Macro and Micro-Nutrient Accumulation and Partitioning in Soybean Affected by Water and Nitrogen Supply.

This study aimed to investigate the influence of water availability and nitrogen fertilization on plant growth, nutrient dynamics, and variables related to soybean crop yield. Trials were performed in Teresina, Piauí, Brazil, using randomized blocks in a split-split plot arrangement. The plots corresponded to water regimes (full and deficient), the split plots to N fertilization (0 and 1000 kg ha-1 N-urea), and the split-split plots to harvest times of soybean plants (16, 23, 30, 37, 44, 58, 65, 79 and 86 days after emergence), with three replicates. In general, the accumulation and partitioning of nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulphur (S), copper (Cu), iron (Fe), manganese (Mn), zinc (Zn) and boron (B) were decreased in plants subjected to water deficit and without N fertilization. Although nitrogen fertilization promoted elevated N accumulation in tissues, it did not result in any significant yield gain, and the highest seed yields were found in plants under full irrigation, regardless of N supplementation. However, deficient irrigation decreased the seed oil content of N-fertilized plants. In conclusion, N fertilization is critical for nutrient homeostasis, and water availability impairs biomass and nutrient accumulation, thereby limiting soybean yield performance.

Crop residues activity against the free-living stages of small ruminant nematodes.

The nematicidal effect of different organic materials was evaluated in order to develop a non-chemical alternative soil treatment for control of the free-living stages of small ruminant gastrointestinal nematodes. The selected organic materials were residues from the juice industry of acerola, cashew, grape, guava, papaya and pineapple, as well as castor residue from the biodiesel industry. LC90 results showed that pineapple residue was the most efficient inhibitor of larval development, followed by castor, grape, cashew, acerola, guava and papaya. Castor residue was also a good source of nitrogen and was used in a greenhouse experiment to prevent larval development in contaminated goat faeces that was deposited in pots containing the grasses Brachiaria brizantha (var. Paiaguás) or Megathyrsus maximus x M. infestum (var. Massai). Castor residue caused a significant (P < 0.05) reduction (85.04%) in Paiaguás grass contamination (L3.dry mass-1) and a reduction of 17.35% in Massai grass contamination (P > 0.05), with an increase in the biomass production of Massai (251.43%, P < 0.05) and Paiaguás (109.19%, P > 0.05) grasses. This strategy, called Econemat®, with good results in vitro shows to be promising on pasture increasing phytomass production.

Crop residues activity against the free-living stages of small ruminant nematodes / Atividade de resíduos de culturas contra os estágios de vida livre de nematoides de pequenos ruminantes

Abstract The nematicidal effect of different organic materials was evaluated in order to develop a non-chemical alternative soil treatment for control of the free-living stages of small ruminant gastrointestinal nematodes. The selected organic materials were residues from the juice industry of acerola, cashew, grape, guava, papaya and pineapple, as well as castor residue from the biodiesel industry. LC90 results showed that pineapple residue was the most efficient inhibitor of larval development, followed by castor, grape, cashew, acerola, guava and papaya. Castor residue was also a good source of nitrogen and was used in a greenhouse experiment to prevent larval development in contaminated goat faeces that was deposited in pots containing the grasses Brachiaria brizantha (var. Paiaguás) or Megathyrsus maximus x M. infestum (var. Massai). Castor residue caused a significant (P < 0.05) reduction (85.04%) in Paiaguás grass contamination (L3.dry mass-1) and a reduction of 17.35% in Massai grass contamination (P > 0.05), with an increase in the biomass production of Massai (251.43%, P < 0.05) and Paiaguás (109.19%, P > 0.05) grasses. This strategy, called Econemat®, with good results in vitro shows to be promising on pasture increasing phytomass production.

Resumo O efeito nematicida de diferentes materiais orgânicos foi avaliado, com o objetivo de desenvolver um tratamento alternativo não químico do solo para o controle dos estágios de vida livre de nematoides gastrintestinais de pequenos ruminantes. Os materiais orgânicos selecionados foram resíduos da indústria de suco de acerola, caju, uva, goiaba, mamão e abacaxi, além do resíduo de mamona da indústria de biodiesel. Os resultados da LC90 mostraram que o resíduo de abacaxi foi o mais eficiente inibidor do desenvolvimento larval, seguido pela mamona, uva, caju, acerola, goiaba e mamão. O resíduo de mamona também se mostrou uma boa fonte de nitrogênio, sendo usado em experimento em casa de vegetação para prevenir o desenvolvimento larval em fezes contaminadas, depositadas em vasos, contendo as gramíneas Brachiaria brizantha (var. Paiaguás) ou Megathyrsus maximus x M. infestum (var. Massai). O resíduo de mamona reduziu (85,04%) significativamente (P < 0,05) a contaminação no capim-Paiaguás (L3.dry massa-1), 17,35% no capim Massai (P> 0,05), e aumentou a produção de biomassa das gramíneas Massai (251,43%, P <0,05) e Paiaguás (109,19%, P> 0,05). Essa estratégia, chamada Econemat®, com bons resultados in vitro, mostra-se promissora nas pastagens aumentando a produção de fitomassa.