Methodologies for recommending the use of agricultural gypsum in different production systems

Author(s)

Isabela Malaquias Dalto de Souza

• Document type: Doctoral Thesis
• Press: Ilha Solteira. 2022-05-12.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Engenharia. Ilha Solteira
• Defense date: 2022-03-18
• Advisor: Marcelo Andreotti; Wander Luis Barbosa Borges

Abstract

The use of gypsum in conservation production systems as croplivestock systems, still generates doubts about the methodology to be used. The present work aimed to evaluate which among the five methodologies of gypsum use recommendation in different sustainable agricultural production systems is the most efficient regarding the movement of gypsum in the soil profile and correlate it with the agricultural productivity of a sandy soil. The methodologies of Sousa, Lobato and Rein (2005), Vitti et al. (2008), Demattê (1986), Raij et al. (1996) and Caires and Guimarães (2016) were used, in three sustainable agricultural production systems: no-tillage system (SSD), agro-pastoral system (SAP) and conventional pasture (PAST). Evaluations of chemical attributes in the layers 0-0.20 and 0.20-0.40m were carried out in October in the year 2017 and April 2018, 2019 and 2020, and of physical attributes in the layers 0-0.05, 0.05-0.20 and 0.20-0.40m in October 2017 and April 2020, and evaluations of agronomic characteristics of corn and soybean crops, as well as dry matter productivity of pasture and crotalaria. The methodologies of Raij et al. (1996), Sousa, Lobato and Rein (2005) and Caires and Guimarães (2016) were used in a parallel project. For this, in April 2020, soil samples were collected in the 0-0.10m layer, in the three sustainable agricultural production systems, and the following evaluations were performed: specific surface area (SE), laser grain size (GL), Fourier transform infrared spectroscopy (FTIR) and elemental analysis. This research aimed to attribute which of the gypsum recommendation methodologies is the most appropriate for the production systems studied and evaluate which of the methodologies provides better conditions for sandy soil texture in the Cerrado region. In no-tillage system (SSD), by the intensive use of sandy soil and high export of nutrients, aiming to improve soil fertility and aggregation, gypsum is recommended based on the methodologies of Caires and Guimarães (2016) or of Raij et al. (1996), however, with variability of methodologies regarding the correlation with the productivity of crops in rotation. In the agro-pastoral system (SAP), due to the longer time of pasture in the system, there was no methodology that stood out regarding the improvement of soil fertility, however in aggregation there was an emphasis on the methodology of Raij et al. (1996). However, regardless of the methodology, the application of gypsum was superior to the control without gypsum, in physical and chemical soil improvement. Only the methodology of Vitti et al. (2008), stood out for increasing the dry matter production of Marandu grass and soybean in succession. In an area of intensive pasture (PAST), but on sandy soil, the methodology of Raij et al. (1996) stood out in the recommendation of annual gypsum, aiming to improve and/or maintain soil fertility. However, for the dry matter productivity of Marandu grass, the methodology with the best correlation was that of Souza, Lobato and Rein (2005). By the use of multivariate analysis, in SSD, the methodologies for calculating the gypsum requirement of Caires and Guimarães (2016) or of Raij et al. (1996) best correlated with V% (best correlated attribute of soil fertility). For the agropastoral system (SAP), in the multivariate analysis, the methodologies for calculating the need for gypsum that best correlated with reduced soil acidity and increased soil pH were those of Souza, Lobato and Rein (2005) and Raij et al. (1996). In a pasture of Marandu grass on sandy soil, by multivariate analysis, the methodology for calculating the need for gypsum by Raij et al. (1996) showed greater correlation with V%. In the analysis of soil characteristics in different production systems after the use of gypsum, there was no effect of gypsum for C, N and C/N ratio, nor for soil granulometry. However, the no-tillage system (SSD) stands out for increasing C and N contents, and for improving aggregation, the perennial pasture (PAST). (AU)

• FAPESP's process: 18/07979-6 - Methodologies of recommendation for the use of agricultural plaster in different production systems
• Grantee: Isabela Malaquias Dalto de Souza
• Support Opportunities: Scholarships in Brazil - Doctorate