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| Author(s): |
Antonio Carlos de Almeida Carmeis Filho
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Botucatu. 2017-01-26. |
| Institution: | Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agronômicas. Botucatu |
| Defense date: | 2016-12-21 |
| Advisor: | Carlos Alexandre Costa Crusciol |
| Abstract | |
Soil chemical and physical disorders are among major limiting factors to improve productive potential of tropical agriculture. The low productive capacity has been associated especially to soil acidity and macronutrient deficient, thus the development of strategies that improve production capacity of tropical acid soils are required. Lime and phosphogypsum (PG) are materials commonly used to improve soil chemical condition, but there is few information about the long-term effects of these products, applied superficially, especially on Oxisol physical properties and organic matter pools. Therefore, this research aimed to evaluate the effect of surface application of lime and PG on the soil chemical and physical attributes, root growth, plant nutrition, yield components, technological characteristics and yield of wheat and common bean, and soil organic matter (SOM) pools considered critical to make agricultural tropical systems sustainable and productive. A randomized complete block design was used and treatments were replicated four times. Four treatments were carried out: control (without lime and gypsum application); PG (2.1 Mg ha-1); lime (2.0 Mg ha-1); and a combination of lime and PG (2.0 and 2.1 Mg ha-1, respectively). Since the experiment was established in 2002, the amendments rates have been applied three times (2002, 2004, and 2010). Superficial liming alleviated Oxisol acidity in the surface and subsurface layers after twelve years under soil acidity management, with positive results of PG associated to lime on soil pH, Ca2+ and Mg2+ levels, and base saturation in the topsoil layers (0-0.10 m). The surface application of lime is effective to improve root growth in subsurface layers, crop nutrition and wheat and common bean grain yield. The high correlation between soil chemical attributes and organic carbon pools shows that the soil organic matter (SOM) input was favored mainly by high levels of Ca and Mg and low levels of exchangeable Al in the soil. The combination lime and PG improved the SOM quality, increasing the formation and stabilization of humic substances in the soil. The use of both soil amendments combined also provided significant improvements on soil physical properties, manly in the formation and stabilization of large aggregates (>1.0 mm). This condition provided better physical protection of SOM, inducing higher organic carbon accumulation in these structures. Consequently, it was observed a better soil structure, resulting in greater macroporosity as well as lower soil bulk density and penetration resistance. Lime rate estimated to increase the base saturation in the topsoil (0-0.20 m) to 70% was considered appropriate for surface liming recommendation in a tropical Oxisol under no-tillage system, but the combination with phosphogypsum provides major benefits on soil chemical and physical attributes and SOM quality. (AU) | |
| FAPESP's process: | 13/18462-0 - Changes in Soil Physical Properties and Soil Organic Matter as affected by lime and gypsum surface application in succession wheat/bean in long-term experiment. |
| Grantee: | Antonio Carlos de Almeida Carmeis Filho |
| Support Opportunities: | Scholarships in Brazil - Doctorate |