Nitrogen mineralized during sorghum growth after soil incorporation of different winter cover crops

Growing catch crops during the autumn/winter period is a strategy of high ecological significance since it allows reducing the residual inorganic-N present in the soil after the summer season (Rodrigues et al., 2002). Thus, winter catch crops reduce the risk of denitrification and nitrate leaching associated to the excess of rain of the autumn/winter months. Incidentally, the evergreen systems confer several other additional benefits, including protection against soil erosion and increasing soil organic matter. In recent years, agronomists and soil scientists have studied the pros and cons of the introduction of cover crops/catch crops in different agro-ecological conditions and cropping systems. Some were focused in comparing the performance of different plant species when they were used as catch crops (Jensen, 1992; Chapot and Robin, 1994). In addition, since winter catch crops precedes summer cash crops, it is important to know the effect of the catch crop in the performance of the cash crop. As a general rule, the catch crop should present good growth rate in winter and improve soil fertility to promote the growth of the summer crop. Theoretically, lupine (Lupinus albus) seems to have both features. It is a species of high biomass production in autumn/winter period (Rodrigues et al., 2013) and, being a legume species with tissues of low C/N ratio, net nitrogen mineralization should occur early in the growing season of the crop that follows lupine in the rotation. In this work, results are presented of the effect of several winter cover crops in nitrogen availability in a soil cultivated with sorghum in the following summer season

The effect of different winter cover crops on sorghum nutritional status and dry matter yield

Growing winter cover crops has a great agroecological meaning, since it allow maintaining the residual inorganic N in the soil/plant system, thus avoiding leaching of N (Rodrigues et al., 2002). As winter cover crops, it can be grown diverse species (Jensen, 1992). If legume species were used, they can access atmospheric N through the establishment of a symbiotic relationship with N-fixing bacteria (Russelle, 2008). Thus, the winter leguminous cover crops can have a dual role: to uptake residual inorganic N; and promoting the growth of the following crop through a green manuring effect, which may reduce the need for expensive N fertilizers. Lupine (Lupinus albus) appears as a suitable legume species to be grown in this region, since it presents high growth rates in winter and a great ability to fix N (Rodrigues et al., 2013). In this work, the use of lupine as a winter cover crop was compared to small grains and natural vegetation (weeds) by measuring their effect on irrigated sorghum grown as a summer crop. The effect of the different winter cover crops was evaluated by comparing sorghum dry matter yield, plant N nutritional status and N recovery by sorghum plants

Nitrogen Use Efficiency and Crop Yield in Four Successive Crops Following Application of Biochar and Zeolites

Two soil amendments, biochar and zeolites, were evaluated in their potential for increasing crop productivity and agro-system sustainability. The effect of biochar and zeolites, in combination with four nitrogen (N) rates [0 (N0), 50 (N50), 100 (N100), and 200 (N200) kg ha−1], on crop yield, N use efficiency, and soil properties was evaluated in a cropping system of irrigated forage maize (Zea mays L.) grown in summer and oats (Avena sativa L.) grown in winter as a catch crop. Biochar increased soil organic carbon (C), pH, cation exchange capacity (CEC), and extractable phosphorus (P), but strongly reduced N recovery in the set of the four cropping cycles. In biochar-amended plots, N50 had a negative apparent N recovery (− 21%), indicating that less N was recovered by the plants than in the N0 treatment without biochar. Biochar reduced maize dry matter (DM) yield by 15.6% in comparison to the untreated control, indicating N immobilization by biochar at low N rates (N0 and N50). Zeolites did not influence crop productivity or soil properties, except for the increase in extractable K, probably the result of its initial K content. N application to maize significantly increased the productivity of both crops, including that of the non-fertilized oats. Under the conditions of this experiment, biochar and zeolites did not prove to be useful soil amendments to increase crop DM yield in the short-term. The use of biochar increased soil organic C, which associated to a high N rate can enable the dual objective of maintaining productivity and the sustainability of the agro-system. The results stressed also the important role of oats as a cover crop to reduce the risk of nitrate leaching and denitrification during winter.info:eu-repo/semantics/publishedVersio

Effect of soil conditioners and nitrogen fertilization in corn’s aboveground biomass and leaves green color intensity

Every crop needs a well-nourished soil and balanced nutrition to have a good development. Nitrogen (N) balance is essential for plant development, and it depends on soil physical, chemical and biological properties. Some soil conditioners may have a relevant role in soil available N. The present work intends to evaluate the effect of soil conditioners such as biochar, zeolites and mineral fertilizers on the performance of plants through the determination of aboveground biomass and green color intensity of plant leaves in field and pot experiments. The field experiment was arranged as a factorial design with three soil conditioners (zeolites, biochar and mineral fertilizer only) and four N rates (0, 50, 100, 200 kg N ha-1). The pot experiment was also arranged in a similar factorial design with only two rates of N. Plant health during the growing season was assessed by the Normalized Difference Vegetation Index (NDVI) determined by using the FIELDSCOUT® CM1000 meter. Aboveground biomass was weighed at the end of the growing season after it had been oven-dried at 70 ºC. NDVI did not discriminate between treatments, with the mean values ranging from 0.80 to 0.85. From the field and pot experiments increased values of biomass yield were recorded to the higher N rates. Comparing soil conditioners zeolites produced the higher results.info:eu-repo/semantics/publishedVersio

Leguminous cover crops improve the profitability and the sustainability of rainfed olive (Olea europaea L.) orchards: from soil biology to physiology of yield determination

The olive sector has a crucial economic, social, cultural and ecological relevance in the Mediterranean region, where tillage and herbicides application still are generalized practices. However, these techniques oppose to the recommendations of UE policy. Thus, other methods are needed to reduce adverse environmental impacts and to improve biodiversity, soil carbon sink and fertility, to save fossil fuels and to increase yield and the safety and nutritional value of food products. Meanwhile, since Mediterranean basin is particularly vulnerable to climate change, including lower precipitation in summer, olive tree will experiment some hard changes, mainly under rainfed conditions. Therefore, we propose an adequate management of cover crops to shift tillage and herbicides, in order to minimize runoff and evaporation water losses, conserve soil moisture storage and promote the infiltration of water in soil. The experiment was carried out during 4 years on a commercial orchard (cv. Cobrançosa) in Northeast Portugal. The treatments laid out were: (1) ordinary tillage techniques (OT) used by local growers (two tillage trips per year); (2) cover crop with self-reseeding annual legume species (AL); (3) natural vegetation fertilized (NVF) with 60 kg N hm2 (as in OT); (4) natural vegetation (NV) left unfertilized. The results revealed that AL treatment is the best option, reaching 37, 53 and 95% higher cumulative yield than NVF, OT and NV, respectively, in a closely association with greater physiological performance during the summer, mainly evidenced by lower oxidative damage and by favourable changes in water status and net photosynthetic rate, due to lower stomatal and mesophyll limitations. Moreover, the AL covered soil presented considerable microbial diversity and enzymatic activities, which may contribute to promote and conserve soil quality and health, as well the stability of ecosystems. Thus, leguminous cover crops improve the profitability and the sustainability of rainfed olive orchards.info:eu-repo/semantics/publishedVersio

Produção, azoto exportado e azoto residual no solo em alface (Lactuca sativa L.) cultivada em vasos quando sujeita à aplicação de vários fertilizantes que retardam a libertação de azoto

As marcas comerciais de fertilizantes ‘especiais’ têm aumentado muito na última década. Este aspecto tem vantagens, pois ficam disponíveis mais soluções fertilizantes para os diferentes condicionalismos agroecológicos. Contudo, urna excessiva proliferação de marcas dificulta o trabalho dos técnicos e agricultores, na medida em que nem sempre é fácil encontrar informação sobre estes fertilizantes para além daquela que fornece a empresa que os comercializa

Discrete symmetries, invisible axion and lepton number symmetry in an economic 3-3-1 model

We show that Peccei-Quinn and lepton number symmetries can be a natural outcome in a 3-3-1 model with right-handed neutrinos after imposing a Z_11 x Z_2 symmetry. This symmetry is suitably accommodated in this model when we augmented its spectrum by including merely one singlet scalar field. We work out the breaking of the Peccei-Quinn symmetry, yielding the axion, and study the phenomenological consequences. The main result of this work is that the solution to the strong CP problem can be implemented in a natural way, implying an invisible axion phenomenologically unconstrained, free of domain wall formation and constituting a good candidate for the cold dark matter.Comment: 17 pages, Revtex

Scarabaeoidea (Insecta : Coleoptera) in the Brazilian Cerrado : current state of knowledge

Besouros pertencentes à superfamília Scarabaeoidea ocupam habitats variados, possuem hábitos alimentares diversifi cados, desempenham importante papel ecológico e diversas espécies apresentam importância agrícola. No entanto, estudos com esse grupo na região do Cerrado são escassos. Nesta revisão realizou-se um levantamento dos artigos publicados nos últimos 30 anos a respeito dos Scarabaeoidea no Cerrado. Foram recuperados 64 artigos, realizados em nove unidades da federação, que focavam quatro temas principais espécies praga, aspectos bioecológicos, biodiversidade e importância ecológica, e técnicas e metodologias de coleta de Scarabaeoidea. Os resultados desta revisão indicam que poucos estudos foram realizados com os Scarabaeoidea no Cerrado brasileiro nas últimas décadas frente à importância e diversidade desse grupo de insetos.Beetles belonging to the superfamily Scarabaeoidea occupy different habitats, present feeding habits diversifi ed, play an important ecological role and several species have agricultural importance. However, studies with this group in the Brazilian Cerrado are scarce. In this review we carried out a survey of scientifi c articles published in the past 30 years concerning Scarabaeoidea in the Cerrado. Were found 64 studies in nine Brazilian states. The studies focused on four main topics: pest species, bioecology, biodiversity and ecological importance, techniques and methodologies for collecting Scarabaeoidea. The results of this review indicate that few studies have been conducted with Scarabaeoidea in the Cerrado in recent decades compared to the importance and diversity of this group of insects

Yield, quality and conservation of heterozygous tomatoes in alcobaça, nonripening and ripening inhibitor loci

O objetivo deste trabalho foi avaliar os atributos de produtividade, qualidade e conservação pós-colheita de tomates, para comparar os efeitos promovidos pelos alelos alcobaça (norA), nonripening (nor) e ripening inhibitor (rin) em heterozigose, isoladamente ou em duplas combinações, sobre frutos de tomateiros híbridos. Foram avaliados dez tratamentos: sete híbridos experimentais quase-isogênicos, com background FloraDade x Tropic de genótipos nor+/norA, rin+/rin, nor+/nor, nor/norA, nor+/norA rin+/rin e nor+/nor rin+/rin; e três testemunhas comerciais (Floradade, Tropic e Carmen F1). Contrariamente aos genótipos rin+/rin e nor+/nor, o genótipo nor+/norA não prolongou, significativamente, a firmeza dos frutos em pós-colheita. Os genótipos duplo-mutantes norA/nor, nor+/norA rin+/rin e nor+/nor rin+/rin foram eficientes em atrasar a perda de firmeza e a evolução da coloração dos frutos; os efeitos dos locos nor+/norA e rin+/rin, juntos, sofreram desvios significativos em relação à soma dos efeitos desses locos, quando atuaram separadamente, no sentido de intensificarem esses atrasos. O uso de híbridos heterozigotos, nas duplas combinações entre os locos norA, nor e rin, mostrou-se vantajoso por propiciar frutos firmes, com maior extensão da vida pós-colheita, em comparação com o uso dos híbridos portadores desses locos isoladamente. A qualidade dos frutos duplo-mutantes não foi limitada pelo atraso na evolução da coloração vermelha.Thie objective of this work was to evaluate yield, quality and postharvest conservation of tomatoes, to compare the effects promoted by the alcobaça (norA), nonripening (nor) and ripening inhibitor (rin) alleles, in heterozygosis, singly or in double combinations on hybrid tomato fruits. Ten treatments were evaluated: seven experimental nearly isogenic hybrids of FloraDade x Tropic background or reciprocal with nor+/norA, rin+/rin, nor+/nor, nor/norA, nor+/norA rin+/rin and nor+/nor rin+/rin genotypes, and three commercial checks (FloraDade, Tropic and Carmen F1). Oppositely to the genotypes rin+/rin and nor+/nor, the genotype nor+/norA did not significantly extend the firmness of the fruits in postharvest. The double mutant genotypes norA/nor, nor+/norA rin+/rin and nor+/nor rin+/rin were efficient in delaying firmness loss and the evolution of fruits colouring; the effects of loci nor+/norA and rin+/rin, together, underwent significant deviations relatively to the sum of these loci effects, when acting singly, in the sense of enhancing those delays. Use of heterozygous hybrids in the double combinations among loci norA, nor and rin proved advantageous for providing firm fruits with a longer postharvest lifetime, as compared with the hybrids carrying these loci singly. The quality of double mutant fruits was not restricted by the delay in the evolution of red coloration