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The aim of this study was to evaluate the effect of forms of application and application rates of phosphate fertilizer on the agronomic characteristics of carrot. A field experiment was car...

Swine wastewater (SW) is considered as a source of nutrients for agriculture. The quantities and frequencies applied may vary according to the soil class, the nature and composition of the waste, the climatic conditions and the cultivated plant species. Therefore, this study aimed to evaluate the effects of application of five Swine wastewater doses (0, 500, 1000, 2000 and 2500 m³ ha-1) in the production of components and grass nutrient extraction Tifton 85 and changes in soil chemical properties after the end of the last application of swine wastewater. To achieve these goals, we evaluated the quantities of extracted nutrients, density and height of the pre-grazing grass, forage accumulation rate and carrying capacity. The experimental design was a randomized block. The production of dry matter was 18159.80 kg ha-1, and the average height of 85 Tifton was 34.83 cm. The higher carrying capacity, 10 AU ha-1 was obtained with the dosage of 2500 m³ ha-1. While, the dose of 2000 m³ ha-1 supplied the nutritional needs of Tifton 85 in nitrogen, potassium, calcium, magnesium, copper, iron, zinc and boron. The quantities of extracted nutrients (kg ha-1) at grass Tifton 85 grazed were: N = 405.14; P = 57.77; K+ = 387.69; Ca2+ = 77.05; Mg2+ = 49.68; S-SO4-2 = 31.48; B = 0.33; Cu2+ = 0.20; Fe = 2.88; Mn2+ = 4.61; Zn2+ = 2.86. The application of increasing doses of SW promoted a linear increase in grass production components Tifton 85, as well, promoted changes in soil chemical properties and quantities of extracted nutrients. Key words: Pasture, liquid waste, nutrient extraction, plant growth.

Purpose Silicate rock powders have been appointed as possible nutrient alternative sources which might enhance the agricultural sector sustainability. However, the application of those materials directly in soil presents as main limitations the low content and solubility of the mineral nutrient sources. In this perspective, the aim of the present study was to evaluate, in a bioweathering perspective, the conjunct application potential of phonolite with organic composts over the nutrients release in soil, as well as the production and nutrition of brachiaria grass (Urochloa decumbens). In addition, it was sought to assess the composting process effectiveness in improving the nutrient release from this rock. Method An experiment was conducted with five treatments (control; enriched compost with powder rock at 10%; mixed compost with powder rock at 10%; solely powder rock; solely compost) and four repetitions. Results The alternative sources positively influenced the productivity, as well as the K and Si contents at the aerial part of the brachiaria grass and the nutrient release in soil. However, the conjunct applications of powder phonolite with organic composts were the source which the best promoted the total nutrient biorelease to soil. Conclusion Nevertheless, there was no evidence that the composting process promotes the phonolite bioweathering. On the other hand, the conjunct application of powder phonolite with organic composts, either as an initial component to the composting pile or additive to the stabilized composts, is a strategy which enhances the nutrient biorelease of the mineral source.

Together with farmers, we evaluated nutrient availability from vermicomposted gneiss powder, assessed its influence on growth promotion, nutrition and heavy metal accumulation in maize plants and the effect on soil chemical properties in the field. Three soil treatments were applied: fertilization with vermicompost with gneiss powder, fertilization with vermicompost without gneiss powder, and soil without fertilization (control), in a randomized block design with five replicates. The dry weight of shoots and the concentrations of potassium, calcium, magnesium, manganese, nickel, chrome and lead in the dry matter of maize were higher with vermicompost with gneiss powder. In the soil, the potential of hydrogen and phosphorus, potassium and calcium concentrations were higher with vermicompost with gneiss. There were no detectable levels of heavy metal wastes in the soil after the experiment. We conclude that vermicomposted gneiss powder has potential for use in agriculture as a nutrient source and can improve soil chemical properties.

Objetivou-se neste trabalho avaliar o efeito de diferentes formulações à base de glyphosate sobre a colonização micorrízica e nodulação no cultivar de soja RR TMG 125. Os experimentos foram desenvolvidos em condições de campo, em Latossolo Vermelho-Amarelo, durante os anos agrícolas 2010/2011 e 2011/2012. Os tratamentos constaram da aplicação da dose de 720 g e.a. ha-1 das seguintes formulações de glyphosate: Trop®, Roundup Original®, Roundup Ultra®, Roundup WG®, Roundup Transorb R® e Zapp Qi®, além de duas testemunhas (capinada e não capinada). Utilizou-se o delineamento em blocos casualizados com quatro repetições. A matéria seca da parte aérea, nodulação e produtividade de soja não foram influenciadas pelas diferentes formulações de glyphosate. Para a colonização micorrízica, observou-se efeito positivo da formulação Roundup Original®, em relação à testemunha capinada; no entanto, esse efeito não foi contínuo nos dois anos de experimento. A variável número de nódulos foi mais afetada pelas formulações de glyphosate testadas. The aim of this study was to evaluate the effect of different glyphosate-based formulations on mycorrhizal colonization and nodulation in soybean cultivar RR TMG 125. The experiments were conducted under field conditions in Red-Yellow Latosol, during 2010/2011 and 2011/2012. The formulations Trop®, Roundup Original®, Roundup Ultra®, Roundup WG®, Roundup Transorb R® and ZappQi® were used at a glyphosate dose of 720 g a.e. ha-1. The experiment was arranged in a randomized block design with four replications and two controls (hoed control and non-hoed control). The variables shoot, nodule dry matter, and soybean yield were not influenced by the different formulations of glyphosate. For mycorrhizal colonization, it was verified that a positive effect of the herbicide Roundup Original® regarding the hoed control was not continuous in the two years of the experiment. The variable number of nodules was the most affected by the glyphosate formulations tested.

The growth of earthworms in substrates enriched with rock (gneiss and steatite) powder, and the potential of vermicomposting in increasing solubilisation of minerals present in rock powder and in promoting plant growth were evaluated. Cattle manure (400 g), was enriched with 0, 5 and 20% of gneiss or steatite powder. Each pot with this mixture received nine earthworms ( Eisenia andrei ), at a density of 1000 indiv. m −3 . After 60 d, earthworms were collected, counted and weighed (fresh and dry). Maize was cultivated in a greenhouse in pots with an Oxisol that was fertilised with the vermicompost obtained above. Treatments with Oxisol fertilised with gneiss or steatite only and unfertilised soil were used as controls. Shoot length was measured weekly from the soil surface to the tips of the leaves. After 73 d, the plants were harvested, the roots washed from the soil and shoots and roots dried and weighed. Plants fertilised with vermicompost enriched with rock powder were taller and heavier than plants fertilised with non-enriched vermicompost. Plants grown on soil fertilised with rock powder but not with vermicompost were larger than plants grown on unfertilised soil. Vermicompost enriched with steatite powder resulted in a larger effect on plant growth than the mere sum of applying vermicompost of non-enriched manure and steatite alone to the soil. A similar, but non-significant effect was also observed for gneiss. The different effects between gneiss and steatite may be associated with the lower resistance to chemical weathering of steatite minerals compared to gneiss minerals, as well as the former being softer than the latter. The effect of vermicompost on the optimisation of nutrient release from silicate rocks seems to depend on the rock type.

Farmers must carefully choose the cultivar to be grown for a successful carrot crop. The yield potential of the cultivar may influence nutrient demand and should be known to plan for fertilization application. The aim of this study was to evaluate the cultivar effect on carrot yield and on the nutrient content and quantities allocated to leaves and roots. Three experiments were set up in two crop seasons in Rio Paranaíba, MG, Brazil. In the first season, typical summer, 10 summer cultivars were sown. In the second season, summer-winter (transition), two experiments were set up, one with summer cultivars and the other with winter cultivars. The treatments consisted of the carrot cultivars distributed in randomized blocks with four replications. Fresh and dry matter of the roots and leaves was quantified. Yield was calculated based on fresh matter of the roots. The nutrient content in leaves and roots was determined at the time of harvest. These contents and the dry matter production of roots and leaves were used to calculate nutrient uptake and export. The greatest average for total and commercial yield occurred in the crop under summer conditions. Extraction of N and K for most of the cultivars in the three experiments went beyond the amounts applied through fertilizers. Thus, there was contribution of nutrients from the soil to obtain the yields observed. However, the amount of P taken up was considerably less than that applied. This implies that soil P fertility will increase after cropping. The crop season and the cultivars influenced yield, nutrient content in the leaves and roots, and extraction and export of nutrients by the carrot crop. A escolha da cultivar de cenoura deve ser planejada cuidadosamente pelo agricultor para o sucesso da exploração da cultura. O potencial produtivo da cultivar pode influenciar a demanda de nutrientes e deve ser conhecido para estabelecer o plano de fertilização. Objetivou-se, com este trabalho, avaliar o efeito de cultivares sobre a produtividade de cenoura, o teor e as quantidades alocadas de nutrientes em folhas e raízes. Foram implantados três experimentos em duas épocas de cultivo em Rio Paranaíba, MG. Na primeira época, caracterizada como verão típico, foram semeadas 10 cultivares de verão. Na segunda, evidenciada como verão-inverno (transição), instalaram-se dois experimentos, um com cultivares de verão; e outro, de inverno. Os tratamentos consistiram das cultivares de cenoura, distribuídos em blocos casualizados, com quatro repetições. Quantificaram-se a matéria fresca e a seca de raízes e folhas. Com base na matéria fresca de raízes, calculou-se a produtividade. Determinou-se o teor de nutrientes em folhas e raízes por ocasião da colheita. Calcularam-se, com bases nesses teores e na produção de matéria seca de raízes e folhas, a absorção e exportação de nutrientes. A maior média de produtividades total e comercial ocorreu no cultivo em condições de verão. A extração de N e K para a maioria das cultivares nos três experimentos superou as quantidades aplicadas via fertilizantes. Assim, houve contribuição dos nutrientes no solo para obter as produtividades alcançadas. Entretanto, para o P, a quantidade absorvida foi consideravelmente menor que a aplicada. Isso implicou que o solo teve sua fertilidade aumentada em P, após o cultivo. A época de cultivo e as cultivares influenciaram a produtividade, os teores de nutrientes nas folhas e raízes, a extração e a exportação de nutrientes pela cultura da cenoura.

Agroforestry systems can be a viable alternative to the preservation of natural resources while contributing to sustainable food production in the tropics. These perennial systems promote beneficial biological interactions between micro-organisms and plant species, especially those formed by arbuscular mycorrhizal fungi and roots. Mycorrhizal fungi increase the soil volume explored by the roots, increase nutrient absorption by the plants, protect the root system against pathogens, toxic elements and certain heavy metals, help the formation and maintenance of soil structure, increase the input of soil carbon, and contribute to the maintenance of biodiversity. Agroforestry systems have the potential to maximize the benefits associated with AMF, which in turn could mitigate negative interactions between trees and annual crops. This beneficial impact between agroforestry management and mycorrhizal action may be depicted as a particular form of symbiosis, and deserves more study.

No Brasil, as espécies Pinus elliottii e Terminalia ivorensis vêm sendo indicadas para reflorestamento. No entanto, pouco se sabe sobre as características ecológicas destas florestas, o ciclo de nutrientes e suas conseqüências sobre a produtividade e sustentabilidade sob condições tropicais. Visando melhor compreender a dinâmica do C nestes ecossistemas, objetivou-se neste trabalho avaliar a atividade microbiana do solo, serapilheira e da mistura solo + serapilheira em povoamentos florestais de P. elliottii e T. ivorensis. Amostras de solos e serapilheira foram incubadas e a atividade microbiana avaliada por meio da evolução de CO2. Ao final da incubação, a respiração acumulada foi superior para a serapilheira de T. ivorensis. Os demais substratos com serapilheira não diferiram entre si, mas diferiram do solo sob T. ivorensis, que, por sua vez, diferiu do solo sob P. elliottii. Nas condições testadas, a incorporação de solo à serapilheira, bem como a incorporação alternada de solo de um povoamento à serapilheira de outro, não promoveu aumentos significativos na respiração da serapilheira, mostrando que as características químicas da própria serapilheira alteram mais fortemente sua velocidade de degradação que as características químicas e microbianas do solo onde é incorporada. ______________________________________________________________________________ SUMMARY In Brazil, the species Pinus elliottii and Terminalia ivorensis are being recommended for reforestation. However, little is known about the ecological characteristics of such forests, the nutrient cycle and possible consequences on yields and sustainability under tropical conditions. For a better understanding of the C dynamic in these ecosystems, this study aimed to evaluate the microbial activity of soil, litter, and the mixture of soil + litter in forest stands of P. elliottii and T. ivorensis. Samples of soil, litter and mixture were incubated and the microbial activity was evaluated on the basis of CO2 released. At the end of incubation, the accumulated respiration was significantly higher in litter of T. ivorensis. The other substrates with litter did not differ from each other, but differed from the soil under T. ivorensis, which in turn differed from soil under P. elliottii. In the tested conditions, the soil incorporation to litter, as well as the alternate incorporation of soil from one forest with the litter of another did not cause a significant increase in litter respiration. This indicates that the influence of the chemical characteristics of the litter itself on degradation speed is stronger than the chemical and microbiological characteristics of the soil where it is incorporated.