Recent declines in returns from primary forest products in New Zealand and projected increases in world food prices have led to the land-use conversion from plantation forest to pastoral farming in many lowland areas. After decades of forest cover the soils are in many cases less than adequate for pastoral farming, as they are acidic, with toxic levels of exchangeable aluminum, and contain low levels of available nitrogen (N), very high carbon (C):N ratio, and are devoid of earthworms and structural integrity. Overcoming the major site limitations of low soil pH and available N was a major priority and a field experiment was established in April 2005 to determine the impact of various rates of lime and N in relation to pasture establishment and production. Concerns about the short and long-term effects of these inputs on biological soil quality gave rise to the present study. The effects of land-use change and establishment inputs were assessed by comparison of selected treatment plots with two adjacent reference sites (long-term pasture and a 60–year Pinus radiata forest) on the same soil type. The effects of lime and N on soil biological quality were investigated under field and controlled environment conditions by determination of: microbial community structure (phospholipid fatty acids - PLFA), microbial biomass (total PLFA), and microbial activity (dehydrogenase activity). Soil physical (percentage water-stable aggregates) and chemical (pH, and total C and N) properties were also determined. Similarly, the effects of earthworm addition on soil biological properties were explored in a short-term glasshouse pot experiment. The role of earthworms as indicators of soil biological quality in the field was assumed by nematodes and these were assessed in field trial plots and the reference sites mentioned above. Land-use change and applications of lime and N contributed to changing the microbial community structure determined by principal component analysis of transformed PLFA data. However, the effect of lime was more pronounced in the field, while N contributed most to changing microbial community structure in the glasshouse. Mean microbial activity in the field increased from 4 µg dwt/hr without lime to 16 and 21 µg dwt/hr where lime was applied at 5 and 10 tons/hectare (t/ha), respectively. Mean microbial activity in the field was markedly higher (7-fold) than in the glasshouse at similar rates of lime. Lime application also increased soil moisture retention in the field, mean gravimetric soil moisture increased from 0.33 in control plots to 0.38 and 0.39 in plots treated with 5 and 10 t/ha lime, respectively. Lime application was associated with greater soil aggregate stability. Soils from test plots treated with 5 and 10 tons/ha lime had 45-50% water-stable aggregates compared to 34% in treatments without lime. After 16 weeks in pots, earthworm treatments increased mean plant dry matter (DM)/pot by at least 19% above the control. The increase was attributed primarily to greater N mineralization in the presence of earthworms. For the duration of the trial the earthworm species tested (Apporectodea caliginosa and Lumbricus rubellus, individually or combined) did not affect any of the measured soil microbial properties. However, the survival rate of A. caliginosa was 83% compared to 25% for L. rubellus. The control not receiving any lime or N and plots treated with 10t/ha lime and 200 kgN/ha had similar nematodes species composition, comprising 40% each of bacterial and fungal feeding nematodes. They differed markedly from the reference sites as the forest soil was dominated by plant associated species (38%) and the long-term pasture had 44% plant parasitic nematodes. Accordingly, the soil food web condition inferred from nematode faunal analysis characterized all test plots as basal, stressed and depleted, while the forest soil was categorized as highly structured and fungal dominated. The findings of this thesis demonstrated that land-use change from forest to pasture can have significant impacts on soil biological properties, earthworms can contribute to pasture productivity even in the short term, and nematode faunal analysis is a robust and reliable indicator of soil biological quality.

This thesis aIms to produce a distinctive model for the sustainable horticultural development of Maori resources, primarily land. It is inclusive of tikanga Maori and indigenous production systems based on the unique body of knowledge aligned to Maori. The integration of this knowledge with western science is both argued and applied through the model itself. The hypothesis applied was that matauranga Maori relevant to horticulture and pedology can inform and add value to the future development of Maori land resources. The thesis is bui lt on a unique set of contributing knowledge bases aligned to soils and horticultural management supported by three case studies, identified through their common association i.e. whakapapa links. The format of the thesis intentionally follows science principles in structure and presentation and some assumptions are made regarding base knowledge surrounding Maori cultural factors and the science disciplines relative to soils and horticul ture. The indigenous element, including Maori knowledge, is incorporated into the model using a triadic kosmos/corpus/praxis approach. Where kosmos is applied as Te A o Miiori, corpus as miitauranga Miiori and praxis as tikanga Miiori, the relationship between each element is clear and the interpretation of the associated knowledge becomes more apparent and can be applied to cultural assessments of resources, i ncluding land. The crux of the cultural assessment model is the quality of information used to assess Maori resources, especially from the cultural perspective. The Maori cultural paradigm, traditional horticulture and pedology, and various decision systems are purposefully accessed to act as contributors to the assessment model and to highlight the diversity and quality of information land managers have at their disposal. The ability to apply a cultural layer drawn from a body of knowledge not previously included in decision models relative to land utility in New Zealand is the key point. of difference of the model. The model is discussed from the perspective of its beneficial role for future use by Maori and how it can be continuously refined to meet the needs of Maori land owners and thus contribute to the rangatiratanga of Maori.

The Participatory Irrigation Management approach was introduced into Cambodia in 2000, which was called the Participatory Irrigation Management and Development (PIMD). The goal of PIMD is to establish Farmer Water User Communities (FWUCs) to take over the management of irrigation schemes in their district in order to improve the performance of irrigation schemes and farmers’ livelihoods. The implementation of FWUCs has resulted in both failure and success. Several studies have identified factors that influence the failure of FWUCs, but little research has focused on their success. By employing a single embedded case study approach, this research selected the most successful scheme in Cambodia to identify factors that influenced the success of the FWUC in irrigation management. The findings of this research could provide concrete assistance to the government, donors, and non-governmental organisations in improving the performance of less successful FWUCs in Cambodia. The result of this research showed that the success of the O-treing FWUC was influenced by five internal and two external factors. The internal factors were: 1) the level of local participation, 2) the governance and management of the scheme, 3) the value of the benefits that flow from the irrigation scheme, 4) the quality of the irrigation infrastructure, and 5) the characteristics of the farmer members within the scheme. The external factors were: 1) the level of external support provided to the scheme, and 2) market access. The success of the FWUC required farmer participation and this participation was enhanced when farmers obtained benefits from it. This research also found that access to markets was critical to make the benefits that flowed from the irrigation scheme more profitable to farmers, leading to farmer participation. Similarly, it was also important to make sure that the irrigation infrastructure was of a high quality to ensure the delivery of an adequate and timely supply of water to farmers so that they could grow crops that provided them with the benefits. This required external support from the Ministry of Water Resources and Meteorology, NGOs, and local authorities to help rehabilitate the scheme. External support was also critical for enhancing the governance and management of the scheme through assistance with the formation process, provision of financial resources, capacity building, rule enforcement, and conflict resolution. The governance and management of the scheme, in particular the leadership capacity of the FWUC was another critical factor because it ensured the maintenance and development of the irrigation infrastructure, the timely and adequate supply of water to farmers, farmers’ trust and respect for leaders, and farmer participation. Finally, the success of the FWUC could not be viewed independently from farmer characteristics within the scheme. Farmers tended to participate in irrigation management when they had a history of self-organisation, when they were relatively homogenous, and when they were dependent upon farming for their livelihoods. This research suggests that the successful implementation of FWUCs requires a focus on the seven factors and the interactions that occur between these factors. Irrigation stakeholders such as the Ministry of Water Resources and Meteorology, donors, NGOs, local authorities, local leaders, and farmers should work together to enhance these factors in order to ensure the success of FWUCs.

The last decade has been a period of great expansion and land use intensification for the New Zealand dairy farming industry with a 44% increase in national dairy cow numbers. Intensive dairy farming is now considered to be a major contributor to the deterioration in the quality of surface and ground water resources in some regions of New Zealand. Previous research has demonstrated intensive dairy farming is responsible for accelerated contamination of wateways by nutrients, suspended solids, pathogenic organisms and faecal material. A number of common dairy farming practices increase the risk of nutrient leaching. In particular, farm dairy effluent (FDE) has been implicated as a major contributor to the degradation of water quality. With the introduction of the Resource Management Act in 1991, the preferred treatment for FDE shifted away from traditional two-pond systems to land application. However, on most farms, irrigation of FDE has occurred on a daily basis, often without regard for soil moisture status. Therefore, it has been commonplace for partially treated effluent to drain through and/or runoff soils and contaminate fresh water bodies. The objectives of this thesis were to design and implement a sustainable land application system for FDE on difficult to manage, mole and pipe drained soils, and to assess the impacts of FDE application, urea application and cattle grazing events on nutrient losses via artificial drainage and surface runoff from dairy cattle grazed pasture. To meet these objectives a research field site was established on Massey University's No.4 Dairy farm near Palmerston North. The soil type was Tokomaru silt loam, a Fragiaqualf with poor natural drainage. Eight experimental plots (each 40 x 40 m) were established with two treatments. Four of the plots represented standard farm practice including grazing and fertiliser regimes. Another four plots were subjected to the same farm practices but without the fertiliser application and they were also irrigated with FDE. Each plot had an isolated mole and pipe drainage system. Four surface runoff plots (each 5 m x 10 m) were established as subplots (two on the fertilised plots and two on the plots irrigated with FDE) in the final year of the study. Plots were instrumented to allow the continuous monitoring of drainage and surface runoff and the collection of water samples for nutrient analyses. An application of 25 mm of FDE to a soil with limited soil water deficit - simulating a 'daily' irrigation regime - resulted in considerable drainage of partially treated FDE. Approximately 70% of the applied FDE left the experimental plots with 10 mm of drainage and 8 mm of surface runoff. The resulting concentrations of N and P in drainage and runoff were approximately 45% and 80% of the original concentrations in the applied FDE, respectively. From this single irrigation event, a total of 12.1 kg N ha-1 and 1.9 kg P ha-1 was lost to surface water representing 45% of expected annual N loss and 100% of expected annual P loss. An improved system for applying farm dairy effluent to land called 'deferred irrigation' was successfully developed and implemented at the research site. Deferred irrigation involves the storage of effluent in a two-pond system during periods of small soil moisture deficits and the scheduling of irrigation at times of suitable soil water deficits. Deferred irrigation of FDE all but eliminated direct drainage losses with on average <1 % of the volume of effluent and nutrients applied leaving the experimental plots. Adopting an approach of applying 'little and often' resulted in no drainage and, therefore, zero direct loss of nutrients applied. A modelling exercise, using the APSlM simulation model, was conducted to study the feasibility of practising deferred irrigation at the farm scale on No 4 Dairy farm. Using climate data for the past 30 years, this simulation exercise demonstrated that applying small application depths of FDE, such as 15 mm or less, provided the ability to schedule irrigations earlier in spring and decreased the required effluent storage capacity. A travelling irrigator, commonly used to apply FDE (a rotating irrigator), was found to have 2-3 fold differences in application depth and increased the risk of generating FDE contaminated drainage. New irrigator technology (an oscillating travelling irrigator) provided a more uniform application pattern allowing greater confidence that an irrigation depth less than the soil water deficit could be applied. This allowed a greater volume to be irrigated, whilst avoiding direct drainage of FDE when the soil moisture deficit is low in early spring and late autumn. A recommendation arising from this work is that during this period of low soil water deficits, all irrigators should be set to travel at their fastest speed (lowest application depth) to minimise the potential for direct drainage of partially treated FDE and associated nutrient losses. The average concentrations of N and P in both 2002 and 2003 winter mole and pipe drainage water from grazed dairy pastures were all well above the levels required to prevent aquatic weed growth in fresh water bodies. Total N losses from plots representing standard farm practice were 28 kg N ha-1 and 34 kg N ha-1 for 2003 and 2004, respectively. Total P losses in 2003 and 2004 were 0.35 kg P ha-1 and 0.7 kg P ha-1, respectively. Surface runoff was measured in 2003 and contributed a further 3.0 kg N ha-1and 0.6 kg P ha-1. A number of common dairy farm practices immediately increased the losses of N and P in the artificial drainage water. Recent grazing events increased NO3--N and DIP concentrations in drainage by approximately 5 mg litre-1 and 0.1 mg litre-1, respectively. The duration between the grazing and drainage events influenced the form of N loss due to a likely urine contribution when grazing and drainage coincide, but had little impact on the total quantity of N lost. Nitrogen loss from an early spring application of urea in 2002 was minimal, whilst a mid June application in 2003 resulted in an increased loss of NO3--N throughout 80 mm of cumulative drainage suggesting that careful timing of urea applications in winter is required to prevent unnecessary N leaching. Storage and deferred irrigation of FDE during the lactation season caused no real increase in either the total-N concentrations or total N losses in the winter drainage water of 2002 and 2003. In contrast, land application of FDE using the deferred irrigation system resulted in a gradual increase in total P losses over the 2002 and 2003 winter drainage seasons. However, this increase represents less than 4% of the P applied in FDE during the lactation season. An assessment of likely losses of nutrients at a whole-farm scale suggests that it is standard dairy farming practice (particularly intensive cattle grazing) that is responsible for the great majority of N and P loss at a farm scale. When expressed as a proportion of whole-farm losses, only a very small quantity of N is lost under an improved land treatment technique for FDE such as deferred irrigation. The management of FDE plays a greater role in the likely P loss at a farm scale with a 5% contribution to wholefarm P losses from deferred irrigation.

This thesis aIms to produce a distinctive model for the sustainable horticultural development of Maori resources, primarily land. It is inclusive of tikanga Maori and indigenous production systems based on the unique body of knowledge aligned to Maori. The integration of this knowledge with western science is both argued and applied through the model itself. The hypothesis applied was that matauranga Maori relevant to horticulture and pedology can inform and add value to the future development of Maori land resources. The thesis is bui lt on a unique set of contributing knowledge bases aligned to soils and horticultural management supported by three case studies, identified through their common association i.e. whakapapa links. The format of the thesis intentionally follows science principles in structure and presentation and some assumptions are made regarding base knowledge surrounding Maori cultural factors and the science disciplines relative to soils and horticul ture. The indigenous element, including Maori knowledge, is incorporated into the model using a triadic kosmos/corpus/praxis approach. Where kosmos is applied as Te A o Miiori, corpus as miitauranga Miiori and praxis as tikanga Miiori, the relationship between each element is clear and the interpretation of the associated knowledge becomes more apparent and can be applied to cultural assessments of resources, i ncluding land. The crux of the cultural assessment model is the quality of information used to assess Maori resources, especially from the cultural perspective. The Maori cultural paradigm, traditional horticulture and pedology, and various decision systems are purposefully accessed to act as contributors to the assessment model and to highlight the diversity and quality of information land managers have at their disposal. The ability to apply a cultural layer drawn from a body of knowledge not previously included in decision models relative to land utility in New Zealand is the key point. of difference of the model. The model is discussed from the perspective of its beneficial role for future use by Maori and how it can be continuously refined to meet the needs of Maori land owners and thus contribute to the rangatiratanga of Maori.

Trifolium repens, Lotus pedunculatus and Holcus lanatus were oversown on two recent soil slip surfaces at AgResearch’s Ballantrae pastoral hill‐country farm near Woodville. The two slip surfaces were located on (Manamahu steepland soil) sedimentary mudstone. One slip had a north aspect and the other had a south aspect. Both slips were located on a land class 6 with slope 28‐330. The pasture species were oversown during early spring and the percentage seedling emergence and early establishment from viable seeds oversown was analysed at early spring (Day 15), late spring (Day 45), early summer (Day 90), and late summer (Day 120). The slip surfaces showed micro‐climatic extremes in terms of both soil moisture and surface temperatures during the summer period. Significant differences (P < 0.05) were found in soil moisture between north and south facing slip surfaces. Higher soil moisture and lower soil mean temperature were recorded on the south aspect slip surface. Significant differences (P < 0.05) were found between the three pasture species in terms of seedling emergence and early establishment. Significant differences (P < 0.05) were also found with aspect. The south aspect slip surface had a higher percentage of seedling emergence and earlier establishment for all the species. Interaction between species by aspect became significantly different (P < 0.05) at Day 90 and Day 120. The main effects of time and species were also significantly different (P < 0.05) illustrating seedling emergence and establishment as a race against time. Trifolium repens was a more successful pasture specie, than L. pedunculatus and H. lanatus due to its higher consistency on both north and south slip surfaces. Oversowing T. repens during early spring is a viable option for rehabilitation of recent soil slips in Manawatu.

Thesis (M. En.)--Miami University, Institute of Environmental Sciences, 2005. / Title from first page of PDF document. Document formatted into pages; contains [1], v, 101 p. : ill. Includes bibliographical references (p. 63-64).

Made available in DSpace on 2016-12-23T13:51:50Z (GMT). No. of bitstreams: 1 Dissertacao Joao Paulo Bestete de Oliveira.pdf: 3212989 bytes, checksum: a465cb7680078a4edb0e33c768805550 (MD5) Previous issue date: 2010-07-22 / The control of erosion requires an understanding of the complex interactions between chemical, physical, hydrological and meteorological. Several mathematical models have been developed and improved in objective to predict the magnitude of soil loss by erosion, like the Water Erosion Prediction Project (WEPP). The potential of projected global climate changes to increase the risk of soil erosion, with related environmental consequences is clear, but the real damage is not yet known and needs to be evaluated. It was objectified with this work to evaluate the impact of climate change on soil loss and water catchment in the Espírito Santo. To reach the proposed objectives was held to characterize the watershed area of stream Jaqueira located in the Alegre-ES city, and the lifting of the input files of the WEPP model (climate, soil, land use and management and topography). Subsequently, we obtained the future climate scenarios through the deviations from expected values for the climatic elements (rainfall, solar radiation, maximum and minimum temperatures), according to the HadCM3 global climate model. Finally, we applied the model to predict soil loss and water through the integration of softwares GeoWEPP, TOPAZ and ArcView to current climatic conditions and relating to different time-slices (2020, 2050 and 2080) and emissions scenarios (A2 and B2). The obtained results allowed to conclude that: the current simulated average losses in the watershed of the stream Jaqueira are of 52.9 mm year-1 for the runoff and 17.5 t ha-1 yr-1; in the current scenario, the areas with the largest losses were secondary regeneration and natural grassland; the hillslope 3, by has average slope, land cover influences; is forecast in 2020 A2, B2 2020 B2 and 2050, increase the runoff and the rate of soil loss, when is expected increase in precipitation, is predicted by 2050 A2, 2080 A2 and B2 in 2080, reducing runoff and soil loss rate, even when expected increase in precipitation / O controle do processo erosivo requer o entendimento das interações complexas entre os processos químicos e físicos do solo, além dos hidrológicos e meteorológicos. Diversos modelos matemáticos vêm sendo desenvolvidos e aperfeiçoados com o objetivo de prever a magnitude das perdas de solo por erosão, como o Water Erosion Prediction Project (WEPP). O potencial das mudanças climáticas globais projetadas em aumentar o risco de erosão do solo, com as conseqüências ambientais relacionadas, é claro, mas o real dano ainda não é conhecido e precisa ser avaliado. Objetivou-se com este trabalho avaliar o impacto das mudanças climáticas globais sobre as perdas potenciais de solo e água em microbacia hidrográfica no Espírito Santo. Para tanto, realizaram-se caracterizações climáticas e físicas da área da microbacia do córrego Jaqueira, localizada no município de Alegre-ES, bem como a criação dos arquivos de entrada do modelo WEPP (clima, solo, uso e manejo do solo e topografia). Posteriormente, foram simulados os cenários climáticos futuros através dos valores dos desvios esperados para os elementos climáticos (precipitação, radiação solar, temperaturas máximas e mínimas), de acordo com o modelo climático global HadCM3. Por fim, aplicou-se o modelo para a predição das perdas de solo e água através da integração dos softwares GeoWEPP, TOPAZ e ArcView, para a condição climática atual e referentes a diferentes time-slices (2020, 2050 e 2080) e cenários de emissões (A2 e B2). Os resultados obtidos permitiram concluir que: as perdas médias atuais simuladas na microbacia do córrego Jaqueira são de 52,9 mm ano-1 para o escoamento superficial e de 17,5 t ha-1 ano-1; no cenário atual as áreas que apresentaram maiores perdas foram regeneração secundária e pastagem natural; a encosta 3, por possuir maior declividade média influencia a cobertura vegetal; há previsão, em 2020 A2, 2020 B2 e 2050 B2, de aumento do escoamento superficial e da taxa de perda de solo, quando esperado aumento da precipitação; há previsão, em 2050 A2, 2080 A2 e 2080 B2, de diminuição do escoamento superficial e da taxa de perda de solo, mesmo quando esperado aumento da precipitação

Made available in DSpace on 2014-07-29T14:52:04Z (GMT). No. of bitstreams: 1 lino carlos borges.pdf: 491790 bytes, checksum: 99dc54d275a0812ac054dab565c3467d (MD5) Previous issue date: 2008-02-27 / There are several works which aim to equate the agricultural production in function of the best use of natural resources as soil and water, in the attempt of obtaining the maximum of effectiveness in the productive system, and upon this context the evaluation of the potential of using the lands has major importance for a correct planning of agricultural activities. The elaboration of maps of agricultural aptitude is of extreme importance for the sustainable use of soil and water, it should be the first and more important instrument of agricultural planning. Because of this, the elaboration of those maps should be accompanied of a discerning methodological process, focused mainly in the socioeconomic aspects aiming to adequate it to the various levels of soil handling present nowadays. This work has as objectives: 1) Research the applicability of the evaluation system of the lands agricultural aptitude regarding the actual conditions of the agricultural productive process for two areas of the State of Goiás, basin of drainage of Córrego das Pedras and of Ribeirão Jurubatuba (nascent of Ribeirão João Leite) and of the immediate surrounding of the National Park of Emas; 2) Look for latent factors responsible for the large variability of the lands aptitude in the studied areas, and detect the similar samples considering this clustering, using for this multivariate techniques of factor analysis of principal components and discriminative. The work considers quantifying and comparing the elements of production among the various classes of agricultural aptitude, establishing qualitative differences among those aptitude classes and the handling levels, comparing the theoretical model proposed in the studies against the several realities of the researched areas. The data related to the soil types, agricultural aptitude and handling levels recommended were gathered from maps elaborated for the two areas being studied. Data regarding productivity, production costs, land value, gross revenue and local adopted technology were obtained from personal visits and direct interviews with a sample of 52 farm properties for the agricultural year of 2006/2007. Based on the information found in the 52 analyzed samples, the use of factor analysis was shown to be promising, for this study area, being an innovative aspect in the interpretation of data related to the agricultural aptitude. Two techniques of statistical multivariate analysis were used: factor analysis aiming to reduce the columns of the original matrix (variables in study) through the identification of latent factors, synthesizing the common information over all variables; and the discriminant analysis with the objective of classifying the observations, with known data. These analyses indicated that productivity and production cost are related and that a possible explanation for it may be due to the levels of handling and technology, as with the gross income it may be explained by other elements as the business opportunity, market value for the products, and not necessarily with the level of technology. It was verified also a need for establishing greater and more meaningful details regarding the handling levels for the cases of pasture and forestry. Because of the peculiarities and diversity of production systems found in the basin of Ribeirão João Leite, the system of agricultural aptitude of the lands proposed by Ramalho Filho & Beek (1995) was considered insufficient, for suggesting only three handling levels, while the dispersion of the data regarding production, productivity, production cost and gross revenue, demonstrates the need of better discrimination or hierarchization of the handling levels. For the area of the immediate surrounding of the National Park of Emas the system of agricultural aptitude was shown to be more appropriate on the handling levels recommended. The system proposed by Ramalho Filho & Beek (1995), in a certain way, plasters or limits the expectations one could have relative to the potential of certain cultures, soils and used labor force, regarding the productivity and profitability of some agricultural and forestry activities. It was verified also that the handling levels are extremely important, and they should be in greater number and more detailed than the existing 3 handling levels (A,B and C) proposed by Ramalho Filho & Beek (1995). / Vários são os trabalhos que buscam equacionar a produção agrícola em função do melhor aproveitamento dos recursos naturais como solo e água, na tentativa de se obter o máximo de eficácia no sistema produtivo, e dentro desse contexto a avaliação do potencial de uso das terras tem grande importância para o correto planejamento das atividades agropecuárias. A elaboração de mapas de aptidão agrícola é de extrema importância para a utilização sustentável do solo e da água, devendo ser o primeiro e mais importante instrumento do planejamento agropecuário. Por isso, a elaboração desse instrumento deve ser acompanhada de um criterioso processo metodológico, focado principalmente no aspecto sócio-econômico procurando adaptá-lo aos diversos níveis de manejo de solo existentes. Este trabalho tem por objetivos: 1) Pesquisar a aplicabilidade do sistema de avaliação da aptidão agrícola das terras frente à realidade do processo produtivo agropecuário de duas regiões do Estado de Goiás, uma incluindo as bacias hidrográficas do Córrego das Pedras e do Ribeirão Jurubatuba (nascentes do Ribeirão João Leite); e outra do entorno do Parque Nacional das Emas; 2) Encontrar fatores latentes responsáveis pela maior variabilidade de aptidão das terras nas regiões pesquisadas, e detectar as amostras semelhantes mediante esse agrupamento, utilizando para isso técnicas de análise multivariada referente à análise fatorial em componentes principais e discriminante. O trabalho envolve a quantificação e comparação dos fatores da produção entre as diversas classes de aptidão agrícola, estabelecendo as diferenças qualitativas entre as diversas classes e os níveis de manejo, comparando o modelo teórico proposto nos estudos com as diversas realidades das regiões pesquisadas. Os dados relacionados aos tipos de solo e a aptidão agrícola e aos níveis de manejo recomendados foram extraídos de mapas elaborados para as duas regiões estudadas. Os dados de produtividade, custo de produção, valor da terra, receita bruta e tecnologia adotada foram obtidos em visitas e entrevistas diretas a 52 propriedades amostradas no ano agrícola 2006/2007. Com base nas informações obtidas nas 52 amostras, a utilização da análise fatorial mostrou-se bastante promissora, para esse tipo de estudo, constituindo uma inovação na interpretação de dados relacionados à aptidão agrícola. Foram empregadas duas técnicas de análise estatística multivariadas: a análise fatorial com o objetivo de reduzir as colunas da matriz original (variáveis em estudo) através da identificação de fatores latentes, sintetizando a informação comum aos grupos de variáveis; e a análise discriminante com o objetivo de classificar as observações, com dados conhecidos. Essas análises indicaram que a produtividade e o custo de produção estão relacionados, possivelmente, devido aos níveis de manejo utilizados. A renda bruta pode ser explicada por outros elementos como a oportunidade de negócios, valor de mercado do produto, e não necessariamente pela tecnologia adotada. Verificou-se também a necessidade de se estabelecer maior detalhamento nos níveis de manejo para pastagem e silvicultura. Pelas peculiaridades e diversidade de sistemas de produção encontrados na Bacia do Ribeirão João Leite, o sistema de aptidão agrícola das terras proposto por Ramalho Filho & Beek (1995) mostrou-se insuficiente, sugerindo somente três níveis de manejo, enquanto a dispersão dos dados referentes à produção, produtividade, custo de produção e receita bruta, mostra a necessidade de melhor detalhamento ou hierarquização dos níveis de manejo. Para a região do entorno do Parque Nacional das Emas o sistema de aptidão agrícola mostrou-se mais adequado aos níveis de manejo recomendados. O sistema preconizado por Ramalho Filho & Beek (1995), de certa maneira, engessa as expectativas em relação ao potencial de certas culturas, dos solos e da mão-de-obra empregada, com relação à produtividade e rentabilidade de algumas atividades agrosilvopastoris. Verificou-se também que os níveis de manejo são extremamente importantes, devendo ser mais diversos e detalhados do que os 3 níveis de manejo (A,B e C) preconizados por Ramalho Filho & Beek (1995).

Deforestation of the Brazilian savanna (Cerrado) region has caused major changes in hydrological processes. These changes in water balance and soil erosion are still poorly understood, but are important for making land management decisions in this region. Therefore, it is necessary to understand the magnitudes of hydrological processes and soil erosion changes on local, regional and continental scales, and the consequences that are generated. The main objective of the study presented in this doctoral thesis was to better understand the mechanism of hydrological processes and soil erosion in the Cerrado. To achieve that, I worked with different scales (hillslope, watershed and continental) and using data from experimental field, laboratory, and remote sensing. The literature review reveals that the annual rainfall erosivity in Brazil ranges from 1672 to 22,452 MJ mm ha-1 h-1 yr-1. The smallest values are found in the northeastern region, and the largest in the north and the southeastern region. I found that the canopy interception may range from 4 to 20% of gross precipitation and stemflow around 1% of gross precipitation in the cerrado. The average runoff coefficient was less than 1% in the plots under cerrado and that the deforestation has the potential to increase up to 20 fold the runoff coefficient value. The results indicate that the Curve Number method was not suitable to estimate runoff under undisturbed Cerrado, bare soil (hydrologic soil group A), pasture, and millet. Therefore, in these cases the curve number is inappropriate and the runoff is more aptly modeled by the equation Q = CP, where C is the runoff coefficient. The water balance from the remote sensing data across the Brazilian Cerrado indicates that the main source of uncertainty in the estimated runoff arises from errors in the TRMM precipitation data. The water storage change computed as a residual of the water budget equation using remote sensing data (TRMM and MOD16) and measured discharge data shows a significant correlation with terrestrial water storage change obtained from the GRACE data. The results show that the GRACE data may provide a satisfactory representation of water storage change for large areas in the Cerrado. The average annual soil loss in the plots under bare soil and cerrado were 15.25 t ha-1 yr-1 and 0.17 t ha-1 yr-1, respectively. The Universal Soil Loss Equation cover and management factor (C-factor) for the plots under native cerrado vegetation was 0.013. The results showed that the surface runoff, soil erosion and C-factor for the undisturbed Cerrado changes between seasons. The greatest C-factor values were found in the summer and fall. The results found in this doctoral thesis provide benchmark values of the water balance components and soil erosion in the Brazilian Cerrado that will be useful to evaluate past and future land cover and land use changes for this region. In addition, I conclude that the remote sensing data are useful to evaluate the water balance components over Cerrado regions, identify dry periods, and assess changes in water balance due to land cover and land use change. / O desmatamento nas regiões de Cerrado tem causado intensas mudanças nos processos hidrológicos. Essas mudanças no balanço hídrico e erosão do solo são ainda pouco entendidas, apesar de fundamentais na tomada de decisão de uso e manejo do solo nesta região. Portanto, torna-se necessário compreender a magnitude das mudanças nos processos hidrológicos e de erosão do solo, em escalas locais, regionais e continentais, e as consequências dessas mudanças. O principal objetivo do estudo apresentado nesta tese de doutorado foi de melhor entender os mecanismos dos processos hidrológicos e de erosão do solo no Cerrado Brasileiro. Para tanto, utilizou-se diferentes escalas de trabalho (vertentes, bacias hidrográficas e continental) e usando dados experimentais in situ, de laboratório e a partir de sensoriamento remoto. O estudo de revisão de literatura indica que a erosividade da chuva no Brasil varia de 1672 to 22,452 MJ mm ha-1 h-1 yr-1. Os menores valores encontram-se na região nordeste e os maiores nas regiões norte e sudeste do Brasil. Verificou-se que os valores de interceptação da chuva variam de 4 a 20% e o escoamento pelo tronco aproximadamente 1% da precipital total no cerrado. O coeficiente de escoamento superficial foi menor que 1% nas parcelas de cerrado e o desmatamento tem o potencial de aumentar em até 20 vezes esse valor. Os resultados indicam que o método Curve Number não foi adequado para estimar o escoamento superficial nas áreas de cerrado, solo exposto (grupo hidrológico do solo A), pastagem e milheto. Portanto, nesses casos o uso do CN é inadequado e o escoamento superficial é melhor estimado a partir da equação Q = CP, onde C é o coeficiente de escoamento superficial. O balanço hídrico a partir de dados de sensoriamento remoto para todo o Cerrado Brasileiro indica que a principal fonte de incerteza na estimativa do escoamento superficial ocorre nos dados de precipitação do TRMM. A variação de água na superfície terrestre calculada como o residual da equação do balanço hídrico usando dados de sensoriamento remoto (TRMM e MOD16) e valores observados de vazão mostram uma correlação significativa com os valores de variação de água na superfície terrestre provenientes dos dados do GRACE. Os dados do GRACE podem representar satisfatoriamente a variação de água na superfície terrestre para extensas regiões do Cerrado. A média anual de perda de solo nas parcelas de solo exposto e cerrado foram de 15.25 t ha-1 yr-1 and 0.17 t ha-1 yr-1, respectivamente. O fator uso e manejo do solo (fator C) da Universal Soil Loss Equation para o cerrado foi de 0.013. Os resultados mostraram que o escoamento superficial, erosão do solo e o fator C na área de cerrado variam de acordo com as estações. Os maiores valores do fator C foram encontrados no verão e outono. Os resultados encontrados nesta tese de doutorado fornecem valores de referência sobre os componentes do balanço hídrico e erosão do solo no Cerrado, que podem ser úteis para avaliar o uso e cobertura do solo atual e futuro. Além disso, conclui-se que os dados de sensoriamento remoto apresentam resultados satisfatórios para avaliar os componentes do balanço hídrico no Cerrado, identificar os períodos de seca e avaliar as alterações no balanço hídrico devido à mudanças de uso e cobertura do solo.