P. R. Warman

The effectiveness and consistency of source-separated municipal solid waste and bark composts as components of container growing media

Abstract Rooted cuttings of Cotoneaster dammeri cv. ‘Coral Beauty’ were grown in containers in combinations of source-separated municipal solid waste (MSW) compost and peat (100:0, 75:25, 50:50, 25:75 by volume), or spruce bark compost and peat (similar proportions) in each of the two consecutive years. MSW compost was obtained from the same commercial composting facility, but it was not consistent in chemical composition, bulk density, soluble salt content or pH from year to year. Plant growth, substrate physical properties and end-of-season foliar nutrient levels were measured for all media treatments. Soluble salt content was initially high in media containing MSW, but declined to −1 within 1 month of potting. Plant growth in MSW-based media was equal to, or greater than that in bark-based media, and was similar for both years. Poorest growth was obtained in 100% bark, and 100% MSW media, but growth was strong at ratios up to and including 75:25 MSW:peat. End-of-season foliar nutrient levels were higher in 1997 than in 1996 in MSW-grown plants, reflecting the generally higher nutrient concentrations in the 1997 compost. Heavy metal uptake was no greater in MSW than in bark media and there were no signs of nutrient deficiency or toxicity at any time during the study. The results indicate that despite inherent variability in the texture and composition of composted MSW, it could form a useful component of a standardized growing medium for woody nursery plants.

Enzymatic hydrolysis of soil organic phosphorus by immobilized phosphatases

Abstract In order to estimate the role of phosphatases in maintaining the potential bioavailable P pool in soils, water and 0.4 M NaOH soil extracts were incubated with immobilized acid phosphatase, alkaline phosphatase, phospholipase and nuclease, separately, and in combinations. Immobilized nuclease at an optimum pH of 7.0 hydrolyzed the most soluble unreactive P (SUP) both in water and 0.4 M NaOH extracts. The combination of immobilized alkaline phosphatase and nuclease increased the hydrolysis of SUP at pH 7.0 by up to 61% in 0.4 M NaOH extracts relative to that due to immobilized nuclease alone. The combination of immobilized acid phosphatase and nuclease, however, did not increase the hydrolysis of SUP in either extract relative to that due to immobilized nuclease alone. Immobilized alkaline phosphatase and phospholipase increased the hydrolysis of SUP at pH 7.0 by up to 62% in 0.4 M NaOH extracts relative to that due to immobilized phospholipase alone. Similarly, immobilized acid phosphatase and phospholipase increased the hydrolysis of SUP at pH 7.0 by up to 49% in 0.4 M NaOH extracts relative to that due to immobilized phospholipase alone. The similarities in the optimum pH of indigenous phosphatases in soils and the immobilized phosphatases used in this study, immobilized on positively charged supports, suggests that indigenous phosphatases could be immobilized on positively charged surfaces in soils.

Evaluation of Seed Germination and Growth Tests for Assessing Compost Maturity

Experiments involved the comparison of three procedures used to determine compost maturity/phytotoxicity. The three tests evaluated were the CCME germination test (1996), a modified Zucconi et al. (1981) extract and a direct seed procedure. Three different plant species and seven types of ‘composts’ were used. The species were cress (Lepidium sativum), radish (Raphanus sativus), and Chinese cabbage (Brassica chinensis). Germination and growth experiments were performed on three types of mature composts: 1) racetrack manure-food waste; 2) two different samples of municipal solid waste; and 3) racetrack manure-sewage sludge), two types of immature composts (farmyard manure-food waste and farmyard manure-yard waste-food waste], and a control (soil or water). Four replicates for each species, ‘compost’ and test procedure were evaluated. The study concluded that the commonly used compost extract test and the compost-soil germination and growth tests were not sensitive enough to detect differences between matur...

Soil Physical Properties and Organic Matter Fractions Under Forages Receiving Composts, Manure or Fertilizer

A field study was conducted to assess the benefits, with respect to soil physical properties and soil organic matter fractions of utilizing composts from a diversity of sources in perennial forage production. A mixed forage (timothy-red clover (Trifolium pratense L.) and monocrop timothy (Phleum pratense L.) sward were fertilized annually with ammonium nitrate (AN) at up to 150kg and 300 N ha−1 yr−1, respectively, from 1998-2001. Organic amendments, applied at up to 600 kg N ha−1 yr−1 in the first two years only, included composts derived from crop residue (CSC), dairy manure (DMC) or sewage sludge (SSLC), plus liquid dairy manure (DM), and supplied C to soil at 4.6 and 9.2 (CSC), 10.9 (SSLC), 10.0 (DMC) 2.9 (DM) Mg C ha−1. Soil samples (0-5cm; 5-10cm;10-15cm) were recovered in 2000 and 2001. Improvements in soil physical properties (soil bulk density and water content) were obtained for compost treatments alone. Composts alone influenced soil C:N ratio and substantially increased soil organic carbon (SOC) concentration and mass (+ 5.2 to + 9.7 Mg C ha−1). Gains in SOC with AN of 2.7 Mg C ha−1 were detectable by the third crop production year (2001). The lower C inputs, and more labile C, supplied by manure (DM) was reflected in reduced SOC gains (+ 2.5 Mg C ha−1) compared to composts. The distribution of C in densiometric (light fraction, LF; >1.7 g cm−3) and particulate organic matter (POM; litter (>2000μm); coarse-sand (250-2000μm); fine-sand (53-250μm) fractions varied with compost and combining fractionation by size and density improved interpretation of compost dynamics in soil. Combined POM accounted for 82.6% of SOC gains with composts. Estimated compost turnover rates (k) ranged from 0.06 (CSC) to 0.09 yr−1 (DMC). Composts alone increased soil microbial biomass carbon (SMB-C) concentration (μg C g−1 soil). Soil available C (Cext) decreased significantly as compost maturity increased. For some composts (CSC), timothy yields matched those obtained with AN, and SOC gains were derived from both applied-C and increased crop residue-C returns to soil. A trend towards improved C returns across all treatments was apparent for the mixed crop. Matching composts of varying quality with the appropriate (legume/nonlegume) target crop will be critical to promoting soil C gains from compost use.

THE EFFECTS OF ORGANIC AMENDMENTS ON MINERAL ELEMENT UPTAKE AND FRUIT QUALITY OF RASPBERRIES

The organic produce industry is gaining popularity with consumers because of the perception for healthier foods and the environmental benefits of this agricultural practice. Common amendments in organic agriculture include compost and compost tea, the latter being a relatively new product in North America. The main objective of this study was to assess the effectiveness of ruminant and municipal solid waste compost and compost teas made from these composts on selected soil, leaf and fruit parameters of raspberries. Generally, foliar compost tea application was as effective as compost addition in raspberry production. Concentrations of K in leaf and fruits were significantly lower (p = 0.05) in compost tea treated raspberries. Furthermore, the compost tea increased leaf Na compared to compost amendments which suggested that raspberries preferentially take up Na via foliar applications compared to root Na applications. The yield, total antioxidant capacity of fruit, and vitamin C content of fruit were not affected by treatment but differed greatly among years. Precipitation also varied greatly among years as did soil nutrient concentrations and may have influenced yield, total antioxidant capacity, and vitamin C content.

Identification of soil organic phosphorus by 31P nuclear magnetic resonance spectroscopy

Abstract Soil samples from different land use systems were collected before cropping (in spring) and after harvest (in fall) for organic phosphorus (P) extractions by 0.4M sodium hydroxide (NaOH) and characterization by 31P nuclear magnetic resonance spectroscopy. To prevent hydrolysis of organic P compounds prior to sample concentration, NaOH was removed from the NaOH soil extracts using a G‐25 Sephadex column. The 31P NMR spectra in the NaOH soil extracts showed the presence of glucose‐6 phosphate (up to 64%), glycerophosphate (up to 45%), nucleoside monophosphates (up to 91%), and polynucleotides (up to 58%) as the major forms of organic P in soils. The relative concentration of nucleoside monophosphates and polynucleotides decreased in some of the soils after harvest. The 31P NMR spectra of the extracts also revealed the presence of phosphoenolpyruvates, a previously unreported form of soil organic P.

Soil and Plant Response to MSW Compost Applications on Lowbush Blueberry Fields in 2000 and 2001

SUMMARY Field experiments were initiated in May 1999 to investigate the application of municipal solid waste (MSW) compost to low-bush blueberry (Vaccinium angustifolium Ait.) fields. Three sites were selected: Debert, NS (Truro sandy loam) and two sites near Musquodoboit, NS (both Rawdon gravely loamy sands). Treatments at each site consisted of a randomized complete block design with six treatments (Control [no fertilizer], NK fertilizer, NPK fertilizer, and three rates of MSW compost) blocked four times. Compost treatments provided the equivalent of 100, 200, and 400 kg ha−1 of total N, respectively. The experimental objectives were to evaluate soil and plant response to the compost and to determine whether the organic amendment could be used as an alternative to chemical fertilizers. Yield, soil fertility, and plant nutrients were evaluated in blueberry leaf tissue and fruit over two years. The MSW compost had a strong (K) and a mild effect (P, Ca, Mg, S, Cu, Zn) on extractable soil nutrients, while a strong effect (Mn) and a mild effect (N, K) was observed on leaf tissue nutrients. The fruit yield was not affected by the treatments. Therefore, the compost treatments provided equivalent amounts of plant essential nutrients without negatively influencing trace element absorption.

The effects of pruning, fertilizers, and organic amendments on lowbush blueberry production

A four-year field study was conducted on a Hebert gravelly sandy loam (pH 4.5) in Nova Scotia to assess the effects of pruning management and seven fertility amendments on lowbush blueberry (Vaccinium augustifolium Ait) production (yield, above ground and root tissue composition) and soil fertility. Pruning by oil burning produced higher fruit yields than flail mowing but burning had the opposite effect on the plant N content (with a lesser influence on above ground Mn and Zn). None of the fertility treatments (chicken manure, dairy manure, swine manure, urea, sawdust, NPK, NPK+S+Lime+Micronutrients) produced fruit yields significantly greater than the control. Treatments provided the equivalent of 50kg total N/ha/2-yr cycle. Treatments influenced tissue N, P, K, Ca, Mg, B, Mn, Cu, Zn and Mo levels. In general, the three manure treatments produced the highest levels of plant macronutrients; the urea treatment produced the lowest levels of plant nutrients. In most cases, extractable levels of soil P, K, Ca and Mg were highly correlated with the plant tissue content of these elements. Overall, the dairy manure treated soils were the highest in soil fertility.

Evaluation of soil sulfate extractants and methods of analysis for plant available sulfur

Abstract A steady decline in sulfur additions to Atlantic Canadian soils has prompted the need for an accurate method of determining their plant available sulfur status. Three soils were extracted with five soil extractants ‐ 0.01M Ca(H2PO4)2‐H2O in 2M HOAc, 0.1M CaCl2, Bray‐1 and de‐ionized water. The soil extracts were analyzed for sulfur or sulfate using inductively coupled argon plasma emission spectrometry (ICAP), AutoAnalyzer (AAN), anion exchange‐high performance liquid chromatography (HPLC‐CD) or atomic absorption spectroscopy (AAS). Results were compared with plant response of sulfur treatments to red clover, ryegrass, canola and wheat in a growth room. Instrument reproducibility and crop response indicated the ideal method of determining plant available soil sulfur was HPLC‐CD using the extractant Ca(H2PO4)2‐H2O.

Enzymatic hydrolysis of ester sulphate in soil organic matter extracts

SummaryA method of assessing the enzymatic hydrolysis of ester sulphate in soil organic matter was developed. Soil organic matter extracted using a mild, chelating resin extraction procedure was incubated with a sulphatase from Helix pomatia in 0.05 M sodium acetate buffer (pH 4–8) at 37°C for 2h and the sulphate released was determined by a high performance liquid chromatography-conductivity detector system. The effect of some soil factors on the enzymatic hydrolysis of ester sulphate was examined. The study showed that part of the ester sulphate in soil organic matter was biochemically reactive. In the three Podzols studied, the ester sulphate hydrolysed accounted for 2%–12% of the hydriodic acid-reducible organic sulphate extracted. The largest amount of hydrolysable ester sulphate was found in the soil with a low pH, high inorganic sulphate and high hydriodic acid-reducible organic sulphate.