Inadequate soil management has led to the degradation of physical, chemical and biological soil properties. The purpose of this work was to evaluate the yields and physical and chemical soil properties of a dystropherric Red Latosol (Oxisol) in the third year of a crop rotation that included green manures, with soybean or corn (summer) and common bean (winter) crops. The following green manure species were used: velvet bean, millet, sunnhemp, pigeon pea, cultivated under conventional tillage and recently adopted no-tillage. […]

The physical conditioning of the soil around seeds is of great importance for an adequate initial development of a crop, ensuring a healthy plant population. A suitable soil-seed contact is a prerequisite for a fast crop germination and good establishment. In this study, computerized tomography of millimeter resolution was used to determine the soil-seed environment in a no tillage system, immediately after soybean planting. A split plot design was used, in which the plots consisted of three contents of soil […]

Soil management systems, with crops under no-tillage (NT), crops (soybean) in rotation with pastures under NT and permanent pastures (Brachiaria sp.), were evaluated for soil aggregation and aggregate stability. Three long-term experiments (9 and 11 years) in the state of Mato Grosso do Sul were sampled in the layers 0-5, 5-10 and 10-20 cm for determination of the aggregate stability in wet and dry sieving. The mean weight diameter (MWD) and the aggregate stability index (IAS) were calculated. In all experiments, the […]

Presently, approximately 60 % of the grain crop area in Paraguay is under no-till (NT). With the expansion of NT in the country, some doubts were raised with respect to the obsoleteness of fertilizer recommendations, especially regarding phosphorus (P). The last P fertilizer recommendation had been established for conventional soil tillage system 15 years earlier. The main objective of this work was to update phosphate fertilizer recommendations for wheat, corn and soybean under NT. Seven different locations in eastern Paraguay were evaluated […]

The critical potassium level for fertilizer recommendation for soils in the State of Rio Grande do Sul (RS) and Santa Catarina (SC) with CEC from 5.1 to 15 cmolc dm-3 is 60 mg dm-3. However, until 2002 concentrations of 80 mg dm-3 had been used. Two experiments were carried out on an experimental area of the Department of Soil Science of the Federal University of Santa Maria (RS-Brazil) on a Sandy Typic Hapludalf under no-tillage. The objective of the study was to evaluate critical potassium levels […]

This study was carried out from 1994 to 1998 in the Agronomy experimental area at the University of Cruz Alta – UNICRUZ, Cruz Alta, State of Rio Grande do Sul, Brazil to evaluate the influence of five soil management systems on bulk density, porous space (total porosity, macro and microporosity) of an clayey Rhodic Hapludox, as well as their effect on soybean, wheat and corn yield. The experiment had a completely randomized block design with four replications. The following management […]

Experiments testing the efficiency of arbuscular mycorrhizal fungi (AMF) originating from the same soil sample complement studies of taxonomic diversity by assessing functional relationships within mycorrhizal communities. In this study fungal isolates from three distinct communities were evaluated regarding their efficiency to increase dry biomass production and P content in two mycotrophic hosts. In the first experiment, the effect of 13 AMF isolates from the JA205, MN414, and VA105 communities were screened in order to test the hypothesis that at least […]

Soybean [Glycine max (L.) Merrill] and common bean (Phaseolus vulgaris L.) crops are of economical and social importance in Brazil; their requirement for nitrogen can be supplied by the symbiosis with bacteria belonging to the order Rhizobiales. However, to guarantee the maximization of the biological nitrogen fixation, seeds must be inoculated with efficient and competitive strains of rhizobia recommended by research. In 2001/2002, 14 million doses of inoculant were sold in Brazil, 99 % of these for soybean and common bean crops. […]

Primavera do Leste is one of the most important farming areas of Mato Grosso State. This study was carried out in a Red-Yellow Latosol to evaluate the microbial biomass and enzyme activities in soils under native vegetation (known as “Cerradão”) and in soils under annual and perennial cropping systems. Soil samples were collected, at the beginning of the rainy season, at two depths (0-5 and 5-20 cm) in areas under a vineyard (row and between rows), annual crops (soybean) and native […]

In Brazil, Bradyrhizobium inoculation has successfully replaced the use of N fertilizer on soybean [Glycine max (L) Merr.] crops. However, with the expansion of no-tillage cropping systems in the Cerrados region, the idea that it is necessary to use small N rates at the sowing to overcome problems related with N immobilization has become widespread, mainly when soybean is cultivated after a non-legume crop. In this study we examined soybean response to small rates of N fertilizer under no-tillage (NT) […]