Alterações estruturais do sistema radicular de soja em resposta à disponibilidade de fósforo no solo

Tendo em vista que os métodos estatísticos tradicionais de análise dos atributos métricos do sistema radicular são insatisfatórios no que diz respeito à identificação e interpretação de estratégias adotadas pela planta em adaptação ao ambiente edáfico, o objetivo do trabalho foi utilizar conceitos de topologia para analisar as alterações estruturais apresentadas pelo sistema radicular da soja (Glycine max L. Merr. cv. Williams 82) em resposta à disponibilidade de fósforo no solo. Plantas de soja foram cultivadas em recipientes de acrílico preto, em condições controladas de temperatura e fotoperíodo. Dois tratamentos foram estabelecidos, pela adição de solução nutritiva ao substrato dos recipientes: +P (15,5 mg L-1 P) e -P (8,5 mg L-1 P). Utilizando-se delineamento experimental inteiramente casualizado, com parcelas subdivididas no tempo, três repetições foram amostradas aos 5, 10, 15, 20, 25 e 30 dias após a germinação. Para cada tratamento, idade de amostragem e repetição foram obtidos o comprimento da raiz principal (ordem 0), e os respectivos números e comprimentos médios das raízes laterais de ordens 1, 2 e 3, de acordo com a posição de origem na raiz principal. Índices topológicos foram definidos e aplicados para cada tratamento, utilizando-se os valores médios das três repetições. Os índices utilizados foram eficientes em detectar as alterações estruturais apresentadas pelos sistemas radiculares das plantas cultivadas sob menor teor de fósforo no solo.Since the analytical framework and quantitative tools associated with classical statistics are not efficient to identify and interpret plant strategies for adaptation to a given soil environment, the objective of this study was to utilize concepts of topology in order to analyze the structural changes in soybean root systems in response to soil phosphorus availability. Soybean plants were grown in black plexiglas boxes under controlled environment (temperature and photoperiod). The boxes were packed with substrate mixed with nutrient solution to achieve uniform P concentration for two treatments: +P (15.5 mg L-1 P) and -P (8.5 mg L-1 P). In a completely randomized experimental design, three replicates were sampled at 5, 10, 15, 20, 25, and 30 days after germination. For each treatment, plant age, and replicate, the following attributes were obtained: main root length (order 0), and average number and length of order-1, order-2, and order-3 lateral roots according to their position of origin along the main root. Topological indexes were defined and calculated for both treatments, using the mean values of three replicates. Indexes used in this study were efficient in detecting the structural changes performed by the soybean root systems growing under lower soil P concentration

Grapevine root distribution in drip and microsprinkler irrigation

A produção de uva (Vitis vinifera L.) em termos quantitativos e qualitativos depende do estado das raízes. Além disso, informações sobre a distribuição radicular são úteis para o manejo de solo e água. Por isso, uma análise de métodos para a avaliação da distribuição radicular de videiras cv. Itália / IAC 313 num Latossolo Vermelho Amarelo irrigadas por gotejamento e microaspersão foi realizada em Petrolina – PE e Juazeiro - BA, no Vale do São Francisco. Os parâmetros medidos pelo método do monolito foram a matéria seca (Dw) e densidade de comprimento de raízes (Lv), enquanto a área de raízes (Ap) foi estimada pelo método do perfil de solo combinado com a análise de imagens digitais. Para ambos os sistemas de irrigação, as raízes estiveram presentes até 1 m de profundidade e estenderam-se lateralmente até 1 m de distância do tronco, mas as videiras irrigadas por microaspersão apresentaram uma maior presença de raízes com o aumento da distância do tronco. Os valores de Ap apresentaram uma boa correlação com Dw e Lv, mas essa correlação foi maior quando se utilizou a distribuição fracional de cada parâmetro. O método do perfil auxiliado pela análise de imagem digital permite a avaliação da distribuição radicular.Grape (Vitis vinifera L.) yield and its quality are dependent of the status of the root system. Root distribution information is also valuable for soil and water management. An analysis of methods to evaluate the root distribution of grapevines for both, drip and microsprinkler irrigation in a Typic Acrustox is presented for the table grape cv. Italia grafted on the rootstock IAC-313, in northeastern Brazil. Measured root parameters using the monolith method were root dry weight (Dw) and root length density (Lv), while root area (Ap) was estimated using the soil profile method in combination with digital image analysis. For both irrigation systems, roots were present to the 1 m soil depth and extended laterally to 1 m distance from the trunk, but grapevines irrigated by microsprinkler showed greater root presence as the distance from the trunk increased. Values of Ap were reasonably well correlated to Dw and Lv. However, correlation values were higher when fractional root distribution was used. The soil profile method in combination with image analysis techniques, allows proper grapevine root distribution evaluation

Global environmental changes impact soil hydraulic functions through biophysical feedbacks

Although only representing 0.05% of global freshwater, or 0.001% of all global water, soil water supports all terrestrial biological life. Soil moisture behaviour in most models is constrained by hydraulic parameters that do not change. Here we argue that biological feedbacks from plants, macro‐fauna and the microbiome influence soil structure, and thus the soil hydraulic parameters and the soil water content signals we observe. Incorporating biological feedbacks into soil hydrological models is therefore important for understanding environmental change and its impacts on ecosystems. We anticipate that environmental change will accelerate and modify soil hydraulic function. Increasingly we understand the vital role that soil moisture exerts on the carbon cycle and other environmental threats such as heatwaves, droughts and floods, wildfires, regional precipitation patterns, disease regulation and infrastructure stability, in addition to agricultural production. Biological feedbacks may result in changes to soil hydraulic function that could be irreversible, resulting in alternative stable states (ASS) of soil moisture. To explore this, we need models that consider all the major feedbacks between soil properties and soil‐plant‐faunal‐microbial‐atmospheric processes, which is something we currently do not have. Therefore, a new direction is required to incorporate a dynamic description of soil structure and hydraulic property evolution into soil‐plant‐atmosphere, or land surface, models that consider feedbacks from land use and climate drivers of change, so as to better model ecosystem dynamics

Climate-smart agriculture global research agenda: Scientific basis for action

Background: Climate-smart agriculture (CSA) addresses the challenge of meeting the growing demand for food, fibre and fuel, despite the changing climate and fewer opportunities for agricultural expansion on additional lands. CSA focuses on contributing to economic development, poverty reduction and food security; maintaining and enhancing the productivity and resilience of natural and agricultural ecosystem functions, thus building natural capital; and reducing trade-offs involved in meeting these goals. Current gaps in knowledge, work within CSA, and agendas for interdisciplinary research and science-based actions identified at the 2013 Global Science Conference on Climate-Smart Agriculture (Davis, CA, USA) are described here within three themes: (1) farm and food systems, (2) landscape and regional issues and (3) institutional and policy aspects. The first two themes comprise crop physiology and genetics, mitigation and adaptation for livestock and agriculture, barriers to adoption of CSA practices, climate risk management and energy and biofuels (theme 1); and modelling adaptation and uncertainty, achieving multifunctionality, food and fishery systems, forest biodiversity and ecosystem services, rural migration from climate change and metrics (theme 2). Theme 3 comprises designing research that bridges disciplines, integrating stakeholder input to directly link science, action and governance. Outcomes: In addition to interdisciplinary research among these themes, imperatives include developing (1) models that include adaptation and transformation at either the farm or landscape level; (2) capacity approaches to examine multifunctional solutions for agronomic, ecological and socioeconomic challenges; (3) scenarios that are validated by direct evidence and metrics to support behaviours that foster resilience and natural capital; (4) reductions in the risk that can present formidable barriers for farmers during adoption of new technology and practices; and (5) an understanding of how climate affects the rural labour force, land tenure and cultural integrity, and thus the stability of food production. Effective work in CSA will involve stakeholders, address governance issues, examine uncertainties, incorporate social benefits with technological change, and establish climate finance within a green development framework. Here, the socioecological approach is intended to reduce development controversies associated with CSA and to identify technologies, policies and approaches leading to sustainable food production and consumption patterns in a changing climate

Soil suitability index identifies potential areas for groundwater banking on agricultural lands

Groundwater pumping chronically exceeds natural recharge in many agricultural regions in California. A common method of recharging groundwater — when surface water is available — is to deliberately flood an open area, allowing water to percolate into an aquifer. However, open land suitable for this type of recharge is scarce. Flooding agricultural land during fallow or dormant periods has the potential to increase groundwater recharge substantially, but this approach has not been well studied. Using data on soils, topography and crop type, we developed a spatially explicit index of the suitability for groundwater recharge of land in all agricultural regions in California. We identified 3.6 million acres of agricultural land statewide as having Excellent or Good potential for groundwater recharge. The index provides preliminary guidance about the locations where groundwater recharge on agricultural land is likely to be feasible. A variety of institutional, infrastructure and other issues must also be addressed before this practice can be implemented widely

Vadose Zone Journal

The Vadose Zone Journal is a new publication published by the Soil Science Society of America. The journal is described as "an outlet for interdisciplinary research and assessment of the vadose zone, the mostly unsaturated zone between the soil surface and the permanent groundwater table." A free online trial is currently available to review full text articles until December 31st of 2002. Although the trial includes only the first two issues, the opportunity to search and browse through the publications without charge should be taken advantage of

Comparison of air and water permeability between disturbed and undisturbed soils. Soil Sci

ABSTRACT flow and transport very difficult. This lack of knowledge on the control of pore geometry on flow and transport Although soil structure and pore geometry characteristics largely has led to incidental microscopic studies that investicontrol flow and transport processes in soils, there is a general lack of experiments that study the effects of soil structure and pore-space gated flow and transport coefficients as a function of characteristics on air and water permeability. Our objective was to geometric soil pore-space properties (e.g., nitions in literature, Clennell (1997) presented a comThis is so because of the inherent complexity and heteroprehensive review of the tortuosity concept for a range geneity of soils, thereby making a physical interpretaof different flow and transport processes in porous metion of the accounting of pore-space characteristics to dia. Although strictly a microscopic concept, pore tortuosity is applied macroscopically with pore structure an