Browsing by Autor "Jorge Paolini"

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Aportes de nitrógeno y fósforo al suelo a través de la hojarasca en dos agroecosistemas de café (coffea arábica) bajo sombra en los andes venezolanos.
(2015) Gabriel Arellano; Jorge Paolini; E A Hoyos Villegas; Miguel Ángel Gallegos-Robles
During one year period , the contribution of nitrogen (N) and phosphorous (P) to the soil through incorporating dead leaves in decomposition in two coffee agroecosystems (coffee arabiga) located in the sector Vitu, Municipality of Pampan , Trujillo State, was evaluated. In system A, coffee plants were mainly in the shade of trees like Ficus caruca and Inga spp, while system B . consisted in coffee in the shade of trees like Inga spp., Persea Americana and Bixa orellana, among others. The research was carried out in three stages ; a fi el stage in which decomposition of dead leaves was determined by means of the “litter bags” method; and a laboratory stage where concentrations of nitrogen (N) and phosphorous (P) were determinated by means of the Kjedahl and blue molybdenus methods, respectively, the controbutions of these parameters to the organic humus were evaluated too. Concentrations of N and P in system A were 2,10 – 3,00 % of coffee, 1,30 – 2,07 % N of tree leaves and 0,07 – 0,12 % of coffee, respectively. In system B, the contribution were: 2,03 – 2,38 % of coffee, 1,90 – 2,69 % N of tree leaves , and 0,11 – 0,16 % of coffee, 0,07 – 0,15 % of tree leaves. The contribution of tree leaves to the organic humus in system A were: N: 83,16 (Kg/ ha/year) and of N: 104,97 (Kg/ha/year) for system B, respectively. Constributions of P for system A was of 3,61 Kg/ha/year) and of 5,73 (Kg/ha/year) for system B. A light increase of values from N and P in dead leaves was also noticed. These results can be attributed to the fact that system B has different shade trees with respect to system A; however, the concentration of N and P in the organic humus are generally similar. Coffee farming in the shade provides an adequate microclime in humidity and temperature, basic for the development of the plant in not best areas for that kind of farming; this fact confers it a great ecological importance. For comparing these results the SAS statistical pack and the one-way variance analysis were used.
Effects of induced water deficit and biofertilization on growth dynamics and bulb yield of onion (<i>Allium cepa</i> L.) in a neotropical semi-arid environment
(Canadian Science Publishing, 2021) Erika Lorena Blanco; Fermín Rada; Jorge Paolini; José Argenis Guerrero
In a scenario of world population increase and climate change, an efficient use of water is key for agricultural production. Onion is one of the most profitable crops and can adapt to particular conditions of water stress. The objective of this research was to determine growing degree-days and accumulated radiation under non-stress conditions and yield of an F1 2000 hybrid of onion (Allium cepa L.) under water deficit (WD) and biofertilization in a semi-arid environment. An established nutrient requirement of 247 kg N, 240 kg P 2 O 5 (105 kg P), 240 kg K 2 O (199 kg K), and two irrigation factors were applied: normal irrigation with a daily and WD with a 3 d interval irrigation frequencies. The effect of biofertilization was evaluated through the inoculation of a microbial consortium (MC) in combination with four NPK fertilizer treatments. The crop accumulated 1334 degree-days and 1188 MJ m −2 ·d −1 at the time of harvest at 71 d after transplanting. The yield was 36 t·ha −1 , similar under both irrigation conditions; and the WD treatment resulted in a 35% water savings, a 47% and 65% increase in water use efficiency and modulus of elasticity, respectively. The MC resulted in a 50% NPK savings under non-limiting water conditions and produced a similar yield compared with the 100% NPK non-inoculated control. The lower irrigation frequency together with the 100% NPK fertilization dose without the MC and the use of the microorganisms and the 50% NPK treatment without water stress are recommended as agrosustainable practices for onion production.