood residuals and crop residues, are produced in abundance in Canada and could be widely used in soil reclamation. Biosolids production is ~0.5 Tg yr-1(dry wt.); paper mill sludge generated in the province of Quebec was ~2 Tg (wet wt.) in 2002. This review paper examines mechanisms through which organic amendments affect soil properties (physical, chemical, biological) and describes the role of organic amendments in reclamation, with emphasis on amendment types and application rates for soil amelioration and biomass production. Single large applications of organic amendments can accelerate initial reclamation and lead to self-sustaining net primary productivity. Readily decomposable organic amendments may provide immediate, but transient, effects, whereas stable, less decomposable materials may provide longer-lasting effects. Using organic amendments for reclamation is mutually beneficial wherein waste products from agriculture, forestry and urban areas help other sectors meet their land reclamation goals.

Changes in total, mineralizable and light fraction soil organic matter with cropping and tillage intensities in semiarid southern Alberta, Canada

Abstract There has been a trend toward increased cropping intensity and decreased tillage intensity in the semiarid region of the Canadian prairies. The impact of these changes on sequestration of atmospheric CO 2 in soil organic carbon (C) is uncertain. Our objective was to quantify the changes in total, mineralizable and light fraction organic C and nitrogen (N) due to the adoption of continuous cropping and conservation tillage practices. We sampled three individual long-term experiments at Lethbridge, Alberta, in September 1992: a spring wheat ( Triticum aestivum L.)-fallow tillage study, a continuous spring wheat tillage study and a winter wheat rotation-tillage study. Treatments had been in place for 3–16 years. In the spring wheat-fallow study, different intensities (one-way disc > heavy-duty cultivator > blade cultivator) of conventional tillage (CT) were compared with minimum tillage (MT) and zero tillage (ZT). After 16 years, total organic C was 2.2 Mg ha −1 lower in more intensively worked CT treatments (one-way disc, heavy-duty cultivator) than in the least-intensive CT treatment (blade cultivator). The CT with the blade cultivator and ZT treatments had similar levels of organic C. The CT treatments with the one-way disc and heavy-duty cultivator had light fraction C and N and mineralizable N amounts that were about 13–18% lower than the CT with the blade cultivator, MT or ZT treatments. In the continuous spring wheat study, 8 years of ZT increased total organic C by 2 Mg ha −1 , and increased mineralizable and light fraction C and N by 15–27%, compared with CT with a heavy-duty cultivator prior to planting. In the winter wheat rotation-tillage study, total organic C was 2 Mg ha −1 higher in a continuous winter wheat (WW) rotation compared with that in a winter wheat-fallow rotation. The lack of an organic C response to ZT on the WW rotation may have been due to moldboard plowing of the ZT treatment in 1989 (6 years after establishment and 3 years before soil sampling), in an effort to control a severe infestation of downy brome ( Bromus tectorum L.). Our results suggest that although relative increases in soil organic matter were small, increases due to adoption of ZT were greater and occurred much faster in continuously cropped than in fallow-based rotations. Hence intensification of cropping practices, by elimination of fallow and moving toward continuous cropping, is the first step toward increased C sequestration. Reducing tillage intensity, by the adoption of ZT, enhances the cropping intensity effect.

Tillage intensity and crop rotation affect weed community dynamics in a winter wheat cropping system

Development of improved weed manage ment systems requires more knowledge on how various weed species respond to changing agronomic practices. A long-term study was conducted to determine weed population responses to various tillage intensities and crop rotations in a winter wheat (Triticum aestivum L.) dominated cropping system. Weed density and species composition differed with tillage, rotation, year, and date of sampling within years. Weed community dynamics were most affected by year-to-year differences in environmental conditions, followed by crop rotation, and then tillage intensity. Russian thistle (Salsola iberica Sennen & Pau) and kochia [Kochia scoparia (L.) Schrad.] densities increased in years of low rainfall and above average temperatures. Winter annual weeds such as downy brome (Bromus tectorum L.) and flixweed [Descurainia sophia (L.) Webb ex Prantl], as well as the perennial weed dandelion (Taraxacum officinale Weber in Wiggers), increased in years where higher than average rainfall was re...

The role of composting in recycling manure nutrients

Larney, F. J., Sullivan, D. M., Buckley, K. E. and Eghball, B. 2006. The role of composting in recycling manure nutrients. Can. J. Soil Sci. 86: 597‐611. Recently, composting has been gaining increased attention as an alternative means of handling manure generated by the livestock industry. Composting is not a new technology, it merely controls what is a natural decomposition process. A major advantage of composting is reduced mass, volume and water content compared with fresh manure which in turn reduces transportation requirements. Concomitant benefits include elimination of pathogens, parasites, weed seeds and odour emissions on land application. However, carbon (C) and nitrogen (N) losses and greenhouse gas (GHG) emissions are associated with composting. Nutrients are stabilized during composting which slows their release once soil-applied. Compost also enhances soil physical and biological properties and has a disease suppression effect. Where the supply of manure currently exceeds land availability for application, or in some future scenario, if producers need to comply with stricter manure application rate regulations, composting may be an option to encourage nutrient export from high-loading watersheds to soils that may benefit from nutrient and organic matter inputs. Composting may be seen as a means of maximizing the potential for recycling manure nutrients by soils and crops while protecting surface and groundwater resources from manure-related contamination.

A biosecure composting system for disposal of cattle carcasses and manure following infectious disease outbreak.

During outbreaks of infectious animal diseases, composting may be an effective method of disposing of mortalities and potentially contaminated manure. Duplicate biosecure structures containing 16 cattle (Bos taurus) mortalities (343 kg average weight) were constructed with carcasses placed on a 40-cm straw layer and overlaid with 160 cm of feedlot manure. At a depth of 80 cm (P80), compost heated rapidly, exceeding 55 degrees C after 8 d and maintained temperatures of 55 to 65 degrees C for > 35 d. Temperatures at 160 cm (P160) failed to exceed 55 degrees C, but remained above 40 degrees C for >4 mo. To investigate rates of microbial inactivation, Escherichia coli O157:H7, Campylobacter jejuni, and Newcastle disease virus (NDV) were inoculated in manure (E. coli O157:H7 and C. jejuni approximately 10(8) CFU g(-1); NDV, approximately 10(6) EID(50) g(-1)), embedded at P80 and P160 and retrieved at intervals during composting. Escherichia coli O157:H7 and NDV were undetectable after 7 d at both depths. The C. jejuni DNA was detected up to 84 d at P80 and >147 d at P160. To estimate degradation of recalcitrant substrates, bovine brain, hoof, and rib bones were also embedded at P80 and P160 and retrieved at intervals. Residues of soft tissues remained in carcasses after opening at 147 d and bovine tissue decomposition ranked as brain > hoof > bone. More than 90% dry matter (DM) of brain disappeared after 7 d and 80% DM of hoof decomposed after 56 d. High degradation of cattle carcasses, rapid suppression of E. coli O157:H7 and NDV and reduction in viable cell densities of >6 logs for C. jejuni demonstrates that the biosecure composting system can dispose of cattle carcasses and manure in an infectious disease outbreak.

Earthworm populations as affected by long-term tillage practices in southern Alberta, Canada

Abstract The number of earthworms under long-term (25 years) zero tillage and conventional tillage in a dryland wheat-fallow rotation were studied. Data were collected from the fallow phase of the rotation on the same field plots in both 1992 and 1994. Earthworm abundance was determined by handsorting. The results showed that there were significantly more earthworms found under zero tillage than under conventional tillage in both 1992 and 1994. The majority of earthworms were in the 5–15 cm depth in both years. All the earthworms were identified as the endogeic species Aporrectodea caliginosa (Savigny) according to Sims and Gerard (1985). We conclude that there is a significant effect of long-term dryland tillage practices on earthworms in southern Alberta, Canada.

Prolonged survival of Campylobacter species in bovine manure compost.

ABSTRACT The persistence of naturally occurring campylobacteria in aerobic compost constructed of manure from beef cattle that were administered chlortetracycline and sulfamethazine (AS700) or from cattle not administered antibiotics (control) was examined. Although there were no differences in population sizes of heterotrophic bacteria, the temperature of AS700 compost was more variable and did not become as high as that of control compost. There were significant differences in water content, total carbon (C), total nitrogen (N), and electrical conductivity but not in the C/N ratio or pH between the two compost treatments. Campylobacteria were readily isolated from pen manure, for up to day 15 from control compost, and throughout the active phase of AS700 compost. Campylobacter DNA (including Campylobacter coli, Campylobacter fetus, Campylobacter hyointestinalis, and Campylobacter jejuni) was detected over the ca. 10-month composting period, and no reductions in quantities of C. jejuni DNA were observed over the duration of the active phase. The utilization of centrifugation in combination with ethidium monoazide (EMA) significantly reduced (>90%) the amplification of C. jejuni DNA that did not originate from cells with intact cell membranes. No differences were observed in the frequency of Campylobacter DNA detection between EMA- and non-EMA-treated samples, suggesting that Campylobacter DNA amplified from compost was extracted from cells with intact cell membranes (i.e., from viable cells). The findings of this study indicate that campylobacteria excreted in cattle feces persist for long periods in compost and call into question the common belief that these bacteria do not persist in manure.

Influence of Loss‐on‐Ignition Temperature and Heating Time on Ash Content of Compost and Manure

Abstract Loss‐on‐ignition (LOI) is a simple method for determining ash content, and by reciprocation, organic matter content of compost and manure. However, reported ignition temperatures and heating times for LOI measurements vary widely, and this brings into question the accuracy of one specific combination of ignition temperature and heating time over another. This study examined the effect of 42 temperature‐heating time combinations (six ignition temperatures from 400 to 650°C in 50°C increments by seven heating times of 1, 2, 8, 12, 16, 20, and 24‐h) on the ash content of a finished compost and a fresh manure. The experiment included the 550°C for 2‐h method recommended in Test Methods for Evaluation of Compost and Composting. The magnitude of the decrease in ash content due to increase in temperature was not consistent across all heating times. For example, after a 1‐h heating time for compost, ash content was 75.7% at 400°C and 67.5% at 650°C, compared to 69.6% at 400°C and 66.8% at 650°C after 24‐h. Irrespective of heating time, an ignition temperature of 400°C overestimated ash content for both compost and manure compared to the TMECC method. The TMECC method with its moderate temperature and short heating time requirement could reduce energy costs without affecting ash content results.

Nitrogen dynamics in soil amended with composted cattle manure

The amount and pattern of plant-available nitrogen (N) release from composts are variable and not well-defined. We used a 425-d canola (Brassica napus L.) bioassay to follow the release of N from eight composted cattle manures applied to soil at 20 g kg-1. Two stockpiled manures, one inorganic fertilizer and an unamended control were also included for comparison. Eight consecutive 30-d growth cycles were conducted in a controlled environment chamber (20°C) and plant N uptake was measured. Total N uptake was greatest from the N fertilizer and least from the wood-chip bedded manure. Addition of compost increased N uptake by 27–99% compared with that in the control. Nitrogen uptake from compost was directly proportional to its inorganic N content (r2 = 0.98; P < 0.0001) showing that the initial inorganic N content of compost, analyzed prior to its application can be used to predict plant available N. In seven of the eight composts studied, less than 5% of organic N was mineralized over 425 d, suggesting that...

Soil quality and productivity responses to simulated erosion and restorative amendments

There is little quantitative information on the interrelatedness of soil erosion, soil quality and soil productivity. A simulated erosion approach was used to quantify erosion and amendment effects on soil quality and subsequent productivity at four southern Alberta sites. Zero, 5, 10, 15 and 20 cm of topsoil were removed (cuts) at each site and subplots were amended with N + P fertilizer, 5 cm topsoil, 70 Mg ha−1 cattle manure or left unamended. Wheat (Triticum aestivum L.) yields in the 2-yr study on the non-amended check plots showed significant correlations with organic C at three of the four sites, and extractable P and inorganic C at all four sites. While manure was the best amendment for enhancing soil productivity, the magnitude of its effect depended on the organic C content of the recipient soil. At an organic C content of 8 g kg−1 on the Lethbridge Dryland site, manure addition increased crop yield by 1.75 Mg ha−1, compared with only 0.27 Mg ha−1 at an organic C content of 15 g kg−1. Our result...