Dissertations / Theses: 'Crop rotation'

1

Shakoor, Arif. "Crop rotation planning using simulated annealing." Master's thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-02232010-020018/.

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2

Potter, Mark. "Biochemical studies of tissue glucosinolates for improvement of canola (Brassica napus) as a disease break within the southern Australian cereal rotation /." Title page, contents and summary only, 1998. http://web4.library.adelaide.edu.au/theses/09PH/09php8678.pdf.

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Thesis (Ph.D) -- University of Adelaide, Depts. of Plant Science and Crop Protection, 1998.
Thesis (Ph.D.)--University of Adelaide, Depts. of Plant Science and Crop Protection, 1999? Bibliographical references: leaves 112-125.

3

Balnytė, Skirmantė. "Agroecosystem Optimization by Crop Rotation, Catch Crop and Manure in Organic Farming." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20110902_143932-39161.

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To analyse the influence of crop rotations with a different ratio of nitrogen-fixing crops, catch crops and fertilisation with organic fertilisers on the following: 1. Soil enzyme activity; 2. Agrochemical properties of the soil and nitrogen balance; 3. Weed response; 4. Weed seed bank in the soil; 5. Crop yield and productivity.
Agroekosistemų optimizavimo augalų kaita, tarpiniais pasėliais ir organinėmis trąšomis ekologinėje žemdirbystėje tyrimai vykdyti 2004–2009 m., Lietuvos žemės ūkio universiteto Bandymų stotyje, sertifikuotame ekologinės žemdirbystės lauke, karbonatingame sekliai glėjiškame išplautžemyje (IDg8-k) – Calcari-Epihypogleyic Luvisol (LVg-p-w-cc). Tyrimų hipotezė. Optimizuoti agroekosistemas ekologinėje žemdirbystėje galima taikant priemonių kompleksą: parenkant sėjomainas su skirtinga azotą fiksuojančių augalų dalimi, auginant tarpinius pasėlius bei tręšiant organinėmis trąšomis. Tyrimų tikslas – įvertinti agroekosistemų optimizavimo galimybes ekologinėje žemdirbystėje derinant sėjomainas su skirtinga azotą fiksuojančių augalų dalimi, auginant tarpinius pasėlius ir tręšiant organinėmis trąšomis. Tyrimų uždaviniai: Ištirti sėjomainų su skirtinga azotą fiksuojančių augalų dalimi, tarpinių pasėlių ir tręšimo organinėmis trąšomis įtaką: 1. dirvožemio fermentų aktyvumui; 2. dirvožemio agrocheminėms savybėms ir azoto balansui; 3. pasėlių piktžolėtumui; 4. dirvožemio armens užteršimui piktžolių sėklomis; 5. augalų derlingumui ir bendrosios energijos kiekiui. Mokslinio darbo naujumas. Ekologinės žemdirbystės sąlygomis kompleksiškai įvertintas sėjomainų su skirtinga azotą fiksuojančių augalų dalimi, tarpinių pasėlių bei tręšimo organinėmis trąšomis poveikis agroekosistemoms. Tai suteikia naujų žinių apie potencialaus dirvožemio derlingumo palaikymo, pasėlių ir dirvos piktžolėtumo kontrolės... [toliau žr. visą tekstą]

4

Isaac, Gura. "Crop rotation and crop residue management effects under no till on the soil quality of two ecotopes in the Eastern Cape, South Africa." Thesis, University of Fort Hare, 2016. http://hdl.handle.net/10353/2934.

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The degradation of soil quality due to undesirable farming practices has reached alarming scales in the Eastern Cape and this has had negative repercussions on soil productivity and the environment in general. There is growing evidence that conservation agriculture (CA) practices involving minimal mechanical disturbance, maintaining permanent surface cover and embracing diverse crop rotations increase soil organic carbon (SOC) and therefore has potential to mitigate soil quality deterioration. A study was carried out at two sites located in two ecotopes to investigate the effects of crop residue retention and crop rotations in a no till system on overall soil quality using the Soil Management Assessment Framework (SMAF) as the soil quality assessment tool. The CA study trials were laid out in 2012 at two different locations, one at the Phandulwazi Agricultural High school within the Phandulwazi Jozini ecotope and the other one at University of Fort Hare Research Farm within the Alice Jozini ecotope. The experiment was laid out as a split-split plot arrangement in a randomized complete block design with three replicates. Tillage treatments were applied on the main plots while crop rotation treatments were applied as subplots. Crop residue retention treatments were applied as sub-sub plots. The rotational treatments were maize-fallow-maize (MFM), maize-fallow-soybean (MFS), maize-wheat-maize (MWM) and maize-wheat-soybean (MWS). The initial assessment of the overall soil quality of the two ecotopes using the SMAF soil quality index (SQI) revealed that the soils at the Alice site were functioning at 80% while the soils at the Phandulwazi site were functioning at 79 percent of their optimum capacity. The slight difference in the soil quality of the two ecotopes could be attributed to their different soil organic C contents where the Alice Jozini ecotope had significantly higher soil organic C contents than the Phandulwazi Jozini ecotope. After 3 years of continuous treatment application, crop residue retention significantly improved most of the measured soil quality parameters. Generally across the sites, more soil organic C, microbial biomass C (MBC), ß-glucosidase (BG) activity, mineral N, extractable P and K, Cu, Zn, Mn, Fe, and macro-aggregates were recorded in treatments where crop residues were retained. Crop rotations alone did not have a significant impact on most of the measured soil quality indicators. The crop rotations influenced significantly the availability of mineral N across the two sites, highlighting the importance of using a legume in rotations on available N for the subsequent crops. Most of the measured soil attributes were not significantly influenced after 3 years of continuously applying combined treatment of CA components. Mineral N (NO3 + NH4), K, Zn and Fe were significantly impacted on by the interactions of CA components at the Phandulwazi site, while N, Cu, Zn and Mn were significantly increased at the Alice site. Low response of SOC to combined CA treatments in the short-term prompted the need to examine treatment effects on individual soil carbon fractions. The interaction of crop rotation and residue management techniques were significant on the fine particulate organic matter – C fractions and microbially respired C. These soil C fractions were more sensitive to short-term treatments of combined CA components than SOC and MBC, therefore they can be used as short-term indicators of CA effects on SOM. Soil organic carbon, MBC, extractable P and K, soil pH, EC, b, AGS (aggregate stability) and BG activity were measured and the Soil Management Assessment Framework (SMAF) used to calculate soil quality index (SQI) values for each treatment. The combination of the crop rotations with crop residue retention showed the potential to significantly improve SQI values in the long term. The highest soil quality improvement at both sites was achieved by the maize-wheat-soybean (MWS) rotation with crop residue retention.

5

Atallah, Therese. "Studies on the effects of organic amendments on nutrient recycling and nitrogen supply in a biological approach to crop production." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364054.

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6

Humble, Shauna Marie. "Weeds and ground beetles (Coleoptera: Carabidae) as influenced by crop rotation type and crop input management." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ62758.pdf.

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7

Castellazzi, M. S. "Spatio-temporal modelling of crop co-existence in European agricultural landscapes." Thesis, Cranfield University, 2007. http://dspace.lib.cranfield.ac.uk/handle/1826/3747.

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The environmental risk of growing genetically modified (GM) crops and particularly the spreading of GM genes to related non-GM crops is currently a concern in European agriculture. Because the risks of contamination are linked to the spatial and temporal arrangements of crops within the landscape, scenarios of crop arrangement are required to investigate the risks and potential coexistence measures. However, until recently, only manual methods were available to create scenarios. This thesis aims to provide a flexible referenced tool to create such scenarios. The model, called LandSFACTS, is a scientific research tool which allocates crops into fields, to meet user-defined crop spatio-temporal arrangements, using an empirical and statistical approach. The control of the crop arrangements is divided into two main sections: (i) the temporal arrangement of crops: encompassing crop rotations as transition matrices (specifically-developed methodology), temporal constraints (return period of crops, forbidden crop sequences), initial crops in fields regulated by temporal patterns (specifically-developed statistical analyses) and yearly crop proportions; and (ii) the spatial arrangements of crops: encompassing possible crops in fields, crop rotation in fields regulated by spatial patterns (specifically-developed statistical analyses), and spatial constraints (separation distances between crops). The limitations imposed by the model include the size of the smallest spatial and temporal unit: only one crop is allocated per field and per year. The model has been designed to be used by researchers with agronomic knowledge of the landscape. An assessment of the model did not lead to the detection of any significant flaws and therefore the model is considered valid for the stated specifications. Following this evaluation, the model is being used to fill incomplete datasets, build up and compare scenarios of crop allocations. Within the GM coexistence context, the model could provide useful support to investigate the impact of crop arrangement and potential coexistence measures on the risk of GM contamination of crops. More informed advice could therefore be provided to decision makers on the feasibility and efficiency of coexistence measures for GM cultivation.

8

Herzog, Craig. "Canola Production as Influenced by Previous Crop and Tillage System." Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1967998321&sid=7&Fmt=2&clientId=1509&RQT=309&VName=PQD.

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9

Alexander, Peter Mark William. "Modelling the UK perennial energy crop market." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/9645.

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Biomass produced from perennial energy crops, Miscanthus and willow or poplar grown as short-rotation coppice, is expected to contribute to UK renewable energy targets and reduce the carbon intensity of energy production. The UK Government has had incentives in place, targeting farmers and power plant investors to develop this market, but growth has been slower than anticipated. Market expansion requires farmers to select to grow these crops, and the construction of facilities, such as biomass power plants, to consume them. Farmer behaviour and preferences, including risk-aversion, are believed to be important to crop selection decisions. Existing research estimating the total potential resource has either only simplistically considered the farmer decision-making and opportunity costs, or has not considered spatial variability. No previous work has modelled the contingent interaction of farmers’ decisions with the construction of biomass facilities. This thesis provides an improved understanding of the behaviour of the perennial energy crop market in the UK, by addressing these limitations, to understand the spatial and temporal dynamics of energy crop adoption. It attempts to determine the factors that govern the rate and level of adoption, to quantify the greenhouse gas abatement potential, and to assess the cost effectiveness of policy mechanisms. A farm-scale mathematical programming model was implemented to represent the crop selection of a risk-averse farmer. This was applied using spatially specific data to produce maps and cost curves economic supply, for the UK. To represent the contingent interaction of supply and demand within the market, an agent-based model was then developed. The results indicate that perennial energy crop supply may be substantially lower than previously predicted, due to the time lags caused by the spatial diffusion of farmer adoption. The model shows time lags of 20 years, which is supported empirically by the analogue of oilseed rape adoption. Results from integrating a greenhouse gas emissions balance shows that directly supporting farmers, via establishment grants, can increase both the carbon equivalent emissions abatement potential and cost effectiveness of policy measure. Results also show a minimum cost of carbon abatement is produced from scenarios with an intermediate level of electricity generation subsidy. This suggests that there is a level of support for electricity generated from energy crops that reduces emissions in the most cost effective manner.

10

Gardiner, Ian O. "The effects of crop rotation and weed management on weed populations." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ39825.pdf.

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11

Melamed, Ricardo. "Corn growth, development and yield response to tillage - crop rotation systems." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1407403698.

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12

Muñoz, Fernando. "Improving nitrogen management in potatoes through crop rotation and enhanced uptake." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0006202.

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13

Semple, Adelaide Mary. "Nitrogen balance and changes in soil nutrients in reduced inputs systems of cropping." Thesis, Queen's University Belfast, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284399.

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14

Jennings, John A. "Rotation interval, soil texture, and zone of influence studies on alfalfa autotoxicity /." free to MU campus, to others for purchase, 1996. http://wwwlib.umi.com/cr/mo/fullcit?p9737851.

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15

Latta, Roy A. "Improving medic pastures in pasture-wheat rotations in the Mallee district of North-Western Victoria /." Title page, contents and abstract only, 1994. http://web4.library.adelaide.edu.au/theses/09A/09al364.pdf.

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16

Stein, Susanne [Verfasser]. "Spatial analysis of crop rotation practice in North-western Germany / Susanne Stein." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://d-nb.info/1218299193/34.

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17

Adu-Tutu, K. O., W. B. McCloskey, S. H. Husman, P. Clay, M. J. Ottman, E. C. Martin, and T. Teegerstrom. "Weed Management and Agronomic Performance of a Cotton-Barely Double Crop Rotation." College of Agriculture, University of Arizona (Tucson, AZ), 2005. http://hdl.handle.net/10150/198166.

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The tillage operations required to grow an annual barley and cotton crop rotation were reduced by eliminating tillage prior to planting cotton, eliminating cultivations for weed control in cotton, and especially by eliminating tillage following cotton. A light activated, weed sensing automatic spot-spray system reduced the amount of spray volume and herbicide used by 40% to 60% at Marana and 36% to 56% at Maricopa in 2004. At Maricopa, a large number of volunteer cotton plants in the furrows of early planted no-till cotton reduced the spray volume savings from using the weed sensing automatic spot-spray system. Weed control was similar with the weed sensing, automatic spot-spray system compared to the conventional continuous spray system for most weed species but weeds with narrow leaf, upright leaf canopies such as sprangletop, barley and skeleton weed were more difficult to detect and control. In both Marana and Maricopa, there were yield differences between treatments related to planting date, with late-planted cotton yielding less than early-planted cotton. At Marana, the early-planted conventional tillage cotton out-yielded the barley cover crop, early-planted no-till cotton treatment. At Maricopa, there were no yield differences between the two early planted cotton treatments; however, the late-planted conventionally tilled cotton yielded 28% more than the late-planted no-till cotton. Although the yield comparisons are not yet definitive, it appears that in some situations no-till cotton may yield less than conventionally tilled cotton. At Maricopa, the height of cereal crop stubble did not affect subsequent cotton establishment, field populations, plant height or lint production (2003 and 2004) and the position or node of the first fruiting branch and the first retained boll were similarly unaffected in 2004.

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Makhuvha, Mmbengeni Constance. "An analysis of financial implications of switching between crop production systems in Middle Swartland." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96805.

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Thesis (MScAgric)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Sustainability issues and the structural over-supply of wheat in the Western Cape since the middle 1990‟s have caused the introduction of alternative crop rotation systems in the Middle Swartland, a dry-land winter cereal production area of the Western Cape. Crop rotation systems typically consist of cereals and oilseed crops and pastures. Alternative crop rotations systems are currently scientifically evaluated at the Langgewens Experimental farm. Currently more than half the cultivated area in the Swartland is still under wheat production, a third of which is wheat monoculture. An issue regarding the adoption of such a crop rotation system is the cash flow and affordability of implementing such an alternative system. The goal of this study is to determine the cash-flow implications of a shift from wheat monoculture to a crop rotation system. Typical strategies available to producers to support such a shift are investigated. The complexity of farm systems as well as the interrelationships between crops within such a crop rotation system necessitates the implementation of a systems approach. A multi-period, whole-farm budget model was constructed to capture the interrelationships of the farm system and to express the financial performance thereof in standard profitability criteria. The farm model is based on a typical farm for the Middle Swartland. The model was used to determine the expected profitability of various crop rotation systems and to evaluate alternative strategies to accommodate the shift to alternative systems. The Langgewens crop rotation trial results are used to determine expected profitability of various crop rotation systems. A wheat-monoculture system serves as basis for the shift to alternative systems with the focus on the practical implications of such as shift. The profitability calculations show that various crop rotation systems are expected to be more profitable than wheat monoculture. The most profitable system is one year canola followed by three years of wheat, followed by a wheat/medic system with Dohne Merino sheep on the medic pastures. The shift from wheat monoculture is simulated by four scenarios. The first evaluated the financial implications of a shift form monoculture to the three year wheat and one year canola system. The second simulates a shift from monoculture to a wheat/medic system within two years and using own funds. The third scenario simulate the same shift with own funding, but over a ten year period. The fourth is similar to the second, but borrowed money is used to fund the shift.Lower input costs and consistently higher yields results in higher expected gross margins for the crop rotation systems, especially with nitrogen fixing plants. The inclusion of medic and medic/clover pastures and alternative cash crops such as canola and lupins show a higher yield on investment than wheat monoculture. Insight into the factors that producers should consider was also generated by this study, concerning changes to crop rotation systems. These factors include; time period over which a shift is planned and the availability of financing options. It seems that a quicker shift, using borrowed funds, is more profitable over the longer term.
AFRIKAANSE OPSOMMING: Volhoubaarheidskwessies, en die strukturele ooraanbod van koring in die Wes-Kaap, het sedert die middel 1990‟s, gelei tot alternatiewe gewasproduksiestelsels in die Swartland, ŉ droëland wintergraanproduserende area van die Wes-Kaap. Gewasproduksiestelsels bestaan tipies uit graan- en oliesaad- en weidings gewasse. Alternatiewe gewas-wisselboustelsels word wetenskaplik gevalueer op die Langgewens proefplaas. Tans is meer as die helfte van die area in die Swartland steeds onder koring produksie, ŉ derde daarvan is koring monokultuur. ŉ Bekommernis rakende die aanneem van wisselboustelsels is die kontantvloei en bekostigbaarheid van die implementering van so ŉ alternatiewe stelsel. Die doel van hierdie studie is om te bepaal wat die kontantvloei implikasies van ŉ skuif van ŉ koringmonokultuurstelsel na ŉ wisselboustelsel is. Tipiese strategieë beskikbaar aan produsente om so skuif te finansier is ook ondersoek. Die kompleksiteit van boerderystelsels en die interverwantskap tussen gewasse in ŉ wisselboustelsel noodsaak die insluiting van ŉ stelselsbenadering. ŉ Multi-periode, geheelplaasbegrotingsmodel is ontwikkel om die interverwantskap van die boerdery te verenig en finansiële prestasie uit te druk in erkende winsgewendheid kriteria. Die boerderymodel is gebaseer op ŉ tipiese plaas vir die Middel-Swartland. Die model is gebruik om die winsgewendheid van verskillende wisselboustelsels te bepaal en om verskillende strategieë te assesseer wat die oorgang van wisselboustelsel kan akkommodeer. Die Langgewens wisselbouproefdata is gebruik om die winsgewendheid van verskillende wisselboustelsels te bepaal. „n Koringmonokultuurstelsel dien as basis vir die oorskakeling na alternatiewe wisselboustelsels, met die fokus op die praktiese implikasies van so ŉ skuif. Die winsgewendheid bepaling wys dat verskeie wisselboustelsels meer winsgewend is as koring monokultuur. Die mees belowende stelsels is een jaar canola gevolg deur drie jaar koring en ŉ koring/medic stelsel met Dohne Merino skape op die medic weidings. Die oorskakeling vanaf koring monokultuur is gesimuleer deur vier scenario‟s. Die eerste scenario evalueer die finansiële implikasie van ŉ skuif van koringmonokultuur na ŉ wisselboustelsel met een jaar canola. Die tweede scenario evalueer ŉ skuif na ŉ koring medic stelsel binne twee jaar met eie fondse. Die derde scenario simuleer dieselfde skuif maar oor ŉ tien jaar tydperk, met eie fondse. Die vierde scenario simuleer dieselfde skuif na koring/medics maar oor ŉ twee jaar periode met geleende fondse. Laer insetkoste en konstante hoër opbrengste lewer hoër brutomarges vir die wisselboustelsels, veral die met stikstofbindende weidingsgewasse. Die insluiting van medic en medic/klawer weidings en alternatiewe kontantgewasse soos canola en lupiene wys ŉ beter opbrengs op kapitaal investering in vergelyking met koringmonokultuur. Bykomende daartoe verskaf die resultate van die studie insig in die faktore wat graanprodusente behoort te oorweeg wanneer ŉ oorskakeling na alternatiewe wisselboustelsels oorweeg word. Die faktore sluit in, die tydperk waaroor die oorskakeling beoog word en die beskikbare finansieringsopsies. Dit blyk dat ŉ vinniger oorskakeling, selfs teen die koste van finansiering, oor die langtermyn meer winsgewend is.

19

Potgieter, F. J. "'n Besluitnemings ondersteuningsmodel vir die bepaling van die mees geskikte wisselboustelsel-ritme vir gemengde graanboerderye in die Koeberg." Thesis, Port Elizabeth Technikon, 2001. http://hdl.handle.net/10948/43.

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Weens die unieke eiesoortigheid van die mens is sy behoeftes vanselfsprekend uiters divers. Wat vir die een persoon prioriteit is, mag vir sy buurman geensins belangrik wees nie. Dit is egter ook ’n gegewe, dat die mens heelwat gemeenskaplike ervarings, emosies en behoeftes deel. Een hiervan is die behoefte wat hy het om te weet dat die besluit wat hy gaan of wil neem die regte een binne die konteks van sy keuse mag wees. Die woord ‘behoefte’ kan waarskynlik in hierdie geval vervang word met die begrip ‘genade’. Sonder om 'n platvorm vir debat te skep, word die stelling gehandhaaf dat ‘genade’ slegs van die Skepper afkomstig is. Met hierdie stelling as agtergrond was dit 'n minder aangename ervaring om vir feitlik twintig jaar te moes toekyk hoe koringboere hul besluite, veral met betrekking tot die samestelling van wisselboustelsels, moes neem, klaarblyklik in totale gebrek aan die gawe van ‘genade’. Nodeloos om te sê, met gepaardgaande negatiewe gevolge. Die meer gemaklike verontskuldiging is om te redeneer dat ons Skepper relatief suinig is met die uitdeel van sy ‘genade’. Alvorens die begrip van Prediker 10:10 nog nie ten volle begryp is nie, kan so 'n stelling dalk makliker gemaak word. Hierdie gedeelte uit die Skrif sê in werklikheid die teenoorgestelde – dat God baie vrygewig is met Sy ‘genade’, maar dat die mens sy gesonde verstand moet gebruik om dit ten volle te benut. Die wens is dat hierdie studie, 'n deel sal uitmaak van die proses om die byl skerp te maak om sodoende die houtkap-proses effektief uit te voer.

20

Gathumbi, Stanley Mwangi. "Nitrogen sourcing by fast-growing legumes in pure and mixed species fallows in western Kenya." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322531.

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21

Barth, Neto Armindo. "Impact of grazing management and crop rotation on integrated crop-livestock system : implication on Italian ryegrass established by self-seeding." reponame:Repositório Institucional da UFPR, 2015. http://hdl.handle.net/1884/38017.

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Orientador : Prof. Dr. Paulo César de Faccio Carvalho
Co-orientador : Prof. Dr. Gilles Lemaire
Tese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Agrárias, Programa de Pós-Graduação em Agronomia. Defesa: Curitiba, 25/02/2015
Inclui referências
Área de concentração: Produção vegetal
Resumo: Sistemas integrados de produção agropecuária (SIPA) são reconhecidos por sua produção sustentável, tanto agrícola quanto pecuária, devido a melhor utilização dos recursos naturais. Diferentes combinações e proporções de espécies animais e vegetais em SIPA são responsáveis por produzir aproximadamente metade da produção mundial de alimentos. Nas regiões subtropicais do mundo, particularmente na América do Sul, a utilização do azevém anual (Lolium multiflorum Lam.) estabelecidos por ressemeadura natural em rotação com milho (Zea mays L.) e/ou soja (Glycine max L.), são amplamente difundido entre os produtores rurais. Em SIPA a prática de ressemeadura natural são considerados economicamente e ambientalmente mais vantajosos, uma vez que economiza gastos e energia (combustível fóssil). Sobre este arranjo em SIPA, diversas questões ainda não foram respondidas sob a influência das práticas de manejo sobre o estabelecimento do azevém anual proveniente de ressemeadura natural. Por exemplo as plantas de soja e milho tem diferentes estruturas de dosséis, que podem afetar o desenvolvimento inicial das plântulas de azevém anual. Outro ponto é o manejo do pastoreio em SIPA, particularmente o efeito dos diferentes método de pastoreio e intensidades de pastejo que podem afetar o crescimento do pasto. Uma vez que o manejo do pastejo pode restringir a seletividade animal (altas intensidades de pastejo e pastoreio rotativo), afetam negativamente o acúmulo da massa de forragem, densidade de perfilhos reprodutivos e produção de sementes. Entretanto, estudos sobre o entendimento das interações e complementariedades entre as fases lavoura e pastagens em SIPA é pouco abordado na literatura, principalmente com o azevém anual estabelecido por ressemeadura natural. A hipótese deste trabalho é que a rotação das culturas de verão (monocultura de soja ou rotação soja-milho) e diferentes manejos do pasto (método de pastoreio e intensidade de pastejo) afetam diferentemente o desenvolvimento e a resiliência do azevém anual em SIPA no curto e longo prazo. Para comprovar esta hipótese foram preparados três artigos com os seguintes objetivos: i) avaliar os efeitos das práticas de manejo, rotação de culturas, método de pastoreio e oferta de forragem afetam o restabelecimento dos pastos de azevém anual por ressemeadura natural e determinar se os pastos são capazes de restabelecer por mais de um ano sem a adição de sementes no solo. ii) avaliar o impacto da rotação de culturas de verão e o manejo do pasto na massa de forragem no inicio e no final da fase pastejo. iii) Analisar e modelizar a dinâmica do azevém anual em SIPA com uma base de dados histórica do ciclo de vida do pasto e determinar a resiliência sob diferentes práticas de manejo sob uma perspectiva de longo-prazo. Palavras chave: Sistemas mistos, intensidade de pastejo, método de pastoreio, soja, milho, resiliência.
Abstract: Integrated crop-livestock systems with no-till (ICLS) are recognized to sustained agriculture and livestock production by the efficiently use of natural resources. Different combinations and proportions of animal and plant species in ICLS are responsible for producing about half of the of the word's food. In subtropical regions of the world, mainly in South America, the utilization of Italian ryegrass (Lolium multiflorum Lam.) established by self-seed in rotation with maize (Zea Mays L.) or soybean (Glycine max L. Merril) is widely widespread. In ICLS, the harnessing of self-seeding is economically and environmentally advantageous because is capable to save money and energy (based on fossil fuel). In ICLS many question are unanswered about the Italian ryegrass established by self-seeding in face of different agricultural practices. For example soybean and maize have different canopy structures that can differently affect the pasture establishment phase. The grazing management in ICLS, particularly the effect of different stocking method and different grazing intensity can affect the dynamic of the pasture production. Since manage the pasture restricting the animal selection (i.e. higher grazing intensity and rotational stocking) affects negatively the herbage mass accumulation, the flowering structure and the seed production. However, the understanding of the interactions and of the complementarity between crops and pasture phases is poorly addressed in the literature, mainly in Italian ryegrass established by selfseeding. The hypothesis is that summer crop rotation (soybean monoculture or soybeanmaize) and the different grazing management (stocking methods and grazing intensities) affects differently the development and the resilience of Italian ryegrass in ICSL in short and long-term. To prove this hypothesis were prepared three articles with the following objective: i) to evaluate the effects of management practices, crop rotation, stocking method and herbage allowance on the re-establishment of Italian ryegrass pastures by self-seeding and determining if the pastures are able to establish themselves following a year without seed production. ii) to evaluate the impacts of summer crop rotation and grazing management on herbage mass at the beginning and at the end of grazing phase in ICLS. iii) to analyse and modelling the dynamics of Italian ryegrass in ICLS from an experimental database, based on a life-cycle basis to determine the resilience of different cropping systems in a long-term perspective. Key words: Mixed systems, grazing intensity, stocking method, soybean, maize, resilience.

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Jones, Stephen. "Nitrogen partitioning within different organic systems incorporating strip intercropping, sheep and crop rotation." Thesis, University of Reading, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.250690.

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Brewer, Marin Talbot. "Effects of Biological Control and a Ryegrass Rotation on Rhizoctonia Disease of Potato." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/BrewerMT2003.pdf.

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Olsen, Davey J. R. "Determining Compost Carryover for Optimal Use in an Organic Corn Squash Rotation." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1458.

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Organically certified farms using compost to improve or maintain fertility rarely consider compost carryover and its impact on the determination of economically optimal application rates. Compost carryover is comprised of nutrient and non-nutrient elements. Both affect crop growth, yet carryover is typically described primarily in terms of nitrogen (N)-carryover only. This study tested a new method for estimating compost carryover on organically certified land and expressed carryover in units that capture both the nutrient and non-nutrient components. Compost carryover for five treatment rates was estimated over four years in an organically certified field trial in a corn and squash rotation. Nitrate (NO3-), phosphorus (P), soil organic matter (SOM) were investigated to determine the residual effect of a one-time compost application. Implications for fertility management and farm profitability were considered. The new method successfully modeled carryover, determining that compost had a persistent and positive effect on crop yields, evident even three years after an initial one-time application. No NO3- carryover was observed in any year, suggesting that yield responses were due primarily to non-N carryover. Compositional changes in SOM corresponding to compost input three years earlier suggested that compost was able to influence non-nutritive soil properties many years after incorporation. High value cash-crops are necessary in organic rotations to offset the high input cost of compost use. In organic fertility management, compost is an important and economical source of non-N fertility, which benefits crop yield many years after incorporation. When used with a dedicated N-fixing cover crop in a rotation that includes a high value cash-crop, complete fertility goals could be met in a sustainable manner. (153 pages)

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Jacobs, Addison Denae. "Influence of Cover Crop Species on Soil Physical Properties in a Corn-soybean Rotation." Thesis, Arkansas State University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10831039.

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As crop land decreases and population increases, soil quality is becoming a concern. Utilizing cover crops in cropping systems could improve soil quality. This study examined 16 treatments of single-species cover crops, cover crop mixes, and two control treatments on a silt-loam soil, in a corn ( Zea mays L.) - soybean (Glycine max L. Merr.) crop rotation under no-tillage, to determine their effect on soil physical properties. Cover crop biomass differed (p<0.10) among treatments and produced a maximum of 15.6 Mg ha^-1 of biomass in the crimson clover treatment. Water infiltration rates increased as much as 282% in the complete-mix treatment compared to the fallow control. Differences in infiltration rates due to cover crop species were shown in two-years. However, these results suggest that it may take more time for cover crops to affect change in bulk density and aggregate stability.

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Ullrich, Silke. "Weed Population Dynamics in Potato Cropping Systems as Affected by Rotation Crop, Cultivation, and Primary Tillage." Fogler Library, University of Maine, 2000. http://www.library.umaine.edu/theses/pdf/Ullrich.pdf.

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Kravchenko, Anatoliy G. "Overcoming the rotational antagonism of corn following wheat in high residue cropping systems." Diss., Connect to online resource - MSU authorized users, 2006.

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Thesis (M. S.)--Michigan State University. Dept. of Crop and Soil Sciences, 2006.
Title from PDF t.p. (viewed on June 19, 2009) Includes bibliographical references (p. 94-99). Also issued in print.

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Schmitt, Mattie Bree. "Factors Affecting Establishment and Growth of Cover Crops in a Corn-Soybean Rotation." Thesis, North Dakota State University, 2020. https://hdl.handle.net/10365/31758.

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In the Midwest, it can be beneficial to interseed cover crops into corn (Zea mays L.) since there is a limited time for them to establish and grow after corn harvest. Research conducted in four environments in North Dakota quantified the impacts of planting method and time of planting when grown with or without corn competition on the establishment, and development of three cover crop species. Limited light intensity (less than 20%) under the corn canopy drastically reduced cover crop development. Soil water can also constrain cover crop establishment. Model simulations suggest soil water is more limiting for cover crop establishment in August compared with June or July. Interseeded cover crops had no effect on corn yield or the following soybean (Glycine max (L.) Merr.] crop due to minimal amounts of biomass produced.

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Simoes, Rui Pedro Mota Raper Randy L. "Reduction of soil compaction in a cotton and peanut rotation using conservation systems." Auburn, Ala., 2008. http://hdl.handle.net/10415/1533.

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Morris, Jennifer L. "Use of herbicides, tillage, and grazing cattle for establishment of corn in rotation with alfalfa and rye." Thesis, Virginia Tech, 1993. http://hdl.handle.net/10919/45050.

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Six combinations of grazing, tillage, and herbicides were studied during 2 yr in a randomized block design to determine alfalfa (Medicago sativa) survival, corn (Zea mays) plant populations and corn growth in an alfalfa-corn rotation. Alfalfa was overseeded with rye (Secale cereale) in autumn prior to planting corn in spring of each year. Treatments were 1) non-grazed control with standard chemical treatments for no-till establishment of corn, 2) grazing alfalfa, then grazing rye until corn planting followed by dicamba application, 3) alfalfa grazing plus glyphosate prior to corn planting, 4) treatment 3 plus grazing prior to rye jointing, and 5) alfalfa grazing plus autumn application of glyphosate, 6) alfalfa grazing plus autumn disking (no herbicides). Grazing until corn planting decreased (P<0.05) alfalfa stands and rye biomass, but increased (P<0.05) corn plant populations and soil bulk density compared to shorter grazing periods. Grazing prior to rye jointing increased (P <0.05) soil bulk density and corn plant populations, and decreased (P<0.05) rye biomass compared to no spring grazing. Autumn disking decreased (P<0.05) bulk density, but generally provided less (P<0.05) control of alfalfa compared to autumn application of glyphosate. Autumn disking and glyphosate application (Trts. 5 and 6) increased (P<0.05) rye biomass compared to no autumn treatment (Trts. 3 and 4). Applying glyphosate prior to corn planting (Trts. 3 and 4) improved (P<0.05) corn populations and growth compared to autumn glyphosate or disking (Trts. 5 and 6) and was similar to conventional no-till establishment (Trt. 1). Herbicides were necessary to completely kill alfalfa, but grazing reduced TNC in alfalfa roots and alfalfa plant persistence.
Master of Science

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McLaughlin, Michael John. "Phosphorus cycling in soil under wheat-pasture rotations /." Title page, contents and summary only, 1986. http://web4.library.adelaide.edu.au/theses/09PH/09phm1615.pdf.

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Human, Hans Jurie. "Identification of soil and biological factors in crop rotation systems with significance to wheat crop performance in the Overberg production area of South Africa." Thesis, Link to the online version, 2008. http://hdl.handle.net/10019.1/2286.

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Pachta, Matthew J. "Risk analysis of tillage and crop rotation alternatives with winter wheat for south central Kansas." Thesis, Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/3577.

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Seibutis, Vytautas. "Trumpų sėjomainos rotacijų agrobiologinis įvertinimas." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2005. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2005~D_20050929_115234-56584.

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Lithuania’s agricultural reform resulted in significant changes in land use, i.e. in the emergence of small individual farms. As a result, the formerly most popular 7, 8, 9-course crop rotations, or even 5-6-course crop rotations became inapplicable on small farms, especially on those not involved in animal production and cultivation of grass forage. Multiple-course crop rotations would disperse the same crops over several places, and the fields would not be unacceptably small. This is especially problematic for market farms, where it is intended to have 1-2-3 main crops and adequately alternate them. In foreign countries short rotations are a common practice in similar cases. However, in Lithuania short rotations have hardly been investigated, except for the sporadic research cases, therefore it is rather complicated to judge the feasibility of market crops growing in short rotations. When the area of cereals is increased in a crop rotation, it is more difficult to choose preceding crops, and continuous growing of crops becomes inevitable. It is of special relevance here to maintain soil fertility, moreover, the adverse effects of crops concentration manifest themselves much more severely than in any other system, namely, heavy occurrence of weeds, diseases and pests, soil depletion and fatigue. On cultivated Central Lithuania’s soils shortening of rotations and proper choice of preceding crops make it feasible to produce profitable, high quality agricultural production... [to full text]

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Amisi, Karen Janila. "Strategies for managing weeds in a wheat, red clover, vegetable crop rotation transitioning to organic production." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1104246323.

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Amisi, Karen Janila. "Strategies for managing weeds in a wheat, red clover, vegetable crop rotation transitioning to organic production /." Connect to this title online, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1070933281.

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Thesis (Ph. D.)--Ohio State University, 2004.
Document formatted into pages; contains 154 p. Includes bibliographical references. Abstract available online via OhioLINK's ETD Center; full text release delayed at author's request until 2005 Dec 28.

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Izard, Erica Jean. "Seeking sustainability for organic cropping systems in the Northern Great Plains: legume green manure management strategies." Thesis, Montana State University, 2007. http://etd.lib.montana.edu/etd/2007/izard/IzardE0807.pdf.

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Frank, Edward Todd Duffy Patricia Ann. "Selected topics in peanut production Economic feasibility of an energy crop on a South Alabama cotton-peanut farm, and, Do economies of scale exist on peanut farms in the Southeast? /." Auburn, Ala., 2005. http://repo.lib.auburn.edu/2005%20Fall/Thesis/FRANK_EDWARD_47.pdf.

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Кірдан, М. А. "Агроекономічний аналіз рослинницької галузі ФГ «БІЛІ РОСИ» Чернігівської обл., Коропського району, с Понорниця та заходи поліпшення технології вирощування гречки в умовах Полісся." Thesis, Чернігів, 2020. http://ir.stu.cn.ua/123456789/20088.

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Кірдан, М. А. Агроекономічний аналіз рослинницької галузі ФГ «БІЛІ РОСИ» Чернігівської обл., Коропського району, с Понорниця та заходи поліпшення технології вирощування гречки в умовах Полісся: дипломна робота : 201 Агрономія/ М. А. Кірдан ; керівник роботи Локоть О. Ю; Національний університет «Чернігівська політехніка», кафедра аграрних технологій та лісового господарства. – Чернігів, 2020. – 73 с.
На сучасному етапі в рослинництві пріоритетним напрямом є виробництво продукції, що потребує меншого застосування ресурсів при максимальному використання потенціалу вирощуваних культур і регіональних особливостей. Відомо, що кращими попередниками гречки є: озима пшениця, ячмінь, цукровий буряк, кукурудза, зернобобові. Гречка для гречки є поганим попередником, недоцільно розміщувати її посіви після суданської трави, соняшнику, які пересушують ґрунт. Основною причиною низьких врожаїв культури є те, що її вважають не вимогливою до ґрунту і попередників. Ідеальні для вирощування гречки (сировини для виробництва гречаної крупи) простори Вінницькій, Київській, Кіровоградській, Полтавській, Сумській, Тернопільській, Харківській і Чернігівській областей. Оберимо для дослідження Чернігівську область, яка розміщена в Поліссі.
At the present stage in crop production the priority is the production of products that require less use of resources with maximum use of the potential of crops and regional characteristics. It is known that the best precursors of buckwheat are: winter wheat, barley, sugar beet, corn, legumes. Buckwheat for buckwheat is a bad precursor, it is impractical to place its crops after Sudan grass, sunflower, which overdry the soil. The main reason for low crop yields is that it is considered undemanding to the soil and predecessors. Areas of Vinnytsia, Kyiv, Kirovohrad, Poltava, Sumy, Ternopil, Kharkiv and Chernihiv regions are ideal for growing buckwheat (raw materials for buckwheat production). Let's choose the Chernihiv region, which is located in Polissya, for research.

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Sudini, Hari Kishan Huettel Robin Norton. "Soil microbial community structure and aflatoxin contamination of peanuts." Auburn, Ala., 2009. http://hdl.handle.net/10415/1875.

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41

Röhricht, Christian, Sven Freydank, and Stefan Schröder. "Energiefruchtfolgen für D-Südstandorte - Entwicklung und Optimierung von standortangepassten Anbausystemen für Energiepflanzen im Fruchtfolgeregime auf D-Südstandorten." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-23886.

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Das Landesamt für Umwelt, Landwirtschaft und Geologie untersuchte auf einem D-Südstandort in der Dübener Heide acht verschiedene Fruchtfolgen mit Energiepflanzen zur Biogasproduktion. Untersucht wurde die Ertrags- und Biogasleistung. Für die Region wird empfohlen, den Anbau in fünfgliedrigen Fruchtfolgen vorzunehmen. Als ertragsstarke und ertragsstabile Energiepflanzen haben sich dabei Energiemais, Sudangras, Zuckerhirse und Kartoffeln bewährt. Sie sollten zu 30 bis maximal 60 % in der Fruchtfolge berücksichtigt werden. Von ökologischem (Humushaushalt) und ökonomischem Vorteil ist dabei der Aufbau von Fruchtfolgesystemen, die sowohl leistungsstarke Energiepflanzen als auch Nahrungspflanzen enthalten. Die leistungsfähigsten Fruchtfolgevarianten erreichen kumulative Trockenmasseerträge von 370 bis zu 430 dt TM/ha. Theoretische Methanleistungen von insgesamt 12.000 m³ Methan/ha sind möglich.

42

Ren, Tusheng. "Soil water and temperature regimes in winter wheat as affected by crop rotation, tillage and row spacing." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21624.pdf.

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43

Riofrío, Ordóñez Carlos Andrés. "Economics of introducing forage and livestock into alternative crop rotation systems during the transition to organic agriculture." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=98779.

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The purpose of this study was to investigate the economic feasibility of alternative crop rotations and to determine the economic implications of including forages and livestock during the transition to organic agriculture in Nova Scotia. The rotation systems were distinguished by: (i) frequency of forage in the rotation, (ii) source of nutrient supply, and (iii) type of farming operation. The economic analysis was divided in two parts. The first part analysed data from a four-year crop rotation experiment, using enterprise budgeting and statistical methods to compare differences among rotations under different treatments. The second part involved the development of a multi-period linear programming (LP) model to simulate a commercial operation.
The results from the statistical analysis suggest that crop enterprise net returns tended to be higher in forage-based rotations and in the livestock systems compared to cash crop rotations and the stockless system. Results from the LP model suggest that including forages and beef cattle during the transition to organic agriculture can provide considerable economic benefits, especially when crops were grown under ruminant compost.

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Babini, Viviana <1963&gt. "Soil tillage and crop rotation effects on Triticum durum (Desf.) yield and mycotoxins content in its grain." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/429/1/Tesi_Viviana21-05-07_con_graf_mico.pdf.

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Babini, Viviana <1963&gt. "Soil tillage and crop rotation effects on Triticum durum (Desf.) yield and mycotoxins content in its grain." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2007. http://amsdottorato.unibo.it/429/.

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46

Salmerón-Miranda, Francisco. "Nitrogen use in a maize-bean rotation in Nicaragua : effects of organic and mineral fertilisers /." Uppsala : Dept. of Crop Production Ecology, Swedish University of Agricultural Sciences, 2008. http://epsilon.slu.se/200896.pdf.

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47

Buckland, Kristine R. "Evaluating Fertilizer Rate, Crop Rotation and Trap Crops for Effects on Onion Growth and Yield, Soil Health, Thrips Densities and Iris Yellow Spot Virus Incidence." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/980.

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Onion production in the United States is seriously affected by the tospovirus Iris Yellow Spot (IYSV), whose symptoms include lenticular-shaped lesions that reduce photosynthesis and bulb yield. Thrips tabacai Lindeman, onion thrips (OT), is the only known vector of the disease and a primary arthropod pest of onion. Frequent insecticide applications, increasing resistance in OT populations to insecticides, high nitrogen (N) fertilization rates and loss of yield to disease and insect pressure threaten sustainable onion production. The objectives of this study were to identify crop management strategies to enhance onion productivity while suppressing OT and IYSV. Three fertilizer rates and two crop rotations were assigned to replicated plots to assess effects on onion growth, yield, bulb storage quality, soil quality, thrips populations and IYSV incidence. Trap crops of carrot, buckwheat and lacey phacelia were established in commercial fields to evaluate impact on thrips populations and IYSV occurence. Reduced nitrogen (N) rates, one-third the standard grower rate (133.8 kg N ha-1), resulted in no yield loss as compared with the standard N rate, despite slower crop maturation. Onions treated with a standard N rate(401.8 kg N ha-1) had greater numbers of adult and immature OT than other treatments. Soil nitrate levels were lower and microbial activity measured as dehydrogenase and biomass were greater in reduced N treatments. Plots with buckwheat and phacelia had greater numbers of both adult and immature OT when trap crop apparancy was high (i.e. when onion plants were relatively smaller). There was no observed effect of trap crops on IYSV levels. Results suggest that reduced rate N applications lower numbers of OT while enhancing the microbial population, reducing potential for nitrate leaching while still maintaining yields. Potential for trap crops of buckwheat and lacey phacelia to attract onion thrips from onions exists with successive stands of highly apparent trap crops.

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Njaimwe, Arnold Ngare. "Tillage and crop rotation impacts on soil, quality parameters and maize yield in Zanyokwe Irrigation Scheme, South Africa." Thesis, University of Fort Hare, 2010. http://hdl.handle.net/10353/460.

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Intensive tillage and monoculture cropping practices reduce soil C accumulation hence increasing soil vulnerability to chemical, physical and biological degradation. This study focussed on enhancing biomass production of wheat and oat winter cover crops as a means of increasing C sequestration in the low organic C soils of the central part of Eastern Cape Province. The specific objectives were (i) to evaluate the short-term effects of no till and cereal-fallow based crop rotations on; soil organic matter related parameters, pH and electrical conductivity, (ii) soil bulk density, water retention and aggregate stability, (iii) soil microbial biomass C and N, mineralizable N, soil respiration, and dehydrogenase enzyme activity, (iv) grain yield, soil nutrient concentration (N, P and K) and their uptake by maize, and (v) to identify soil parameters with high sensitivity to tillage under maize-fallow-maize, maize-wheat-maize and maize-oat-maize rotational cover cropping practices. The experiment was laid out as a split-plot arrangement in a randomized complete block design with 4 replicates. Tillage treatments (CT and NT) were applied on the main plots which measured 8 × 18 m while crop rotation treatments were applied in the subplots which measured 8 × 6 m. The rotation treatments were maize-fallow-maize (MFM), maize-wheat-maize (MWM) and maize-oat-maize (MOM). Weed control in NT plots involved preplant application of glyphosate to control mainly the grass weeds while post emergence weed management was done using Atrazine (485 atrazine and 15 g l-1 triazines). Initial weed control in CT plots was achieved through ploughing to a depth of 20 cm followed by disking while post emergence weed iii management was done by hand hoeing. Soil parameters measured were; (i) particulate organic matter (POM), soil organic carbon (SOC), total nitrogen (TN), pH and electrical conductivity (EC), (ii) soil bulk density (b), moisture at field capacity (FC), aggregate mean weight diameter (MWD) determined by fast wetting (FW), slow wetting (SW), mechanical breakdown by shaking (MB) and the stability index (SI), (iii) soil microbial biomass C (MBC) and N (MBN), mineralizable N (MN), soil respiration (SR), and dehydrogenase enzyme activity (DHEA). No-till increased POM and TN compared to CT in Lenye and Burnshill, respectively. The MWM and the MOM rotations increased TN relative to the MFM rotation in Lenye. The MWM and MOM rotations enhanced SOC relative to MFM in all sampled soil depths at Burnshill and similar observations were made under MOM rotation in the 5-20 cm depth in Lenye. The MWM and MOM rotations tended to depress soil pH relative to the MFM rotation in both sampled soil depths in Lenye while NT reduced soil pH relative to CT on the surface soil layer in Burnshill. Soil EC and pH varied with depth across tillage practices but both parameters remained within the ideal range for successful crop production over the study period. Soil stability index (SI) and aggregate MWD determined by FW, SW and MB were higher in Lenye compared to Burnshill. The MOM rotation enhanced the SI relative to MFM and MWM rotations at both sites. Scanning electron microscope (SEM) showed that more organic C was incorporated into the soil under NT and MOM rotation compared to CT and MFM rotation which had few organic coatings on the soil particles. Microbial properties varied with plant biomass input as influenced by tillage and type of rotational cover crop at both sites. Like in other past studies, NT showed higher levels of MBC, MBN, NM and SR at the soil surface layer compared to CT in Burnshill. No till increased MN iv relative to CT in both sampled soil depths in Lenye and resulted in higher DHEA compared to CT in Burnshill. The MOM rotation increased MBC, MBN, MN relative to MFM rotation especially within surface soil layer. Similar observations were made with respect to MN and SR in both sampled soil layers at Lenye. By contrast, the DHEA was higher under the MFM relative to the MWM and MOM rotations in Lenye but similar under the MFM and MOM rotations in Burnshill. Maize grain yield was not affected by both tillage and crop rotations but varied with cropping season. Comparable grain yields observed under the two tillage practices with similar fertilizer application rates indicated the advantage of NT over CT in saving on labour costs in maize production without compromising yields. High plant biomass retention under NT relative to CT contributed to high soil N and P levels under the former compared to the latter tillage practice especially on soil surface layer at both study sites. Principal component analysis (PCA) revealed that soil chemical and biological parameters closely linked to organic matter, namely SOC, MN, MBC and MBN showed the highest sensitivity to tillage and crop rotation treatments. Soil aggregate MWD determined by SW and b were the physical parameters which were highly altered by agronomic management practice. The MWM and MOM rotations were clustered together and clearly separated from the MFM rotation and this observed trend only applied to the 0-5 and 5-20 cm depths in Lenye site only. No till, MWM and MOM rotations enhanced POM, SOC and TN relative to CT and MFM rotation suggesting these practices have greater potential to improve soil chemical properties compared to intensive tillage and maize monoculture based production practices. Reduced soil b under MOM rotation and improved SI under NT compared to MFM and CT, respectively v indicate that these practices have the potential to improve degraded soils. Although not significantly different, NT values for MBC, MBN, MN, SR and DHEA were higher compared to CT indicating the potential of the practice to improve soil biotic activity relative to conventional tillage practices. No till enhanced surface soil nitrate N and extractable P compared to CT at both sites revealing the long-term potential of NT in improving the supply of these essential plant nutrients compared to CT. Principal component analysis showed that SOC, MN, K, P, MBC, MBN, soil aggregate MWD determined by SW and b were the most sensitive parameters to tillage and crop rotations. Therefore, these parameters could constitute the minimum data set for assessments of the impact of selected CA practices on soil quality attributes.

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Abbott, Melissa Anne. "Denitrification and mineralization in agricultural soil in Eastern Canada, as affected by nitrogen fertilizer, tillage, and crop rotation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0002/MQ29640.pdf.

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50

Abbott, Melissa. "Denitrification and mineralization in agricultural soil in eastern Canada, as affected by nitrogen fertilizer, tillage, and crop rotation." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=27266.

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Abstract:

The fate of fertilizer N is of primary concern for both agricultural productivity and environmental quality. Concerns include denitrification, leaching losses, mineralization of organic N as plant available N. Denitrification is an important source of N$ sb2$O, a greenhouse gas but field measurements are difficult. Two methods of measuring denitrification are soil core (SC) incubation and closed chamber (CC) methods. These methods were assessed on soil under monoculture corn, monoculture soybean, and alfalfa in a corn soybean alfalfa rotation. Greater concentrations were found in the CC method than the SC method. Denitrification rates ranged from less than 15 g N ha$ sp{-1}$h$ sp{-1}$ to nearly 2000 g N ha$ sp{-1}$h$ sp{-1}$. The CC method was more sensitive to treatment effects. The denitrification rates were dependent on the soil type, being higher on soils with high clay content. The variables that had the highest degree of relationship with denitrification were water filled pore space, soil NH$ sb4$-N and NO$ sb3 $,-N concentrations. Higher rates of N increased denitrification. As to assessment of available soil N, this was accomplished N and C mineralization measurements. Potentially mineralizable N(N$ sb0$) ranged from 144 mg N kg$ sp{-1}$ to 30.3 mg N kg$ sp{-1}$. Higher rates of organic amendment resulted in higher measured values on Brandon soil while higher rates of inorganic N on Chicot and Ste. Rosalie soils caused no change in mineralizable N or respired C. Total N, organic C, water soluble organic C (WSOC) and microbial biomass C (MBC) increased with increasing amounts of organic or inorganic N amendment on Brandon soil. Higher rates of inorganic N resulted in lower WSOC and MBC on Chicot and Ste. Rosalie soils. Nitrogen mineralized, C respired, total N, organic C, WSOC and MBC were all related to soil texture. MBC and WSOC were found to have a strong positive relationship with potentially mineralizable N.

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