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https://hdl.handle.net/10182/337

The electronic full-text versions of theses and dissertations in this collection are not publically viewable. In most cases the full-text is viewable only by current Lincoln University staff and students. See the item record of each thesis or dissertation for a description of access rights.

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An investigation of the effects of added sulphur and nitrogen to S-responsive and S-non-responsive soils from Canterbury on the digestibility and chemical composition of perennial ryegrass plants (Lolium perenne L.) : A thesis submitted in partial fulfilment of the requirements for the Degree of Bachelor of Agricultural Science (Hons) in the University of Canterbury
(Lincoln College, University of Canterbury, 1976)
Several recent studies (Stewart & Porter, 1969; Baker et al, 1973) on crop plants and grass forages have shown that responses on large nitrogen (N) fertiliser applications were often limited by a deficiency of sulphur ( S). An inadequate supply of S not only affects yields, but also the quality of the herbage produced. In view of this close relationship between N and S nutrition in plants, the present study was undertaken to examine the interaction of N and S fertilisation on the yield and composition of perennial ryegrass in a pot experiment. The present study therefore attempts to determine: 1. effects of N and S fertilisation on the top and root yields of the grass ; 2. the influence of N and S on the quality of the grass herbage - as reflected by the percentage digestibility, chemical composition of N and S fractions and the amino acid composition of these plants , and 3. the S nutrition status of the grass from information concerning the quantity of N and S in the herbage.
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Sense of community, shyness and loneliness in Lincoln Village: A thesis submitted in partial fulfillment of the requirements for the Degree of Bachelor of Social Science with Honours at Lincoln University
(Lincoln University, 2002) Hall, Carly Joanne
This study used quantitative research methods to investigate the relationships between sense of community, loneliness and shyness. A review of the literature indicated that sense of community had a negative association with loneliness, and that shy people were more likely to experience loneliness than non-shy people. Whilst also attempting to replicate previous research results between loneliness and shyness, and loneliness and sense of community, it was hypothesized that a further relationship would emerge between shyness and sense of community. A questionnaire was developed which included demographic questions, the UCLA Loneliness Scale, (version 3), (Russell, 1996), the revised Cheek and Buss shyness scale (Cheek, Cheek & Rothstein, 1986) and an adapted version of the Sense Of Community Index (SCI). A multi-stage cluster sample of 120 Lincoln residents produced 33 participants. There were no reliable correlations between the three variables, indicating rejection of the proposed hypothesis. Possible reasons for the results are discussed and future recommendations are presented. Despite the results, it is maintained that theoretical reasons warrant further investigation into these areas.
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Management planning for a city's parks and recreation system : Planning the parks and recreation system to benefit the urban community: [dissertation, Diploma in Parks and Recreation, Lincoln College]
(Lincoln College, University of Canterbury, 1981) Brown, Anthony
The following dissertation outlines an approach to Management Planning for a city Parks and Recreation System. Christchurch City, the administrative area under the authority of the Christchurch City Council, covering an area of 10158 hectares with a population of 164,256 people is used as an example.
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The organic and bio-dynamic food product markets in Canterbury : A dissertation submitted in partial fulfilment of the requirements for the Degree of Horticultural Science (Honours)
(Lincoln University, 1991) Keir, J. M.
Consumer, grower and retailer perspectives on the Canterbury organic and bio-dynamic markets were studied. The study consisted of two parts: a quantitative survey of Canterbury consumers coordinated in 1990 by Charlie Lamb and analyzed and written up by the author, and a qualitative series of interviews of Canterbury growers and retailers of organic and bio-dynamic food products. Literature reviewed suggested that a group of potential organic and bio-dynamic food purchasers existed, whose characteristics could be identified, to focus the promotion of the organic and biodynamic movements. Barriers of availability and lack of correct information, to the sale of organic and bio-dynamic produce were identified in the literature. Intrinsic and extrinsic reasons for organic and bio-dynamic food purchases were recognized. Results showed a group of potential organic and bio-dynamic consumers which consists of 32 % of consumers in the total New Zealand domestic market. Availability barriers were identified as restricting the potential increase of the organic and bio-dynamic markets. Health benefits were the drive behind the majority of organic and bio-dynamic food product purchases. It is concluded that a high profile of organic growers and retailers is essential to assist market expansion in Canterbury. This must involve an extensive education program and should target consumers concerned with their health, their family life and the environment. Involvement of controlling authorities in education and promotion would aid in this implementation.
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Supervision of casual labour during fruit harvesting: A dissertation submitted in partial fulfilment of the requirements for the diploma of horticultural management
(Lincoln College, University of Canterbury, 1985) Newton, P. J.
Contained in this report are details of a study made of NZ fruit grower's supervisory methods for casual labour during the fruit harvest "season". Research was by means of case study, using a standardised questionaire, of a total of twelve fruit growing properties, in three regions - Auckland, Nelson and Canterbury. The properties chosen for the study employed sufficient casual labour for supervision of this labour to be an identifiable need, and between them showed a range of fruit crops and labour force characteristics. The questionnaire aimed at defining the supervisory practices and problems of these growers. Results from the case studies, together with a discussion based on review of relevant literature, are presented. The report concludes with recommendations for supervisory methods to be considered in the selection of supervisors for casual harvest labour, and for general staff policy.
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Improving labour productivity in apple harvesting
(Lincoln College, University of Canterbury, 1978) Longley, Brett
Very little study has been done on ways ofimproving labour productivity in horticulture in New Zealand. Productivity can be increased by increasingoutput and/or lowering inputs. In apple harvesting output can be raised by increasing the picking rate. Inputs can be lowered by lowering costs to the grower. Various factors affect picking rate. A number of these were selected for study and measured. Cropcondition was defined by the measurements of thesefactors. A work measurement technique was used to relate differences in picker performance to differences in crop condition, and to predict appropriate picking times. Different rates of pick under different crop conditions were related to different piece rates of pay via an "intended level of earnings" based on the award hourly rate plus allowances for holiday pay and a performance-related bonus. This variable piece rate system of payment enabled picker output to be increased by its incentive characteristic, and growers harvesting labour costs to be minimized by relating the per unit cost of picking the fruit to the crop condition. One main advantage of the variable piece rate system is that different rates are set according to objective measurements rather than subjective estimates. Another advantage is that the system outlined enables productivity-per man to be raised at much lower cost than by mechanizing harvesting operations.
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The effects of contracts on orcharding : A dissertation submitted in partial fulfilment of the requirements for the Diploma in Horticultural Management
(Lincoln University, 1991) Homan, Grant
Contained in this report are details of a study made of New Zealand fruit growers with regard to their systems of payment. Research was by means of case studies, using a standardised questionnaire, of a total of five fruit growing properties in two regions - Canterbury and Central Otago. The properties chosen for the study employed both contract labour and hourly rate labour, with comparisons between the two being made. The questionnaire aimed at defining the problems of both systems for the growers. Results from the case studies, together with a discussion on their interpretation, are presented. The report concludes with recommendations for growers wishing to consider using contract labour on their orchards.
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Horticultural training for the intellectually handicapped : A dissertation submitted in partial fulfilment of the Diploma in Horticultural Management in Lincoln College, Canterbury
(Lincoln College, University of Canterbury, 1986) Bodsworth, David Rawhiri S.
This report describes the current horticultural training techniques employed on training units for the intellectually handicapped in New Zealand and discusses the therapeutic value of horticulture. It is based on case studies of two Rural Training Units of the New Zealand Society for the Intellectually Handicapped. Information was collected by means of semi-structured personal interviews with managers and supervisors of the units and the intellectually handicapped trainees themselves. Similar problems were found on both units. Some conflict appeared to exist between the production and training goals of management. There was also a regular turnover of the unit supervisors as a result of 'burnout'. Following the discussion of these and other findings the report concludes with recommendations for defining unit objectives, the use of horticulture on the units, staff selection and training, and other associated problems.
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Leaching losses of nitrate from undisturbed soil lysimeters under continuous and intermittent rainfall : A dissertation submitted in partial fulfilment of the requirement for the degree of Bachelor of Agricultural Science (Honours) at Lincoln College
(Lincoln College, University of Canterbury, 1988) Deane, T. H.
The amounts of NO₃⁻₋N leached from small undisturbed soil lysimeters (180mm diameter x 200-210mm deep) were compared under continuous and intermittent simulated rainfall conditions. Examination of breakthrough curves from both treatments indicated extensive preferential flow of solute had occurred through macropores such as earthworm burrows, plant root channels, natural structural cracks and large inter-aggregate spaces. Trends indicated that leaching of nitrate was initially less efficient under intermittent versus continuous rainfall. It was suggested that this was due to solute diffusion into intra-aggregate pores during the interval between intermittent rainfall events slowing down leaching losses. This mechanism also delayed the peak leachate NO₃⁻₋N concentrations by approximately 0 . 1 pore volume under intermittent versus continuous rainfall. Leaching losses under continuous and intermittent rain-fall of up to respectively were calculated to occur from NO₃⁻₋N fertiliser applied to the lysimeters offer 100 mm rainfall. It was suggested that fertiliser N losses would be less when several small rainfall or irrigation events immediately followed fertiliser application rather than one large rainfall/irrigation event.
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Effects on green manure crops on nitrogen loss and availability: A dissertation submitted in partial fulfilment of the requirements for the degree of Bachelor of Agricultural Science with Honours At Lincoln University
(Lincoln University, 2002) Fowler, C. J. E.
Nitrogen (N) is the nutrient required in the largest quantity by arable crops. However, it is also a difficult nutrient to manage due to its susceptibility to loss through leaching, particularly in winter. In certified organic cropping systems, the supply of N to crops is further restrained by restrictions on fertiliser inputs. These factors have lead to a renewed interest in the use of green manure crops for improving N-use efficiency in conventional and organic arable cropping systems. This study involved a comparison between three green manure crops (oats (Avena saliva), lupins (Lupinus auguslifolius), oats-lupins biculture) and a fallow for their ability to conserve N over winter and influence N availability to a subsequent crop. Intact soil monolith lysimeters (19cm diameter x 30cm deep) were taken from an established organic farm and the experiment included four replicates of each treatment. Nitrate leaching losses from the various treatments were measured over the green manure growth period (March - October). All the green manure crops reduced the amount of N that was leached over winter. Cumulative N leaching loss was similar for the three green manure treatments (4.1 - 4.9 kg N ha⁻¹), and these were significantly lower than N loss from the fallow treatment (8.4 kg N ha⁻¹ ). Nitrogen uptake in green manure herbage was 100, 162, and 126 kg N ha⁻¹ for the oats, lupins, and oats-lupins, respectively, with corresponding herbage C:N ratios of 18, 13, and 16. Annual ryegrass (Lolium mulliflorum) was sown three weeks after green manure incorporation to assess their impact on N availability. Dry matter yield and N uptake by ryegrass was significantly greater for the oats lupins (689 kg DM ha⁻¹ , 22 kg N ha⁻¹) than the fallow treatment (297 kg DM ha⁻¹ , 9 .4 kg N ha⁻¹ ). The findings of this study demonstrated that a green manure is an effective means of reducing N leaching loss over winter and improving N supply to a subsequent crop.
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Amounts, forms and availability of nitrogen and phosphorus in soil under conventional and organic cropping: A dissertation submitted in partial fulfilment of the requirement for the degree of Bachelor of Science with Honours at Lincoln University
(Lincoln University, 2002) Horrocks, A. J.
Organic farming is increasingly being promoted as a sustainable alternative to conventional farming. There is, however, a need for a greater understanding of how the organic system can function sustainably within a New Zealand agricultural setting. This study investigated the amounts, forms and availability of nitrogen (N) and phosphorus (P) in soil under conventional and organic cropping. Soil samples were taken to a depth of 70 cm from the conventionally managed Lincoln Mixed Cropping Farm (LCF) and the organically managed Biological Husbandry Unit (BHU) in Canterbury. These sites were chosen for comparison because they had the same soil type (Wakanui-fine sandy loam) and provided an opportunity to examine the effect of 25 years of contrasting management on nutrient amounts and availability. Analyses included organic carbon (C), total N and total P measurements. A 7-day anaerobic incubation was used to determine potentially mineralisable nitrogen (PMN), while isotopic exchange kinetics (IEK) was used to determine soil inorganic P availability. It was found that past management systems had not substantially affected organic C, total N and P levels of the topsoil (0-15 cm) but had significantly affected amounts of C and nutrients in the subsoil (15- 70 cm). Amounts of N, organic C and organic P were gre~ter at the BHU, which was attributed to the utilisation of deep rooting species. Inorganic P was greater in the LCF subsoil which may have been partially due to preferential leaching given the comparative lack of deep rooting species and the apparent high P fixing capacity (determined by IEK) of the subsoil. Greater pools of solution and readily available inorganic P in the BHU 0-7 .5 cm of soil indicated that the different cropping management systems had modified soil properties. The greater amounts detected at the BHU may reflect tillage regimes, intensity of production and the absence of animal grazing in the system. This study demonstrates the important role the subsoil plays regarding the nutrient fertility of cropping systems.
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A re-evaluation of soil variability and soil fertility in relation to experimental forest plots at Bridgehill Flat, Craigieburn Research Area, Canterbury, New Zealand : A thesis submitted in partial fulfilment of the requirements for the postgraduate diploma of Applied Science at Lincoln University Canterbury, New Zealand
(Lincoln University, 1994) Hassall, Leanne Jane
In 1979 Forest Research Institute (FRI) established a trial on high country forest and pastoral landuse at Flock Hill Station, in Canterbury. The soils of the trial site on a terrace, fan and hill slopes adjacent to Cave Stream, were surveyed in 1978, and in 1979 forests were planted on Craigieburn and Cass (Typic Allophanic Brown) and Castlehill (composite - Acidic Sandy Brown) soils. The area was stratified on the basis of the soil map and uneroded and eroded sites within delineations were sampled separately for soil fertility assessment in 1982 and 1984. Following the 1982 survey, the area was oversown with legumes and topdressed (300 kg ha⁻¹ superphosphate; 0.2 kg ha⁻¹ sodium molybdate). The current study (1994) includes a reassessment of soil fertility, improved definition of soil mapping units, and the analysis of soils not sampled at the time of the original survey. A Landform units map, a geomorphic surfaces map and soil map for the Bridgehill Block are all recorded. In twelve years the soil fertility under the trees is different than under adjacent grassland. In many plots available phosphorus (Bray P) levels have shown a sharper decline under grassland compared with adjacent forest, while the pH has decreased more in the soils under forest compared to those under grass.
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The relationship between extractable soil cobalt and the cobalt content of ryegrass and red clover grown on 12 New Zealand soils : A dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Agricultural Science (Honours) in the University of Canterbury
(Lincoln College, University of Canterbury, 1983) Hogg, D. S.
In New Zealand soil tests for macroelements such as phosphorus, sulphur, magnesium and potassium are satisfactory but there is a distinct lack of such tests for the micronutrients. New Zealand soils are not naturally fertile and often contain only small amounts of micronutrients. This is aggravated by the fact that these micronutrients have only limited availability in the soil and may be strongly retained by certain soil constituents. Cobalt: a micronutrient is essential for ruminant nutrition and for the growth and development of legume species. More precisely, cobalt is necessary for the symbiotic nitrogen-fixing bacteria associated with some legume species. As New Zealand pastoral agriculture is based on a low cost and low nitrogen input system, adequate supplies of cobalt are essential. Furthermore, the production of prime meat on these pastures, many of which occur on known cobalt deficient areas, benefits from good soil cobalt levels. With the movement towards more intensive agriculture and horticulture in New Zealand there is good economic reason for the development of a cobalt soil test to diagnose deficiencies and to provide both development and maintenance requirements. This project looked at total acetic acid-, EDTA- and calcium nitrate-extractable soil cobalt. Attempts were made to correlate these results with the cobalt content and uptake of perennial ryegrass and red clover grown on a wide range of New Zealand soils. Other soil constituents which affect the availability of cobalt were also considered. Species differences and the effect of the method of application on the cobalt content and uptake of the plant were studied.
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Strategies for farming out of a loss situation on a typical northland hill country farm: A dissertation presented in partial fulfilment of the requirements for the Diploma in Farm Management in Lincoln College
(Lincoln College, University of Canterbury, 1988) Mein, P. J.
Many farmers in the sheep and beef agricultural sector are facing major financial problems at present. Rural Bank general manager Mr Ray Chappel stated at a seminar (26/5/88) that 2500 farmers were either insolvent or had such a high debt that they would eventually be forced off their farms. Perhaps an even more serious threat to the industry are the 15000 Rural Bank customers whose debt exceeds 50 percent of their assets, which is considered unsatisfactorily high in farming circles. The aim of this dissertation therefore is to explore: Other ways of farming a designated model farm. The options investigated are: 1 Sharefarming 2 Working off farm 3 Two different lease options 4 Two different bull beef policies 5 A new cow policy 6 All wool farming
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An assesssment of Travis Wetland water quality
(Lincoln University, 1999) Holland, J. M.
This report documents the results of a water quality survey of Travis Wetland, undertaken by two Lincoln University third-year students. Field sampling was undertaken in five different areas of the swamp to ensure representability, while data was collected over four occasions between April 14 and September 23, 1999 to examine variations in water quality over time. The four areas examined included the upper unmodified reaches, the willowshaded stretch and lower open reaches of Travis Stream, the central ponding area, and Angela Stream. Because of its unmodified nature, the upper Travis was used as a control from which the water quality of modified areas was compared. Standard water quality parameters were examined in order to provide a set of baseline information to the Christchurch City Council. Field observations including bird counts, a riparian assessment and an evaluation of the bank and channel conditions, whilst rainfall data was collected for analysis from the Burwood Hospital gauge. From this data, two simple hypotheses were tested- (i) that water quality would improve over time primarily as a result of the cessation of works; and (ii) that areas that had experienced the longest period since renovations would have the highest water quality. The first hypothesis was not conclusively supported by the results of the study. Although some parameters (including nitrate, turbidity and conductivity) are showing improvements, others (most notably reactive phosphates) depict either worsening or at best stable water quality over time. The second hypothesis was more favourably supported by the results. Highest overall water quality is found in the weir, which has had the longest period to recover. However, the lake, which had only just been completed prior to the beginning of fieldwork, showed surprisingly low nutrient levels, while the control exhibited the worst clarity despite remaining in its unmodified state throughout renovations. The major factors that may have upset the aforementioned hypotheses were identified as substrate type, riparian conditions (especially whether open or sheltered) and rainfall. The interrelatedness of these factors complicates the future management of water quality in the swamp. Therefore, further studies identifying and isolating the effects of such factors are required.
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Alternative workplace solutions for university academic staff : A dissertation submitted in partial fulfilment of the requirements of the degree of Master of Property Studies at Lincoln University
(Lincoln University, 2001) Randrup, C. R. C.
Work roles and patterns are changing dramatically. Australian and New Zealand university academic staff have had their workload and the hours worked in an average working week increased. The nature of their work has radically changed to incorporate greater time on administration and less on research and teaching. Where and how academic staff work is now under review. The office workplace has evolved as tertiary organisations are looking at ways to improve their competitiveness, productivity and to accommodate within building resources the new direction of education delivery. In the 1960's office landscapes experienced new directions with the introduction of the burolandschaft or open office plan design. The office continues to undergo change, with current and emerging trends in technology enabling the development of the non-traditional approach to office space such as the concept of Alternative Workplace Strategies. These strategies provide for a variety of transient work patterns, undertaken at a variety of locations and venues. This research examines recent workplace strategies in tertiary organisations by investigating as a case study, Auckland University of Technology. It also endeavours to understand the changing working environment of academic staff and to ascertain the best-suited workplace approach or approaches. A questionnaire was prepared, circulated to two thirds of AUT academic staff and analysed. The research concludes that AUT academic staff should now be working in a variety of work settings, preferably a blend of the cell and club office arrangement. This approach provides the flexibility in workplace management withou~ causing major changes to the culture and organisational management processes of AUT.
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A review of forests and production forest management in New Zealand: A report submitted in partial fulfilment of the requirements for the degree of Master of Applied Science in the University of Canterbury
(Lincoln College, 1981) Novis, J. B.
This review was prepared while gathering data for a Master of Applied Science thesis concerning the Energy Requirements of ExoticProduction Forestry. In addition to providing background information for this thesis, a further objective of the report was to serve as an introduction for students of the Joint Centre for Enviromnental Sciences, Lincoln College, to forestry and production forest management in New Zealand. A brief outline of the impact of man on the natural forest environment, his gradual development of a forest policy and evolvement of an exotic forest estate, is followed by a review of production forest management practices, The report concludes with a discussion on the management for timber production of New Zealand is merchantable indigenous forests. The review is based on a literature survey which encorporated FRI symposiums, FRI branch reports, articles from the N.Z. Journal of Forestry, LIRA reports and numerous. relevant publications available in the libraries of the University of Canterbury, In addition, a considerable quantity of information was forwarded by well informed individuals actively engaged in forest management.
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Irrigation on the edge: Irrigation effectiveness on the edge of the season, in a context of water resources under increasing pressure and on the edge of low restriction use: Master thesis Irrigation and Water Engineering submitted in partial fulfilment of the degree of Master of Science in International Land and Water Management at Wageningen University, the Netherlands
(Lincoln University, 2006) Leers, Kelly
Why was the study undertaken? Water is used by many different users with varying purposes. Agriculture takes up a major share of consumptive water use, mainly in the form of irrigation. Of all water allocated in New Zealand, irrigation encompasses about 77% (Redward, 2002) and Canterbury takes up a 70% share of all irrigated land in New Zealand (Ministry of Agriculture and Forestry, 2004). About 500000 hectares are irrigated in Canterbury, and irrigated farming brings about an enormous increase in revenues, by '1 billion dollars' compared to dryland farming (Redward, 2002). Over the period 2000 to 2010, it is predicted that the national irrigated area is likely to increase by 28%, with about 40% of this increase, equivalent to 60500 hectares, taking place in Canterbury. Although in general it is not foreseen that the demand for irrigation water will exceed the supply over this period, water shortages or water access difficulties are likely to become a serious local problem in certain areas and catchments (Nimmo-Bell & Company Ltd, 2001 ). Environment Canterbury (the regional authority responsible for the protection of Canterbury's natural resources) has recently intensified regulations regarding irrigation water use. This was done in order to guarantee a fair water distribution amongst different user-groups, especially with these future developments in the agricultural sector in mind. With irrigation playing such a dominant role in the national, and especially Canterbury's, water use, more effective irrigation applications could greatly contribute to improving the effectiveness of water use in the region, and open up the resource to other uses. Considering the great expansions in dairy farming and irrigation predicted for the near future, it becomes increasingly attractive to both farmers and regulators to better tune irrigation applications towards crop demand. In this context of increasing pressure on the water resource, regulations regarding water use becoming stricter and irrigation being the main actor in these developments, the idea for this research was developed. Professionals in the Canterbury water sector, connected to both Lincoln University and the private sector, observed that pasture irrigation in Canterbury continues relatively late into the irrigation season, and doubts arose on the necessity or intensity of these irrigation applications on the 'edge' of the season. By investigating the effectiveness of irrigation applications in the autumn 'shoulder' of the season, the possibility is created to tune water applications better towards plant demand and to avoid over-irrigation. The positive outcomes of such a practice would be noticeable in different areas: the environment (reduced water use, water logging and possible drainage or runoff of contaminants); the availability of water to share amongst different users (agriculture, forestry, environment, recreation, drinking water, household water); and reduced expenditures on the farm level, as the daily running costs (mainly electricity) of a centre pivot irrigator in Canterbury are expected to be NZ$250 a day on average (T. Davoren, pers. comm., 2006)
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Selenium prill applications to pasture: Effect on herbage selenium concentrations: A thesis submitted in partial fulfillment of the requirements for the postgraduate diploma of Agricultural Science at Lincoln University Canterbury, New Zealand
(Lincoln University, 1990) McLenaghen, Roger David
Under the conditions of pot and field trials, selenium applied to the soil as prills rapidly raised the selenium content of both ryegrass and clover. The herbage selenium concentrations declined steadily back to control levels after the initial uptake peak. The results of both experiments would indicate that total recovery of applied selenium is dependant on how soon the pasture is first cut (grazed) after the application of the selenium prills. Results of the field trial indicate that an application rate of 10 g Se/ha is sufficient to raise the selenium content of the herbage above the critical value for prevention of deficiency in grazing livestock, but without approaching dangerously high values which might cause toxicity. Timing of selenium fertilizer application favours spring topdressing with up to seven times greater uptake than from autumn topdressings.
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Ammonification and nitrification in acid forest soils : A dissertation submitted in partial fulfilment of the requirements for the degree of Bachelor of Horticultural Science (Honours) in the University of Canterbury
(Lincoln College, University of Canterbury, 1987) Olykan, Sonya Theresa
A substrate amendment technique was used to identify the mechanism of N0₃⁻-N production in two Pinus radiata samples. Site 1 had an initial pH of 4.68 and a predominant N-form of NH4⁺. The initial pH of site 2 was 5.95 and N0₃⁻ was the predominant form of N. Nitrogen was added at 150μg/g of oven dry humus (in peptone and ammonium sulphate) and C was added at 550μg/g as starch. The samples amended with peplone (organic N) increased N03- production compared to the control after a 42 day incubation. The addition of ammonium sulphate inhibited the production of N0₃⁻-N for site 1 but significantly increased it in the site 2 sample. The starch amendment (a source of readily-mineralisable C) produced N0₃⁻-N levels equivalent to those of the control for site 1 but significantly suppressed N0₃⁻-N production in the site 2 sample. These results suggested that site 1 produced N0₃⁻ heterotrophically whereas in site 2 N0₃⁻ production occurred via the autotrophic pathway. A further incubation used acetylene to block the autotrophic oxidation (by Nitrosomonas) of NH4⁺ to N0₂⁻ and chlorate to block the oxidation of N0₂⁻ to N0₃⁻ by the autotroph Nitrobacter. These inhibitors were not expected to affect N0₃⁻ production by the heterotrophs. The results showed that both acetylene and chlorate interfered with the heterotrophic production of N0₃⁻ occurring in the site 1 sample. Acetylene effectively blocked the production of N0₃⁻ in the site 2 sample which also showed a significant increase in the levels of NH4⁺ -N compared to the control. Chlorate reduced N0₃⁻ production in the site 2 sample but did not inhibit it. The effect of rates of N at 150 and 300μg/g. added in ammonium sulphate and peptone. and rates of readily-mineralisable C at 550, 1100, 2200, 11000μg/g, added as starch, were used to investigate the mechanism of heterotrophic nitrification in the site 1 sample during a 35 day incubation. The addition of ammonium sulphate inhibited N0₃⁻-N production while peptone promoted it. The starch amendment at 550μg/g increased the production of N0₃⁻-N above the control level. Starch additions above 1100μ gig resulted in the immobilization of inorganic N. These results suggested that the limitation to heterotrophic nitrification in the site sample was a lack of readily -mineralisable C.

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