Em um contexto global de aumento da demanda por produtos agrícolas, especialmente de proteína animal, concomitante às mudanças climáticas e escassez de áreas para expansão agrícola, o processo de intensificação sustentável da pecuária é colocado como um importante \"piloto\" frente às políticas públicas setoriais. O Plano ABC, exemplo deste tipo de política pública, destina recursos através do Programa ABC para a recuperação de pastagens degradadas. A identificação de pastagens degradadas se dá através de indicadores de baixa produtividade da pecuária, principalmente pautados na baixa lotação animal. Esta premissa nem sempre é verdadeira, pois há áreas com baixa capacidade de suporte, em função de limitações físicas, mas que não se encontram necessariamente degradadas. A utilização de modelos biofísicos de crescimento de forragem é uma possível alternativa de abordagem à problemática, que pode auxiliar na identificação espacial de áreas onde a pecuária poderia se intensificar sem implicar em impactos ambientais, de modo a melhor direcionar políticas públicas que busquem estimular este processo. O objetivo deste estudo foi determinar para o estado de São Paulo a eficiência na produção e o yield gap (lacuna de produtividade) explorável da pastagem via modelagem mecanística para identificar as áreas com maior potencial de intensificação da pecuária e compará-las com a geografia de aplicação do crédito agrícola do Programa ABC para recuperação de pastagens degradadas. O estudo foi organizado da seguinte forma: a primeira parte (Capítulo 2) apresenta uma discussão acerca das áreas de pastagem com maior potencial de incremento de produtividade com base nas simulações no CROPGRO Perennial Forage para crescimento da pastagem de modo a definir a eficiência produtiva e os yield gaps da pastagem para o estado de São Paulo; a segunda parte (Capítulo 3) traz a análise de desempenho do Programa ABC em relação à aplicação desse recurso para recuperação de pastagem degradada (RPD), ou seja, avaliar se o crédito está sendo aplicado em regiões de maior potencial para incremento de produtividade, com base nos valores de yield gap explorável encontrados anteriormente. A eficiência média atual da produção de pastagens (razão entre produtividade real e produtividade atingível) encontrada via simulação no estado de São Paulo foi de 46,4% e um yield gap médio explorável de 5,8 Mg.ha-1.ano-1 de biomassa úmida. Estes resultados indicam que há um significativo espaço para incremento de produtividade das pastagens neste estado. A priorização de áreas de maior yield gap para intensificação pode contribuir para a redução da pressão por abertura de novas áreas de pastagem em locais com baixo potencial produtivo, áreas estas que podem ser ocupadas para produção agrícola ou para a regularização ambiental, evitando a expansão do desmatamento. O presente estudo buscou contribuir, através de resultados em escala estadual, para futuros estudos em escala nacional, mostrando que o uso de modelos mecanísticos como o CROPGRO Perennial Forage podem ser instrumentos de grande utilidade na avaliação e no direcionamento de políticas públicas condizentes com a construção de diretrizes para o desenvolvimento rural sustentável. / In a global context of increasing demand for agricultural resources, especially animal protein, combined with climate change and scarcity of areas for agricultural expansion, the process of sustainable intensification of livestock farming is placed as an important public policie issue. The ABC Plan, an example of this type of public policy, allocates resources through the ABC Program for the recovery of degraded pastures. The identification of degraded pastures occurs through indicators of low productivity of livestock, mainly based on low animal stocking (UA.ha-1). This premise is not always true, as there are areas with low support capacity , due to physical limitations, but that are not necessarily degraded. The use of biophysical models of forage growth is an alternative approach to this problem, which may help in the spatial identification of areas where livestock could be intensified without environmental impacts, in order to guide public policies seeking to stimulate this process . The objective of this study was to determine pasture yield efficiency and yield gap for São Paulo State , using models to identify areas with the greatest potential for livestock intensification and compare them with the geography of the ABC program application. The study was organized as follows: the first part (Chapter 2) presents a discussion about pasture areas with the greatest potential for productivity increase, based on simulations in CROPGRO Perennial Forage for the growth of Brachiaria brizantha cv Marandu in order to define the productive efficiency and the yield gaps of the pasture for São Paulo State; the second part (Chapter 3) presents the performance analysis of the ABC Program in relation to the application of this resource for degraded pasture recovery (RPD), i.e., to evaluate if the credit is being applied in regions with greater potential for productivity increase, based on the explorable yield gap values previously found. The current average efficiency of pasture production (ratio between real productivity and attainable productivity) found by simulation in São Paulo State was 46.4% and an average yield gap of 5.8 Mg.ha-1.year-1 . These results indicate that there is a significant space to increase pasture productivity in this State. Prioritization of areas with a higher yield gap for intensification may contribute to the reduction of pressure for opening new pasture areas in areas with low productive potential, areas that can be occupied for agricultural production or for environmental regulation, avoiding the expansion of deforestation.The present study sought to contribute, through statewide results, to future studies on a national scale, showing that the use of mechanistic models, such as CROPGRO Perennial Forage, can be very useful for evaluating and directing public policies aimed at rural sustainable development.

Thesis (M.Sc. (Soil Science)) --University of Limpopo, 2013 / Large amount of pre-plant nitrogen (N) fertilizer results in low nutrient-use-efficiency due to poor synchrony between soil N supply and maize demand, especially during N sensitive growth stages. Optimum maize production is dependent on adequate N availability to the crop during the critical vegetative and reproductive growth stages. High N fertilizer prices and maize yield decline are the main challenges faced by the Limpopo Province farmers. The objectives of this study were to compare growth and yield of maize under conventional and site-specific N management in a dryland farming system. The study was conducted in Leeukraal, Towoomba, Ga-Marishane and Radium in the Limpopo Province, South Africa. Experimental plots were laid out in a randomized complete block design, with four replications. Phosphorus was applied through band placement using a planter in all plots at a rate of 42 kg P/ha. Hybrid maize SNK 2147 was planted on a 20 by 20 m plot with Inter-row and Intra-row spacing of 0.9 and 0.35 m respectively. Treatments consisted of 3 N management strategies as follows, (i) No N application (N0), (ii) Site-specific N at a rate ranging between 18 and 33 kg N/ha (N1) and (iii) Conventional N application at 58 kg N/ha (N2). Treatment N2 was applied at a uniform rate during maize planting. Sufficiency index as an indication for N deficiency was determined using CCM-200 for treatment N1. The sufficiency index was determined during leaf stage V6, V10 and V14, and thereafter N was applied only when needed. Data were subjected to analysis of variance through Statistical Analysis System package. Mean separation tests were computed using Duncan’s Multiple Range Test. Maize grain yield at Leeukraal of 5.2 t/ha for N1 was higher than 3.2 and 4.0 t/ha of N0 and N2, respectively. There was no difference amongst the three N management approaches on the grain yield at Towoomba. The grain yield at Ga-Marishane for N1 of 2.2 t/ha was significantly higher than 1.7 t/ha of the N0. Conventional management approach, which is a traditional approach used by farmers in the Limpopo Province, had 2.6 t/ha grain yield that was significantly higher than the N0 and N1. The maize growth and yield under N2 and N1 was compared, N1 required between 43 and 69% lesser N fertilizer as compared to N2. Therefore site-specific nutrient management approach sustains and improves growth and yield of maize using minimal inputs of N compared to conventional approach. This therefore saves input costs and avoids unnecessary environmental consequences. Key words: maize yield, nitrogen management, site-specific approach / Vlaamse Interuniveritatire Raad and Limpopo Department of Agriculture

Changes in landscape pattern caused by changes in forest management, namely the Sustainable Forestry Initiative (SFI), and the implications of these structural changes on landscape processes were analyzed. Landscape structure was studied based upon the comparison of landscapes with different management histories. Ecological processes were analyzed based upon simulation of stand and landscape attributes of habitats for several vertebrate species and upon simulation of hydrological processes such as water and sediment yield. A methodology to integrate landscape and stand pattern and dynamics with landscape processes was developed for this work. It integrates a forest landscape structure model, several stand level growth and yield models, vertebrate habitat models, and a hydrological model. The comparisons among landscapes revealed that forest management has a strong influence on landscape structure. The SFI program increases fragmentation of the landscape indicated by the presence of more and smaller patches, more edges, more complex shapes, and less and smaller core areas. Traditional intensive and extensive management show comparable patterns characterized by high aggregation and connectivity. Landscapes managed according to the SFI program show higher Habitat Suitability Index (HSI) values for American woodcock, American beaver, wild turkey, fox squirrel, and gray squirrel. HSI is higher for pine warbler in the landscape not managed according to the SFI program. Downy woodpecker and barred owl present very reduced HSI values in either landscape. The SFI program induced fragmentation of the habitat of pine warbler and the establishment of narrow and elongated habitats in a network structure for the remaining species. Both patterns are determined by SMZs. The scenario representing management according to the SFI program presents higher sediment yield at the watershed level than the scenario representing management not according to the SFI program due to higher channel erosion related to the absence of buffer strips in the non-SFI scenario. In general, management according to the SFI program increases landscape diversity and evenness, habitat suitability for most species, potential vertebrate diversity, and provides habitat structure suitable for most species. This management also decreases sediment loss at the watershed level.

Field pea is an important crop in western Canada. The current recommended seeding rate in field pea is 88 plants m-2. As certain pea genotypes have the ability for increased branching, it may be possible for a producer to seed at a lower plant population without reduced yield or to choose a highly branched cultivar to have reduced risk of yield loss under conditions of poor emergence. The objective of this research was to determine how differences in branching among seven representative pea cultivars affected crop yield at different seeding rates, and to determine if branching affected the competitive ability of pea cultivars. In the plant population experiment, seven pea cultivars were seeded at five target plant populations (10, 30, 90, 120, and 150 plant m-2) during 2005 and 2006 at Rosthern and Saskatoon, Saskatchewan. The competition experiment involved eight cultivars being seeded at 50 plants m-2 to measure competitiveness with weeds. Plant emergence, number of branches, light interception, harvest index and grain yield were measured. Growth, seasonal temperature and rainfall were near normal in 2005. Severe terminal drought occurred in 2006 which may have lead to decreased yields. Branching was greatest at low plant densities and decreased as plant density increased. Grain yield increased as plant density increased until it plateaued at 80 100 plants m-2. The response of yield to plant density differed to some extent among cultivars, with CDC Acer and CDC Bronco achieving more of their potential yield at lower densities, while Carrera and Courier required higher densities to reach the same proportion of potential yield. Weed biomass was lowest in plots sown to longer vined cultivars with normal leaf type. Branching habit did not affect the competitiveness of pea cultivars. Potential exists to plant highly branched cultivars to reduce risk of yield loss in situations where low plant emergence might occur.

Field pea is an important crop in western Canada. The current recommended seeding rate in field pea is 88 plants m-2. As certain pea genotypes have the ability for increased branching, it may be possible for a producer to seed at a lower plant population without reduced yield or to choose a highly branched cultivar to have reduced risk of yield loss under conditions of poor emergence. The objective of this research was to determine how differences in branching among seven representative pea cultivars affected crop yield at different seeding rates, and to determine if branching affected the competitive ability of pea cultivars. In the plant population experiment, seven pea cultivars were seeded at five target plant populations (10, 30, 90, 120, and 150 plant m-2) during 2005 and 2006 at Rosthern and Saskatoon, Saskatchewan. The competition experiment involved eight cultivars being seeded at 50 plants m-2 to measure competitiveness with weeds. Plant emergence, number of branches, light interception, harvest index and grain yield were measured. Growth, seasonal temperature and rainfall were near normal in 2005. Severe terminal drought occurred in 2006 which may have lead to decreased yields. Branching was greatest at low plant densities and decreased as plant density increased. Grain yield increased as plant density increased until it plateaued at 80 100 plants m-2. The response of yield to plant density differed to some extent among cultivars, with CDC Acer and CDC Bronco achieving more of their potential yield at lower densities, while Carrera and Courier required higher densities to reach the same proportion of potential yield. Weed biomass was lowest in plots sown to longer vined cultivars with normal leaf type. Branching habit did not affect the competitiveness of pea cultivars. Potential exists to plant highly branched cultivars to reduce risk of yield loss in situations where low plant emergence might occur.

Relatively little change in national soybean (Glycine max) yield over the previous years have led many farmers to creating management regimes focused on plant stress. Field experiments consisting of two different relative maturity (2.8RM and 4.5 RM) soybean cultivars were established at three locations across Kentucky in 2013 and 2014. Each maturity group received a single application, sequential applications, or a combination of the following treatments: N’N-diformyl urea, lactofen, lambda-cyhalothrin with thiamethoxam, and azoxystrobin with propiconazole. Relative maturity and yield environment*treatment interactions were observed to be significant (p 0≤.05). 4.5 RM soybean cultivars yielded significantly greater (800 kg ha-1) than 2.8 RM cultivars. Compared to the untreated check, no treatment in the yield environment*treatment interaction significantly increased yield. Significant yield decrease varied across yield environment, but was observed for treatments containing a combination of lactofen and N’N-diformyl urea. Application of stress management practices was not a consistent approach to improving soybean yield.

Changes in landscape pattern caused by changes in forest management, namely the Sustainable Forestry Initiative (SFI), and the implications of these structural changes on landscape processes were analyzed. Landscape structure was studied based upon the comparison of landscapes with different management histories. Ecological processes were analyzed based upon simulation of stand and landscape attributes of habitats for several vertebrate species and upon simulation of hydrological processes such as water and sediment yield. A methodology to integrate landscape and stand pattern and dynamics with landscape processes was developed for this work. It integrates a forest landscape structure model, several stand level growth and yield models, vertebrate habitat models, and a hydrological model. The comparisons among landscapes revealed that forest management has a strong influence on landscape structure. The SFI program increases fragmentation of the landscape indicated by the presence of more and smaller patches, more edges, more complex shapes, and less and smaller core areas. Traditional intensive and extensive management show comparable patterns characterized by high aggregation and connectivity. Landscapes managed according to the SFI program show higher Habitat Suitability Index (HSI) values for American woodcock, American beaver, wild turkey, fox squirrel, and gray squirrel. HSI is higher for pine warbler in the landscape not managed according to the SFI program. Downy woodpecker and barred owl present very reduced HSI values in either landscape. The SFI program induced fragmentation of the habitat of pine warbler and the establishment of narrow and elongated habitats in a network structure for the remaining species. Both patterns are determined by SMZs. The scenario representing management according to the SFI program presents higher sediment yield at the watershed level than the scenario representing management not according to the SFI program due to higher channel erosion related to the absence of buffer strips in the non-SFI scenario. In general, management according to the SFI program increases landscape diversity and evenness, habitat suitability for most species, potential vertebrate diversity, and provides habitat structure suitable for most species. This management also decreases sediment loss at the watershed level.

Corn (Zea mays L.) defoliation experiments have been conducted for more than 120 years. However, there is limited data on the effect of row width on defoliation in modern hybrids. A two-year experiment was conducted in Lexington, Kentucky with two hybrids (113 relative maturity (RM) and 120 RM), two row widths (38 and 76 cm) and a combination of defoliation timings and severities: 0% defoliation (control), V7-100%, V14-50%, V14-100%, R2-50% and R2-100%. No yield difference among hybrids was observed in 2012. Yields were 26% greater in 38-cm rows than 76-cm rows in 2012. For 2013, corn yield for 38-cm was 10% greater, but hybrid, row width and defoliation interacted. Lowest yields were caused by V14-100% followed by R2-100%. Defoliations of V14-50% and R2-50% reduced yields in some cases. Complete defoliations at V7 did not reduce yields in most comparisons. Light interception below 80% during the critical period was enough to attain maximum yields in defoliated plants. Kernel number and kernel weight were most reduced by V14-100% and R2-100% defoliations, respectively. There is a potential for narrow rows to reduce grain yield losses after a defoliation event, when compared with wide rows.

[Truncated abstract] It is well known that cows produce more milk if they are comfortable at milking, because stress from milking may cause them milk ejection problems. Temperament is an intrinsic characteristic of the animals so may affect the level of comfort at milking, and stress from the milking process itself may have a greater impact on animals with nervous temperament than on those of nervous temperament. When the milking becomes a stressor, it may affect secretion of milk ejection hormones that, in turn, may affect milk yield and composition. There is little evidence for how animal temperament affects milk quality in different farm animals. In this thesis, I have examined the effects of temperament on quantity and quality of the milk from Merino ewes and Holstein cows. I also tested whether temperament affected the processing performance (clotting properties) of the milk from Merino ewes. The general hypotheses tested were: 1. Calm ewes would produce more milk of better quality than nervous ewes, and, consequently, the clotting properties would be better in the milk from calm ewes than from nervous ewes. 2. Calm cows would produce more milk of better quality than nervous cows.

This thesis deals with yield formation with the 12 varieties of winter wheat during growing season 2013/2014. The experiment was established in four repetitions on the plot of Faculty of Agriculture, University of South Bohemia in České Budějovice. Examined yield components were the amount of spikes per 1 m2, amount of grains per spike and weight of thousand grains. Furthermore evaluated were the amount of plants per 1 m2, amount of spikelets in spike, real and theoretical yield, spike length and density. The next step was the processing of the results where the average value of all the varieties in the amount of ears per 1 m2 was 783 units/m2. The second element of the yield varieties reached the average number of grains per spike 36.2 pieces. And the mean weight of´thousand grains was 44.42 grams.