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The effect of fertiliser management practices on soil organic matter production in the semi-arid areas : a field and modelling approachGeorgis, Kidane. January 1997 (has links) (PDF)
Bibliography: leaves 155-169. Studies the effect of nitrogen fertilizer on dry matter production under differing watering regimes. Investigates the accuracy of different crop and soil organic matter models for predicting crop yield, nitrogen uptake and changes in soil organic carbon and nitrogen. Compares the models with data from long-term field experiments on wheat in Australia and sorghum in Ethiopia. Finds that a higher crop yield and better nitrogen and water utilisation can be achieved if addition of nitrogen fertilizer is balanced with soil water.
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The effect of fertiliser management practices on soil organic matter production in the semi-arid areas : a field and modelling approach / by Kidane Georgis.Georgis, Kidane January 1997 (has links)
Bibliography: leaves 155-169. / xiv, 169 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Studies the effect of nitrogen fertilizer on dry matter production under differing watering regimes. Investigates the accuracy of different crop and soil organic matter models for predicting crop yield, nitrogen uptake and changes in soil organic carbon and nitrogen. Compares the models with data from long-term field experiments on wheat in Australia and sorghum in Ethiopia. Finds that a higher crop yield and better nitrogen and water utilisation can be achieved if addition of nitrogen fertilizer is balanced with soil water. / Thesis (Ph.D.)--University of Adelaide, Dept. of Agronomy & Farming Systems, 1997?
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Poultry manure and inorganic fertiliser effects on soil fertility and microbial communities in wheat and corn agroecosystemsDupuis, Eartha M. January 2006 (has links)
Many producers in North America are finding it profitable to make the transition from conventional farming to organic agriculture. Organic fertilisers may affect crop production and soil quality differently than inorganic fertilisers. The objectives of this study conducted in Ste.-Anne-de-Bellevue. Quebec were to examine crop yield, grain quality, soil fertility and microbial community parameters in wheat and corn agroecosystems receiving poultry manure or inorganic fertiliser. Wheat grain yield declined and corn grain yield did not increase with higher N rates, suggesting that increased N supply did not encourage grain production. Soil analyses demonstrated high inherent soil fertility at the study site, and fertilisation led to an environmentally undesirable increase in residual soil NO3 concentrations. Microbial biomass and respiration in corn agroecosystems were greater with poultry manure amendments than inorganic fertiliser, but not in wheat agroecosystems due to significant variation among field replicates. Phospholipid fatty acid analysis revealed significant differences between wheat and corn soil microbial community composition, but differences due to fertilisation were less evident. Further work is needed to uncover the relationships among N fertilisation, crop nutrition and soil microbiology in organic agroecosystems.
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The effect of nitrogen fertilization and stage of re-growth on the nutrititive value of kikuyu in the Midlands of KwaZulu-Natal.Dugmore, Trevor John. January 2011 (has links)
Kikuyu pasture was fertilized at low and high levels of nitrogen (N), namely 50 and 200 kg N/ha, after
mowing and clearing the plots, to induce low and high levels of N in the herbage. The subsequent growth
was harvested at 20-, 30- and 40-d re-growth. These treatments were conducted in spring, summer and
autumn. Treatments included level of N, stage of re-growth and season as variables in digestion trials using
sheep and voluntary feed intake (VFI) trials using long yearling heifers in pens equipped with Calan gates.
Nitrogen fertilization level had no impact on herbage dry matter digestibility (DMD). Stage of re-growth
influenced digestibility in the spring and summer, the highest values recorded in the 30-d treatment.
However, in the autumn, the 20-d re-growth recorded the greatest digestibility. Digestibility declined as the
season progressed. Digestibility was not correlated to any of the chemical fractions measured in the
herbage, including in vitro DM digestibility (IVDMD). Voluntary feed intake (VFI) followed a similar
trend to digestibility, with peak values recorded for the 30-d treatment in the spring and summer, while the
20-d material induced the greatest intake in the autumn. Nitrogen fertilization had a negative impact on
VFI over all seasons. Similarly to digestibility, VFI was not correlated to any of the chemical fractions
measured, but was correlated to digestibility and moisture concentration of the herbage.
Nitrogen degradability was determined using the in situ bag technique. Differences (p<0.05) were
recorded for the quickly degradable N (a) and potentially degradable N (b) fractions within season, but not
for the degradation rate of the slowly degraded fraction (c) per hour. The effective degradability (dg) was
not influenced by N fertilization level in the spring, while N fertilization increased the dg values in the
summer and autumn. Stage of re-growth exerted a positive effect (P<0.05) on the dg values.
Rumen pH, rumen ammonia and blood urea nitrogen (BUN) levels were measured in rumen fistulated
sheep. Rumen pH increased also with increasing level of N fertilization and declined with advancing stage
of herbage re-growth in the autumn. Rumen ammonia increased with time of sampling post feeding to 4 hrs
and then tended to decline by 6 hrs. Nitrogen fertilization level influenced rumen ammonia levels (p<0.05),
with the low N level producing the lowest rumen ammonia levels. Rumen ammonia levels were highest at
20-d re-growth stage in summer and at the 40-d re-growth stage in autumn. DM concentration of the
herbage had an inverse relationship with rumen ammonia. BUN levels were increased by high N
fertilization and were positively correlated to rumen ammonia levels.
Five years of digestibility data (82 digestion trials) and three years of intake trials (38 trials) data was
pooled. These data, chemical composition of the herbage and the daily maximum temperatures, rainfall and
evaporation recorded at and prior to the digestion and intake trials at Cedara were analysed using multiple
regression techniques. Rainfall and temperature in the period of cutting and fertilization had a negative
effect on digestibility, irrespective of the stage of re-growth at harvesting, 20, 30 or 40 days later, and a
combination of the two proved significant, accounting for the most variance in DDM. Temperature
depressed DMD by 11.4 g/kg DM per degree rise in temperature (Degrees C). Temperatures recorded during the
cutting and fertilization phase were highly negatively correlated to VFI, irrespective of stage of re-growth.
The DM concentration of the herbage as fed accounting for 32% of the variance in DMD, the NPN content
of the herbage accounting for only 12.2% of the variance and the ash concentration of the herbage
accounting for 15.9% of the variance in digestibility. Non-protein nitrogen was negatively correlated to
VFI. Both DMD and VFI were highly negatively influenced by the moisture concentration of the herbage.
Overall, the results of these trials demonstrated that environmental factors such as rainfall and temperature
had a far greater impact on the digestibility of kikuyu herbage than the chemical composition, which had a
minimal effect. Nitrogen fertilization did not influence herbage digestibility overall, but exerted a highly
negative impact on voluntary intake. / Thesis (Ph.D.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.
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Management of nitrogen from underseeded clover and manures in spring wheatGarand, Marie-Josée. January 1999 (has links)
Manure and underseeded clover are sustainable N sources for spring wheat on gleysolic soils of the St. Lawrence lowlands. Farmers rely on little information to manage adequately, these alternatives to fertilizer N. This study documents in spring wheat red (Triticum aestivum L. cv Algot) (i) the agronomic value of (Trifolium pratense L. cv Arlington); (ii) the impacts of application time and underseeded clover an manure N recovery; (iii) the residual NO3-- in the soil profile that constitutes a potential risk of N transfer from soil to air and water associated to clover alone or combined with manures and, (iv) the use of a plant N availability index. A four year field experiment was established an a St. Urbain clay (Orthic Humic Gleysol) at St. Bruno de Montarville (45°33'N; 73°21'W) in 1993. Ammonium nitrate at 0 to 160 kg N ha--1, swine liquid manure (SLM) and dairy solid manure (DSM) were used either alone or in combination with clover ploughed down in fall as green manure. Manures were applied at pre-seeding, in post-emergence or after harvest. The impact of clover on wheat yield was related solely to an improved N nutrition. Clover supplied fertilizer N equivalents of approximately 30 kg ha --1 to the succeeding wheat crop. Clover combined with manures increased available N in the soil profile so that estimated recovery of manures N was strongly reduced in 1995. Apparent N recovery of SLM was higher than for DSM with values of 5% and 17% in 1994 and 1995 compared to 2 and 4% for DSM. Application time did not significantly affect manure N recovery. Limited risk of N transfer to water and air was associated with post-harvest manure application and underseeded red clover because those practices increased soil profile NO3-- in fall and the end of April. Fluxes of N estimated by NH4+ and NO3 -- sorbed in situ on ionic exchange membranes (IEMs) provided better monitoring of N released by added organic N sources than N extracted by 2M KCl and also were bette
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Soil nitrate and ammonia levels as affected by no-till and conventional tillage, monoculture corn and soybean, corn-soybean and corn- soybean-alfalfa rotations, and added NGaliano, Norma Graciela. January 1996 (has links)
Corn (Zea mays L.) production under monoculture and conventional tillage systems may land to soil degradation and nitrate (NO$ sb3 sp-$) pollution of surface and groundwater. This study evaluated the impact of no-till and conventional tillage, monoculture corn and soybean, corn-soybean rotations and corn-soybean-alfalfa rotations, and three fertilizer N rates applied to monoculture corn or soybean, and corn in rotation, on soil NO$ sb3$-N and NH$ sb4$-N levels. Experimental sites were a Ste-Rosalie clay (Humic Gleysol) and an Ormstown silty clay loam (Humic Gleysol). Results obtained from fall 1992 to spring 1995 showed that tillage had no effect on soil N levels under corn. Soil N levels under corn showed a linear response to added N, specially in the fall. Soil N levels under corn did not change considerably during the non-growing season. Higher spring NO$ sb3$-N levels, particularly in plots under conventional tillage and alfalfa or soybean, compared to fall values indicated greater nitrification and/or mineralization than denitrification, immobilization or leaching. Low NH$ sb4$-N levels indicated that nitrification processes were active. No consistent estimation could be made of fertilizer N credits for corn from either soybean or alfalfa based on NO$ sb3$-N levels in soil.
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The effect of fertiliser management practices on soil organic matter production in the semi-arid areas : a field and modelling approach / by Kidane Georgis.Georgis, Kidane January 1997 (has links)
Bibliography: leaves 155-169. / xiv, 169 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Studies the effect of nitrogen fertilizer on dry matter production under differing watering regimes. Investigates the accuracy of different crop and soil organic matter models for predicting crop yield, nitrogen uptake and changes in soil organic carbon and nitrogen. Compares the models with data from long-term field experiments on wheat in Australia and sorghum in Ethiopia. Finds that a higher crop yield and better nitrogen and water utilisation can be achieved if addition of nitrogen fertilizer is balanced with soil water. / Thesis (Ph.D.)--University of Adelaide, Dept. of Agronomy & Farming Systems, 1997?
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Shallot (Allium cepa var. ascolonicum) responses to plant nutrients and soil moisture in a sub-humid tropical climate /Woldetsadik, Kebede. January 2003 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2003. / Härtill 5 uppsatser.
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Nitrogen use in a maize-bean rotation in Nicaragua : effects of organic and mineral fertilisers /Salmerón-Miranda, Francisco, January 2008 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2008. / Härtill 4 uppsatser.
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Oxidative ammonolysis of technical lignins and lignitesTyhoda, Luvuyo January 2003 (has links)
Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Today there is renewed interest in using soil improvers with fertilising capability as
the use of inorganic fertilisers results in ground water pollution through leaching and
formation of nitrates in plant materials. Lignin is an important precursor of humic
material in soils and with modification, can be used as a raw material for producing
slow release nitrogenous fertilisers. This project focussed on the use of industrial
residues such as technical lignins which are produced by the South African pulping
industry as well as low grade coals such as lignite occurring in South Africa, for the
production of high-grade humic substances like Novihum TM, using the special
technology developed by the Institute of Plant and Wood Chemistry of the Technical
University of Dresden in Germany. Technicallignins derived from kraft lignin, sugar
cane baggase, autohydrolysis lignin with a trade name Sucrolin, a calcium
lignosulphonate and South African lignites mined in the Kraaifontein and BraekenfeIl
areas as well as German brown coal were subjected to oxidative ammonolysis with
the aim to produce slow release nitrogenous fertilizers.
Curie Point Pyrolysis GCIMS was used to determine the structural composition of the
raw materials and products. Oxidative ammonolysis reactions were carried out on a
laboratory and a pilot plant scale. Highest nitrogen contents were obtained with
Sucrolin lignin followed by the lignite from Germany. The amount of nitrogen that
could be fixed with oxidative ammonolysis varied between 1.44 - 10% for the various
raw materials. The CIN ratios obtained were in the range between 5 - 34. Marginal
differences were observed between the materials modified on lab and pilot plant
scales. There were improvements in the total incorporated nitrogen when the raw
materials were pre-activated with oxidising agents such as hydrogen perxide and a
fungal species, Phanaerochateae chrysosporium prior to oxidative ammonolysis.
Variable amounts of differently bonded nitrogen forms were obtained for the
materials tested due to their structural differences. / AFRIKAANSE OPSOMMING: Daar is deesdae hernude belangstelling in die gebruik van grondverbeteringsmiddels wat
ook 'n bemestingsfunksie het, aangesien die gebruik van anorganiese kunsmis
besoedeling van grondwater deur uitlogingen insypeling veroorsaak, wat weer tot die
vorming van nitrate in plantmateriaallei. Lignien is 'n belangrike voorloper van humiese
materiale in grondstowwe en kan dmv modifisering gebruik word as 'n grondstof vir die
produksie van stadigstikstof vrystellende nitro gene kunsmisstowwe. Die huidige projek
het gefokus op die gebruik van industriële residue en tegniese ligniene wat deur die Suid-
Afrikaanse pulpnywerheid geproduseer word, sowel as lae-graad steenkool soos ligniet
wat in Suid-Afrika aangetrefword, vir die produksie van hoë-graad humiese stowwe soos
Novihum TM. Hierdie produk is mbv spesiale tegnologie deur die Instituut van Plant- en
Houtchemie van die Tegniese Universiteit van Dresden in Duitsland ontwikkel.
In hierdie ondersoek is verskeie Suid-Afrikaanse tegniese ligniene soos Kraft lignien,
suikerriet bagasse, 'n outohidrolise lignien met die naam van Sucrolin en 'n
kalsiumlignosulfonaat sowel as SA ligniete, afkomstig van Brackenfell en Kraaifontein,
gebied en Duitse bruinkool, aan oksidatiewe ammonolise onderwerp om sodoende
verskillende, stadigvrstellende, stikstofryke kunsmisstowwe te vervaardig.
Curie Punt Pirolise GC/MS is gebruik om die chemiese struktuur van die grondstowwe
en produkte vas te stel. Oksidatiewe ammonolise reaksies is op 'n laboratorium en
loodsaanlegskaal. uitgevoer. Die hoogste stikstofinhoud is met Sucrolin lignien verkry,
gevolg deur die ligniet van Duitsland. Die hoeveelheid stikstof wat dmv oksidatiewe
ammonlise bereik kon word, het tussen 1.44 en 10% gewissel. Die CIN verhoudings wat
verkry was, het varieer tussen 5 en 34. Marginale verskille is tussen laboratorium - en
loodsaanlegsskaal gemodifiseerde grondstowwe waargeneem. Daar was verhogings in
stikstofinhoud wanneer die grondstowwe vooraf met oksiderende middels soos
waterstofperoksied of swamkultur soos Phanaerochatae chrysosporium, aktiveer is.
Stikstof is op verskillende maniere en in verskillende hoeveelhede gebind.
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