Viabilidade econômica da implantação do sistema hidropônico para alface com recursos do PRONAF em Matão-SP = Economic feasibility of implementing the system for hydroponic lettuce with PRONAF resources in Matão-SP

A Organização das Nações Unidas para Alimentação e Agricultura - FAO, afirma que, a agricultura familiar, através de sua grande importância econômica e social, recebe no Brasil e no mundo, políticas públicas de apoio e incentivo. Diante disso, este trabalho teve por objetivo estudar a viabilidade econômica e financeira da implantação do sistema de hidroponia para produção de alface no regime de agricultura familiar em uma propriedade rural no município de Matão, SP. A hidroponia exige um alto investimento inicial, mas exibe vantagens para o cultivo de folhosas em relação ao cultivo tradicional na terra. O estudo foi feito de acordo com o conceito brasileiro de agricultura familiar e para conseguir recursos financeiros, buscou-se avaliar a possibilidade do uso dos recursos de financiamento do programa PRONAF Mais Alimentos, na quantia de oitenta mil reais. Esta linha de crédito disponibiliza recursos para investimentos em máquinas e equipamentos com juros baixos, carência de 03 anos e 10 anos para pagamento. Para realizar o estudo de análise econômica, utilizou-se análise de Valor Presente Líquido - VPL, Taxa Interna de Retorno- TIR e Payback descontado. Com a metodologia aplicada, utilizando uma taxa de atratividade - TMA de 7%, foi possível encontrar um VPL de projeto de R$101.862,76. A TIR apresentou um patamar de 30,1$ 101,862.76 and the IRR was 30.1% p.a. The return on investment was in four years showing high viability of installing the project

Soil-app: a tool for soil analysis interpretation

New apps have changed the traditional way of learning and teaching; they are also applied as a quickly executed and effective method in agriculture. Soil-app is a web application with a friendly click-point interface built through packages lodged in R software. The app is an advanced model of an open-source platform to support teaching and learning activities in soil analyses and fertilizer recommendations. Soil-app includes soil test interpretation, soil amendment calculations (lime and gypsum), the fertilizer rate for the most important crops in Brazil, an NPK blend calculator, and NPK blend evaluation. It also includes experimental statistical analysis as applied to soil science. Soil-app is a user-friendly and high-performance tool, garnering fast adoption by both students and professionals. It is available for network use through the following link: http://www.genetica.esalq.usp.br/alogamas/R.htm

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Stabilized urea in nitrogen fertilization of sugarcane

A adubação nitrogenada de soqueira de cana-de-açúcar no Brasil normalmente é feita no período seco do ano e a principal fonte de N é o nitrato de amônio, apesar de a ureia ser o principal fertilizante nitrogenado consumido no Brasil e no mundo. Para viabilizar o uso de ureia em áreas de cana-de-açúcar colhida sem queima, com grande quantidade de palha recobrindo o solo, devem ser adotadas estratégias que reduzam as perdas de amônia por volatilização, como uso de ureia estabilizada com inibidores de urease. Trabalhos prévios indicaram a necessidade de aumentar a concentração do inibidor de urease NBPT na ureia para reduzir perdas de amônia por volatilização em áreas de cana-crua, porém os efeitos na produtividade da cultura ainda não foram estudados. A hipótese deste trabalho é de que o aumento da concentração do inibidor de urease NBPT na ureia irá proporcionar ganhos de produtividade comparado à ureia convencional, demonstrando a viabilidade do uso de ureia estabilizada para adubação de soqueira de cana-crua. O presente trabalho foi executado em dois locais (Experimento 1, Latossolo Vermelho-Amarelo distrófico de textura muito argilosa e Experimento 2, Latossolo Vermelho-Amarelo eutrófico de textura média) para avaliar o comportamento produtivo de soqueiras de cana-de-açúcar em função de doses de N nas formas de nitrato de amônio, ureia e ureia estabilizada com diferentes concentrações de NBPT. O delineamento experiemental foi de blocos inteiramente casualizados no esquema fatorial 6 x 2 + 1, sendo seis fontes de N (nitrato de amônio, ureia e ureia estabilizada com quatro doses de NBPT variando de 530 a 2000 mg kg-1), duas doses de N (50 e 100 kg ha-1 de N) e um tratamento adicional (Controle, sem adubação nitrogenada). Foram avaliados o perfilhamento, teor foliar de N, índice SPAD, produtividade de colmos, acúmulo de N na parte aérea e os atributos tecnológicos. Também foi avaliada a atividade enzimática da glutamina sintetase (GS) e nitrato redutase (NR) no Experimento 2. Os dados foram submetidos a análise de variância ao nível de 10 % de significância pelo teste F, e os fatores significativos foram comparados pelo teste Tukey a 10 % de significância. Os teores foliares de N não foram alterados pela interação dos fatores, sendo mais importante o aumento da dose de N, o que também ocorreu para atividade das enzimas GS e NR e para o índice SPAD. A produtividade de colmos foi influenciada distintamente entre as áreas. No Experimento 1, houve resposta significativa para as doses de N, independente da fonte de N . No Experimento 2 não houve diferença significativa na produtividade de colmos entre as doses e fontes de N. Os resultados deste trabalho indicam que não é necessário aumentar a concentração de NBPT na ureia e que, tanto a ureia convencional quanto a ureia estabilizada podem ser utilizadas para adubação nitrogenada de soqueira de cana-de- açúcar como fontes opcionais ao nitrato de amônio.Nitrogen fertilization of sugarcane ratoon in Brazil is usually performed in the dry period of the year and the main source of N is ammonium nitrate, although urea is the main nitrogen fertilizer consumed in Brazil and in the world. In order to allow urea usage in green cane trash blanketing (GCTB) systems, with high amount of straw left on soil surface, strategies that reduce ammonia losses are required, such as the use of urea stabilized with urease inhibitors. Previous research indicated the need to increase the concentration of the urease inhibitor NBPT in urea to reduce ammonia losses in GCTB systems, but the effects on such increase on yield performance is unclear. This study was undertaken to test the hypothesis that increasing the concentration of NBPT in urea will provide yield gains when compared to untreated urea, demonstrating the feasibility of using stabilized urea in GCTB areas. Two field trials (Experiment 1, Oxisols of very clayey texture and Experiment 2, medium-texture Oxisols) were set up to evaluate the yield performance of sugarcane fertilized with N rates as ammonium nitrate, urea and urea stabilized with different concentrations of NBPT. The experimental design was a complete randomized blocks on factorial scheme 6 x 2 + 1, with six N sources (ammonium nitrate, urea and urea stabilized with NBPT concentration ranging from 530 to 2000 mg kg-1), two doses of N (50 and 100 kg ha-1 of N) and an additional control (no N fertilization). It was evaluated the tillering, foliar N content, SPAD index, crop yield, shoot N accumulation and the technological attributes. The enzymatic activity of glutamine synthetase (GS) and nitrate reductase (NR) was also evaluated in Experiment 2. Data were submitted to analysis of variance at the 10 % level of significance by the F test, and the significant factors were compared by the Tukey test at 10 % significance. Leaf N contents weren\'t affected by the interaction of the factors, being more important the increase of the dose of N, which also occurred for the activity of GS, NR and for the SPAD index. Sugarcane response to N fertilization varied among sites. In Experiment 1, there was a significant response to N rates, independently of N sources evaluted. In Experiment 2 there was no significant effect of N sources or rates on sugarcane yield. The results of this study indicate that increasing NBPT concentration in urea will not improve sugarcane yield. However, both urea and stabilized urea resulted in similar yield performance when compared to ammonium nitrate for fertilization of GCTB systems

Desenvolvimento, caracterização e eficiência de fertilizante nitrogenado associado a nanopartícula de molibdênio

Nitrogen (N) use efficiency is directly associated with sustainable agriculture. The use of renewable energy sources and increase in productivity have increased the amountof fertilizers used and strategies to improve their use are required. Among the strategies to increase the efficiency of N fertilizers are the use of urease inhibitors, nitrification inhibitors, addition of micronutrients, polymers, among others. Therefore, the molybdenum (Mo) addition is a promising alternative due to its potential to influence N metabolism in plants and its utilization, and Mo can be supplied as soluble sources (ammonium molybdate) or as nanoparticles (Mo trioxide). Studies were conducted to evaluate the interaction between Mo sources, urea and N-(n-butyl) thiophosphoric triamide (NBPT) on physical-chemical characteristics, ammonia (NH3) volatilization, recovery of 15N by sugarcane and metabolism and N uptake by corn in nutrient solution. Mo sources were granulated with urea, whereas NBPT was treated as a cover. After fertilizers characterization it was found that Mo reacts with NBPT, eliminating its effect as a urease inhibitor. The N- NH3 losses of urea + NBPT were close to 44% of the N applied, while only urea + NBPT reached 33%. Then, the fertilizer with best physical-chemical characteristics were selected among the mixtures of urea and Mo, using the average rate 600 g of Mo per 100 kg-1 of N, as the appropriate one to proceed with the evaluations that consisted of applying the fertilizer to sugarcane seedlings. At this point, the recovery of 15N-urea by sugarcane was evaluated and it was observed that there was no change as a function of the source and addition of Mo, with an overal recovey of 80% by the plant. The biomass production and N content were also not influenced, presenting the average of 408 g pot-1 and 3.8 g pot-1. In order to evaluate the metabolic changes and the uptake preference of N forms as a function of Mo addition, an experiment was conducted with corn under controlled conditions. The treatments consisted of the omission of Mo and N and the supply of these nutrients 28 days after transplanting the seedlings into a nutrient solution. It was verified that the Mo added to the nutrient solution after 28 days resulted in similar productivity as the treatments with N and Mo, approximately 215 g pot-1. In this condition it was also observed that in the absence of Mo and supply of N the plants absorbed a greater amount of ammonium, proving that Mo favors nitrate absorption. The finding is that the addition of Mo to urea is a feasible strategy of uniform distribution of the nutrient in crops, but with no potential in affecting the metabolsim of the recovery of N by the plant.A eficiência do uso do nitrogênio (N) está associada diretamente a agricultura sustentável. O uso de fontes renováveis de energia e o aumento de produtividade demandam cada vez mais a utilização de fertilizantes e estratégias para melhorar o uso dos fertilizantes. Dentre as estratégias para aumentar a eficiência dos fertilizantes nitrogenados temos o uso de inibidores de urease, inibidores de nitrificação, adição de micronutrientes, polímeros, dentre outros. Neste sentido a adição de molibdênio (Mo) é uma alternativa promissora devido seu potencial de influenciar o metabolismo e oaproveitamento do N pelas plantas, podendo ser aplicado na forma de fontes solúveis (molibdato de amônio) ou nanopartículas (trióxido de Mo). Foram conduzidos alguns estudos para avaliar a interação entre fontes de Mo, ureia e N-(n-butil) tiofosfórico triamida (NBPT) nas características físico-quimicas, volatilização de amônia (NH3), recuperação do 15N pela cana-de-açúcar e metabolismo e absorção de N pelo milho cultivado em solução nutritiva. As fontes de Mo foram granuladas com a urea, enquanto o NBPT foi aplicado como recobrimento. Após a caracterização dos fertilizantes verificou-se que o Mo reage com o NBPT, eliminando seu efeito como inibidor de urease. As perdas dessa mistura foram próximas a 44% do N aplicado, enquanto apenas adição de NBPT à ureia resultou em perda de 33% de N- NH3. Em seguida foi selecionado dentre as misturas de ureia e Mo as que apresentaram as melhores características físico-químicas, utilizando-se a dose média de 600 g de Mo por 100 kg-1 de N, como a adequada para prosseguir com as avaliações do fertilizante em mudas de cana-de-açúcar. Neste momento foi avaliado a recuperação do 15Nureia e observou-se que não houve alteração em função da fonte e adição de Mo, com média de 80% na planta. A produção de biomassa e o conteúdo de N também não foram influenciados, sendo respectivamente 408 g vaso-1 e 3,8 g vaso-1. Com o objetivo de avaliar as mudanças metabólicas e a preferência de absorção das formas de N em função da adição de Mo foi conduzido experimento em condições controladas com a cultura do milho. Os tratamentos consistiram da omissão de Mo e N e do suprimento destes nutrientes 28 dias após o transplante das mudas para solução nutritiva. Verificou-se que o Mo adicionado na solução nutritiva resultou na mesma produtividade do tratamento com N e com Mo, aproximadamente 215 g vaso-1. Nesta condição observou-se também que na ausência de Mo e suprimento de N as plantas absorveram maior quantidade de amônio, comprovando que o Mo favorece absorção de nitrato. Portanto, a adição de Mo à ureia é viável como estratégia de distribuição uniforme do nutriente nas lavouras, porém sem afetar o metabolismo ou a recuperação do N pela planta

Omission and Resupply of Nitrogen Affect Physiological and Enzymatic Activities and the Gene Expression of Eucalypt Clones

ABSTRACT: The mineral nutrient uptake of plants in the field occurs in pulses, due to variations in the substance concentrations at the root surface. The fluctuations in nutrient supply probably induce changes in the plant, which are to date unknown for Eucalyptus. This study evaluated these changes in plant growth, nutritional status, photosynthesis, and gene expression, which can serve as biomarkers of the nitrogen status, of four eucalypt clones exposed to N omission and resupply. A greenhouse experiment with four Eucalyptus clones was installed, and after initial growth exposed to N omission for 21 d, followed by N resupply in nutrient solution for 14 d. Nitrogen omission decreased the total N and photosynthetic pigments, net photosynthesis and photochemical dissipation, and increased enzyme activity especially in leaves and the gene expression in leaves and roots. Nitrogen resupply decreased these variations, indicating recovery. The total N concentration was highly and significantly correlated with net photosynthesis, enzyme activity, expression of genes GS2;1 and Gln1;3 in the leaves and AMT1;2 in the roots, contents of chlorophyll a and b, and photochemical energy dissipation. The enzymes GS and NR in the leaves and the genes AMT1;2, GS2;1 and Gln1;3 proved to be sensitive N indicators

Omission and Resupply of Nitrogen Affect Physiological and Enzymatic Activities and the Gene Expression of Eucalypt Clones

ABSTRACT: The mineral nutrient uptake of plants in the field occurs in pulses, due to variations in the substance concentrations at the root surface. The fluctuations in nutrient supply probably induce changes in the plant, which are to date unknown for Eucalyptus. This study evaluated these changes in plant growth, nutritional status, photosynthesis, and gene expression, which can serve as biomarkers of the nitrogen status, of four eucalypt clones exposed to N omission and resupply. A greenhouse experiment with four Eucalyptus clones was installed, and after initial growth exposed to N omission for 21 d, followed by N resupply in nutrient solution for 14 d. Nitrogen omission decreased the total N and photosynthetic pigments, net photosynthesis and photochemical dissipation, and increased enzyme activity especially in leaves and the gene expression in leaves and roots. Nitrogen resupply decreased these variations, indicating recovery. The total N concentration was highly and significantly correlated with net photosynthesis, enzyme activity, expression of genes GS2;1 and Gln1;3 in the leaves and AMT1;2 in the roots, contents of chlorophyll a and b, and photochemical energy dissipation. The enzymes GS and NR in the leaves and the genes AMT1;2, GS2;1 and Gln1;3 proved to be sensitive N indicators