Ivani Pozar Otsuk

Combinations between crop intercropping and forage production in a no-tillage system are not well established for environments under low water retention and soil fertility conditions. Our study aimed to evaluate the potential interactions between soybean-grass intercropping with residual nitrogen in a no-tillage system. The experimental design was a randomized block with four replications in a subdivided plot scheme. The main plots in the summer season were: 1) soybean monoculture; 2) soybean - Aruana Guinea grass (Megathyrsus maximus cv. Aruana) intercropping, and 3) soybean - Congo grass (Urochloa ruziziensis cv. Comum) intercropping. The subplots were the nitrogen rates of 0, 50, 100, and 150 kg ha-1, applied as side-dressing in maize and grasses during the autumn-winter season. Here, the results of the summer seasons are shown. To do so, the parameters evaluated were soybean agronomic traits, dry biomass production, and macronutrient concentrations of plants intercropped. The main effects and interactions were studied. Our findings showed that soybean-Aruana Guinea grass intercropping is an alternative to no-tillage system implementation. Moreover, residual nitrogen from the autumn-winter season directly interfered with the dry biomass production of grasses intercropped with soybeans in the summer season. In short, the systems studied seem suitable for implementing a no-tillage system, which aims to neutralize degraded pastures and produce forage for ensilage. Despite the changes in macronutrient concentrations within the intercropping system and residual nitrogen, and among intercropped crops over the years, Congo grass intercropped with soybeans in the summer season showed great capacity for phosphorus, potassium, and magnesium cycling.

This study evaluated the productivity and nutrient concentrations of organic cherry tomatoes and leguminous green manures grown in intercropping systems in rotation with maize. The experimental design was a complete randomised block design with five replications and eight treatments, as follows: monocrop of cherry tomato adding residual maize crop residue (straw) as a mulch (control), monocrop of cherry tomato without the addition of maize crop residue (control), cherry tomatoes intercropped with jack bean, sun hemp, dwarf velvet bean, mung bean, white lupin or cowpea bean grown as green manures. In this production system, which was evaluated between 2011 and 2013, maize was cultivated from January to April, and the cherry tomatoes, with or without leguminous green manures, were grown from May/July to November/December. The number and weight of total and marketable fruits of tomatoes were 70% – 88% higher in 2011 than in 2012 and the number of damaged fruits was 12% lower in 2011 than in 2012. In 2011, the weights of total and marketable fruits in the intercropping treatment with white lupin were lower than that in the controls and in the intercropping treatments with dwarf velvet and cowpea bean. The white lupin and sun hemp green manures produced the highest biomass dry weight, followed by the jack bean, cowpea bean, mung bean and dwarf velvet bean. The different treatments had no effect on the yield of the maize.

The aim of this study was to investigate the transfer of N from different legumes to cherry tomatoes in the intercropping system under residual straw of the previous green corn crop using the ¹⁵N natural abundance method. We also investigated the temporal variation in nitrogen transfer to a cherry tomato, the biological nitrogen fixation (BNF) of legumes, and the N concentration of green corn cultivated in the intercrop succession. The experimental design was a complete randomized block with eight treatments and five replications, described as follows: two controls consisting of a monocrop of cherry tomato with or without residual straw, cherry tomato and jack bean, sun hemp, dwarf velvet bean, mung bean, and white lupine or cowpea bean in intercropping system. The BNF was responsible for more than half of the N accumulated in the legumes. The N of legumes was transferred to cherry tomato in similar quantities, and the leaves and fruits of cherry tomato received more N transfer than shoots. It was shown that N transfer increases with the growth/development of cherry tomatoes. The intercropping system with legumes did not affect the ¹⁵N natural abundance of leaves and the aboveground biomass of green corn cultivated in succession.

Nosemosis is an important disease that affects honey bees (Apis mellifera Lineu), caused by obligate intracellular parasites, Nosema apis and/or Nosema ceranae. Since the initial detection of N. ceranae in A. mellifera coincided with recent large-scale losses of bee colonies worldwide, the impacts of this parasite under field conditions are of great interest. Here we test two hypotheses, the first one, whether the climatic variables (temperature, air humidity and precipitation) influence the intensity of infection of the microsporidium Nosema spp. in Africanized honey bees (Apis mellifera), and the second, whether the local of hive installation (outdoor or roofed) influences the intensity of infection of these spores in Africanized honey bees. Between August 2013 and August 2016, samples of Africanized bees were collected weekly from 20 colonies, of which ten were located in an open area (outdoor apiary) and ten under a roof on a concrete floor (roofed apiary). N. ceranae was the only species present. The type of apiary did not influence (p > 0.05) the number of spores of N. ceranae in Africanized bees. However, the infection intensities of the roofed apiary colonies were lower in the autumn. Regarding the meteorological parameters, there was a negative correlation between the winter infection intensities and the minimum temperature in the roofed apiary and the humidity in the outdoor apiary. The highest infection intensities occurred in both apiaries in the spring and summer, which may be related to higher pollen production. On average, the infection intensity was 16.19 ± 15.81 x 105, ranging from zero to 100.5 x105, and there were no records of collapse during the three years.

The corn-grass intercropping system began to be used in the dry season, as it provides increased straw production for the no-tillage system. However, corn and grass are plants demanding in nitrogen. The corn cultivated in the dry season is called out-of-season corn in Brazil. The objective of this study was to evaluate the productivity and nutrients concentrations of out-of-season corn and Congo-grass intercropped in the no-tillage system, as a function of the nitrogen rates applied in sidedressing. The treatments were four nitrogen rates, 0, 30, 60 and 90 kg ha⁻¹. The experimental design was randomised complete blocks with four replicates. The experimental period corresponded to the harvests of 2015 and 2016. There were evaluated: corn grain yield, dry mass production and nutrient concentration in the shoots of the plants intercropped. The evaluations were carried out at the physiological maturity stage of the corn and at the time of desiccation of the grass. Nitrogen increased grain yield and dry mass production of the plants intercropped. Nitrogen maximised the magnesium concentration in out-of-season corn and the nitrogen, calcium, magnesium and sulphur concentrations in Congo grass. Excess nitrogen promoted reduction of the phosphorus in the Corn-Congo grass intercropping system in the dry season.

The response of legumes to the supply of either phosphorus (P) or calcium (Ca) alone has been extensively investigated but no prior studies have evaluated their combinations in the perennial legume Macrotyloma axillare (Macrotyloma legume). This study assessed the mineral composition of Macrotyloma legume in response to the combined application of P and Ca in an Ultisol. The experiment was conducted in a greenhouse in Nova Odessa city, São Paulo, Brazil. Five rates of P and Ca, respectively, were combined in a 52 incomplete fractional factorial design. Thus, the treatments consisted of 13 P and Ca combination rates (respectively, in mg dm−3): 0‒0, 0‒40, 0‒80, 15‒20, 15‒60, 30‒0, 30‒40, 30‒80, 45‒20, 45‒60, 60‒0, 60‒40 and 60‒80 arranged in a randomised block design with four replications. Mineral composition was evaluated after two harvests (53 d after sowing and 34 d after the first harvest). During the initial growth of the Macrotyloma legume, P × Ca interactions occurred. The P supply antagonistically ...

RESUMO Foram realizados dois ensaios, ambos utilizando delineamento em blocos casualizados em esquema fatorial (3x2), onde foram avaliados três níveis de inclusão de feno de alfafa (0,0%; 5,0% e 10,0%) e dois níveis de frutoligossacarídeo - FOS (0,0% e 0,3%). No Ensaio 1, com o objetivo de avaliar o desempenho zootécnico, foram utilizados 72 leitões desmamados, de linhagem comercial, de ambos os sexos (1 macho + 1 fêmea/baia), seis repetições, com peso inicial de 5,95 ± 0,73kg, com idade aproximada de 21 dias. Não foi observada interação entre os fatores estudados. No período dos 21 aos 59 dias de idade o ganho de peso não apresentou diferenças entre os tratamentos. O grupo que consumiu ração com adição de 0,3% de FOS apresentou maior consumo em relação ao grupo controle (0,0% FOS). Observou-se melhora na conversão alimentar das dietas que não possuíam inclusão de FOS, porém, não houve diferença significativa entre a dieta controle e as demais dietas em relação aos níveis de alfafa. No Ensaio 2 determinou-se a digestibilidade dos nutrientes, o balanço nitrogenado e as energias digestível e metabolizável das rações. Concluiu-se que a inclusão de FOS incrementou o consumo de dietas ricas em alfafa. A adição do feno de alfafa reduziu os coeficientes de digestibilidade dos nutrientes com exceção do extrato etéreo, porém não influenciou o balanço do nitrogênio

Esse trabalho foi realizado com o objetivo de avaliar os conteúdos de alguns nutrientes do rami, em quatro freqüências de corte, cada uma das quais adubadas com nitrogênio mineral (sulfato de amônio) ou orgânico (resíduo de limpeza de piso aviário). De maio de 2006 a maio de 2007 foram realizados 13, 10, 08 e 07 cortes nas freqüências 28, 35, 42 e 49 dias, respectivamente. Em cada freqüência, o rami era adubado após cada corte na dosagem de 100 kgN/ha, parcelada pelo número de cortes. Após o corte de uniformização, o solo do rami foi corrigido com calcário dolomítico e adubado com P, K e N, e, para melhor incorporação do corretivo, a área foi submetida a um pisoteio animal e irrigada. Determinaram-se a altura da planta e os teores de proteína bruta (PB), fibra bruta (FB), digestibilidade “in vitro” da MS (DIVMS), cálcio (Ca) e fósforo (P). Os teores variaram de 12,3% a 28,3% em PB; 39,5% a 79,9% em DIVMS; 2,0% a 5,2% em Ca e 0,26% a 0,51% em P. Com exceção ao efeito do IEC na PB, onde houve um decréscimo gradativo linear do IEC de 28 dias para o de 49 dias, em todas as demais variáveis estudadas, seja entre fontes de N (FN) nos intervalos entre corte (IEC), seja entre os IEC, as diferenças foram praticamente insignificantes. Os teores dos nutrientes estudados foram bastante expressivos, comparáveis e até maiores aos citados para leguminosas como guandu e leucena, cortadas também para alimentação de pequenos ruminantes. Os teores de Ca foram altos e maiores cuidados devem ser tomados na relação Ca: P para formulação de rações balanceadas.