Submitted by Eunice Novais (enovais@uepg.br) on 2018-08-29T21:33:28Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Michele Cristina Lang.pdf: 1612200 bytes, checksum: 2518ad086c2dc79114626dedc37c24a9 (MD5) / Made available in DSpace on 2018-08-29T21:33:28Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Michele Cristina Lang.pdf: 1612200 bytes, checksum: 2518ad086c2dc79114626dedc37c24a9 (MD5) Previous issue date: 2018-02-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A cenoura (Daucus carota L), destaca-se entre as hortaliças produzidas na região centro-oriental do Paraná, no entanto, a interferência de plantas daninhas representa um dos fatores de maior impacto na redução da produtividade da cultura. Por tanto, o objetivo deste trabalho foi determinar o período anterior a interferência (PAI) para cenoura Alvorada cultivada com e sem mulch de aveia preta sob o solo. O experimento foi instalado na Fazenda Escola Capão da Onça, na primavera de 2016, com delineamento de blocos ao acaso em esquema fatorial 2X5 com 5 repetições. O primeiro fator consistiu de cobertura de solo com mulch (10 t ha-1 de palha de aveia preta) e sem mulch, já o segundo fator correspondeu a cinco períodos de convivência das plantas daninhas com a cultura (0, 15, 30, 60 e 110 dias após a emergência). No experimento foram identificadas 10 espécies de plantas daninhas pertencentes à 7 famílias botânicas em que as principais foram a Euphorbia heterophylla, Galinsoga ciliata, Eragrotis pilosa, Rhaphanus raphanistrum e Braquiaria plantaginea. O diâmetro das raízes de cenoura tanto nas parcelas com mulch quanto sem mulch reduziu exponencialmente ao longo dos períodos com convivência com o mato, observando-se perdas de até 68,51% e 74,57% em relação ás testemunhas nos canteiros com mulch e sem mulch respectivamente. O comprimento das raízes de cenoura tanto nas parcelas com mulch quanto sem mulch reduziu linearmente ao longo dos períodos com convivência com o mato, observando-se perdas de até 65,91% e 81,5% em relação ás testemunhas nos canteiros com mulch e sem mulch respectivamente. A extração de todos os macronutrientes avaliados (N, P, K e S) foram influenciados negativamente pela convivência com as plantas daninhas. Os maiores níveis de convivência com as plantas daninhas proporciou menor acúmulo de nitrogênio, fósforo, potássio e enxofre na parte aérea e raízes das plantas de cenoura. O teor de nutriente mais afetado pela interferência da matocompetição foi do K, na parte aérea observou-se perdas de até 64,69% e 68,11% em relação ás testemunhas capinadas nos canteiros com mulch e sem mulch respectivamente e perdas na raiz de até 68,68% e 61,52% em relação a testemunhas capinadas nos canteiros com mulch e sem mulch respectivamente. A utilização do mulch foi eficiente para elevar os teores de K na parte aérea em 13,02% nas testemunhas capinadas em relação as testemunhas capinadas em canteiros sem mulch, assim como, durante todos os períodos de convivência. Essa tendência segue para os demais nutrientes e observou-se que pequenas reduções nos teores dos nutrientes na planta afetam muito a produtividade já nos primeiros 15 (DAE). O crescimento das plantas de cenoura foi influenciado negativamente com a interferência de plantas daninhas, principalmente no início de desenvolvimento após os 15 (DAE), período em que se inicia a maior diferença na velocidade de crescimento (TCA) entre as testemunhas capinadas e em convivência com as plantas daninhas. A maior TCA foi observada nas testemunhas capinadas nos canteiros com mulch e redução de 19,80% nas testemunhas capinadas sem mulch em relação a testemunha capinada com mulch, no entanto, nas plantas em convivência com as plantas daninhas a TCA não evoluiu ao longo dos períodos de convivência com o mato. A taxa de crescimento relativo (TCR) reduziu exponencialmente após os 30 (DAE) para todos os tratamentos. Os maiores valores observados foram nas testemunhas nos canteiros com mulch e redução de 8% nas testemunhas capinadas sem mulch e nas plantas em convivência 12%, 20% em canteiros com mulch e sem mulch respectivamente em relação a testemunha capinada com mulch. A taxa de assimilação líquida (TAL) foi maior nas testemunhas capinadas com mulch com redução de 30,23% nas testemunhas capinadas sem mulch e nas plantas em convivência 34,11%, 53,49% em canteiros com mulch e sem mulch respectivamente. Na razão massa de raiz (RPR) as testemunhas capinadas em canteiros com mulch obtiveram maior razão com 0,6 (g -1) ou 60 % da massa seca em raiz, com redução de 3,3% nas testemunhas capinadas em canteiros sem mulch; 10% nas plantas em convivência com as plantas daninhas em canteiros com mulch e 15% nas plantas em convivência em canteiros sem mulch em relação as testemunhas capinadas com mulch. A perda na produtividade de raízes totais foi de 97,67% no cultivo sem mulch e 94,51% no cultivo com mulch. O período anterior a interferência foi de 3 e 4 (DAE) considerando a produtividade total para as cultivos com e sem mulch respectivamente, e 3 e 3 (DAE) considerando a produtividade comercial para as cultivos com e sem mulch respectivamente. / The carrot (Daucus carota L.) stands out among the vegetables produced in the central-eastern region of Paraná, however, weed interference represents one of the factors that have the greatest impact on the reduction of crop productivity. Therefore, the objective of this work was to determine the period prior to interference (PAI) for Alvorada carrot grown with and without black oat mulch under the soil. The experiment was installed at Fazenda Escola Capão da Onça, in the spring of 2016, with a randomized block design in a 2X5 factorial scheme with 5 replications. The first factor consisted of soil cover with mulch (10 t ha-1 of black oat straw) and no mulch, while the second factor corresponded to five periods of weed cohabitation with the crop (0, 15, 30, 60 and 110 days after the emergency). In the experiment, 10 weed species belonging to 7 botanical families were identified, in which the main ones were Euphorbia heterophylla, Galinsoga ciliata, Eragrotis pilosa, Rhaphanus raphanistrum and Braquiaria plantaginea. The diameter of the carrot roots in both the mulch and mulch plots decreased exponentially over the periods with coexistence with the weeds, with losses of up to 68.51% and 74.57% in relation to the weed beds with mulch. without mulch respectively. The length of the carrot roots in both the mulch and mulch plots reduced linearly over the periods with coexistence with the weeds, with losses of up to 65.91% and 81.5% in relation to the controls in mulch beds. without mulch respectively. The extraction of all evaluated macronutrients (N, P, K and S) were negatively influenced by the coexistence with weeds. The higher levels of coexistence with weeds provided less accumulation of nitrogen, phosphorus, potassium and sulfur in the shoots and roots of carrot plants. The nutrient content most affected by the matocompetition interference was K; in the aerial part losses were observed up to 64.69% and 68.11% in relation to the weed witnesses in the beds with mulch and without mulch respectively and losses in the root of up to 68.68% and 61.52% in relation to weeding witnesses in the beds with mulch and without mulch respectively. The use of the mulch was efficient to increase K content in the aerial part in 13.02% in the weeded witnesses in relation to the weed witnesses in beds without mulch, as well as, during all periods of coexistence. This trend continues for the other nutrients and it has been observed that small reductions in nutrient content in the plant greatly affect productivity in the first 15 (AED). The growth of carrot plants was negatively influenced by weed interference, especially at the beginning of development after 15 (DAE), when the greatest difference in growth speed (TCA) between weed and cohabitation with weeds. The highest TCA was observed in the weed control in the mulch beds and a reduction of 19.80% in the mulch weed control in relation to the mulch weed control, however, in the plants living with weeds the TCA did not evolve over the years. periods of coexistence with the bush. The relative growth rate (TCR) decreased exponentially after 30 (DAE) for all treatments. The highest values were observed in mulch and mulch seedlings and 8% reduction in mulch weed control and 12%, 20% in mulch and mulch seedlings respectively. The net assimilation rate (TAL) was higher in the mulch weed control with a reduction of 30.23% in the weed control without mulch and in the coexisting plants 34.11%, 53.49% in mulch and mulch, respectively. In the root mass ratio (RPR), the weeds in mulch beds obtained a higher ratio with 0.6 (g -1) or 60% of the dry mass at the root, with a 3.3% reduction in weed control in mulch ; 10% in plants living with weeds in beds with mulch and 15% in plants living in beds without mulch in relation to mulch weeded controls. The loss of total root yield was 97.67% in mulch and 94.51% in mulch. The period prior to the interference was 3 and 4 (DAE), considering the total productivity for the crops with and without mulch respectively, and 3 and 3 (DAE) considering the commercial productivity for the crops with and without mulch respectively.

L’Agriculture de conservation (AC) repose sur trois principes: le minimum de travail du sol, la couverture permanente du sol et la diversification des espèces cultivées. Elle a été introduite vers la fin des années 90 dans la région du lac Alaotra, Madagascar, dans l’objectif d’augmenter la productivisté de l’agriculture pluviale qui, généralement, pâtit des problèmes liés à la faible fertilité des sols, aux contraintes hydriques et à l’enherbement. L’objectif principal de la thèse consiste à quantifier et caractériser les impacts des fonctions agro-écologiques de l’AC dans l’amélioration du rendement en riz pluvial par rapport aux pratiques conventionnelles (CT). Une revue de la littérature sur les fonctions agro-écologiques du mulch en fonction de leur quantité retenue sur la parcelle a tout d’abord montré que la quantité de couverture nécessaire va dépendre essentiellement des fonctions agro-écologiques attendues. Une quantité de couverture de 2 à 3 t ha-1 permet d’obtenir des effets très nets en ce qui concerne l’amélioration de l’infiltration de l’eau, la limitation du ruissellement et de l’érosion du sol. En revanche, les données sur le contrôle de l’enherbement, la disponibilité des nutriments ainsi que la faune du sol en fonction de la quantité de mulch étaient très variables, suggérant l’interaction de ses fonctions agro-écologiques avec d’autres facteurs, notamment le type de résidus et les conditions pédoclimatiques. Une première expérimentation dont l’objectif était la quantification des effets physiques du mulch sur l’enherbement, avec différentes quantités de résidus de 0 à 45 t ha-1 a montré que l’émergence et la biomasse des adventices sur les parcelles couvertes dépend essentiellement de la quantité et de la distribution de la pluviométrie durant la saison culturale. L’émergence ainsi que la biomasse des mauvaises herbes diminuent en général avec l’augmentation de la quantité de mulch maintenue sur les parcelles. Toutefois, une quantité de résidus de l’ordre de 10 t ha-1 est nécessaire pour réduire significativement la pression des adventices sur le riz par rapport à un sol nu dans les conditions de notre dispositif expérimental. Un deuxième dispositif maintenu durant 6 ans (2009/10 à 2014/15), combinait une rotation biennale de maïs + dolique // riz et une rotation triennale de maïs + stylosanthes // stylosanthes // riz ; trois modes de gestion du sol et des résidus et deux niveaux de fertilisation. Deux niveaux d’enherbement en split plot ont été ajoutés en 2013/14 et 2014/15. L’amélioration du rendement en riz sur les parcelles en AC par rapport aux parcelles en CT est essentiellement liée à une diminution de la pression des adventices sur les parcelles AC pendant la période de végétation du riz. La dynamique de l’eau dans le sol ainsi que la dynamique de l’azote minéral sont fortement influencées par le régime pluviométrique et ne différent généralement pas entre AC et CT. Enfin, l’analyse de stabilité et l’écart de rendement au potentiel utilisés pour étudier les variations de rendements en riz sur les 6 saisons culturales du second dispositif expérimental ont montré que les effets des traitements étaient en interaction avec d’autres facteurs probablement liés à la variabilité spatiale du sol sur le dispositif expérimental. Les résultats de cette étude nous suggèrent de tenir compte aussi bien des fonctions agro-écologiques du mulch attendues que les régimes pluviométriques lors de la promotion d’un système AC pour améliorer la productivité des cultures. L'AC avec une quantité de résidus généralement retenus dans les parcelles de l'agriculteur (i.e. 1 - 2 t ha-1) serait efficace pour lutter contre le ruissellement et l'érosion. Cependant, des quantités supplémentaires de résidus, qui pourraient être produites avec l’introduction de rotations culturales avec une forte production de biomasse, seraient nécessaires pour lutter efficacement contre les adventices et diminuer les charges liées au sarclage. / Conservation agriculture (CA) is based on the principles of minimum soil disturbance, permanent soil cover and diversification of crop species grown in rotations and/or associations. CA was introduced in the late 90s in the Lake Alaotra region, Madagascar, in order to improve rainfed crop productivity which is commonly constrained by low soil fertility, soil water stress and weed infestation. The main objective of this study was to quantify and understand the impact of CA on rainfed rice productivity as compared to the practice of conventional tillage (CT). First, a review of literature was conducted on the agro-ecological functions of mulching with crop residues in relation to their quantity. The literature review showed that the optimal amount of residues required principally depends on the agro-ecological function searched for. Residue amounts of 2 to 3 t ha-1 had clear positive effects in terms of improving water infiltration and limiting water runoff and soil erosion. On the other hand, results on weed control, nutrient availability and soil fauna in relation to the amount of mulch were highly variable, suggesting the interaction of these agro-ecological functions with other factors, including residue type and soil-climate conditions. Second, two field experiments were monitored at the research center of FOFIFA in the Lake Alaotra region. A first experiment aiming at quantifying the physical effect of a mulch of crop residues on weed infestation, with amounts of surface residues ranging from 0 to 45 t ha-1 showed that the emergence and biomass of weeds on mulched plots depend mainly on the quantity and distribution of rainfall during the cropping season. Overall, weed emergence and biomass decreased with increasing amounts of mulch. However, a large quantity of residues, i.e. in the order of 10 t ha-1, was required to significantly (p<0.05) reduce weed pressure as compared to a bare soil under the agro-ecological conditions of our experiments. The second experiment was conducted during six years (2009/10 to 2014/15), and a 2-year rotation of maize + Dolichos lablab // rice and a 3-year rotation of maize + Stylosanthes guianensis // S. guianensis // rice were combined with three soil/residue management practices and two level of fertilization. Two levels of weed pressure were added as split-plot in 2013/14 and 2014/15. Higher rice grain yields on CA plots as compared to CT plots in the fifth and sixth year of the CA practice were mainly related to a decline of weed pressure under CA. Soil water and mineral nitrogen dynamics did not differ markedly between CA and CT and were strongly influenced by the rainfall pattern. Finally, the use of the concept of stability analysis and the yield gap approach to analyze the variation of rice yield under the 6 crop seasons from 2009/10 to 2014/15 showed that the effects of treatments including crop rotation, soil and residue management, and fertilization levels interact with other factors likely related to the spatial variability of the experimental design. Results of our study suggest that both agro-ecological function of mulch searched for and rainfall conditions should be taken into account when promoting CA systems to improve crop productivity in the Lake Alaotra region. Practicing CA with typical amounts of residues that are produced on farmer’s field (i.e. 1 – 2 t ha-1) is sufficient to control water runoff and soil erosion. However, extra amounts of crop residues are required to effectively control weed infestation. These extra amounts could be produced with the introduction of high biomass-producing crop rotations and could decrease the labor pressure from weeding.

En Afrique sub-saharienne (ASS), l'agriculture de conservation (AC) est diffusée afin de d'améliorer durablement la productivité de l'agriculture familiale. Cette AC est basée sur les principes de travail réduit du sol, d'une couverture permanente et de rotations introduisant des légumineuse. Parmi tous les bénéfices potentiels de l'AC, le mulch peut améliorer le bilan hydrique et tamponner le stress hydrique, et donc sécuriser les rendements, lorsque les pluies sont limitées et/ou aléatoirement distribuées. A Madagascar, la région du lac Alaotra connaît une forte expansion de la riziculture pluviale. Etant caractérisée par une distribution des pluies très erratique, la pratique de l'AC semble pertinente pour sécuriser la production pluviale. L'objectif de cette étude est donc d'évaluer dans quelle mesure cet aléa climatique est tamponné par l'AC. Tout d'abord, à travers revue de la littérature scientifique, nous avons ouvert à une problématique plus large. En effet, au regard des projections de croissance démographique et de changement climatique (CC) en ASS, l'AC est proposée comme solution ‘climate-smart' ; i.e. une agriculture capable d'augmenter la productivité et de s'adapter au CC tout en l'atténuant. Les études identifiées en ASS montrent une capacité de l'AC à augmenter les rendements sur le long-terme, et à plus court-terme dans les contextes climatiques où les pluies sont faibles et/ou mal distribuées. Cela suggère donc une capacité de l'AC à s'adapter au CC qui prévoit une augmentation de la variabilité de la distribution des pluies en ASS. La capacité de l'AC à atténuer le CC en séquestrant du carbone (C) dans les sols reste en suspens car le stockage du C se fait principalement en surface et la stabilité de ce C est questionnée. Nous nous sommes ensuite recentrés sur le sujet et la zone de cette étude afin d'évaluer le potentiel de l'AC à tamponner l'aléa pluviométrique. En se basant sur les données de suivi de parcelles en transition vers l'AC sur quatre saisons contrastées, nous avons constaté une augmentation des rendements moyens en riz pluvial dès la première année de pratique, avec une augmentation progressive des rendements et une diminution de la variabilité. Les données ont également suggéré une sécurisation des semis précoces et tardifs en AC. Nous avons constaté un poids important du climat sur la variabilité des rendements dans la zone d'étude. Cette analyse exploratoire nous a donc permis d'observer des effets positifs de l'AC dans le contexte climatique du lac Alaotra, suggérant notamment un effet potentiel sur la ressource hydrique. Mais les informations à notre disposition ne nous ont pas permis de vérifier cette hypothèse. Nous nous sommes donc intéressés à l'impact du mulch sur le bilan hydrique et les rendements en riz pluvial dans les conditions agro-climatiques de la zone d'étude. Nous avons effectué une expérimentation virtuelle, en utilisant le modèle PYE-CA. Nous avons confirmé la capacité du mulch à réduire le ruissellement. Nous avons identifié les dates de semis pour lesquelles le riz pluvial est le moins impacté par le stress hydrique dans la région. Les résultats nous ont indiqué que pour les dates de semis majoritairement pratiquées par les agriculteurs, et dans un éventail de conditions de sol, la disponibilité en eau est très peu affectée par une modification du ruissellement. Les bénéfices d'une réduction du ruissellement apparaissent dans des conditions hydriques plus stressantes telles que des dates de semis précoce ou une intensification, en diminuant la variabilité des rendements. Cette étude nous a permis de mieux appréhender les impacts de l'AC sur le bilan hydrique dans le contexte climatique de notre zone d'étude. Pour faire sens, ces résultats sont à intégrer à l'échelle exploitation, voire plus large, pour identifier les contraintes et avantages induits par les systèmes en AC dans le contexte socio-économique du lac Alaotra. / Conservation agriculture (CA) is widely disseminated at large scale in sub-Saharan Africa (SSA) in order to restore soil fertility and sustainably increase crop production of family farming. As defined by the FAO, CA is based on the three principles of minimal soil disturbance, permanent soil cover, and complex crop rotation. Among all the beneficial functions of CA, its ability to improve water balance through mulching can buffer water stress during crop cycle, and hence secure yields when rainfall are limited or poorly distributed. In the Lake Alaotra region of Madagascar, the area under rainfed upland rice has expanded lately. The region being characterized by an erratic rainfall distribution, intra- and inter-annually, CA practice seems appropriate to secure rainfed production. The main objective of this study is to evaluate to which extent this climate hazard can be buffered through the practice of CA. Firstly, we ran a review of the scientific literature to better understand the impact of CA in a wider context. Regarding the projections of population growth and climate change for SSA, CA is considered as a climate-smart option, i.e. an agriculture able to simultaneously mitigate climate change, adapt to this change, and sustainably increase productivity. The different studies illustrated the capacity of CA to maintain, or even increase production in the long-term, and in the shorter-term under limited or poorly distributed rainfall African contexts. These results suggested an ability of CA to adapt to climate change, predicting an increase in rainfall variability in SSA. However, the climate change mitigation through carbon sequestration under CA remained unclear because of a superficial storage which may be unsteady. Then, we focused on the study area to evaluate the potential of CA to buffer rainfall hazard. Using a 4-year dataset monitoring farmers' fields transitioning to CA, we observed a gradual increase in upland rice average yield with a decrease in variability over the consecutive years of CA practice. The data also suggested a capacity of CA to secure early or late sowing. But agro-environmental factors were mainly impacting yields in the region. This exploratory analysis allowed us to observe positive impacts of CA under the climate conditions of the Lake Alaotra region, suggesting an impact on water balance but no information was available to validate this hypothesis. Finally, we focused more precisely on the impact of mulch on water balance and upland rice yields under the climate conditions of the region, using a modeling approach. We ran an virtual experiment with the model PYE-CA to simulate a range of soil and climate conditions met in the region. We confirmed the ability of mulch to reduce, or even suppress, efficiently surface water runoff. We identified the sowing period within which rice growing would be the least impacted by water stress in the region. The results indicated that water availability for rice cropping was slightly impacted by a decrease in runoff for the majority of soil conditions and farmers' usual sowing dates. Beneficial effects of runoff reduction appeared under higher water stress conditions such as early sowing date or crop intensification and yield variability was decreased. This study allowed us to better apprehend the impacts of CA on water balance in the specific climate context of the study area. It would be interesting to integrate these results at the farm-level to identify the pros and cons of adopting CA under the socio-economic context of the Lake Alaotra region of Madagascar.

Im Rahmen der Neugestaltung des Innenhofes an der Fachschule für Gartenbau in Dresden-Pillnitz wurde eine Freianlage mit unterschiedlichen Bepflanzungstypen hergestellt und drei Jahre gesichtet. Der Pflegeaufwand ging in diesen drei Jahren deutlich zurück. Ein Großteil der Bepflanzungen ist für anspruchsvollere, halböffentliche und öffentliche Außenanlagen attraktiv.

La connaissance du flux d'eau que le sol peut transmettre entre une nappe peu profonde et la surface est d'importance pour la gestion de la ressource en eau et la pérennité des périmètres irrigués. En régime permanent, on estime classiquement ce flux en résolvant la loi de Darcy ; on admet donc que le processus de remontée capillaire s'effectue sous la forme d'un écoulement liquide isotherme. La solution de l'équation présente une asymptote : pour un sol et une profondeur de nappe donnés, il existe un flux limite indépendant des conditions à la surface du sol. A partir de mesures sur une colonne de sol et de calculs basés sur un modèle de transferts d'eau et de chaleur dans le sol et l'atmosphère, nous étudions l'effet de la diffusion vapeur et du couplage entre le sol et l'atmosphère sur le flux dans la zone non saturée. Nous montrons que la loi de Darcy est bien adaptée à l'estimation de ce flux d'autant que les variations climatiques diurnes sont sans conséquence sur le flux moyen.

In the organic cropping system, with the use of soil mulching it is possible to significantly reduce weed incidence in a crop stand, to enrich the soil with nutrients and to obtain the highest yield of satisfactory quality. Having discontinued mulching, its residual effect on agricultural crops persists. The effect of previously used and soil-incorporated organic mulches on weed emergence, soil properties and agricultural crops persists for a different period of time and becomes weaker with time. / Ekologinės žemdirbystės sistemoje, naudojant dirvožemio mulčiavimą, galima iš esmės sumažinti pasėlio piktžolėtumą ir praturtinti dirvožemį maisto medžiagomis bei gauti didžiausią geros kokybės derlių. Atsisakius dirvožemį mulčiuoti išlieka mulčio liekamasis poveikis žemės ūkio augalų pasėliams. Anksčiau naudotų ir įterptų į dirvožemį organinių mulčių poveikis piktžolių dygimui, dirvožemio savybėms ir žemės ūkio augalams trunka nevienodą laikotarpį ir silpnėja.

Limitações nas reservas de combustíveis fósseis e a crescente concentração de gases de efeito estufa na atmosfera tem aumentado o interesse para incrementar a participação da cana-de-açúcar como fonte de biomassa para geração de energia renovável. O uso dos resíduos de colheita da cana-de-açúcar para produção de eletricidade e etanol de segunda geração foi intensificado nos últimos anos, sem haver conhecimento claro das implicações da retirada total ou parcial da palha na produtividade da cultura e qualidade do solo a médio e longo prazo. O objetivo deste estudo foi avaliar a produtividade da cana-de-açúcar, os atributos químicos e os estoques de C e N no solo sob níveis de remoção de palha em áreas com e sem rotação com crotalária. Os parâmetros produtivos da cana-de-açúcar foram avaliados em áreas experimentais localizadas em Quirinópolis/GO, Chapadão do Céu/GO, Iracemápolis/SP e Quatá/SP, enquanto os atributos químicos e os estoques de C e N do solo foram avaliados em Quirinópolis/GO e Quatá/SP, locais com solos de textura argilosa e arenosa, respectivamente. Em cada local, foram instalados dois experimentos, um com rotação com crotalária e outro sem rotação com crotalária (pousio) na renovação do canavial. Após a colheita da cana-planta, foram instalados os tratamentos de soqueira referentes aos níveis de 0, 50 e 100% de manutenção de palha. Os parâmetros produtivos foram avaliados nos dois anos seguintes, enquanto os efeitos no solo foram avaliados no final do segundo ciclo agrícola. A manutenção de palha aumentou a produtividade de colmos em três áreas (Quirinópolis/GO, Chapadão do Céu/GO e Quatá/SP) e reduziu a produtividade em um local (Iracemápolis/SP).O efeito benéfico da rotação com crotalária foi menos persistente no tempo do que a manutenção da palha. Os atributos químicos do solo foram mais influenciados pelos tratamentos no solo argiloso do que no solo arenoso. No solo argiloso, a interação da rotação com crotalária e manutenção da palha aumentou os teores de Mg e o V%, e reduziu a acidez potencial do solo. A rotação aumentou os teores de P, K nos dois solos estudados e a CTC no solo argiloso. A rotação com crotalária não afetou os estoques de C e N, enquanto que a manutenção de palha favoreceu o acumulo de C nos dois tipos de solo. / The limited fossil reserves and the growing concentration of greenhouse gases in the atmosphere, have augmented the interest for a greater participation of sugarcane as a source of biomass for renewable energy generation. The use of sugarcane harvest residues for the production of electricity and second generation ethanol has been intensifying in recent years, without having a clear understanding of the implications of total or partial removal of the straw on the crop productivity and soil quality in the medium and long term. The objective of this study was to evaluate sugarcane productivity, soil chemical attributes and C and N stocks in the soil under straw removal levels in areas with and without sunn hemp rotation. The productivity parameters of sugarcane were evaluated in experimental areas located in Quirinópolis / GO, Chapadão do Céu / GO, Iracemápolis / SP and Quatá / SP, while the chemical attributes and the soil C and N stocks were studied in Quirinópolis / GO and Quatá / SP, places with clay and sandy soils respectively. In each site, two experiments were installed, one with sunn hemp rotation and the other without sunn hemp (fallow) in the renovation of the cane field. After harvesting of the cane-plant, were installed the ratooning treatments referring to the levels of 0, 50 and 100% of straw maintenance were installed. The productive parameters were evaluated in the following two years, while the effects on the soil were evaluated at the end of the second agricultural cycle. The straw retention increased the yield of stalks in three areas (Quirinópolis / GO, Chapadão do Céu / GO and Quatá / SP) and reduced productivity in one place (Iracemápolis / SP). The beneficial effect of rotation with sunn hemp was less persistent in the time than the maintenance of the straw. The chemical attributes of the soil were more influenced by treatments in the clay soil than in the sandy soil. In the clay soil, the rotation interaction with crotalaria and straw maintenance increased the Mg and %BS, and reduced the potential acidity of the soil. The rotation increased the P, K content in the two studied soils and the CEC in the clay soil. Sunn hemp rotation did not affect soil C and N stocks, and maintenance of straw favored C accumulation in both types of soil.

O presente trabalho foi desenvolvido com o objetivo de avaliar os efeitos da intensidade de chuva e diferentes quantidades de palha de cana-de-açúcar sobre a eficácia de herbicidas aplicados em pré-emergência no controle da tiririca. Foram realizados dois experimentos, ambos conduzidos em casa-de-vegetação. O delineamento experimental adotado foi o de blocos casualizados, com 4 repetições, para os dois experimentos. No primeiro experimento os tratamentos foram distribuídos em um esquema fatorial 3 x 3 x 2 x 2, constituídos pela combinação entre quantidades de cobertura morta de palha de cana-de-açúcar que foram adicionadas à superfície do solo (0, 10, 20 t/ha), herbicidas aplicados em pré-emergência (sulfentrazone a 0,8 kg i.a./ha e imazapic a 147 g i.a./ha) e um tratamento sem aplicação de herbicida, intensidades de chuva (10 e 20 mm), e épocas em que foram simuladas chuvas após a aplicação dos herbicidas (24 e 168 horas). No segundo experimento os tratamentos foram distribuídos em um esquema fatorial 2 x 3 x 5, constituídos pela combinação entre quantidades de cobertura morta de palha de cana-de-açúcar (0, 15 t/ha), herbicidas aplicados em pré-emergência (sulfentrazone a 0,8 kg i.a./ha e imazapic a 147 g i.a./ha) e um tratamento sem aplicação de herbicida, e épocas em que foi simulada chuva após a aplicação dos herbicidas (0, 3, 6, 9 e 12 dias). Em ambos experimentos foram avaliados: o número de plantas por vaso, biomassas secas da parte aérea e das estruturas do sistema subterrâneo, e número de tubérculos e bulbos sadios. A partir da análise dos resultados, para o primeiro experimento conclui-se que, para o herbicida sulfentrazone, a presença de 20 t/ha de palha de cana-de-açúcar diminuiu a eficácia do herbicida. O herbicida imazapic teve um bom desempenho tanto na ausência quanto na presença de palha, e causou redução das variáveis estudadas independente da intensidade de chuva. A intensidade de chuva de 10 mm, não foi suficiente para transpor o herbicida sulfentrazone na quantidade de 20 t/ha de palha. Já a intensidade de 20 mm foi suficiente para lixiviar o herbicida até mesmo na maior quantidade de palha. O herbicida sulfentrazone suporta mais a permanência na palha, pois apresentou melhor eficácia em relação ao imazapic, quando a chuva foi simulada 168 horas após a aplicação dos herbicidas. Para o segundo experimento pode-se concluir que, as épocas em que foram simuladas as chuvas, não afetaram as variáveis estudadas, não havendo, portanto, diferença se a chuva ocorreu no dia em que foi aplicado o herbicida, ou se ocorreu um período sem chuva de 12 dias. Os herbicidas sulfentrazone e imazapic reduziram o número de plantas, o número de tubérculos, biomassa seca de bulbos, biomassa seca de rizoma e raiz, e biomassa seca da parte aérea, independente da presença de palha. / The present work was developed with the objective of assessing the effects of the intensity of rain and different quantities of sugar cane mulch residue on the efficacy of herbicides applied in pre-emergence for the purple nutsedge control. Two experiments were performed, both conducted in greenhouses. The experiments were performed by randomly choosing blocks with four repetitions. In the first experiment, the treatments were distributed in a factorial scheme 3 x 3 x 2 x 2, constituted by the combination between quantities of dead coverage of sugar cane mulch residue which were added to the soil surface (0, 10, 20 t/ha), herbicides applied in preemergence (sulfentrazone at 0,8 kg i.a./ha and imazapic at 147 g i.a./ha) and a treatment without the application of herbicides, rain intensities (10 and 20 mm), and seasons in which were simulated rains after the application of herbicides (24 and 168 hours). In the second experiment, the treatments were distributed in a factorial scheme 2 x 3 x 5, constituted by the combination between quantities of dead covering of sugar cane mulch residue (0, 15, t/ha), herbicides applied in pre-emergence (sulfentrazone at 0,8 kg i.a./ha and imazapic at 147 g i.a./ha), a treatment without the application of herbicides and seasons in which were simulated rains after the application of herbicides (0, 3, 6, and 12 days). It was evaluated in both experiments: the number of plants per vase, dry biomasses from the aerial parts, from the underground system structures and the number of healthy tubers and bulbs. From the analysis of the results of the first experiment, it may conclude that, to the herbicide sulfentrazone, the presence of 20 t/ha of sugar cane mulch residue diminished its efficacy. The herbicide imazapic had a good performance with the absence as well as with the presence of the mulch residue, and caused a reduction in the varieties studied independently of the intensity of rain. The intensity of rain of 10 mm, wasn’t sufficient to overpass the herbicide sulfentrazone in the quantity of 20 t/ha of mulch residue. But the intensity of 20 mm was enough to lixiviate the herbicide even in the biggest quantity of mulch residue. The herbicide sulfentrazone endures more the abiding on the mulch residue, because it presented a better efficacy in relation to the imazapic, when the rain was simulated 168 hours after the application of the herbicides. From the second experiment it may conclude that the season in which was simulated rains, it didn't affect the varieties studied, therefore there was no difference when the rain occurred on the day when the herbicide was applied, or if it occurred on a 12 day period without rain. The herbicides sulfentrazone and imazapic reduced the number of plants, the number of tubers, dry biomass of bulbs, dry biomass of rhizoma roots and dry biomass of the aerial parts, independently of the presence of mulch residue.

Limitações nas reservas de combustíveis fósseis e a crescente concentração de gases de efeito estufa na atmosfera tem aumentado o interesse para incrementar a participação da cana-de-açúcar como fonte de biomassa para geração de energia renovável. O uso dos resíduos de colheita da cana-de-açúcar para produção de eletricidade e etanol de segunda geração foi intensificado nos últimos anos, sem haver conhecimento claro das implicações da retirada total ou parcial da palha na produtividade da cultura e qualidade do solo a médio e longo prazo. O objetivo deste estudo foi avaliar a produtividade da cana-de-açúcar, os atributos químicos e os estoques de C e N no solo sob níveis de remoção de palha em áreas com e sem rotação com crotalária. Os parâmetros produtivos da cana-de-açúcar foram avaliados em áreas experimentais localizadas em Quirinópolis/GO, Chapadão do Céu/GO, Iracemápolis/SP e Quatá/SP, enquanto os atributos químicos e os estoques de C e N do solo foram avaliados em Quirinópolis/GO e Quatá/SP, locais com solos de textura argilosa e arenosa, respectivamente. Em cada local, foram instalados dois experimentos, um com rotação com crotalária e outro sem rotação com crotalária (pousio) na renovação do canavial. Após a colheita da cana-planta, foram instalados os tratamentos de soqueira referentes aos níveis de 0, 50 e 100% de manutenção de palha. Os parâmetros produtivos foram avaliados nos dois anos seguintes, enquanto os efeitos no solo foram avaliados no final do segundo ciclo agrícola. A manutenção de palha aumentou a produtividade de colmos em três áreas (Quirinópolis/GO, Chapadão do Céu/GO e Quatá/SP) e reduziu a produtividade em um local (Iracemápolis/SP).O efeito benéfico da rotação com crotalária foi menos persistente no tempo do que a manutenção da palha. Os atributos químicos do solo foram mais influenciados pelos tratamentos no solo argiloso do que no solo arenoso. No solo argiloso, a interação da rotação com crotalária e manutenção da palha aumentou os teores de Mg e o V%, e reduziu a acidez potencial do solo. A rotação aumentou os teores de P, K nos dois solos estudados e a CTC no solo argiloso. A rotação com crotalária não afetou os estoques de C e N, enquanto que a manutenção de palha favoreceu o acumulo de C nos dois tipos de solo. / The limited fossil reserves and the growing concentration of greenhouse gases in the atmosphere, have augmented the interest for a greater participation of sugarcane as a source of biomass for renewable energy generation. The use of sugarcane harvest residues for the production of electricity and second generation ethanol has been intensifying in recent years, without having a clear understanding of the implications of total or partial removal of the straw on the crop productivity and soil quality in the medium and long term. The objective of this study was to evaluate sugarcane productivity, soil chemical attributes and C and N stocks in the soil under straw removal levels in areas with and without sunn hemp rotation. The productivity parameters of sugarcane were evaluated in experimental areas located in Quirinópolis / GO, Chapadão do Céu / GO, Iracemápolis / SP and Quatá / SP, while the chemical attributes and the soil C and N stocks were studied in Quirinópolis / GO and Quatá / SP, places with clay and sandy soils respectively. In each site, two experiments were installed, one with sunn hemp rotation and the other without sunn hemp (fallow) in the renovation of the cane field. After harvesting of the cane-plant, were installed the ratooning treatments referring to the levels of 0, 50 and 100% of straw maintenance were installed. The productive parameters were evaluated in the following two years, while the effects on the soil were evaluated at the end of the second agricultural cycle. The straw retention increased the yield of stalks in three areas (Quirinópolis / GO, Chapadão do Céu / GO and Quatá / SP) and reduced productivity in one place (Iracemápolis / SP). The beneficial effect of rotation with sunn hemp was less persistent in the time than the maintenance of the straw. The chemical attributes of the soil were more influenced by treatments in the clay soil than in the sandy soil. In the clay soil, the rotation interaction with crotalaria and straw maintenance increased the Mg and %BS, and reduced the potential acidity of the soil. The rotation increased the P, K content in the two studied soils and the CEC in the clay soil. Sunn hemp rotation did not affect soil C and N stocks, and maintenance of straw favored C accumulation in both types of soil.

Thesis (MSc. (Horticulture)) -- University of Limpopo, 2018 / Rainwater harvesting is an old age practice used in water-scarce rainfed crop production areas. It is practiced to supplement additional water for crops with insufficient amounts of rainfall for optimum production. The aim of this study was to assess yield responses of Swiss chard under In-field rainwater harvesting techniques (IRWH) and catchment areas. The trials were conducted at two sites, University of Limpopo experimental farm (Syferkuil) and on farmer’s field at Apel. The main plots were two catchment areas (2 m (1 m runoff strip plus 1 m basin)) and (3 m (2 m runoff strip plus 1 m basin)), while the subplots were five IRWH techniques namely; Control (farmers practice), Rainfed, IRHW (without mulch + irrigation), IRWH+Mulch and IRWH+Mulch+Irrigation. The results obtained showed no significant differences in yield of Swiss chard in relation to catchment areas of 3 and 2 m respectively. However, significant differences in plant height, plant vigour, number of leaves and chlorophyll contents were obtained under different IRWH techniques. Significantly, highest average plant height of 40.75 cm was obtained in IRWH+Mulch compared to Rainfed with the lowest average 28.50 cm at Syferkuil. A similar trend was obtained at Apel. There were significant differences in number of leaves under IRWH techniques; the highest mean of 16.00 was obtained in the control (farmers practice) treatment, while the lowest mean of 9.00 was obtained in IRWH treatment at Apel. At Syferkuil, significantly highest average number of leaves was obtained in the IRWH+Mulch+irrigation treatment, while the lowest average number of leaves was obtained in the rainfed treatment. Regarding the yield of Swiss chard, the significantly highest average yield was obtained under IRWH+Mulch+irrigation and 3 m catchment treatment combination which was 84.86 t ha-1 compared to 20.66 t ha-1 in rainfed and 3 m catchment treatment combination at Syferkuil. Similar trend was found at Apel with the highest average yield recorded in IRWH+Mulch+irrigation treatment combination. Hence, IRWH technique with mulch and irrigation could be adopted by growers in a water-scarce environment like the Limpopo Province of South Africa.