Suchergebnisse

An improvement in soil chemical properties and crop development with silicate application has been confirmed in several plant species. The effects of silicate application on soil chemical properties and wheat growth were investigated in the present study. The experiment was carried out in 8-L plastic pots in a greenhouse. Treatments were arranged in a randomized block design in a 3 × 5 factorial: three soils [Rhodic Acrudox (Ox1), Rhodic Hapludox (Ox2) and Arenic Hapludult (Ult)] and five silicate rates (0, 1, 2, 4 and 6 Mg ha–1 of calcium/magnesium silicate), with four replications. The plant length, number of spikes per pot, shoot dry matter and grain yield, were measured after 115 days of wheat (Triticum aestivum L.) growth. Changes in the soil chemical properties (pH, H+ + Al3+, Al3+, P, K, Ca, Mg, Si, Cu, Zn, Fe and Mn) were analyzed after wheat harvest. Application of calcium/magnesium silicate reduces the potential acidity (H+ + Al3+) and Al3+ phytotoxic; and increases the soil pH, available Ca, Mg and Si, cation exchange capacity (CEC) and soil base saturation. Silicate application did not affect the available P, exchangeable K and availability of micronutrients (Cu, Zn, Fe and Mn) in the three soils. The application of calcium/magnesium silicate in an acid clayey Rhodic Hapludox improves the development and yield of wheat; however, the silicate application in soil with pH higher to 5.3 and high Si availability does not affect the agronomic characteristics and grain yield of wheat. An improvement in soil chemical properties and crop development with silicate application has been confirmed in several plant species. The effects of silicate application on soil chemical properties and wheat growth were investigated in the present study. The experiment was carried out in 8-L plastic pots in a greenhouse. Treatments were arranged in a randomized block design in a 3 × 5 factorial: three soils [Rhodic Acrudox (Ox1), Rhodic Hapludox (Ox2) and Arenic Hapludult (Ult)] and five silicate rates (0, 1, 2, 4 and 6 Mg ha–1 of calcium/magnesium silicate), with four replications. The plant length, number of spikes per pot, shoot dry matter and grain yield, were measured after 115 days of wheat (Triticum aestivum L.) growth. Changes in the soil chemical properties (pH, H+ + Al3+, Al3+, P, K, Ca, Mg, Si, Cu, Zn, Fe and Mn) were analyzed after wheat harvest. Application of calcium/magnesium silicate reduces the potential acidity (H+ + Al3+) and Al3+ phytotoxic; and increases the soil pH, available Ca, Mg and Si, cation exchange capacity (CEC) and soil base saturation. Silicate application did not affect the available P, exchangeable K and availability of micronutrients (Cu, Zn, Fe and Mn) in the three soils. The application of calcium/magnesium silicate in an acid clayey Rhodic Hapludox improves the development and yield of wheat; however, the silicate application in soil with pH higher to 5.3 and high Si availability does not affect the agronomic characteristics and grain yield of wheat.

In conservation management systems, such as no-till (NT), it is important to analyze the pattern of changes in soil quality as a function of the time since adoption of the system. This study evaluated the physical fractions of organic matter and soil aggregation in management systems in areas cultivated with different times since implementation of NT: 6, 14, and 22 successive years of soybean and maize/wheat crops (NT6, NT14, and NT22, respectively); 12 years of no-till with successive years of soybean and maize/wheat crops, and the last 4 years with integration of maize and ruzi grass (Brachiaria ruziziensis) - (NT+B); pasture; and forest. Physical fractionation of organic matter determined the total carbon (TC), particulate organic matter (POM), and mineral organic matter (MOM) by calculating the carbon management index (CMI) and variables related to soil structural stability. Forest and pasture areas showed the highest contents of TC, POM, and MOM, as well as higher stocks of POM and MOM. Among the cultivated areas, higher TC and particulate fractions of organic matter and the best CMI values were observed in the area of NT22. There were changes in aggregation indices, depending on the time since implementation of NT. Areas of NT22, pasture, and forest showed the greatest evolution in C-CO2, indicating increased biological activity, with positive effects on soil structural stability.

Agriculture can considerably change the composition and richness of the edaphic macrofauna, affecting the ecological and biological functions exerted by the fauna. This study was carried out in commercial production systems in the municipality of Guaíra, state of Paraná, Brazil. The objective of this study was to evaluate the effect of no-tillage systems (NTS) and seasonality on the diversity, richness, and composition of the edaphic macrofauna. Three areas managed under NTS for different periods 7 years (NTS-7), 14 years (NTS-14), and 23 years (NTS-23) under crop succession with soybean (summer) (aNTS7) and maize/wheat (winter) (NTS14 and NTS23) were evaluated, in addition to a native Atlantic Forest segment, which was used as a reference. Faunal samples were collected in the dry season (September 2013) and rainy season (February 2014). The edaphic macrofauna was evaluated using the method proposed by the Tropical Soil Biology and Fertility Program. Parametric statistics were applied, and the results were compared using Tukey's test at a level of significance of 5%. Species density and total richness were usually higher in the NTS14 and NTS23 in the dry season. However, higher indexes of equability were not detected because of the dominance of groups Formicidae and Isoptera. The areas with the highest equability were the reference area in the dry season and NTS23 in the rainy season, corresponding to 0.87 and 0.61, respectively. These results indicate the higher faunal diversity in these areas, which reflects the greater stability of the ecosystem.

Wheat is a plant that accumulates silicon (Si). The application of silicon to the soil may influence the absorption of nutrients by the plant and, therefore, its nutritional balance. In this study, we aimed to evaluate the effects of calcium and magnesium silicate (CaSiO3/MgSiO3) on the ability of wheat (Triticum aestivum L.) to utilize silicon and absorb nutrients from soils collected in the state of Paraná, Brazil. The experiment was carried out in a greenhouse using 8-L plastic pots and three types of soil. Treatments were arranged in randomized blocks (3 × 5 factorial design): three soils [Rhodic Acrudox (Ox1), Rhodic Hapludox (Ox2), and Arenic Hapludult (Ult)], five silicate rates (0, 1, 2, 4, and 6 t ha–1 of calcium/magnesium silicate), and four replications were performed. The effects of calcium and magnesium silicate on the concentrations of Si, N, P, K+, Ca2+, Mg2+, S, Cu2+, Zn2+, Fe2+, and Mn2+ within leaves were evaluated. Silicon concentrations in wheat leaves and stems increased with increasing rates of calcium and magnesium silicate applied to the soil. Wheat shoots accumulated averages of 28.2% (Ox1), 60.61% (Ult), and 74.14% (Ox2) of the Si from the silicate applied to the soil. Silicate fertilization increased the amount of Ca+2 and Mg+2 within leaves and reduced the amount of Zn2+ and Mn2+ within leaves. Calcium and magnesium silicate prevented excessive amounts of Mn2+ from being absorbed by wheat, improving the balance in the absorption of this nutrient.

In no-tillage (NT) soils, changes in the quantity and quality of soil organic matter (SOM) have been observed over time. These changes can interfere with the dynamics of P in surface soil layers. Thus, the objectives of this study were: to evaluate the organic and inorganic fractions of P and their degree of lability (labile, moderately labile, and moderately recalcitrant) in an Oxisol under NT for 6 years (NT6), 14 years (NT14), and 22 years (NT22) and cultivated with a succession of soybean and corn/wheat. The fractions were evaluated for 16 years of NT, with the last four years under integrated corn second crop and Brachiaria (NT16+B). We also analyzed an area of native forest, as well as analyzing the correlations between the results of the P fractions of these areas with other attributes such as total carbon content, vegetable waste deposited on the ground, phosphorus and humic fractions remaining in SOM. From each of the areas, samples were collected at 0.00-0.05 m and 0.05-0.10 m. A completely randomized design with 5 replicates was used. Management of phosphorus fertilization and SOM following adoption of the SPD of time (6 to 22 years) increased the levels of all fractions of inorganic P (0.0 to 0.10 m), as well as the fractions of labile (0.05-0.10 m), moderately labile (0.0-0.10 m), and moderately recalcitrant (0.05-0.10 m) organic phosphorus. The correlation matrix shows interactions between the evaluated soil attributes, especially between inorganic phosphorus fractions and fulvic and humic acids and between the moderately recalcitrant organic phosphorus and humin fraction.