The species that can be used as cover plants are many, which makes it difficult to make a choice, since there is no ideal plant, and it is necessary to make a survey of the most favorable species. The objective of this study was to evaluate the biomass productivity of cover crops in autumn and winter (Poaceaea and Fabaceae), and their effects on soil physical properties at different depths.The experimental design was of randomized blocks with subdivided plots, with six replications. The plots consisted of four cover crops in autumn and winter; two Poaceae (black oats and brachiaria) and two Fabaceae (fried pea and white lupine). The subplots were at different depths of evaluations; 0 -0.05; 0.05 -0.10 and 0.10 -0.15 m to determine the pore volume and soil density; and 0 to 0.40 m to resistance to penetration. Were evaluated: dry mass yield; soil surface cover index; volume of macropores, micropores, total porosity; soil density; and soil resistance to penetration. It was verified that the family of plants Fabaceae showed higher dry matter yield (4400 kg•ha −1 ), however, the lower soil cover rate (68.71%). The highest volume of macropores (0.05 m 3 •m −3 ) and the lowest soil resistance to penetration were observed in the soil cultivated with Poaceae family cover plants, in the respective depths of 0 -0.10 m and 0.05 -0.20 m.

The system of intercropping maize with other plant species has been a common practice for several years, but its use has been increasingly mainly to improve the quality of soil physical properties of notillage system. The objective of this study was to investigate the effect of intercropping using different cover plants on the physical properties of soil and the productivity of maize. Field experiments were conducted on the property of Mr. Arno Paulo Deimling, located in Linha São João, in the municipality of Quatro Pontes-PR. The experiment was carried out using a randomized complete block design, with four treatments and five repetitions. The treatments were winter maize intercropped with Urochloa brizantha, Urochloa ruziziensis or black oats (Avena strigosa), and maize sown in monoculture. In winter period, the production of maize used for silage and the production of dry matter from cover crops were assessed. The physical properties of soil samples were also investigated. Cover crops did not influence the productivity of winter maize used for silage, but it promoted improvements in soil macroporosity. The cover crops promoted improvements in the macroporosity of the soil and reduction at soil penetration resistance, particularly in the area planted with U. brisantha, demonstrating its potential in improving water infiltration and soil aeration.

Technological development has triggered a steady increase in Brazilian agricultural production, but also brought problems due to the excessive land use. The lack of care with proper management practices has led to soil physical degradation, mainly the formation of impermeable layers, which can lead to a reverse effect, a reduction in crop yield. It can be potentiated in silage production and with the lack of cover crops. To minimize the negative impacts of soil compaction, scarification is recommended, but its effectiveness has been questioned in no-tillage system. Thus, an experimental field was implemented in Brazil in 2015-2016 season, to evaluate the mechanical scarification on soybean production in succession to silage and grain corn intercropped with Brachiaria (Urochloa ruziziensis) as well as the physical properties of the soil. The experimental layout was a complete randomized block design with four replications. The plots were composed of second crop maize (autumn) intercropped with brachiaria, in two systems: silage and dry grains. The subplots were composed of three management system: no-tillage, reduced tillage cultivation with Terrus scarifier and Fox scarifier. Corn harvesting systems as well the scarifiers use did not affect soybean production and its yield components. The use of scarifiers reduced soil coverage, plant population, and soil penetration resistance. The data suggest that there was no persistence in the benefits presented by scarification. Soybean was able to break through the compacted layers, even above the critical level, corroborating with the hypothesis that the use of scarifiers does not bring benefits in no-tillage system.

This experiment aimed to study the effects on grain and forage productivity in dual-purpose wheat cv. BRS Tarumã under cutting handlings and nitrogen fertilization. The experiment was conducted in area of Rhodic Hapludox in the city of Marechal Cândido Rondon, Paraná State, in a randomized block design with 12 treatments and four replications. The treatments consisted of surface nitrogen levels (0, 60, 120 and 180 kg ha -1 ) and number of cuttings accomplished (0, 1 and 2). The topdressing was split in two applications for handling of just a cutting (27 and 65 days after sowing -DAS), and three applications for handling with two cuttings (27, 65 and 96 days after sowing -DAS). Data were subjected to analysis of variance (p≤0.05). The use of one or two cuttings and the comparison between the first and second cuttings were done by F test (5%) whereas nitrogen doses were studied by regression analysis. For all variables, there was significant interaction of nitrogen doses in surface and the number of cuttings. Grain yield and its yield components were responsive to levels of nitrogen fertilization in surface as well as forage production and its quality, but the same factors were reduced with the use of cuttings. This handling increased the dry matter content and crude protein in grains.

This study aimed to evaluate production components, yield of maize intercropped with jack bean and soil resistance to penetration using different doses of gypsum. The experimental design was a randomized complete block design in split plots with four replications and was carried out during season 2013/2014. The main plots were maize intercropped with jack beans and maize sown alone, and the subplots were six doses of gypsum (0, 1, 2, 3, 4, 5 t ha-¹). Thirty days before maize sowing gypsum doses were manually applied to soil surface. The spacing between rows was 0.70 m, 4.2 sowing seeds per meter. Jack bean was manually sown two days after maize was sown in inter-row spacing. Production components and maize yield were assessed. After maize harvest, soil resistance to penetration was assessed. Gypsum doses promoted linear increases in the stem diameter of maize. Maize intercropping with jack bean (Canavalia eusiformis) did not affect the maize components of production and productivity, but reduced the soil penetration resistance. Rates of agricultural gypsum did not influence the productivity; however, it promoted a reduction in SPR at dose of 2.0 t ha -1 .

Várias são as maneiras possíveis de se trabalhar o solo para melhorar suas propriedades físicas, amenizando os efeitos prejudiciais da compactação e aumentando a capacidade e eficiência de armazenamento de água no solo. O objetivo deste trabalho foi avaliar o efeito de plantas de cobertura cultivadas em plantio direto e preparo reduzido nas propriedades físicas do solo. O experimento foi conduzido na Estação Experimental da Universidade Estadual do Oeste do Paraná, em delineamento de blocos casualizados, em esquema de parcelas subdivididas, com quatro repetições. Nas parcelas principais foram alocados dois sistemas de manejo: plantio direto e preparo reduzido do solo com o uso de escarificador de hastes. As subparcelas constaram do cultivo de diferentes espécies vegetais de inverno: trigo; um mix de aveia preta com ervilha forrageira; e um mix de aveia preta com nabo forrageiro. O preparo reduzido com escarificador foi eficiente para descompactar o solo, promovendo aumento da porosidade de aeração e diminuição da densidade e resistência a penetração, mas não promoveu alterações na estabilidade dos agregados do solo. Os mix de plantas de cobertura com diferentes famílias aumentaram os macroporos na superfície do solo, mas atuaram igualmente na agregação do solo e na resistência do solo à penetração.

The present study aimed to evaluate the dry matter yield of cover crops cultivated in monoculture and intercropped in a no-till system and its effects on the soil physical properties. The experimental design was of randomized blocks, with four replicates. Treatments used were black oat, black oat + forage radish, forage radish, black oat + field pea, field pea and the control (fallow). After 100 days after sowing the cover crops, the dry matter yield was evaluated, with the highest values found in the intercropped crops. After desiccation, undeformed soil samples were collected for the determination of macroporosity, microporosity, total porosity and soil bulk density in the 0 - 0,10; 0,10 - 0,20; 0,20 - 0,30 and 0,30 - 0,40 m layers. Soil penetration resistance was evaluated with a digital penetrometer. The intercrop of black oat with field pea and with forage radish provided the highest dry matter yield, showing the potential of dry matter accumulation in relation to monoculture. The cover crops were capable of improving the macroporosity, bulk density and soil penetration resistance when compared to the fallow area (control); however, they had no influence in soil aggregation due to the high compaction degree in the area.

The objective of this research was to assess soybean productivity in succession to cover crops grown during the winter, in addition to assessing physical properties macroporosity (Ma), microporosity (Mi), total porosity (Pt), soil density (Sd) and aggregate stability by means of the following variables: aggregate stability index, geometric mean diameter and weighted mean diameter after soybean crop cultivation. The experiment was conducted in the municipality of Quatro Pontes, PR, using a randomized-block design with six treatments and four replications. Treatments consisted of soybean crop grown on top of different cover plants' haystack: black oat, black oat + forage turnip, forage turnip, black oat + forage pea, forage pea and control. Significant differences were observed for soil macroporosity and density. At the depth of 0.10 m, the highest Ma was observed in the area with oat and oat + turnip haystack. At other depths, all cover crops were superior to control. Treatments with cover crops were efficient in reducing soil PR. As for soil aggregation, the treatment with pea was superior to control for weighted mean diameter. The treatments with soybean sown after intercropping obtained greater mass, as well as higher productivity.