The relative isotopic abundance (<i>δ</i>¹³C, <i>δ</i>¹⁵N) during composting of agricultural wastes in relation to compost quality and feedstock

<p>Variations in the relative isotopic abundance of C and N (<i>δ</i>¹³C and <i>δ</i>¹⁵N) were measured during the composting of different agricultural wastes using bench-scale bioreactors. Different mixtures of agricultural wastes (horse bedding manure + legume residues; dairy manure + jatropha mill cake; dairy manure + sugarcane residues; dairy manure alone) were used for aerobic–thermophilic composting. No significant differences were found between the <i>δ</i>¹³C values of the feedstock and the final compost, except for dairy manure + sugarcane residues (from initial ratio of −13.6 ± 0.2 ‰ to final ratio of −14.4 ± 0.2 ‰). <i>δ</i>¹⁵N values increased significantly in composts of horse bedding manure + legumes residues (from initial ratio of +5.9 ± 0.1 ‰ to final ratio of +8.2 ± 0.5 ‰) and dairy manure + jatropha mill cake (from initial ratio of +9.5 ± 0.2 ‰ to final ratio of +12.8 ± 0.7 ‰) and was related to the total N loss (mass balance). <i>δ</i>¹³C can be used to differentiate composts from different feedstock (e.g. C₃ or C₄ sources). The quantitative relationship between N loss and <i>δ</i>¹⁵N variation should be determined.</p

Low-cost automatic station for compost temperature monitoring

ABSTRACT Temperature monitoring is an important procedure to control the composting process. Due to cost limitation, temperature monitoring is manual and with daily sampling resolution. The objective of this study was to develop an automatic station with US$ 150 dollars, able to monitor air temperature at two different points in a compost pile, with a 5-min time resolution. In the calibration test, the sensors showed an estimated uncertainty from ± 1 to ± 1.9 ºC. In the field validation test, the station guaranteed secure autonomy for seven days and endured high humidity and extreme temperature (> 70 °C)

Low-cost automatic station for compost temperature monitoring

<div><p>ABSTRACT Temperature monitoring is an important procedure to control the composting process. Due to cost limitation, temperature monitoring is manual and with daily sampling resolution. The objective of this study was to develop an automatic station with US$ 150 dollars, able to monitor air temperature at two different points in a compost pile, with a 5-min time resolution. In the calibration test, the sensors showed an estimated uncertainty from ± 1 to ± 1.9 ºC. In the field validation test, the station guaranteed secure autonomy for seven days and endured high humidity and extreme temperature (> 70 °C).</p></div