Melhoria dos atributos químicos da camada de enraizamento e seu efeito sobre a produtividade das culturas em sistema plantio direto

• Autor(a) principal: Dalla Nora, Douglas
• Data de Publicação: 2017
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Manancial - Repositório Digital da UFSM
• Texto Completo: http://repositorio.ufsm.br/handle/1/11722
• topic: Gesso; Calcário; Camada de enraizamento; Restrição hídrica; Cálcio; Gypsum; Lime; Root layer; Water restriction; Calcium; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO

The adoption of no-tillage system led to several physical, chemical and biological improvements in the soil. However, these improvements have been restricted to the superficial layers of the soil, limiting the root development in subsurface. This study aimed to evaluate the effect of the gypsum applied alone or in combination with lime in the chemical improvement of soil root layer compared to physical and chemical management methods and their effect on growth and crop yield in no-till under normal rainfall conditions and under induced drought. Were made five initial experiments followed by two experiments aggregates to initials, all in Typic Hapludoxs managed under no-till in RS State between 2009 to 2016. The experimental design was a randomized block design with three replications. Two experiments were established in 2009 in Carazinho with treatments ranging from 0.0 to 6.5 Mg ha-1 of gypsum. Two experiments were implemented in São Miguel das Missões and Tupanciretã in 2011. In São Miguel das Missões used a split plot design, the main plots were composed of gypsum doses ranging of 0.0 to 5.0 Mg ha-1, and subplots without lime and rate of 2.0 Mg ha-1. In Tupanciretã used a split plot design, the main plots were composed of gypsum doses ranging from 0.0 to 6.0 Mg ha-1 and subplots ranging of 0.0 to 4.8 Mg ha-1. In Palmeira das Missões was deployed the fifth experiment in 2013 and consists of split plot design, the main plots were composed of gypsum doses ranging from 0.0 to 6.0 Mg ha-1 and subplots ranging of 0.0 to 6.0 Mg ha-1. In São Miguel das Missões sixth experiment was installed from the subdivision of plots with the restriction of 100 % of the precipitation. Palmeira das Missões have added new treatments composing a seventh experiment, the treatments were based on reapplication of gypsum and lime, lime incorporation. The soil samples were made in the stratified layer of 0.00 to 0.60 m. There was increase in levels of Ca2+ and S-SO42- in the profile, and reduce the saturation of Al3+ and increase in BS and Ca2+ saturation. By improvement of chemical quality rooting layer was found increased yield of soybean, corn and wheat. In experiments with better chemical quality, the layers that were related to yield stood at greater depth (layer of 0.25-0.40 m for the Exp. I and 0.00 to 0.40 m in Exp. II). In the experiments with worse chemical quality the layers that were related to the yield were located closer to the surface (layer of from 0.00 to 0.10 m for the Exp. III and 0.00 to 0.25 m to Exp. IV). The increase in the amount of grain produced per mm of rain, resulting from the application of gypsum, was higher when there was drought in the critical period of crop. The chemical improvement of rooting layer attenuated soybean and corn yield loss associated with water restriction. The results of Study V and VI are still under evaluation. The increase in the content of S-SO42- showed a significant relationship with the increase of the Ca+2 contents in the deeper layers. Considering an economic recovery time of five to six years, the rate of gypsum that maximizes the soybean, maize and wheat crops yield is 4.4 Mg ha-1. Similar increments of the yield were recorded when lime was incorporated or applied to the surface, although the lime application did not affect the yield, and the rate was calibrated to reach 70% SB in the 0.00-0.20 ma layer.