PAE / No Brasil a produção de leite e carne tem como principal característica a produção quase que exclusiva a pasto, essa característica tem suas vantagens e desvantagens, dentre as vantagens a principal é o baixo custo de produção. Como desvantagem seria conseguir produzir alimento de qualidade e quantidade o ano todo. Objetivou-se com o trabalho avaliar o efeito da adubação nitrogenada na produção e no valor nutricional das forragens,bem como a eficiência do uso do nitrogênio e a extração dos macronutrientes (N, P, K)do solo, nas culturas do sorgo forrageiro cv. Jumbo e da aveia preta cv. Iapar 61. O trabalho foi desenvolvido na área experimental da Universidade Tecnológica Federal do Paraná, Câmpus Dois Vizinhos. Para o desenvolvimento do trabalho foram utilizadas culturas anuais de ciclo estival e hibernal. Para o período de verão dos anos agrícolas de 2010/2011 e 2011/2012, foi utilizada a cultura do sorgo forrageiro cv. Jumbo e para a cultura anual de inverno, ano de 2011, foi utilizada a aveia preta cv. Iapar 61. O delineamento experimental utilizado foi o de blocos completamente casualizados, com três repetições. Para o sorgo forrageiro nos dois ciclos de verão foi utilizada uma densidade de 15 kg ha-1 de sementes viáveis, sendo testadas as doses de 0; 37,5; 75; 150; 225; 300 e 375 kg de N ha-1, distribuídas em três aplicações iguais, 1/3 na semeadura, 1/3 após o primeiro corte e 1/3 após o terceiro corte. Para a aveia preta, foi utilizada uma densidade de 40 kg ha-1 de semente viáveis, testando as doses de 0; 40; 80; 120; 160; 200 e 240 kg de N ha-1, sendo essas doses também distribuídas em três aplicações, 1/3 no perfilhamento, 1/3 após o primeiro corte e 1/3 após o terceiro corte. A coleta do material forrageiro do sorgo produzido durante o verão foi realizado quando a cultura atingia uma altura média entre 0,70 a 0,80 m, deixando um resíduo médio de planta de 0,20 m de altura para rebrote e nova coleta. Para a aveia preta a coleta do material ocorreu quando a cultura atingia altura de 25 cm, com um corte manual a 10 cm do solo de uma área conhecida de 0,25 m2 por unidade experimental. Para determinação das características bromatológicas de ambas as culturas, o material foi seco em estufa a 60 oC até peso constante, moído em peneira de 1 mm e em seguida foram avaliados os seguintes parâmetros: massa seca (MS), proteína bruta (PB), fibra em detergente neutra (FDN), fibra em detergente ácido (FDA), digestibilidade in vitro da matéria seca (DIVMS), determinação dos macronutrientes N, P e K; recuperação, eficiência de recuperação e eficiência fisiologia do nitrogênio. Todos os dados avaliados foram submetidos à análise da variância pelo programa SAS 8.1 a 5% de probabilidade de erro. As doses de 288 e 264 kg de N ha-1, foram as que apresentaram a maior produção de forragem para o sorgo forrageiro nos anos agrícola de 2010/2011 e 2011/2012, respectivamente. Já para a aveia, a dose de 187 kg de N ha-1 foi a que apresentou a maior produção de forragem. As doses de 349 e 328; 212 e 207 kg de N ha-1 foram as que apresentaram os maiores teores de PB e DIVMS para sorgo, nos anos agrícolas de 2010/2011 e 2011/2012, respectivamente. Os teores de FDN e FDA não foram influenciados pelas doses de N no cultivo do sorgo. Para a aveia preta, a dose de 220 kg ha-1 de N foi a que apresentou o maior teor de PB, enquanto que a DIVMS, FDN e FDA as doses de N não tiveram efeito significativo. As maiores extrações de N, P e K foram atingidas quando sob as doses de 298; 375 e 271 kg de N9 ha-1, respectivamente para a cultura do sorgo no ano de 2010/2011, já para o ano de 2011/2012 essas doses foram 234; 375 e 324 kg de N ha-1, respectivamente. Para a aveia preta as doses de 218, 240 e 198 kg ha-1 de N sãos as que proporcionam as maiores extrações de N, P e K, respectivamente. Quanto aos valores de recuperação, eficiência e recuperação e eficiência fisiologia do nitrogênio, as menores doses de N são as mais eficientes para ambas as culturas. / In Brazil the production of milk and meat has as main feature the production almost exclusively on pasture, this trait has its advantages and disadvantages; among the main advantages is the low cost of production. The disadvantage would be able to produce food with quality and quantity throughout the year. The aim of this study was to evaluate the effect of nitrogen fertilization on the production and nutritional value of forage as well as he efficiency of nitrogen use and extraction of macronutrients (N, P, K) of the soil through crop of sorghum cv. Jumbo and oat cv. Iapar 61. The study was conducted in the experimental area of the Universidade Tecnológica Federal do Paraná, Câmpus Dois Vizinhos. For the development of the work, annual crop cycle summer and Winter. For the summer period of the crop years 2010/2011 and 2011/2012, was used forage sorghum cv. Jumbo and culture winter annual, year 2011, was used oat cv. Iapar 61. The experimental design was a completely randomized block design with three replications for each treatment. For forage sorghum in the two summer cycles we used a density of 15 kg ha-1 of viable seeds, being tested doses of 0, 37.5, 75, 150, 225, 300 and 375 kg N ha-1, distributed in three applications equal 1/3 at sowing, 1/3 after the first cut and 1/3 after the third cut. For black oat, we used a density of 40 kg ha-1 of viable seeds, testing doses of 0, 40, 80, 120, 160, 200 and 240 kg N ha-1, were also distributed in three applications , 1/3 at tillering, 1/3 after the first cut and 1/3 after the third cut. Material collection orage sorghum produced during the two summer was performed with manual harvesting of crops, when the culture reached an average height between 0.70 and 0.80m, leaving a residue of plant average of 0.20 m height for regrowth and new collection. For the oat sample collection occurred when the culture reached a size for grazing 25 cm tall, with a manual cut to 10 cm of soil from a known area of 0.25 m2 each. To determine the chemical characteristics of both cultures, the material was dried at 60 oC for 72 hours or until constant weigh, ground through 1 mm sieve, and then evaluated the following parameters:dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), in vitro dry matter digestibility (IVDMD), determination of macronutrients N, P and K, recovery, recovery efficiency and physiological efficiency of nitrogen. All evaluated data were subjected to analysis of variance using SAS 8.1 to 5% of error probability. Doses of 288 and 264 kg N ha-1, showed the most forage production for sorghum forage in agricultural years 2010/2011 and 2011/2012 respectively, for black oat the dose of 187 kg N ha-1 was that with the highest forage yield. Doses of 349 and 328, 212 and 207 kg N ha-1 were those that showed the highest levels of CP and IVDMD for sorghum, the crop years 2010/2011 and 2011/2012 respectively. NDF and ADF were not affected by N in sorghum crop. For oats, the dose of 220 kg ha-1 N was the one with the highest content of CP, for IVDMD, NDF and ADF doses of N had no significant effect. The major extractions of N, P and K were achieved when applied doses of 298, 375 and 271 kg N ha-1, respectively for sorghum in 2010/2011 already for the year 2011/2012 these doses were 234, 375 and 324 kg N ha-1, respectively. For oats the doses of 218, 240 and 198 kg N ha-1 was that provided the largest extraction of N, P and K, respectively.The values of recovery, recovery efficiency and physiological efficiency of nitrogen, the lowest N are the most efficient for the cultivation of sorghum and oats.

O trigo é um cereal de inverno importante nas propriedades agrícolas no esquema de rotação de culturas e, principalmente para gerar renda. O nitrogênio é o nutriente exigido em maior quantidade pela cultura e o é grande responsável pelo rendimento de grãos e pela composição da qualidade industrial de panificação. O manejo desse nutriente é de suma importância para que se forneça N em todos os estádios da planta, sendo necessário aplicá-lo de forma parcelada. O objetivo do trabalho foi avaliar a resposta do parcelamento da adubação nitrogenada sobre o rendimento de grãos e a qualidade de panificação de dois cultivares de trigo. Conduziram-se experimentos em Pato Branco e Curitibanos em delineamento experimental de blocos ao acaso em esquema bifatorial com três repetições. Foram testados dois cultivares de trigo e 11 formas de parcelamento da adubação nitrogenada + testemunha sem N. Foram utilizados os cultivares BRS Gralha Azul e Quartzo. Com exceção da testemunha, os tratamentos receberam 20 kg N ha-1 na semeadura, parcelando-se 100 kg N ha-1 da seguinte forma: 100-00-00, 00-100-00, 00-60-40, 00- 70-30, 00-80-20, 60-00-40, 70-00-30, 80-00-20, 50-50-00, 70-30-00, 30-70-00, no estádio de duplo anel, espigueta terminal e emborrachamento, respectivamente. Foram avaliados os caracteres morfológicos, componentes de rendimento, rendimento de grãos, índice de clorofila Falker, teor de nitrogênio no tecido vegetal e qualidade industrial de panificação. Nos dois locais de avaliação ocorreu estresse hídrico no desenvolvimento da cultura. O rendimento de grãos e a qualidade de panificação são pouco influenciados pelo parcelamento da adubação nitrogenada, especialmente em áreas que apresentam níveis elevados de matéria orgânica no solo. O cultivar BRS Gralha Azul produziu farinha de alta qualidade de panificação. A utilização de N na cultura do trigo aumenta o rendimento de grãos e a qualidade de panificação, porém sem resposta suficiente para indicar a melhor forma de parcelamento. / Wheat is a winter cereal important for farm in the crop rotation scheme and, primarily to generate income. Nitrogen is the nutrient most required for the culture and is largely responsible for the yield and the composition of industrial breadmaking quality. The management of this nutrient is of paramount importance to provide N in all stages of the plant, being necessary to apply it in installments. The objective of this study was to evaluate the response of split nitrogen fertilization on grain yield and quality of two cultivars of bread wheat. Experiments were conducted in Pato Branco and Curitibanos in randomized block designer in a factorial scheme with three replications. Two bread wheat and 11 forms installment of nitrogen fertilization + control without N. Were used the cultivars BRS Gralha Azul and Quartzo. Was parceled 100 kg N ha-1 following: 100-00-00, 00-100-00, 00-60-40, 00-70-30, 00-80- 20, 60-00-40, 70-00-30, 80-00-20, 50-50-00, 70-30-00, 30-70-00, in double ring, terminal spyke and booting stages, respectively. Were evaluated the morphological characters, yield components, grain yield, Falker chlorophyll index, nitrogen content in plant tissue quality and industrial bakery. In both evaluation sites occurred drought stress on crop development. Grain yield and wheat baking quality were little influenced by split nitrogen fertilization, especially in lanes that showed high levels of organic matter in soil. The BRS Gralha Azul produced a high quality wheat bakery. The use of N in wheat baking quality and yield increases, but not enough to indicate the best way to answer parceling.

O uso de diferentes técnicas conservacionistas propicia condições de manutenção do potencial produtivo dos solos, merecendo atenção de pesquisas na área. Dessa forma, objetivou-se avaliar a produção de abobrinha de tronco (Cucurbita pepo) comparando os sistemas de cultivo convencional e plantio direto. Foi desenvolvido um experimento no Campus Experimental da UTFPR - Dois Vizinhos sob um Nitossolo Vermelho. O delineamento utilizado foi de blocos casualizados com parcelas subdivididas. Foram avaliados dois sistemas de cultivo do solo, plantio direto e convencional. No período hibernal foram utilizadas as culturas de cobertura de aveia solteira em Plantio Convencional – (PC) e Plantio Direto (PD) e um consórcio de aveia, ervilhaca e nabo implantado também em PD. Foram realizadas duas épocas de adubação localizada em covas: uma antes da semeadura da cultura de cobertura hibernal (Antecipada) e outra logo após o manejo com rolo-faca antecedendo a semeadura da abobrinha (Normal). A adubação orgânica foi resultante de compostagem de cama de aviário. A cultura da abobrinha foi implantada no mês de setembro. A colheita dos frutos foi efetuada quando os mesmos atingiram padrão comercial entre 15 e 20 cm. Após o término do ciclo da abobrinha toda a área foi capinada e recebeu um policultivo de milho + leguminosa, sendo o milho implantado nas mesmas covas que comportava abobrinha e a leguminosa na entrelinha de cultivo. As variáveis dos frutos analisadas foram: massa(kg), circunferência (cm), comprimento (cm), número de frutos e ciclo. As avaliações do solo se referem ao estoque de carbono (C) e nitrogênio (N) do solo e ao fracionamento da matéria orgânica. As culturas de cobertura foram avaliadas quanto a produção de matéria seca e teor de N nos resíduos vegetais. Os sistemas de manejo do solo e épocas de adubação interferiram no comprimento e no número de frutos produzidos. O sistema convencional de cultivo foi o mais produtivo ao final do experimento. Os teores de N e C total do solo bem como o COP não foram influenciados pelos sistemas de manejo e épocas de adubação. A adubação antecipada afetou os teores de N do solo após três ciclos de cultivo, sendo menores que o sistema de adubação normal. / The use of different conservation techniques provides conditions to maintain the productive potential of soils, deserving attention of the researches in the area. Thus, the objective was to evaluate the production of zucchini trunk (Cucurbita pepo) comparing the conventional cropping systems and direct planting. This experiment was conducted in the Experimental Campus UTFPR - Two neighbors under a Red Nitosoil. The experimental design was randomized blocks with split plots. We evaluated two systems of cultivation, direct and conventional drilling. In the winter period were used cover crops of single oat in Conventional Planting - (CP) and Direct Planting (DP) and a consortium of oat, vetch and radish also implemented in DP. We performed two periods of fertilization located in pits: one before crop sowing of winter covers (Advance) and another shortly after management with roller-knife prior to sowing squash (Normal). The organic fertilization was resulted from composting poultry litter. The culture of zucchini was implanted in September. The harvest fruit was made when the same achieved commercial standard between 15 and 20 cm. After termination of the cycle of zucchini whole area was weeded and received a polyculture corn + leguminous, corn being deployed in the same pits that contained zucchini and legume cultivation between rows. The variables analyzed were the fruits: mass (kg), circumference (cm) length (cm), number of fruits and cycle. The assessment of soil refers to the stock of carbon (C) and nitrogen (N) of the soil and the organic matter fractionation. The cover crops were evaluated for the production of dry matter and the content of N in vegetable waste. The systems of management of soil and fertilization times interfered in the length and number of fruits produced. The tillage system was more productive at the end of the experiment. The concentrations of N and C of the soil and the COP were not influenced by tillage systems and times of fertilization. The early fertilization affected the levels of N in the soil after three cycles of cultivation, being smaller than the system of regular fertilization.

Orientador: Itamar Andrioli / Banca: Renato de Mello Prado / Banca: José Carlos Barbosa / Banca: Alba Leonor da Silva Martins / Banca: Adilson Pelá / Resumo: Para uma agricultura lucrativa, racional e sustentável o reconhecimento da fragilidade do solo modificado pelo homem deve servir de parâmetros para a utilização e busca de novas alternativas tecnológicas. Sendo assim, vem sendo utilizado um sistema de semeadura direta, que tem como seus princípios o não revolvimento do solo, permitindo o acúmulo de material vegetal na superfície do solo. O objetivo deste trabalho foi avaliar os atributos químicos e físicos do solo e a produtividade da cultura do milho com doses de nitrogênio, em sistemas de manejo de plantas de cobertura cultivadas em pré-safra. Foram utilizadas durante três anos, as seguintes plantas: mucuna cinza (Stilozobium cinereum), lab lab (Dolichos lablab L.), milheto (Pennisetum americanun (L). Leeke), feijão guandu anão (Cajanus cajan (L) Millsp), feijão-de-porco (Canavalia ensiforms L) e pousio (vegetação espontânea), e as doses de nitrogênio: 0, 60, 120,180 kg/ha, na forma de ureia em cobertura, em sistema de semeadura direta. Todas as plantas de cobertura aumentaram a quantidade de matéria orgânica na camada superficial do solo e as leguminosas plantadas em pré-safra à cultura do milho tornam dispensável a aplicação de N em cobertura / Abstract: For a profitable, rational and sustainable agriculture, acknowlegment of soil frailties must serve as parameter for the use and seek of new technological alternatives. Therefore, no-tillage farming system has been used since the 70s in the Southeast and South of the country, which has as main principle the non-disturbance of the soil, allowing the accumulation of crop residues on the soil surface. The objective of this study was to evaluate the chemical and physical attributes of the soil and corn yield of an oxisol moderate A horizon clayey texture, and yield in different management systems of cover crops grown in pre-season (September to November). The following plants were used in the study, in three years: gray velvet bean (Stilozobium cinereum), lab lab (Dolichos lablab L.), millet (Pennisetum americanun (L.) Leeke), dwarf pigeon pea (Cajanus cajan (L) Millsp), jack-bean (Canavalia ensiforms L) and fallow (spontaneous vegetation), and doses of nitrogen: N0 = 0; N1 = 60; N2 = 120; N3 = 180 kg N / ha in the form of urea in coverage and in no-tillage system. All cover crops increased the amount of organic matter in the upper layer of the soil and the tested leguminous crops make dispensable any nitrogen fertilization after planting / Doutor

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Submitted by Mario BC (mario@bc.ufrpe.br) on 2017-03-16T13:51:43Z No. of bitstreams: 1 Bruna Morais de Souza.pdf: 1707041 bytes, checksum: aa1ce764250111f69962f0b91c1a0a0e (MD5) / Made available in DSpace on 2017-03-16T13:51:43Z (GMT). No. of bitstreams: 1 Bruna Morais de Souza.pdf: 1707041 bytes, checksum: aa1ce764250111f69962f0b91c1a0a0e (MD5) Previous issue date: 2015-07-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Corn is one of the main products produced and marketed worldwide. However, to obtain high productivity necessary to apply synthetic chemical fertilizers, which usually can be harmful to the environment. Because of this, the objective to evaluate the effect of application of organic matter via compost and green manure on corn productivity. The experiment was conducted in a randomized block design, installment scheme subdivided (3 x 3 +1), three vegetables on the plots (Sunn hemp, pigeon pea beans and dwarf beans macassar), three volumes of organic compound in sub-subparcelas (0, 20 and 40 t ha-1) and an additional witness (Chemistry). The variables analyzed were: height of the plants; height of insertion of the first COB; culm diameter; leaf area; chlorophyll content; foliar N content; crude protein content; dry mass; average number of spikes per plant; diameter and length of spikes; number of row of grain; number of grains per row; mass of 1,000 grains; grain productivity; total organic carbon and soil organic matter. The data were subjected to analysis of variance and averages compared by Tukey test at 5% probability. To the study of organic compound concentrations was employed to linear regression analysis. The statistical analyses were performed by Software SAEG 9.1 version. There was no significant difference to chlorophyll a and b, N and crude protein content, just to the right a/b. Maize plants subjected to the green bean fertilizer macassar showed difference with respect to total chlorophyll, being higher than the other legumes. For leaf area production variables, diameter of the cob, COB length, number of Spike and productivity showed a statistically significant difference. Total organic carbon and soil organic matter after the cultivation of corn, showed no statistical difference. The amount of 40 t ha-1 of the organic compound fertilizer green beans macassar caused greater yields of corn. / O milho é um dos principais produtos produzidos e comercializados em todo o mundo. Entretanto, para obtenção de alta produtividade se faz necessário a aplicação de adubos químicos sintéticos, que via de regra podem ser prejudiciais ao ambiente agrícola. Devido isso, objetivou-se avaliar o efeito da aplicação de matéria orgânica via adubação verde e composto orgânico na produtividade do milho. O experimento foi conduzido em um delineamento de blocos ao acaso, em esquema de parcela subdividida (3 x 3 +1), sendo três leguminosas nas parcelas (crotalária, feijão guandu anão e feijão macassar), três quantidades de composto orgânico nas sub-subparcelas (0, 20 e 40 t ha-1) e uma testemunha adicional (químico). As variáveis analisadas foram: altura das plantas; altura de inserção da primeira espiga; diâmetro do colmo; área foliar; teor de clorofila; teor de N foliar; teor de proteína bruta; massa seca; número médio de espigas por planta; diâmetro e comprimento de espigas; número de fileira de grãos; número de grãos por fileira; massa de 1.000 grãos; produtividade de grãos; carbono orgânico total e matéria orgânica do solo. Os dados foram submetidos a análise de variância e as médias comparadas pelo teste de Tukey a 5% de probabilidade. Para o estudo das concentrações do composto orgânico foi empregado a análise de regressão linear. As análises estatísticas foram efetuadas pelo Software SAEG versão 9.1. Não houve diferença significativa para clorofila a e b, teor de N e proteína bruta, apenas para a variável razão a/b. As plantas de milho submetidas ao adubo verde feijão macassar mostrou diferença com relação a clorofila total, sendo superior as demais leguminosas. Para as variáveis de produção área foliar, diâmetro da espiga, comprimento da espiga, número de espiga e produtividade apresentaram diferença estatística significativa. Carbono orgânico total e matéria orgânica do solo após o cultivo do milho, não apresentou diferença estatística. A quantidade de 40 t ha-1 de composto orgânico aliado ao adubo verde feijão macassar ocasionou maiores produtividades de milho.

Graduation date: 1993

Cabbage is one of the most important and widely grown crops in KwaZulu-Natal (KZN). In cabbage production, no clear cropping methods exist (other than succession cropping) to allow the soil to recover its fertility status naturally after the harvested has crop absorbed nutrients from the soil. Succession cropping system is extensively practiced by cabbage farmers. Succession cropping is when a succeeding vegetable crop is planted immediately after harvesting the preceding crop. This does not allow soil fertility status to be balanced by soil microbes in an environmentally friendly approach. Instead, synthetic fertilizers are heavily used to rectify soil fertility status and these have negative impacts on the soil in the long term, followed by yield decline. However, the economic downturns and green environment awareness have caused researchers and some farmers to focus more on developing environmentally healthy crop production technologies. A priority in this study was to elucidate effects of cover crops-green manure as rotational crops in cabbage production. The experimental site is located at Cedara Research Station. In 2009, soil samples were taken from the top 30 cm of the soil profile, in a zigzag pattern in 5 m x 5 m grids for fertility analysis. Results were used to determine nutrient deficiencies, and blanket application of phosphorus and potassium followed according to each grid’s deficiency. The study was divided into two cycles, with each cycle consisting of season one and season two. The study was conducted over a two year period. Cycle one, season one, 2009/2010 (Dec-Mar): four treatments (sunn hemp: planted at 50 kg/ha seeding rate; forage sorghum: planted at 50 kg/ha seeding rate; mixture of sunn hemp-forage sorghum: each planted at 25 kg/ha seeding rate and control: cabbage planted at 30 cm within rows x 60 cm between rows) were used. The statistical design of the study was a 4x4 Latin Square experiment repeated twice in adjacent fields (347 m2 each) 6 m apart, with a total of 32 plots. Each experimental plot was 8.5 m x 9 m. Genstat Package, 9th Edition was used for data analysis. Standard cabbage production recommendations were followed in control treatments. Cabbage yield was determined in all control plots. Weed coverage percentages were determined in all four treatments. Cycle one, season two, 2010, (Apr-Aug): all 32 plots from season one were each split into four, in a Split Plot design, resulting in a total of 128 plots in both fields. Nitrogen was applied at four different levels: 0, 80, 160 and 240 kg N/ha. Standard cabbage production methods were followed again as in the control treatment in season one. Cover crops were replaced by planting cabbage. Cabbage was repeated in the control plots. Cabbage yield, cabbage leaf nutrients, soil nitrate and ammonium nitrate and soil carbon to nitrogen (C:N) ratio were measured. Cycle two, season one, 2010 (Sep-Dec): The same method in cycle one, season one was repeated. Cycle two, season two, 2010/2011, (Dec-Apr): The same method in cycle one, season two was repeated. Although in this study there was visibly a large amount of residues left over after the trial was harvested, the use of a tractor-drawn slasher was not very effective. The slashed material was not chopped into smaller pieces, as it would if a roll-chopper had been used. A tractor-drawn slasher was used because it is a tool available to many farmers. As a result, it was not a simple process to transplant seedlings mechanically, due to the amount of organic matter that was in the soil after it had been incorporated. The mechanical planter pulled off, removed and became blocked by the residues, and as a result it was not able to operate as it would in normal soils. The residues removed soil from the furrows and that caused seedlings to fall over as all the soil for the root system support had been moved by the planter and stuck residues. The planter had to be assisted by hand planting seedlings that were not properly planted mechanically. Hence, from the operational perspective, the choice of tools for chopping were not effective in this study and this is something to be considered in future studies, where it will be necessary to compare different tools for planting and cover crop incorporation into the soil. During the present study, soil N content in different plots had significant differences (P=0.05). The control showed high levels of total N content, but this was not related to the low yields exhibited by cabbage after cabbage at all levels of N. Since, where there were cover crops, the N content was low, this could mean that N was immobilized, compared to the cabbage treatments where plenty of N was available. Immobilized N is thus not available for leaching, polluting the environment. The yield of cabbage was significantly lowest in controls. The study showed that cover crop-green manure use has a positive effect in terms of yield improvement. The cabbage yields from the sunn hemp plots at a 0 kgN/ha were significantly different from the yield of cabbage planted following cabbage at 240 kgN/ha N. The study also showed that N is not the only yield determinant in cabbage production. Too much N has a tendency to suppress cabbage yields. The cover crop-green manures selected for this study were shown to be ineffective in suppressing weeds. This was true even though the weed coverage percentage in each of the cover crop-green manure plots was above 65%, except for the cabbage crop. This study did not separate different weeds, but the most dominant weeds were Amaranthus hybridus (pigweed), Galinsoga parviflora (gallant soldier), Bidens pilosa (common blackjack) and Cyperus esculentus (yellow nutsedge). These weeds were effectively controlled in the cabbage sole crop by the use of herbicides and mechanical weeding. The result of cover crop-green manures not suppressing weeds was significantly associated with the cover crop-green manure seeding rate. This study has been a starting point in the development of cover crops-green manure as rotational crops in cabbage production. It is concluded that cover crop-green manure (sunn hemp and forage sorghum) used in this study for vegetable (cabbage) production has proven to be successful in improving yields. Yields obtained from cover crop-green manure treatments were better than yields obtained from - conventional tillage methods for cabbage production (control). However, in cabbage, weed suppression and soil N content, failed to improve significantly in response to the cover crop green manures used. The high plant population density under a cover crop, combined with weed population, may lead to high uptake of soil N for plant growth, leaving less N in the soil and in the plant. In the sole cabbage crop, because of low competition, there was adequate uptake of N for plant growth and yet the crop was not exhaustive of soil N. Further research is required in the following areas: comparison of cabbage with other vegetable crops in response to the effect of the selected cover crops; comparison of mechanical weeding and herbicide use as means of controlling weeds during cover crop-green manure growth; identification of dominant weeds in the presence and absence of cover crops, and monitoring of soil water relations and other fertiliser effects. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

[Truncated abstract] Weeds are a major limitation to agricultural and horticultural production and the main method of control is the use of herbicides. In addition to the resulting chemical pollution of the environment, the wide spread and continues use of herbicides have resulted in many weeds developing resistance to commonly used herbicides. This study investigated the potential of using green manures as a cultural method of control of weed invasion in agricultural fields. To understand the general mechanisms involved in the suppression of seed germination in green manure amended soils, seeds of crop species with little or no dormancy requirements were used in certain studies. Lettuce (Lactuca sativa) and cress (Lepidium sativum) seeds were sown to a sandy soil amended with green manures of lupin (Lupinus angustifolius), Brassica juncea, or oats (Avena sativa) to determine if the amendments affected seed germination and/or decay. It was hypothesised that the addition of plant material would increase the microbial activity of the soil thereby increasing seed decay, under laboratory and greenhouse conditions. Initial experiments used lettuce, cress and lupin seeds. Lettuce and cress are commonly used as standard test species for seed viability studies. Subsequent experiments used seeds of annual ryegrass (Lolium rigidum), silver grass (Vulpia bromoides), wild radish (Raphanus raphanistrum) and wild oat (Avena fatua) as these weed species are commonly found throughout agricultural regions in Western Australia. Amending the soil with lupin or Brassica green manure was established as treatments capable of developing environments suppressive to seed germination. Lupin residues as green manure showed the strongest inhibition of seed germination and seed decay. The decay of certain seeds was enhanced with changes to soil microbial activity, dissolved organic carbon and carbon and nitrogen amounts in lupin amended soil. Seeds of weed species were decayed in lupin amended soil, but showed varied degree of decay. Annual ryegrass and silver grass were severely decayed and wild oat and wild radish were less decayed, in lupin amended soil.

Thesis (doctoral)--Swedish University of Agricultural Sciences, 2005. / Thesis documentation sheet inserted. Appendix consists of reproductions of 5 published papers and manuscripts, four co-authored with others. Includes bibliographical references. Issued also electronically via World Wide Web in PDF format; online version lacks appendix of papers; map in online version displays in color.