Spatial modeling via geostatistics of the bed in a compost barn system: thermal performance assessments

Abstract

For all the benefits of a compost barn system to be achieved, the management, especially with the bedding, must be done correctly. One should consider the requirements regarding the revolving of the material, use of good quality organic matter, suitable ventilation, and an ideal animal stocking rate, so that the composting occurs efficiently. Given this, this work aimed to evaluate the spatial variability of thermal characteristics of rice straw bedding, using values of temperature (surface and internal) and humidity. The temperature and moisture values of the litter were recorded at intervals during the morning shift, from 6:00 am to 7:00 am and from 8:00 am to 9:00 am, and during the afternoon shift, from 3:00 pm to 4:00 pm and from 5:00 pm to 6:00 pm, considering the management of the turn-over, that is, before and after the movement of the litter. Litter variables were collected at points distributed on a 39-point grid. There were no differences between litter surface temperatures before and after turning over in the morning shift, but in the afternoon shift, the surface temperature was lower (P < 0.05) before, when compared to after turning. The internal temperature and litter moisture were higher (P < 0.05) before revolving in both shifts. Spatial dependence was verified (IDE) for the variables studied. Based on the geostatistical analysis, it is concluded that the IDE was rated as strong for surface and internal temperatures, which demonstrates heterogeneity among the points evaluated and a large spatial variability regarding bed temperatures. In the case of litter moisture, the greatest variability occurred in the morning period. The litter surface temperature values did not exceed the ambient air temperature values.