Soil carbon and nitrogen mineralization caused by pig slurry application under different soil tillage systems

O objetivo deste trabalho foi avaliar as alterações na mineralização de C e N do solo resultantes da aplicação de dejetos líquidos de suínos (DLS) em sistemas de preparo do solo convencional (CT) e plantio direto (NT). O experimento foi conduzido em um Latossolo Vermelho eutrófico, de textura argilosa, em Palotina, PR, Brasil. Doses crescentes de DLS (0, 30, 60 e 120 m3 ha-1 por ano) foram aplicadas nos dois sistemas de preparo do solo, com três repetições. Metade das dosagens de DLS foi aplicada antes do preparo do solo da cultura de verão e a outra metade antes do da cultura de inverno. As áreas foram cultivadas com soja (Glycine max L.) e milho (Zea mays L.) nos verões de 1998 e 1999, respectivamente, e trigo (Triticum sativum Lam.) nos invernos de ambos os anos. As amostras de solos foram coletadas nas profundidades de 0–5, 5–10 e 10–20 cm. A aplicação de DLS aumentou a mineralização de C e de N, tanto no sistema CT como no NT. Contudo, o aumento da dose de DLS diminuiu a razão de mineralização entre C e N. No sistema de NT, a mineralização de C e de N foi maior que no CT.The objective of this work was to evaluate the change in soil C and N mineralization due to successive pig slurry application under conventional tillage (CT) and no tillage (NT) systems. The experiment was carried out in a clayey Latossolo Vermelho eutrófico (Rhodic Eutrudox) in Palotina, PR, Brazil. Increasing doses of pig slurry (0, 30, 60 and 120 m3 ha-1 per year) were applied in both tillage systems, with three replicates. Half of the pig slurry was applied before summer soil preparation, and the other half before the winter crop season. The areas were cultivated with soybean (Glycine max L.) and maize (Zea mays L.) in the summers of 1998 and 1999, respectively, and with wheat (Triticum sativum Lam.) in the winters of both years. Soil samples were collected at 0–5, 5–10, and 10–20 cm depths. Under both CT and NT systems, pig slurry application increased C and N mineralization. However, increasing pig slurry additions decreased the C to N mineralization ratio. Under the NT system, C and N mineralization was greater than in CT system

Arbuscular mycorrhizal fungal communities and soil aggregation as affected by cultivation of various crops during the sugarcane fallow period

Management systems involving crop rotation, ground cover species and reduced soil tillage can improve the soil physical and biological properties and reduce degradation. The primary purpose of this study was to assess the effect of various crops grown during the sugarcane fallow period on the production of glomalin and arbuscular mycorrhizal fungi in two Latosols, as well as their influence on soil aggregation. The experiment was conducted on an eutroferric Red Latosol with high-clay texture (680 g clay kg-1) and an acric Red Latosol with clayey texture (440 g kg-1 clay) in Jaboticabal (São Paulo State, Brazil). A randomized block design involving five blocks and four crops [soybean (S), soybean/fallow/soybean (SFS), soybean/millet/soybean (SMS) and soybean/sunn hemp/soybean (SHS)] was used to this end. Soil samples for analysis were collected in June 2011. No significant differences in total glomalin production were detected between the soils after the different crops. However, total external mycelium length was greater in the soils under SMS and SHS. Also, there were differences in easily extractable glomalin, total glomalin and aggregate stability, which were all greater in the eutroferric Red Latosol than in the acric Red Latosol. None of the cover crops planted in the fallow period of sugarcane improved aggregate stability in either Latosol

Effect of tillage systems and permanent groundcover intercropped with orange trees on soil enzyme activities

The objective of this study was to evaluate the effect of different soil tillage systems and groundcover crops intercropped with orange trees on soil enzyme activities. The experiment was performed in an Ultisol soil in northwestern Paraná State. Two soil tillage systems were evaluated [conventional tillage (CT) across the entire area and strip tillage (ST) with a 2-m strip width] in combination with various groundcover vegetation management systems. Soil samples were collected after five years of experimental management at a depth of 0-15 cm under the tree canopy and in the inter-row space in the following treatments: (1) CT-Calopogonium mucunoides; (2) CT-Arachis pintoi; (3) CT-Bahiagrass; (4) CT-Brachiaria humidicola; and (5) ST-B. humidicola. The soil tillage systems and groundcover crops influenced the soil enzyme activities both under the tree canopy and in the inter-row space. The cultivation of B. humidicola provided higher amylase, arylsulfatase, acid phosphatase and alkaline phosphatase than other groundcover species. Strip tillage increased enzyme activities compared to the conventional tillage system