Jambu (Acmella oleracea (L.) R.K.) is a short-cycle leafy vegetable from the Amazon region, which needs an adequate availability of water and nutrients, mainly nitrogen, to obtain a rapid mass increase. This research aimed to study the effect of different soilwater stresses and nitrogen doses on jambu cultivation in the state of Pará. The experiments were conducted at the Igarapé-Açu experimental farm of the Federal Rural University of Amazonia (UFRA). The Jamburana variety was used in a 10 × 10 cm spacing, using a randomized block design in a 4 × 4 factorial scheme with three replications. Each plot had a dimension of 0.4 × 0.5 m (0.2 m 2 ), totaling 20 plants in 4 rows, but only the plants of the central rows were useful. Treatments consisted of four soil-water stresses (12, 18, 24, and 30 kPa) as an indication of the irrigation time (critical stress), using drip irrigation, and four nitrogen doses (0, 50, 100, and 150 kg ha −1 ). The use of soil-water stress of 12 kPa associated with nitrogen fertilization at a dose of 150 kg ha −1 is recommended for better development and production of jambu under the conditions this experiment was conducted.

Research conducted with Terra Preta Nova (TPN) experiment has been directed in the attempt to replicate soils known as Archeological Black Earth (ABE), characterized by being highly fertile and stable soils, associated with deposit of vegetal and animal residues origin by prehistoric man. The aims of this study were to evaluate the influence of soil chemical attributes on incorporation of wood residues and animal wastes in Terra Preta Nova experiment. The experimental design was randomized blocks, with 17 treatments consisting of incorporation of substrates in soil, individual or combined, of charcoal (C); wood sawdust (WS); MDF residues (MDF); bone meal residues (BNR); animal fat (AF); and control treatment (CT), without incorporation of substrate in soil, with four replicates. The incorporation and combinations of substrates promoted increase in soil organic matter, verifying that individual treatment based on charcoal resulted in a value of 70.35 g kg-1 of SOM, for P nutrient verified value of 332.76 mg kg-1 (C+BNR). For N and exchangeable bases contents (K, Na, Ca, and Mg), verified low values, without modifications with incorporation of different substrates in soil. The areas conducted with Terra Preta Nova experiment showed values of low soil chemical attributes compared to Archeological Black Earth, suggesting that time in which residues were incorporated was not sufficient for formation of soil fertility, characteristic of Archeological Black Earth.