Marcos Rodrigues

Legacy phosphorus and no tillage agriculture in tropical oxisols of the Brazilian savanna.

Crop production in the Brazilian Cerrado is limited by soil phosphorus (P) supply without large inputs of inorganic P fertilizer, which may become more costly and scarce in the future. Reducing dependency on fertilizer P requires a greater understanding of soil P supply in the highly weathered soils in this important agricultural region. We investigated the impact of no tillage (NT) and conventional tillage (CT) agriculture on accumulated (legacy) soil P and P forms in four long-term sites. Compared to the native savanna soils, tilled soils receiving regular annual P fertilizer inputs (30-50 kg P ha(-1)) increased all forms of inorganic and organic P, except highly recalcitrant P associated with the background lithology. However, 70-85% of the net added P was bound in moderately labile and non-labile forms associated with Fe/Al oxyhydroxides rather than in plant available forms. Under NT agriculture, organic P forms and labile and non-labile inorganic P forms were all significantly (P<0.05) increased in the surface soil, except for one site with maize residues where labile inorganic P was increased more under CT agriculture. The contribution of organic P cycling in these tropical soils increased after conversion to agriculture and was proportionally greater under NT. The results highlight the large amounts of unutilized legacy P present in Brazils Cerrado soils that could be better exploited to reduce dependency on imports of finite phosphate rock. No tillage agriculture confers a positive albeit relatively small benefit for soil P availability and overall soil function.

Inflammatory sensitization of nociceptors depends on activation of NMDA receptors in DRG satellite cells

Significance The present study provides evidence for a role of glutamate as a neuromodulator of the afferent nociceptive information. Our results show that the nociceptive impulse generated by an inflammatory event in the peripheral tissue is regulated in the dorsal root ganglia (DRG) by a system that involves satellite glial cells and glutamatergic NMDA receptors. To our knowledge, this work is one of the first demonstrations of the involvement of glutamate in a modulatory process in the DRG, a site where there are no synapses, in addition to its classical role as a neurotransmitter. The present study evaluated the role of N-methyl-d-aspartate receptors (NMDARs) expressed in the dorsal root ganglia (DRG) in the inflammatory sensitization of peripheral nociceptor terminals to mechanical stimulation. Injection of NMDA into the fifth lumbar (L5)-DRG induced hyperalgesia in the rat hind paw with a profile similar to that of intraplantar injection of prostaglandin E2 (PGE2), which was significantly attenuated by injection of the NMDAR antagonist d(-)-2-amino-5-phosphonopentanoic acid (d-AP-5) in the L5-DRG. Moreover, blockade of DRG AMPA receptors by the antagonist 6,7-dinitroquinoxaline-2,3-dione had no effect in the PGE2-induced hyperalgesia in thepaw, showing specific involvement of NMDARs in this modulatory effect and suggesting that activation of NMDAR in the DRG plays an important role in the peripheral inflammatory hyperalgesia. In following experiments we observed attenuation of PGE2-induced hyperalgesia in the paw by the knockdown of NMDAR subunits NR1, NR2B, NR2D, and NR3A with antisense-oligodeoxynucleotide treatment in the DRG. Also, in vitro experiments showed that the NMDA-induced sensitization of cultured DRG neurons depends on satellite cell activation and on those same NMDAR subunits, suggesting their importance for the PGE2-induced hyperalgesia. In addition, fluorescent calcium imaging experiments in cultures of DRG cells showed induction of calcium transients by glutamate or NMDA only in satellite cells, but not in neurons. Together, the present results suggest that the mechanical inflammatory nociceptor sensitization is dependent on glutamate release at the DRG and subsequent NMDAR activation in satellite glial cells, supporting the idea that the peripheral hyperalgesia is an event modulated by a glutamatergic system in the DRG.

Transitions to sustainable management of phosphorus in Brazilian agriculture

Brazil’s large land base is important for global food security but its high dependency on inorganic phosphorus (P) fertilizer for crop production (2.2 Tg rising up to 4.6 Tg in 2050) is not a sustainable use of a critical and price-volatile resource. A new strategic analysis of current and future P demand/supply concluded that the nation’s secondary P resources which are produced annually (e.g. livestock manures, sugarcane processing residues) could potentially provide up to 20% of crop P demand by 2050 with further investment in P recovery technologies. However, the much larger legacy stores of secondary P in the soil (30 Tg in 2016 worth over

Long-term effects of alum-treated litter, untreated litter and NH 4 NO 3 application on phosphorus speciation, distribution and reactivity in soils using K-edge XANES and chemical fractionation

40 billion and rising to 105 Tg by 2050) could provide a more important buffer against future P scarcity or sudden P price fluctuations, and enable a transition to more sustainable P input strategies that could reduce current annual P surpluses by 65%. In the longer-term, farming systems in Brazil should be redesigned to operate profitably but more sustainably under lower soil P fertility thresholds.

Eficiência Técnica Do Setor Canavieiro Do Estado De São Paulo (Technical Efficiency in Sugarcane Production in the State of São Paulo)

Whereas soil test information on the fertility and chemistry of soils has been important to elaborate safe and sound agricultural practices, micro-scale information can give a whole extra dimension to understand the chemical processes occurring in soils. The objective of this study was to evaluate the effects that the consecutive application of untreated poultry litter, alum-treated litter or ammonium nitrate (NH4NO3) had on P solubility in soils over 20 years. For this, we used soil test data, sequential chemical fractionation (SCF) of P, and P K-edge XANES and μ-fluorescence spectroscopies. Water extractable P data indicated that application of alum to poultry litter was a very effective treatment for reducing P solubility. On the basis of our SCF of P data, P was primarily found within the 0.1 M NaOH pool across the applied rates and regardless of the treatment, where application of alum-treated litter accounted for as much as 59 ± 2% of the total, followed by NH4NO3, 49 ± 4%, and untreated litter, 40 ± 2%. It was also shown that in soils where alum-treated litter was applied, the Resin pool accounted for 10 ± 1% of the total, followed by NH4NO3, 13 ± 4%, and untreated litter, 18 ± 2%, indicating that P was less readily available in soils where alum-treated litter was applied. Phosphorus XANES indicated that P was predominantly associated to Fe > Al > Ca > organic molecules, regardless of the treatment or applied rates, though the formation of PoAl complexes was only found in soils that received application of alum-treated litter and was positively related to the applied rates. The combination of P-XANES with SCF or μ-fluorescence data was shown to provide valuable information about P reactivity and distribution in soils and should thus be used to address the fate of applied P amendments in soils.

Biological and morphological traits of sugarcane roots in relation to phosphorus uptake

Portuguese Abstract: O Estado de Sao Paulo, maior produtor de cana-de-acucar do Brasil, possui produtividade superior a media nacional, principalmente em funcao dos investimentos em pesquisa de institutos de pesquisa, das universidades estaduais, alem das empresas do setor privado que tem contribuido para a continuidade da pesquisa da cana-deacucar. Para analisar a eficiencia tecnica dos produtores a nivel municipal no Estado, foi utilizada a metodologia de Analise de Fronteira Estocastica. O fator de producao terra - e o que mais influenciou a producao e a eficiencia tecnica no setor canavieiro do Estado de Sao Paulo, a partir dos dados do Levantamento Censitario das Unidades de Producao - Projeto LUPA, do IEA e da CATI. Em relacao a ineficiencia tecnica, os resultados mostraram que ha um efeito negativo no uso de carregadeiras, sementes melhoradas, adubacao verde e assistencia tecnica. E, efeito positivo dos engenhos, usinas e destilarias, colheita manual e analise do solo. Assim, para aumentar a eficiencia na producao de cana-de-acucar, em Sao Paulo, os produtores devem utilizar as variaveis que diminuam a ineficiencia, como carregadeiras, sementes melhoradas, adubacao verde e assistencia tecnica. Para verificar a heterogeneidade da eficiencia, procedeu-se a analise de cluster dos municipios. As mesorregioes que sao sedes de programas de melhoramento (pesquisa, difusao, etc.) e que sao regioes tradicionais de producao, como a mesorregiao de Piracicaba e Ribeirao Preto, apresentaram valores elevados de eficiencia (Alto-Alto). Ha, tambem, indicios sobre o efeito transbordamento as regioes proximas a essas duas, como e o caso de Sao Jose do Rio Preto e Araraquara, proximos a Ribeirao Preto. Alem disso, ha municipios com baixo valor de eficiencia, principalmente nas regioes do Litoral e do Vale do Paraiba. English Abstract: This paper evaluated the technical efficiency of sugarcane production in the largest Brazilian producer state, Sao Paulo, through stochastic frontier analysis and spatial analysis. The most influential factor on sugarcane production and technical efficiency was the land. The technical inefficiency analysis revealed negative effects due to loaders, genetic improved seeds, green manure and technical assistance factors; and positive effects for mills, sugarcane plants and distilleries, manual harvesting and soil analysis factors. The local indicator analysis of spatial association revealed potential formation of clusters of technical efficiency, suggesting that traditional sugarcane producer regions have spillover effects on neighboring regions. Beyond that, the results revealed meso-regions as network of sugarcane improvement programs (research, diffusion, etc.) and traditional crop production regions, e.g. Piracicaba and Ribeirao Preto as meso-regions which displayed high levels of efficiency (Upper-Upper). There is also evidence of the spillover effect in the region near to these two cities, such as e.g. Sao Jose do Rio Preto and Araraquara, which are close to Ribeirao Preto. Additionally, there are cities with low efficiency levels, especially in the coast region and Vale do Paraiba.

Phosphorus Fractionation in Soil Cultivated with Sugarcane Fertilized by Filter Cake and Phosphate Sources

Appropriate management of phosphorus (P) in soil will lead to higher yields and sustainability for sugarcane production. Our study evaluated the importance of differences in root structure and function, and the differential composition of the bacterial community in four sugarcane cultivars, in relation to the efficiency for P uptake and also to assess changes in soil P with distance from the rhizoplane. Experiments were performed in pot trials using a sandy clay loam Ferralsol. In the first experiment, the effect of P application (78.4 mg P kg-1 soil as triple superphosphate) on sugarcane cultivars RB92-579; RB85-5156; RB86-7515 and RB96-6928 was investigated. Secondly, we evaluated P rates of 0; 9.8; 19.6; 39.2 and 78.4 mg kg-1 soil using cultivar RB96-6928 which was shown to be one of the more growth responsive cultivars. The cultivar RB96-6928 exhibited the highest root dry matter and root surface area, while the bacterial communities found in the rhizosphere of these plants were not different from other cultivars, as determined by PCR-DGGE. From the P dose-dependent experiment for this cultivar, optimal plant performance occurred at a P supply up to 38.5 mg P kg-1 soil. Collectively, our results indicate that P efficiency in sugarcane was predominantly associated with the generation of high root biomass and surface area.

A Taxonomy of Strategies for Developing Spatial Decision Support System

Studies of phosphorus (P) forms in high-weathering soils, after long periods of phosphate fertilizer application associated with organic residues, are important to optimize P fertilization. This study aims to evaluate the effect of filter cake application and other distinct phosphate sources on organic and inorganic P fractions in Red Eutrophic Argisoil cultivated with sugarcane. The experiment was established between 2012 and 2014, in Sao Paulo State, Brazil. The treatments were as follows: control (without P), triple superphosphate, natural phosphate from Araxá, and naturally reactive phosphate Bayóvar on the presence and absence of filter cake at 7.5 t ha−1 (dry mass). The P rate was 90 kg ha−1 of phosphorus pentoxide (P2O5) soluble in citric acid. The experiment was arranged in a randomized block, in a 4 × 2 factorial with three repetitions. After 22 months of treatments, soil samples were collected on sugarcane planting lines and P fractionation was analyzed. The greatest percentage of P is found as nonlabile P fractions, regardless of filter cake application or not. The use of low solubility sources, such as natural phosphate from Araxá, in association with filter cake has promoted greater solubility of P bound to calcium (Ca), which can enhance the crop uses. Filter cake increases most of labile and moderately labile inorganic P forms in the soil (resin; sodium bicarbonate, NaHCO3; and sodium hydroxide, NaOH, 0.1 mol L−1), which characterizes the importance of this source to sugarcane nutrient supply.

Do cover crops change the lability of phosphorus in a clayey subtropical soil under different phosphate fertilizers

Due to their extension and complexity, problems concerned with geographic space are usually classified as ill or unstructured. For these reasons decision-making processes (DMP) that conclude with the selection of optimal or satisfactory solutions require effective and efficient means of support. Spatial Decision Support Systems (SDSS) are computer systems developed to support DMP in which the problems have geographic dimensions and whose structure is complex or impossible to delineate. These systems are functionally composed of data and scientific models managed with the aim of providing maximised support to DMP. The component represented by spatial data is one of the main obstacles that have to be overcome for SDSS to give effective support. Geographic Information Systems (GIS) have been a paradigm in SDSS development strategies, fundamentally due to their capacity to collect, store, and handle spatial data. The scientific modelling component, represented by mathematical models of natural physical processes, usually is implemented in SDSS through specific software subsystems. Especially in the last seven years there has been great scientific interest in SDSS accompanied by a proliferation of adjacent technologies. Some authors have attempted to classify SDSS without, however, reaching a generally accepted proposal. This lack of clarity has made detailed analysis of existing systems and development of new projects more difficult. The aims of this research were: a) identify and analyse the main variables that determine current application software development methodologies in the field of SDSS; b) provide a taxonomy of these methodologies, with the objectives of being generic, general, and practical; c) identify and analyse the strategy that presents the greatest flexibility to develop effective SDSS. The research was based on a bibliographic survey and is part of the doctoral thesis of first author. The paper presents and criticises relevant issues about different development strategies and the respective systems produced. Three main variables were identified and guided the development of the taxonomy of the strategies. The paper proposes five taxonomic classes of coupling GIS technology and scientific modelling subsystems. These classes are defined and the paper argues that they are sufficient to categorise the main current methodologies as well as suggest places to expect new technologies. Each class is also exemplified with a number of SDSS applied to the watershed DMP domain. Within these classes, the research identified and analysed the one most likely to show the greatest flexibility to develop effective SDSS