The objective of this work was to evaluate the effect of soil cover species and management systems in improving the physical characteristics of a Haplortox and its effects on grain yield and soybean oil content. The experimental area, consisted of 15 treatments in a completely randomized experimental design. Each plot had size of 20 × 25 m. The treatments consisted of: traditional no-tillage system (control), no-tillage system with application of gypsum, no-tillage with scarification and 12 treatments with cover species called soil structure reclaimers. Soil samples were collected in the layers of 0-0.10; 0.10-0.20 and 0.20-0.30 m, with four replicates. The physical attributes evaluated were bulk density, total porosity, microporosity, macroporosity and saturated hydraulic conductivity in the periods of 2014, 2015 and 2016. In the soybean crop the grain yield, oil content, weight of 100 grains, average height of plants and number of plants/m were evaluated in each treatment with four replications. The oil content was performed by the low-field nuclear magnetic resonance method. The averages of the treatments were compared by the Tukey test at 5% of significance. The results showed that five months after soil scarification did not affect bulk density. Eleven months after gypsum application discrete improvements in density, total porosity, microporosity and soil hydraulic conductivity occurred in the 0-0.10 and 0.10-0.20 m layers. It was also concluded that grain yield, oil content, weight of 100 grains and number of plants per meter were not influenced by the soil cover species and soil management systems.

This work aimed to evaluate the dynamics of physical and hydric attributes of a clayey Latosol cultivated with different cover species. The experimental area was located in the Agronomic Institute of Paraná (IAPAR), in the regional hub of Santa Tereza do Oeste, Paraná, Brazil. The experiment was comprised of seven cover species also called treatments is the course of this work. Three of them were isolated summer species notably Crotalaria juncea, Crotalaria spectabilis, Cajanus cajan (pigeon pea), and the other four treatments winter species cultivated individually or in association including Avena strigosa (Black oat), + (Avena stirgosa + Raphamus sativus (radish), Avena strigosa + Lupinus albus (Lupin bean), and (Avena strigosa + Pisum sativum (pea). The treatments were distributed on a completely random plots of 20 m × 25 m without replication. Soil density, macroporosity, and saturated hydraulic conductivity were measured to follow the changes of the soil structure. Statistical analyses showed that cover crops species did not lead to a significant improvement in soil structural status. Soil density varied between 1.08 and 1.12 Mg m-3, macroporosity from 15.22 and 16.90%, and saturated hydraulic conductivity ranged from 28.83 to 45.07 mm h-1. Soybean grain yield were considered satisfactory in 2016 (mean = 1909.68 kg ha-1) and in 2017 (mean = 3355.30 kg ha-1) most probably due to the good initial structural conditions of the soil, alongside with the good climatic conditions during the two campaigns. Furthermore, the soybean grain yield was positively influenced by Ds which ranged from 1.0 to 1.17 Mg m-3.

An experiment was conducted at the Agronomic Institute of Paraná -IAPAR, at the Experimental Station of the municipality of Santa Tereza do Oeste -PR, in Hapludox of clayey soil. Studies with the use of plants cover crops with vigorous root system in different systems of soil management systems are needed, in order to have a diversity of species capable of producing different amounts of crop residues which by decomposing, can alter the physical attributes and consequently, the productivity of the successor culture. The objective of this study was to evaluate the effect of crambe crop and plant cover crops in succession on the physical characteristics of a Haplortox under no-tillage system. The experimental area has been cultivated under no-tillage system for 18 years. The experimental area consisted of 15 plots, each plot with 20x25 m. In 12 plots, plant cover crops were planted, six species of summer and six of winter and the last three consisted of plots with no-tillage system with gypsum application, no-tillage system with scarification and traditional no-tillage (control) in a completely randomized design. The physical attributes of this soil were soil density (DS), total porosity (PT), microporosity (Micro), macroporosity (Macro) and saturated hydraulic conductivity (Ksat) of the soil in the periods of 2014 (initial characterization of the soil) and 2015 (after crambe culture). The microporosity (0.0-0.1 m layer) and Ksat (all soil layers) presented significant differences between treatments in the period of 2015. Microporosity was lower in the pigeon pea coverage (PP) (36.08%), while the largest occurred in the coverage of crambe C5 (45.38%). The Ksat was higher in the dwarf pigeon pea (DPP) (298.20 mm h -1 ) and sunn hemp (SH) (163.39 mm h -1 ) coverage in the 0.0-0.1 m layer. The highest Ksat was observed for crambe C9 (96.81 mm h -1 ), C8 (74.13 mm h -1 ), velvet bean (70.95 mm h -1 ) and C5 (53.94 mm h -1 ) respectively, in the soil layer of 0.1-0.2 m.

The inappropriate use of herbicides has increased the resistance of weeds; thus, the study of allelopathy becomes of paramount importance. The ability of certain plants to interfere with the metabolism of others by means of substances released into the environment, either by their aerial or roots system, becomes an alternative to combat invasive plants, dispensing with or reducing the use of herbicides. The objective of this work was to evaluate the plant species most sensitive to the allelopathic potential of aqueous extracts. One of the plant species studied was lettuce because it had a rapid response potential, thus showing the benefits obtained through allelopathy.

Con el objetivo de evaluar la respuesta productiva del maíz para silaje a la aplicación de riego suplementario y fertilización estratégica en Argiudoles del centro de la provincia de Santa Fe se realizó un ensayo en tres épocas de siembra, dos condiciones de agua -riego y secano -y diferentes híbridos de maíz en cada época. Se evaluó la producción de materia seca total, producción de granos, índice de cosecha, índice de área foliar y el área foliar específica. Para todas las variables estudiadas fueron encontradas diferencias significativas entre riego y secano, destacándose la producción de granos que se incrementó entre un 130 y 285% y la biomasa total, con aumentos que variaron entre 52 y 155%, dependiendo de la época de siembra e híbrido. Estos resultados permiten concluir que se pueden esperar importantes respuestas productivas a la aplicación de riego suplementario y fertilización estratégica en maíces destinados a silaje.Palabras clave: silaje de maíz, riego suplementario, época de siembra, híbridos.