L'adozione di (agro)ecosistemi sostenibili viene indicata come una efficace strategia in grado sequestrare carbonio (C) nel suolo, mitigando così il cambiamento climatico e migliorando la fertilità. Sebbene il potenziale di sequestro del C della non-lavorazione (NT) sia stato generalmente sovrastimato, esso risulta essere di 0,26 Mg ha-1 anno-1 superiore rispetto al regime arativo. Inoltre, il 76,6% di questo quota è localizzato in frazioni considerabili come relativamente stabili. Il NT aumenta lo sviluppo radicale delle colture erbacee (es. mais, soia, frumento) negli stati superficiali del suolo (0-5 cm). Le correlazioni tra i parametri di densità radicale e le proprietà fisiche del suolo mostrano come lo sviluppo radicale sia un fondamentale indicatore di qualità del suolo in NT. I residui delle cover crops influenzano le emissioni di protossido d’azoto (N2O) in NT: i residui di segale favoriscono l'immobilizzazione dell’azoto (N), aumentandone così l'efficienza d’utilizzo e diminuendo le emissioni, mentre i residui di veccia vellutata aumentano l’N2O come conseguenza della mineralizzazione dell’N. Le emissioni di N2O e la produttività dei prati stabili possono essere positivamente correlate, perché meccanismi diversi rispetto alla regolazione indotta dalla disponibilità di N possono controllare l'N2O: il C potrebbe essere un principale fattore di regolazione per nitrificazione e denitrificazione. / Adoption of sustainable (agro)ecosystems has been widely suggested to increase soil organic carbon (C) sequestration, to mitigate climate change and enhance soil fertility. Although its carbon sequestration potential has been generally overestimated, no-till (NT) results in an extra C sequestration of 0.26 ± 0.18 Mg ha-1 yr-1 as compared to conventional tillage and 76.6% of this extra C is located in C pools which could be considered relatively stable. NT increases root development of field crops (i.e. maize, soybean, winter wheat) in the top soil (0-5 cm), while does not in the deeper soil (5-60 cm). Positive correlations between root density and soil physical parameters shows how roots are main drivers of soil physical properties under NT. Cover crop residues may affect nitrous oxide (N2O) emissions under NT: rye residues enhances soil-nitrogen (N) immobilization, thus increasing N use efficiency and decreasing N2O, while hairy vetch residues as cover crop under NT increases N2O as a consequence of soil-N mineralization. N2O emissions and shoot productivity may be positive correlated in grasslands, because other mechanisms than plant-induced regulation of soil N pool may control N2O: C could be a major factor regulating nitrification and denitrification processes.

Cette thèse visait à caractériser et à modéliser la dynamique des trois ressources principales que sont l'eau, l'azote et le rayonnement dans une association en relais maïs-plante de couverture en semis direct en région tropicale subhumide et ses conséquences sur la productivité de la culture principale et de l'ensemble du système et sur les flux d'eau et d'azote dans le sol. Le travail repose sur un dispositif expérimental mis en place dans les Cerrados, à Unaí (Minas Géras, Brésil) en 2007 pour deux années agricoles, d'une part en station expérimentale permettant un effort de mesure intense et d'autre part dans un réseau de parcelles d'agriculteurs offrant une large gamme de situations pédoclimatiques et de modalités de mise en œuvre des systèmes de culture étudiés. Dans ces derniers, la culture principale était un maïs, et la plante de couverture associée en relais était une culture fourragère tropicale, soit la légumineuse, Cajanus cajan soit la poacée, Brachiaria ruziziensis. Deux dates de semis, précoce et tardive étaient considérées pour le semis de la plante de couverture au sein du maïs, dans le cas de l'essai en station. Ce travail montre que rendement du maïs n'a pas été significativement affecté par la présence de la plante de couverture semée précocement au sein du maïs, en comparaison avec le rendement du maïs en culture pure. En revanche, la production en biomasse de la plante de couverture a été significativement réduite dans l'association. Le semis précoce de la plante de couverture au sein du maïs permet une production en biomasse significativement plus importante qu'un semis tardif (20 jours après floraison du maïs), et une production totale en biomasse de l'ensemble de l'association significativement plus importante par rapport aux cultures pures. Cette production totale a été plus du double comparée à celle de la culture pure de maïs dans le cas de l'association maïs-Cajanus. Les valeurs du Land Equivalent Ratio (LER) du rendement en grain de maïs et de la production de biomasse ont été supérieures à 1, atteignant jusqu'à 2.03 témoignant d'une meilleure valorisation des ressources par les espèces associées et l'avantage de tels systèmes pour produire à la fois du grain et du fourrage. La thèse montre aussi la forte variabilité du potentiel de production de ces systèmes en parcelles de producteurs et suggère que lorsque les ressources en eau et en azote sont moins disponibles que dans l'essai de station, des compétitions entre maïs et plantes de couverture peuvent réduire les performances agronomiques du maïs et/ou de la plante de couverture comparativement par rapport à la culture pure équivalente. La biomasse totale produite reste cependant supérieure à celle de la culture pure de maïs, sauf pour de rares exceptions où de plus faibles disponibilités en ressources, parfois accentué par des difficultés de gestion technique, le maïs semble souffrir de compétition plus forte et/ou la plante de couverture ne produit que très peu de biomasse. La thèse évalue la capacité d'un modèle de simulation de culture associées, STICS-CA, à fournir une analyse plus fine de la dynamique du partage des ressources dans ces systèmes et à en estimer les performances agronomiques et certains impacts environnementaux en fonction de conditions techniques et édapho-climatiques différentes de celles de notre dispositif. Des modifications mineures et le calage du modèle ont conduit à une simulation satisfaisante des cultures pures de maïs et Brachiaria et de l'association maïs-Brachiaria en semis direct sur mulch pailleux. En revanche il n'a pas été possible d'obtenir une simulation satisfaisante du maïs en semis conventionnel sur sol labouré, ni du Cajanus en culture pure et de l'association maïs-Cajanus en semis direct. . La thèse fournit des informations sur les imperfections du modèle et propose des améliorations aussi bien en termes de formalismes pour la prise en compte de la minéralisation du mulch, qu'en termes de dispo exp / This thesis dealt with characterizing and modeling the dynamics of the three principal resources which are water, nitrogen and radiation in a no-tillage relay intercropping maize-cover crop systems, under sub-humid tropical area climate. Moreover, productivity of the main crop and of the whole system and nitrogen and water flows in the soil are assessed.The study was based on an on-field approach/experimental design carried out during two crop growing seasons in Cerrados region, in Unaí (Minas Géras, Brazil) since 2007. Firstly, an experimental station was used allowing an intense effort of measurement and secondly, a whole of several farmer's fields offering a wide range of soil and climate conditions and modalities of implementation of the studied cropping systems. In the latter, main crop was maize, and intercropped cover crop was a tropical fodder crop, either leguminous, Cajanus cajan or gramineous, Brachiaria ruziziensis. Two dates of sowing, early and late were considered for the sowing of the cover crop in established maize, in the case of the experimental station. This study showed that maize yield was not significantly affected by the presence of the relay cover crops in comparison with maize as the sole crop, even when the cover crop was sown soon after maize emergence in comparison with maize sole crop. In contrast, the production of biomass by the cover crop was significantly lower when grown with maize than when it was grown as a sole crop. In the intercropped systems, when sown early, the cover crop produced higher total biomass than when sown late (20 days after maize flowering). Moreover, total aboveground biomass production of maize intercropped with a cover crop was much higher than that of any of the crops sown alone. Total biomass produced by maize and pigeon pea (Cajanus cajan) was more than double that maize grown alone. The Land Equivalent Ratio (LER) values of both maize grain yield and biomass production were higher than one, whatever the intercrop system, reaching up to 2.03 providing better available resources use efficiency by the intercropped plants. Thus, such systems permit to produce both maize grains and forage.The thesis shows also the strong variability of the production potential of these systems in farmer's fields and suggests that when water and nitrogen resources are less available than in the experimental station, competitions between maize and cover crops can reduce the agronomic performances of maize and/or the cover crop when compared to the equivalent pure sole crop. Total biomass produced by intercropping remained however higher than that of maize sole crop, except for rare exceptions where lower resources availability, sometimes accentuated by difficulties of technical practice, maize seems to suffer from stronger competition and/or the cover crop produced only very little biomass. The thesis evaluates the capacity of the STICS intercrop model, STICS-CA, to provide a finer analysis of the dynamics of the resource sharing in these systems and to estimate their agronomic performances and certain environmental impacts according to technical practices and soil and climate conditions that were different from those of our experimental station. Minor modifications and model calibration led to obtain satisfying simulations of the sole crops maize and Brachiaria and intercrop maize-Brachiaria in no-tillage under mulch. On the other hand, it was not possible to obtain satisfying simulations of sole crop maize in conventional tillage, nor of sole crop pigeon pea and intercrop maize-pigeon pea in no-tillage under mulch. The thesis provides information on the model imperfections and as well proposes improvements in terms of formalisms to take into account the mineralization of the mulch, as in terms of experimental design.

L’intensificazione sostenibile delle pratiche agricole rappresenta un paradigma per il passaggio da sistemi agricoli tradizionali all’applicazione di tecnologie e tecniche moderne per la produzione agricola. A livello globale si è diffuso l’interesse verso il modello di Agricoltura Sostenibile (AS), in vista di alcuni problemi che possono minacciare la sicurezza alimentare mondiale: crescita della popolazione mondiale, cambiamenti nella domanda delle produzioni agricole, percentuale elevata di persone sottonutrite, cambiamenti climatici, diminuzione delle risorse naturali. Il progetto “Produzione di cibo appropriato: sufficiente, sicuro, sostenibile”, ancora in corso, lavora per raggiungere alcuni scopi: (1) rilevare e valutare la disponibilità quantitativa e qualitativa degli alimenti destinati al consumo umano, (2) proporre nuovi sistemi di produzione agro-zootecnica, (3) sviluppare tecniche appropriate per processare e conservare gli alimenti, al fine di ottenere uno stato di sicurezza alimentare e sostenibilità ambientale ed economica. L’obiettivo generale di questo lavoro è quello di mostrare quali sono le possibili alternative ai sistemi agricoli tradizionali, sia nei Paesi Sviluppati sia in quelli in Via di Sviluppo, al fine di aumentarne l’efficienza e diminuirne gli impatti sull’ambiente, aumentando lo stato globale di sicurezza alimentare. Per i Paesi in Via di Sviluppo l’attenzione si concentra sulle pratiche di sviluppo rurale integrato, al fine di implementare quantitativamente la produzione alimentare e, conseguentemente, la sicurezza alimentare, preservando nel contempo l'ambiente. Per i Paesi Sviluppati, in cui i rendimenti agricoli sono già potenzialmente molto elevati, l’attenzione viene focalizzata sul migliorare la produttività del suolo, riducendo gli input esterni e le emissioni di gas ad effetto serra, attraverso l’adozione di sistemi agricoli conservativi. / Sustainable intensification of agricultural practices represents a paradigm shift from traditional farming systems to the application of modern technologies and techniques to crop production. At global level it has been widespread interest towards Sustainable Agriculture (SA) model, in view of some issues that will may threaten the world food security: growing world population, changes in agricultural product’s demand, high prevalence of undernourishment, climate changes, decreasing of natural resources. The project “Production of proper food: sufficient, safe, sustainable" is still working to achieve some purposes: (1) to detect the availability quantity and quality of food for human consumption, (2) to propose new agro-livestock production systems, (3) to develop appropriate techniques for processing and storage of foodstuffs, in order to achieve food security, environmental and economic sustainability. The objective of this work is to show what are the possible alternatives ways at traditional agricultural systems, both in Developed and Developing Countries, in order to increase the efficiency and to decrease the impacts on the environment, raising a global condition of food security. For Developing Countries the attention is focused on integrated rural development practices in order to implement food production and the state of food security, while preserving the environment. For Developed Countries, in which yields are already potentially higher, the attention is focused on enhance soil productivity while reducing external farming input and greenhouse gases emission by the adoption of conservation agricultural systems.

<p>For agricultural soils to be perpetually productive, farmers must maintain and improve the physical, chemical, and biological properties of the soil. The loss of soil to erosion is a major challenge to soil health, contributing to farmland loss and declines in productivity. This is a long-term problem for agriculture because there is a limited amount of topsoil available. Another costly loss happens when<em> residual nitrogen is lost to leaching or carried away in runoff. This is a particular problem in the fall and winter months when fields lie fallow, and there are no plants to take up excess nitrogen. Losing nitrogen is a problem for both the nutrient content of the soil as well as a serious concern in terms of water contamination.</em><em> </em>Cover crops provide a way to at least partially address each of these and many other agronomic and soil health issues. Although there has been a steady increase in cover crop use, adoption has been relatively slow. This is likely due to a lack of economic information and understanding of the associated risk. To address this problem, field level data was gathered from farmers across central and northeastern Indiana. The data included information on cash crop yield, cover crops grown, fertilizer use, among many other variables. The sample was trimmed based on the estimated propensity to cover crop, in order to reduce selection bias. Using this data, the effect of cover crops on the mean and variation of the subsequent cash crop yield was estimated using regression analysis. This information was combined in a stochastic analysis of a farm enterprise budget. The effects of cover crops on farm finance and risk were evaluated. These final analyses provide agricultural producers with more information to make informed decisions regarding the adoption of cover crops. The information may also provide insight to policy makers, who may wish to understand more completely the private economics of cover crops. The results indicated that cover crops have the ability to provide economic benefits when grown prior to corn in our study region. These include increased yield, reduced need for nitrogen fertilizer, and increased temporal yield stability. These benefits translate into higher revenue from the sale of the grain, lower input costs, and lower risk and uncertainty. However, the results for soybeans showed cover crops had a negative, albeit statistically insignificant, effect on desirable measures. This led to lower projected revenue, higher projected costs, and increased expected risk. Even so, the average corn-soybean contribution margin with cover crops was nearly equal to the baseline scenario. Furthermore, the analysis of risk showed that the corn-soybean two-year average would be preferred by farmers with moderate to high risk aversion. The difference between the effect of cover crops in corn and soybeans may be due to differences in the crop’s inherent nitrogen needs and the difficulty of cover crop establishment after corn in the region.<br></p>

Orientador: Ciro Antonio Rosolem / Banca: Maria Helena Moraes / Banca: Juliano Carlos Calonego / Banca: Sandro Roberto Brancalião / Banca: Sônia Carmela Falcci Dechen / Resumo: O manejo inadequado do solo ocasiona a formação de camadas compactadas que prejudicam o desenvolvimento radicular das plantas, diminuindo a disponibilidade de água e nutrientes, enquanto que o acúmulo de carbono pode melhorar a qualidade do solo. Em sistemas com semeadura direta (SSD), com a menor mobilização do solo, pode-se usar, em rotação, plantas com sistema radicular vigoroso, capaz de crescer em condições adversas. Este trabalho teve como objetivo avaliar a ação de espécies de cobertura, gramíneas e uma leguminosa, em rotação com a cultura da soja, nos atributos físicos de um Latossolo, no acúmulo de carbono, nas diferentes frações da matéria orgânica e na produção da soja, em semeadura direta, ao longo de três anos. O experimento foi conduzido em um Latossolo Vermelho distroférrico de textura argilosa, na Fazenda Experimental Lageado, Unesp/Botucatu, nos anos agrícolas de 2006/2007, 2007/2008 e 2008/2009. No outonoinverno foram estabelecidas parcelas com braquiária (Brachiaria ruziziensis), sorgo granífero (Sorghum bicolor) e sorgo consorciado com braquiária. Na primavera, foram cultivados, em subparcelas, milheto (Pennisetum glaucum), cober crop [Sorghum bicolor (L.) Moench x Sorghum sudanense Piper Stapf], crotalária (Crotalaria juncea) ou pousio. A soja foi cultivada como safra de verão. Em março do primeiro ano foram retiradas amostras para caracterização da área experimental. Após o manejo das espécies cultivadas na primavera, no primeiro e terceiro ano, foram retiradas amostras indeformadas nas camadas de 0-5; 7,5-12,5; 15-20; 27,5-32,5 e 47,5-52,5 cm para determinação da densidade do solo, porosidade e curva de retenção de água no solo. Nas mesmas épocas, a estabilidade de agregados foi avaliada em amostras coletadas nas camadas de 0-5 e 5-10 cm. No terceiro ano do experimento, o intervalo hídrico ótimo (IHO) foi determinado... (resumo completo, clicar acesso eletrônico abaixo) / Abstract: Compacted layers resulting from inappropriate soil management may impair root growth, thus decreasing water and nutrient acquisition by crops. Conversely, soil quality is improved with soil carbon accumulation. In areas under no-till, crop rotation with plants with vigorous root systems may alleviate soil compaction, as well as increase soil carbon. In this experiment the effects of cover crops on soil physical properties, carbon accumulation, organic matter quality and soybean production under no-till in a compacted soil were studied for three years. The experiment was conducted on a clayey Rhodic Ferralsol, Lageado Experimental Farm, Unesp/Botucatu, in 2006/2007, 2007/2008 and 2008/2009. Congo grass (Brachiaria ruziziensis), grain sorghum (Sorghum bicolor) and a mix of both were cropped during fall-winter. Then, in the spring, pear millet (Pennisetum glaucum), cober crop [Sorghum bicolor (L.) Moench x Sorghum sudanense Piper Stapf] and indian hemp (Crotalaria juncea) were cropped and a treatment under fallow was set on sub-plots. Soybean was cropped as a summer crop. In March of the first year, samples were taken for characterization of the area. Right after spring crops were chemically desiccated in 2006 and 2008, undisturbed soil samples were taken from the layers 0-5; 7.5-12.5; 15-20; 27.5-32.5 and 47.5-52.5 cm to determine bulk density, porosity and water retention curve. At the same time, samples taken from the depths 0-5 and 5-10 cm were used to determine aggregate stability. In the third year, least limiting water range (LLWR) was evaluated in the 7.5-12.5 and 27.5-32.5 cm soil layers. Organic matter characterization was done in the third year, in the depths of 0-5 and 5-10 cm. Roots of spring crops were sampled in the layers 0-5; 5-10; 10-20; 20-40 and 40- 60 cm, one day before chemical desiccation in all growing seasons. Soybean roots were sampled in the same depths at R2 each... (Complete abstract click electronic access below) / Doutor

Orientador: Enes Furlani Júnior / Banca: Marcelo Andreotti / Banca: Salatiér Buzetti / Banca: Luiz Henrique Carvalho / Banca: Edivaldo Cia / Resumo: A aplicação de nitrogênio em cobertura e a manutenção da palhada, realizadas na semeadura direta, devem respectivamente, atender as necessidades da cultura e promover a conservação do solo. Dessa forma o presente trabalho teve por objetivo avaliar o efeito da aplicação de nitrogênio em pré-semeadura do algodoeiro e das plantas de cobertura, implantadas em semeadura direta, sobre as propriedades físicas e químicas do solo e sobre o desenvolvimento e produtividade do algodoeiro. O delineamento experimental empregado foi o de blocos ao acaso composto por três plantas de cobertura (nabo forrageiro, aveia preta e aveia branca) e quatro doses de nitrogênio (0, 30, 60, e 90 kg de N ha-1) aplicadas sobre a palhada do milheto e em pré-semeadura do algodoeiro. Aos 80 dias após a emergência do algodoeiro, nos anos agrícolas de 2006/07 e 2007/08 foram coletas folhas para a análise foliar dos macronutrientes. No mês de abril de 2006, abril de 2007 e abril de 2008 foram realizadas as colheitas das parcelas experimentais com a cultura do algodoeiro. Em maio de 2006 e maio de 2007 foram retiradas amostras de solo nas profundidades de 0-5, 5-10 e 10-20 cm com o intuito de analisar os nutrientes do solo e em agosto de 2006 e agosto de 2007 foram realizadas as análises físicas do solo para as profundidades de 0-15, 15-30, 30-45 e 45-60 cm. De acordo com os resultados obtidos verifica-se em função da utilização de sulfato de amônio em doses crescentes ocorreu diminuição do pH, Ca e do Mg em superfície do solo, assim como o aumento do Al+3 trocável e do teor de enxofre até 20 cm. A utilização do nabo forrageiro proporcionou aumento dos teores de K nas folhas do algodoeiro e a utilização de doses de N até 90 kg ha-1 em pré-semeadura proporcionaram aumento nos teores de N e S. O nabo forrageiro é uma planta de cobertura que proporciona aumento da produtividade do algodoeiro / Abstract: The application of nitrogen and former crop residues maintenance, held in the till, must respectively meet the needs of culture and promote soil conservation.This study aimed to evaluate the effect of nitrogen pre-sowing of cotton crop and cover crop, established in tillage on the physical and chemical properties of soil and cotton plant development and yield. The experimental design was a randomized block consisting of three cover crops (radish, white oat and black oat) and four nitrogen levels (0, 30, 60, and 90 kg N ha-1) applied to the millet and cotton pre-sowing. At 80 days after cotton emergence in season of 2006/07 and 2007/08 leaves were collected for macronutrients foliar analysis. In April 2006, April 2007 and April 2008 cotton crop plots were harvested. In May 2006 and May 2007 soil samples were taken from depths of 0-5, 5-10 and 10-20 cm in order to analyze the soil nutrients and, in August 2006 and August 2007 were carried out the physical soil analysis to depths of 0-15, 15-30, 30-45 and 45-60 cm. The results obtained in depending on the use of ammonium sulphate in increasing doses, there was a decrease in pH, Ca and Mg in the surface soil, as well as the increase in exchangeable Al+3 and the sulfur content of up to 20 cm. The radish provides increased levels of K in leaves of cotton, and the use of doses N 90 kg ha-1 in presowing provided increased levels of N and S. The radish is a cover crop that provides yield increased. The cotton yield increased with the use of N 90 kg ha-1 in pre-sowing / Doutor

Orientador: Sérgio Hugo Benez / Banca: Maria Helena Moraes / Banca: Joaquim Odilon Pereira / Resumo: O presente trabalho teve como objetivo estudar o desenvolvimento do sistema radicular de amaranto (Amaranthus cruentus, variedade BRS Alegria), de milheto (Pennisetum glaucum (L.), variedade BN-2) e de pé de galinha (Eleusine coracana L.) em função de quatro níveis de compactação, caracterizados pelas densidades de 1,21; 1,31; 1,41 e 1,51 Mg.m-3 em duas classes de solo, classificados como Latossolo Vermelho Distrófico e Nitossolo Vermelho Distroférrico. O experimento foi conduzido no campo da Faculdade de Ciências Agronômicas - UNESP, Campus de Botucatu/SP, durante os meses de Novembro de 2002 à Fevereiro de 2003, em um delineamento experimental de blocos ao acaso com quatro repetições em arranjo fatorial de 2 x 3 x 4. Os vasos foram montados com quatro anéis de PVC sobrepostos, com diâmetro interno de 19,5 cm, totalizando 40 cm de altura. Estes comportaram um volume de 12,56 litros de solo, sendo que somente um anel foi compactado, correspondendo à profundidade de 10 a 20 cm. Os vasos, assim montados, foram enterrados a 40 cm de profundidade, encerrando-se o experimento na fase da inflorescência de cada cultura. A seguir, determinou-se o comprimento radicular, volume radicular, diâmetro radicular, massa seca radicular, bem como a massa seca e altura das partes aéreas das plantas. Os dados obtidos foram submetidos à análise de variância com teste de Tukey a 5 % de probabilidade para comparar as médias. Os resultados mostraram que o pé de galinha apresentou, em relação ao amaranto e ao milheto, o sistema radicular com maior comprimento, volume e massa seca, penetrando nas camadas compactadas dos solos até a densidade 1,41 Mg.m-3, aumentando, desta forma, a aeração dos solos e incorporando a matéria orgânica em profundidade; o milheto proporcionou maior quantidade de massa seca na parte aérea em ambos os solos, mostrando... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This paper aimed to study the development of root system of amaranth (Amaranthus cruentus, BRS Alegria variety), milhet (Pennisetum glaucum (L.) BN-2 variety) and "pé de galinha" (Eleusine coracana L.) according to four density levels of soil compaction, characterized by 1,21; 1,31; 1,41 and 1,51 Mg.m-3 densities within two soil types, classified as Distrofic Red Latosoil and Distroferic Red Nitosoil. The experiment was carried out at Faculdade de Ciências Agronômicas - UNESP - Botucatu/SP, from November 2002 to February 2003, in a randomized block experimental design with four repetitions and 2 x 3 x 4 factorial desing. The pots were assembled with four rings of overlayed PVC tubes, 19,5 cm of inner diameter, summing up 40 cm high, containing 12,56 liters of soil, with only ring compacted at 10 to 20 cm depth. Tubes were assembled and buried at 40 cm depth. The experiment was finished at influorescence phase of each culture. Measurement of root length, root volume, root diameter, root dry matter were measured as well as dry matter and lenght of aerial part of plants. Obtained data were submitted to variance analysis under Tukey's test with 5 % of probability for mean comparison. Results showed that the "pé de galinha" showed, regarding to amaranth and milhet, root system with longer length, volume and dry matter working in compacted soil layer up to 1,41 Mg.m-3 density increasing soil aeration and incorporating organic matter; milhet showed the highest aumont of dry matter at aerial part in both soils showing to have good characteristic for soil covering, compared to amaranth and "pé de galinha"; amaranth was sensitive to soil compaction in all the studied densities and variables compared to milhet and "pé de galinha"; and the Distrophic Red Latosoil showed best easy terms to plants development, to present a lower resistance to root penetration compared to Distropheric Red Nitosoil. / Mestre

Made available in DSpace on 2017-07-10T17:37:11Z (GMT). No. of bitstreams: 1 Tiago_Madalosso.pdf: 2572164 bytes, checksum: 04f38c061e9c675c1dc4b7c079f8fa9f (MD5) Previous issue date: 2015-08-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In Brazil it is possible for two or more per year grain crop cultivation, but there is evidence that the cultivation tillage system with only commercial crops has resulted in soil degradation. The objective of this study was to evaluate the balance and efficiency of use of N, P and K, the effect on the chemical properties of soil and biometric variables of crops in grain production systems in western Parana region, encompassing different fertilization and probate cultures. The experiment was designed in randomized blocks with the treatments arrangement in divided plots with 4 repetitions. In the plots were installed the winter successions (5), wheat, oats, sunn hemp, corn second crop + brachiaria and corn 2nd harvest and the subplots fertilizers (3) organic, organomineral and mineral. The summer crop was planted to soybeans. The test was conducted for three seasons, starting with the planting of soybeans in 2013. Soil samples were collected after the 3rd growing at 0-10 and 10-20 cm. In the first crop, the use of organic fertilizer promoted increase in grain yield, mass of thousand grains, at the height of soybean plants, the bedding, the number of pods per plant, increased the leaf content and export of N by grain soybeans. In the third crop, there were no differences between the fertilizer and succession to black oat and sun hemp provided higher-yielding soybeans. The oat presented the highest dry matter yield, higher concentration of P in the shoot and greater extraction of N, P and K. Corn consortium + brachiaria reduced the yield of maize grain compared to monocrop. The application of poultry litter and the use of oat or crotalária as cover crops in winter, provide increased grain yield for the soybean crop. Using the same dose of P and K there is no difference in the yield of soybeans, corn and wheat between mineral fertilizers and organomineral. A use of poultry litter promotes increase of soil P and K soil, but does not increase the levels organic matter. P and K use efficiency is higher in soy succession - 2 nd harvest corn. The efficiency of use of N, P and K is lower in the fertilizer with organic fertilizer. There is no difference in the use efficiency of P and K between organomineral and mineral fertilizers, as for N, the mineral fertilizer has higher efficiency. ON was the nutrient with the most negative balance in the soil and the use of cover crops (black oats and crotalaria) increases the N balance in the soil. OP showed balance in the soil near zero being lower in succession with wheat and oats. The K balance in the soil was negative and was not different between the tested grain and fertilizer production systems / No Brasil é possível o cultivo de duas ou mais safras de grãos por ano, porém há evidências de que o cultivo em sistema plantio direto apenas com culturas comerciais tem resultado na degradação do solo. O objetivo deste trabalho foi avaliar o balanço e eficiência de utilização de N, P e K, o efeito sobre as propriedades químicas do solo e variáveis biométricas das culturas em sistemas de produção de grãos na região oeste do Paraná, englobando diferentes adubações e sucessões de culturas. O experimento foi delineado em blocos ao acaso com arranjo dos tratamentos em parcelas divididas, com quatro repetições. Nas parcelas foram instaladas as sucessões de inverno (5), trigo, aveia preta, crotalária, milho 2a safra + braquiária e milho 2a safra e nas subparcelas os fertilizantes (3), orgânico, organomineral e mineral. A safra de verão foi cultivada com soja. O ensaio foi conduzido por três safras, iniciando com a semeadura da soja em 2013. As amostras de solo foram coletadas após o 3° cultivo nas profundidades de 0-10 e 10-20 cm. No primeiro cultivo, a utilização de fertilizante orgânico promoveu incremento no rendimento de grãos, na massa de mil grãos, na altura de plantas de soja, no acamamento, no número de vagens por planta, incrementou o teor foliar e exportação de N pelos grãos de soja. No terceiro cultivo, não houve diferenças entre os fertilizantes e as sucessões com aveia preta e crotalária proporcionaram maior rendimento de grãos de soja. A aveia preta apresentou a maior produção de massa seca, maior concentração de P na parte aérea e maior extração de N, P e K. O consórcio de milho + braquiária reduziu o rendimento de grãos de milho quando comparado ao cultivo solteiro. A aplicação de cama de frango e a utilização de aveia preta ou crotalária como planta de cobertura no inverno, proporcionam maior rendimento de grãos para a cultura da soja. Utilizando a mesma dose de P e K não há diferenças no rendimento de grãos de soja, milho e trigo entre os fertilizantes mineral e organomineral. A utilização de cama de frango promove incremento dos teores de P e K do solo, porém não incrementa os teores de matéria orgânica. A eficiência de uso de P e K é superior na sucessão soja - milho 2ª safra. A eficiência de uso de N, P e K é inferior na adubação com fertilizante orgânico. Não há diferença na eficiência de uso de P e K entre os fertilizantes organomineral e mineral, já para o N, o fertilizante mineral apresenta eficiência superior. O N foi o nutriente com o balanço no solo mais negativo e a utilização de plantas de cobertura (aveia preta e crotalária) incrementa o balanço de N no solo. O P apresentou balanço no solo próximo a zero sendo menor nas sucessões com trigo e aveia preta. O balanço de K no solo foi negativo e não foi diferente entre os sistemas de produção de grãos e fertilizantes testados

Submitted by Celso Magalhaes (celsomagalhaes@ufrrj.br) on 2017-10-13T12:25:06Z No. of bitstreams: 1 2016 - Pedro Antonio Pa??.pdf: 2520523 bytes, checksum: dbda485ebbcb8e6720ce729890cb05ad (MD5) / Made available in DSpace on 2017-10-13T12:25:06Z (GMT). No. of bitstreams: 1 2016 - Pedro Antonio Pa??.pdf: 2520523 bytes, checksum: dbda485ebbcb8e6720ce729890cb05ad (MD5) Previous issue date: 2016-03-04 / This study aimed to evaluate the performance of a succession of corn and bean, submitted to organic management associated with green manure from a mixture of species with different spatial arrangements. The experiment was conducted in the Sistema Integrado de Produ??o Agroecol?gica - SIPA, located in Serop?dica - RJ, Brazil. The statistical design was a completely randomized blocks with six treatments and four replicates, totaling twenty four plots. In this sense, the experiment was planned in two parts, the first part was the study of spatial arrangements of planting, consisting in a mixture (Canavalia ensiformis, Crotalaria juncea and Helianthus annuus) of cover crops species (ECS) for green manure contemplating: intercropping with corn (cv. Caatingueiro) in double rows. The treatments consisted : ECS haul sowing; ECS furrow sowing; ECS haul sowing in a intercropping with corn; ECS furrow sowing in a intercropping with corn; corn monoculture; fallow (control). The evaluated parameters were: cover soil provided by ECS; fresh and dry biomass productivity; chemical composition of ECS aerial part; and corn grains productivity. The second part of the experiment took place in the same area, and bean (cv. Constanza) was planted in the same plots of the first part of the experiment. It was evaluated the influence of cover crops species on weed reinfestation and on the productivity of beans. As a general conclusion it was observed that the ECS covered the soil faster than the current spontaneous vegetation on fallow did. The fresh and dry biomass productivity and the cumulative quantity of nutrients in the biomass of the treatments that took in the ECS were higher than in corn monoculture. It was noted that the presence of the ECS influenced positively on weed reinfestation control. The corn grains productivity was lower when intercropping with ECS, however, the yield of beans was not influenced. The sowing way, haul or furrow, showed no differences, one interesting finding because the smallholder have freedom to choice the sowing way, without concern with related losses. / O presente estudo teve como objetivo avaliar o desempenho produtivo de uma sucess?o envolvendo milho e feijoeiro, submetidos ao manejo org?nico, associada ? aduba??o verde formada de uma mistura de esp?cies com diferentes arranjos espaciais. O experimento foi conduzido no Sistema Integrado de Produ??o Agroecol?gica ? SIPA (UFRRJ/Embrapa Agrobiologia/PESAGRO-RIO), localizado no munic?pio de Serop?dica, regi?o da Baixada Fluminense, RJ. O delineamento estat?stico adotado foi o de blocos casualizados, com seis tratamentos e quatro repeti??es, totalizando vinte e quatro parcelas. Neste sentido, o experimento foi planejado em duas partes, onde a primeira foi o estudo de arranjos espaciais de plantio composta por uma mistura de esp?cies (Canavalia ensiformis, Crotalaria juncea e Helianthus annuus) de plantas de cobertura do solo (ECS) para aduba??o verde, contemplando cultivos consorciados com o milho (variedade Caatingueiro) em fileiras duplas. Os tratamentos constaram de: ECS semeadas a lan?o; ECS semeadas em sulcos; ECS semeadas a lan?o em cons?rcio com o milho; ECS semeadas em sulcos em cons?rcio com o milho; monocultivo de milho; pousio (controle). Avaliou-se a cobertura do solo proporcionada pelas ECS; produtividade de biomassa fresca e seca; composi??o qu?mica da parte a?rea das esp?cies de cobertura do solo; e a produtividade de gr?os de milho. Na segunda parte do trabalho, na mesma ?rea em sucess?o, cultivou-se o feijoeiro (cv. Constanza) nas parcelas empregadas na primeira parte. Avaliou-se a influ?ncia das esp?cies de cobertura do solo na reinfesta??o de esp?cies espont?neas e a produtividade de gr?os de feij?o. Como conclus?o geral, observou-se que as ECS cobriram com maior velocidade o terreno do que a vegeta??o espont?nea presente no sistema em pousio. As produtividades de biomassa fresca e seca da parte a?rea e a quantidade acumulada de nutrientes na biomassa a?rea dos tratamentos que continham as ECS foram maiores do que no monocultivo do milho. Notou-se que a presen?a das ECS influenciou positivamente no controle da reinfesta??o das esp?cies espont?neas. A produtividade de gr?os de milho foi menor quando consorciado com as ECS, no entanto, a produtividade de gr?os de feij?o n?o foi influenciada. O modo de semeadura, a lan?o ou em sulcos, n?o demonstrou diferen?as nas avalia??es realizadas, sendo um dado interessante pelo fato do agricultor, dessa maneira, ter livre escolha quanto ao modo de semeadura, sem ter a preocupa??o de preju?zos correlacionados

In 2016 the Iowa Watershed Approach (IWA) was created to increase community resiliency against flooding, to develop hydrologic assessments that would identify strategies to reduce flooding, and to implement those strategies within nine identified watersheds that experienced flooding between 2011 and 2013. One of the nine watersheds was the Upper Iowa watershed located in northeast Iowa. This thesis focuses on the work that has been done to create a hydrologic assessment of the Upper Iowa watershed. The hydrologic assessment identifies potential conservation practices, creates a hydrologic model to assess the hydrologic cycle over the past ten years, and identifies strategies to reduce flooding within the watershed. Many potential agricultural conservation practices within the Upper Iowa watershed were identified and trends relating to the soil, land use, and topography were determined. In addition, a methodology to compare potential conservation practices with existing conservation practices actually in place was developed including a tool to estimate the size of grassed waterways to NRCS design guidelines. The comparison validated the methodologies used to identify potential practice placements, identified locations where potential practices could be implemented, and showed how stakeholder preferences influence conservation implementation. Additionally, a hydrologic model of the Upper Iowa watershed was developed, using the new Generic Hydrologic Overland-Subsurface Toolset model and calibrated to simulate the time period of 2007 through 2016. The model was evaluated against water balance ratios and performance statistics calculated from measured data. The model achieved Nash Sutcliffe Efficiency scores for streamflow above 0.7 and percent bias scores between ±12% for the three wettest years of 2008, 2013, and 2016. With the calibrated model, the benefits of continuous cover crop implementation were investigated under current conditions and under increased extreme precipitation intensity expected from climate change over the next half century. The results of this investigation determined that continuous cover crops increased evapotranspiration within the early half of the year creating more storage within the soil. Thus the flood risk from convective storms during the summer was lowered. In addition, the benefits from cover crops in terms of peak flow and volume reductions were cumulative increasing each consecutive year and were proportional to the percentage of cover cropped area. Lastly, a scenario using cover crops in a future extreme precipitation environment resulted in a reduction of peak discharge to current conditions. The results of this thesis will guide both future work within the Upper Iowa watershed and contribute to the knowledge of hydrologic planning and modeling within agricultural watersheds.