ABSTRACT Phosphorus is a major limiting nutrient for crops in tropical regions. In addition, another major challenge for the future agriculture will be to maintain water levels in the soil to ensure satisfactory crop development. This study inserted in this context aimed to evaluate the conditioning caused by phosphorus fertilization and water availability in the soil over the biomass production and nutritional efficiency of plants of crambe (Crambe abyssinica Hochst). To this end, the experiment was conducted in a greenhouse, with four levels of phosphorus fertilization and three levels of water availability, along of 45 days, in order to obtain information about the production of biomass, nutritional contents, and the patterns of the nutritional efficiency of crambe plants. The results show that increasing the phosphorus supply in the soil promotes greater biomass production in crambe plants. In addition, the increase in water availability and levels of phosphorus fertilization near the recommended level promotes greater nutritional efficiencies in absorb, translocate and use the phosphorus available in the soil.

RESUMEN La disponibilidad de agua y fósforo es una limitante para los cultivos en las regiones tropicales. El objetivo de este estudio fue evaluar el efecto de la fertilización fosfatada y la disponibilidad de agua en el suelo sobre la producción de biomasa y la eficiencia nutricional de las plantas de crambe (Crambe abyssinica Hochst). Las plantas fueron cultivadas en un invernadero, con cuatro niveles de fertilización de fósforo y tres niveles de disponibilidad de agua, para estudiar el comportamiento vegetativo entre emergencia y floración. Se evaluó la biomasa, contenido nutricional y patrones de eficiencia nutricional de las plantas. Los resultados muestran un aumento de biomasa al fertilizar con fósforo. Se observa un efecto sinérgico al aumentar la disponibilidad de agua y fósforo, mejorando la eficiencia en la absorción del fósforo disponible en el suelo.

ABSTRACT Due to the possibility of enhancing the physiological responses by modulating the architecture of coffee trees, the objective of the study was to analyze the leaf gas exchanges and biomass allocation of Arabica coffee cultivated with different numbers of orthotropic stems. The experiment was carried out in a plantation located in Santa Teresa-ES, Brazil, cultivated with spacing of 2.5×1.0 m, using the cultivar Catuaí Vermelho IAC44. The gas exchange rates were monitored along stages of the phenological cycle (2014/2015), following a split-plot scheme, 3×3 (number of orthotropic stems per plant in three levels: 1, 2 and 3; and the phenological stages in three levels: flowering, fruit formation and maturation). The allocation of biomass in the plagiotropic branches was also analyzed during the phenological stage of fruit maturation. The management of the number of orthotropic stems affected the photosynthetic responses and biomass allocation of coffee trees. Under the studied conditions, cultivating the plants with two orthotropic stems created conditions which promoted the photosynthetic responses. Keeping more stems promotes the availability of leaves per amount of produced fruits in the plagiotropic branches, allowing the plant to sustain the production with less metabolic wearing.

A grande quantidade de resíduos industriais que constituiu atualmente sérios problemas ambientais tem alertado para a utilização adequada desses materiais que, além de reduzir os impactos ambientais, tem demonstrado potencial para utilização na agricultura. O objetivo deste estudo foi avaliar os efeitos químicos da aplicação de diferentes doses de escória de siderurgia e óxido de magnésio em dois solos sob o cultivo de café arábica. O estudo foi desenvolvido em casa de vegetação do Centro de Ciências Agrárias da Universidade Federal do Espírito Santo, em vasos de 10 dm³. O delineamento experimental foi instalado em blocos casualizados, com distribuição fatorial de 2 x 3 x 6, com três repetições, sendo os fatores: dois solos (Latossolo Vermelho-Amarelo distrófico de textura argilosa e Latossolo Vermelho-Amarelo distrófico de textura média); três insumos (calcário como controle e escória de siderurgia e óxido de magnésio como resíduos); seis doses dos materiais corretivos (0; 25; 50; 75; 100 e 125% da necessidade de calagem). Após 180 dias de cultivo, procedeu-se as análises de pH, H+ + Al3+, Al3+, Ca2+ e Mg2+. Os resultados mostraram que as aplicações de doses crescentes de escória e óxido de magnésio até o limite estudado neste trabalho favorecem um decréscimo da acidez do solo. O óxido de magnésio demonstrou maior potencial como corretivo de acidez de solo e como fonte de magnésio para o solo.

The large amount of industrial waste which currently causes serious environmental problems has demonstrated the need for the appropriate use of those materials which not only reduce environmental impact but have shown potential for agricultural use. The aim of this study was to evaluate the chemical effects of different amounts of slag and magnesium oxide on two soils planted with coffea arabica. The study was carried out using pots of 10 dm³ in a greenhouse at the Center for Agrarian Sciences of the Federal University of Espirito Santo. The experimental design was of randomized blocks with a factorial distribution of 2 x 3 x 6, and three replications, the factors being: two soils (dystrophic red-yellow clay loam and dystrophic red-yellow medium-texture loam), three additives (limestone as control and slag and magnesium oxide as waste), six amounts of corrective materials (0; 25; 50; 75; 100 and 125% of the required liming). After 180 days of culture, analysis of pH, H+ + Al3+, Al3+, Ca2+ e Mg2+ was carried out. The results showed that applications of increasing doses of magnesium oxide and slag, up to the limit of this study, further a decrease in soil acidity. Magnesium oxide has shown the greatest potential for soil-acidity correction and also as a source of magnesium for the soil.