Dryland salinity is increasing in the upper catchments of central and northern New South Wales, Australia. Consequently, salts may be exported downstream, which could adversely affect cotton irrigated-farming systems. In order to assess the potential threat of salinity a simple salt balance model based on progressively saline water (i.e., ECiw 0.4, 1.5, 4.0 and 9.0 dS/m) was used to simulate the potential impact of salinisation due to the farming systems. The study was carried out in the lower Namoi valley of northern New South Wales, Australia. A comparison has been made of the various non-linear techniques (indicator kriging, multiple indicator kriging and disjunctive kriging) to determine an optimal simulation method for the risk assessment. The simulation results indicate that potential salinisation due to application of the water currently used for irrigation (ECiw) is minimal and may not pose any problems to sustainability of irrigated agriculture. The same results were obtained by simulation based on irrigation using slightly more saline water (ECiw 1.4 dS/m). However, simulations based on irrigation using water of even lower quality (ECiw of 4 and 9.0 dS/m), shows potential high salinisation, which will require management inputs for sustainable cropping systems, especially legumes and wheat, which are used extensively in rotation with cotton. Disjunctive kriging was the best simulation method, as it produced fewer misclassifications in comparison with multiple-indicator kriging and indicator kriging. This study thus demonstrates that we can predict the salinity risk due to application of irrigation water of lower quality than that of the current water used. In addition, the results suggest here problems of excessive deep drainage and inefficient use of water might be a problem. The second part of this thesis deals with soil information required at the field scale for management practices particularly in areas where deep drainage is large. Unfortunately, traditional methods of soil inventory at the field level involve the design and adoption of sampling regimes and laboratory analysis that are time-consuming and costly. Because of this more often than not only limited data are collected. In areas where soil salinity is prevalent, detailed quantitative information for determining its cause is required to prescribe management solutions. This part deals with the description of a Mobile Electromagnetic Sensing System (MESS) and its application in an irrigated-cotton field suspected of exhibiting soil salinity. The field is within the study area of part one of this thesis-located about 2 km south west of Wee Waa. The EM38 and EM31 (ECa) data provide information, which was used in deciding where soil sample sites could be located in the field. The ECa data measured by the EM38 instrument was highly correlated with the effective cation exchange capacity. This relationship can be explained by soil mineralogy. Using different soil chemical properties (i.e. ESP and Ca/Mg ratio) a detailed transect study was undertaken to measure soil salinity adjoining the water storage. It is concluded that the most appropriate management option to remediation of the problem would be to excavate the soil directly beneath the storage floor where leakage is suspected. It is recommended that the dam not be enlarged from its current size owing to the unfavourable soil mineralogy (i.e. kaolin/illite) located in the area where it is located.

Dryland salinity is increasing in the upper catchments of central and northern New South Wales, Australia. Consequently, salts may be exported downstream, which could adversely affect cotton irrigated-farming systems. In order to assess the potential threat of salinity a simple salt balance model based on progressively saline water (i.e., ECiw 0.4, 1.5, 4.0 and 9.0 dS/m) was used to simulate the potential impact of salinisation due to the farming systems. The study was carried out in the lower Namoi valley of northern New South Wales, Australia. A comparison has been made of the various non-linear techniques (indicator kriging, multiple indicator kriging and disjunctive kriging) to determine an optimal simulation method for the risk assessment. The simulation results indicate that potential salinisation due to application of the water currently used for irrigation (ECiw) is minimal and may not pose any problems to sustainability of irrigated agriculture. The same results were obtained by simulation based on irrigation using slightly more saline water (ECiw 1.4 dS/m). However, simulations based on irrigation using water of even lower quality (ECiw of 4 and 9.0 dS/m), shows potential high salinisation, which will require management inputs for sustainable cropping systems, especially legumes and wheat, which are used extensively in rotation with cotton. Disjunctive kriging was the best simulation method, as it produced fewer misclassifications in comparison with multiple-indicator kriging and indicator kriging. This study thus demonstrates that we can predict the salinity risk due to application of irrigation water of lower quality than that of the current water used. In addition, the results suggest here problems of excessive deep drainage and inefficient use of water might be a problem. The second part of this thesis deals with soil information required at the field scale for management practices particularly in areas where deep drainage is large. Unfortunately, traditional methods of soil inventory at the field level involve the design and adoption of sampling regimes and laboratory analysis that are time-consuming and costly. Because of this more often than not only limited data are collected. In areas where soil salinity is prevalent, detailed quantitative information for determining its cause is required to prescribe management solutions. This part deals with the description of a Mobile Electromagnetic Sensing System (MESS) and its application in an irrigated-cotton field suspected of exhibiting soil salinity. The field is within the study area of part one of this thesis-located about 2 km south west of Wee Waa. The EM38 and EM31 (ECa) data provide information, which was used in deciding where soil sample sites could be located in the field. The ECa data measured by the EM38 instrument was highly correlated with the effective cation exchange capacity. This relationship can be explained by soil mineralogy. Using different soil chemical properties (i.e. ESP and Ca/Mg ratio) a detailed transect study was undertaken to measure soil salinity adjoining the water storage. It is concluded that the most appropriate management option to remediation of the problem would be to excavate the soil directly beneath the storage floor where leakage is suspected. It is recommended that the dam not be enlarged from its current size owing to the unfavourable soil mineralogy (i.e. kaolin/illite) located in the area where it is located.

The impact of long term management strategies of irrigation with saline water in semi-arid region of Gordonia, South Africa is the highest interest to optimize water consumption, soil conservation, and crop yield for sustainable water allocations to human food production and ecosystem without irreversible damages to soil and water body. An integrated ecosystem assimilation, in shape of soil-water storage model based on physical approach for 30-year simulation run defined in form of digital ecosystem modelling with help of CoupModel tool to assemble together the most important underlying processes of soil hydraulics, irrigation demands, leaching fraction, evapotranspiration, salt transport. Two scenarios of water management strategy; surface as traditional and drip as subsurface irrigation considered to apply water and salt into the ecosystem model. Gaining high food production for human with respect to ecosystem sustainability, in each water management scenario studied by evaluating general and detailed result from water and salt balance for the entire simulation period plus long term nitrogen and carbon turnover as crop yield indicator. Non-productive water losses, salt accumulation in root zone, carbon and nitrogen turnover, salt transport to aquifer via deep percolation observed thoroughly. Decline in crop yield due to water and salt stress, conducted by monitoring biomass production with respect to water consumption and soil osmotic pressure in root zone. Drip scenario had better functionality to perform less water wastage by decreasing soil evaporation as non-productive water loss almost 40 %, however productive water consumption decreased 20 % due to insufficient leaching fraction and also salt accumulation increased in root zone. Precipitation had a significant role to accomplish leaching deficiency and removing salt from root zone. Salt accumulation flushed out from root zone by more leaching, though resulting more water wastage and more possibility of salinization threatening beneath aquifer. Ecosystem in terms of soil-water and plant responding differently facing salinity in different water management practices and salt as source of pollution could either stabilized in soil by accumulating in root zone causing anthropogenic soil desertification or percolate to beneath aquifer resulting aquifer salinization.

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No. of bitstreams: 2 Dissertação - Ricardo de Sousa Bezerra - 2015.pdf: 3022255 bytes, checksum: bb0af8f3ee8d663be0d877158dd8032b (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-02-26 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The application of high level of fertilization and inappropriate irrigation management in substrate cultivation tomato (Solanum Lycopersicum L.) causes salinity in cultivation environmental, imbalance nutritional and physiological disorders in plants, which normally leads to decrease yield and cause economic losses. The aim of this study was to test the effect of different fertigation techniques controlled by an automatic irrigation system, consisting of programmable logic controllers (PLC) and Irrigas® sensors, on growth and yield of tomato plants in greenhouses. The experiment was conducted in a greenhouse at the experimental area of the Agronomy School of the Federal University of Goiás (UFG), in Goiânia, GO, Brazil, from May 23 to September 26, 2014. It was used Mascot F1 hybrid that is a mini tomato type grape. The experimental design was a randomized complete block with five blocks and four replications in block. The experimental unit was one plant. The treatments consisted of four forms of fertigation management, as follows: a) Treatment 1 - fertigation with application of 20% leaching fraction; b) Treatment 2 - fertigation throughout the day and application of water with 20% leaching fraction at the end of the day; Treatment 3 - initial application of water leaching fraction of 20% followed by fertigation; Treatment 4 - fertigation using the nutrient solution reuse with application of 20% leaching fraction. We evaluated the electrical conductivity (EC) of the leached solution; the nutrient content in the dry matter of leaves; height and diameter of the stalk; number of bunchs; total yield and marketable fruit yield; the fruit quality was evaluated by size, color, total titratable acidity, soluble solids content and texture of fruits. To evaluate the automation system was done operation tests and also an cost analysis to construction of the fertigation control system. The differents forms of fertigation not influence the vegetative growth of tomato; the use of standard nutrient solution with 20% leaching fraction (treatment 1) and the reuse of the leached solution, also with 20% leaching fraction (treatment 2), provided the largest marketable production (1616.85 g plant-1 and 1401.90 g plant-1), fruit production with higher soluble solids (5.82 and 5.65 ° Brix, respectively), and increase blossom end rot in minitomato; it is possible reuse the nutrient solution drained of pots if the EC of solution were adjusted daily; the fertigation control system works fine and presents low cost compared to comercial system control of fertigation. / O uso de elevadas doses de adubação e o manejo inadequado da irrigação no cultivo do tomateiro (Solanum Lycopersicum L.) em vasos causam, além da salinidade no ambiente de cultivo, desequilíbrio nutricional e desordens fisiológicas nas plantas, provocando normalmente redução de produtividade e prejuízos econômicos aos produtores. O objetivo deste trabalho foi verificar o efeito de diferentes técnicas de fertirrigação sobre o desenvolvimento e produção do tomateiro cultivado em ambiente protegido e avaliar o sistema automático de fertirrigação utilizado. O experimento foi conduzido dentro de uma casa-de-vegetação na área experimental da Escola de Agronomia da Universidade Federal de Goiás, em Goiânia-GO, no período de 23/05 a 26/09/2014. Cultivou-se minitomates do tipo grape, híbrido Mascot F1. O delineamento experimental utilizado foi blocos completos casualizados, com cinco blocos e quatro repetições por bloco. Cada planta representava uma parcela. Os tratamentos corresponderam a quatro formas de manejo da fertirrigação, sendo: a) Tratamento 1 - fertirrigação com aplicação de fração de lixiviação de 20%; b) Tratamento 2 – fertirrigação ao longo do dia e aplicação de água com fração de lixiviação de 20% no final do dia; Tratamento 3 - aplicação inicial de água com fração de lixiviação de 20% seguida de fertirrigação; Tratamento 4 - fertirrigação usando a solução nutritiva de reuso com aplicação de fração de lixiviação de 20%. Avaliaram-se a condutividade elétrica da solução percolada; o teor de nutrientes na matéria seca das folhas; altura e diâmetro da haste; número de cachos; produção total e comercial; e atributos de qualidade de frutos, como tamanho, coloração, acidez total titulável, teor de sólidos solúveis e textura. Para avaliação do sistema de automação, realizaram-se testes do funcionamento e a análise de custo para a sua aquisição e montagem. Os diferentes manejos de fertirrigação testados não influenciam o desenvolvimento vegetativo do tomateiro; o uso da solução nutritiva padrão com fração de lixiviação de 20% (tratamento 1) e o reuso da solução percolada, também com fração de lixiviação de 20% (tratamento 4), proporcionam maior produção comercial (1616,85 g planta-1 e 1401,90 g planta-1), maior teor de sólidos solúveis (5,82 e 5,65 ºBrix, respectivamente) e maior incidência de podridão apical nos frutos de minitomates; é possível reutilizar a solução nutritiva no cultivo em substrato do tomateiro corrigindo-se diariamente a condutividade elétrica da solução; o sistema de controle das fertirrigações não apresenta problemas de mau funcionamento e ainda apresenta baixo custo quando comparado aos controladores comerciais.