Pengaruh Abu Vulkanik Hasil Letusan Gunung Semeru Terhadap Indeks Kesuburan Biologi pada Pola Tanam Monokultur dan Tumpangsari

Abstract

The presence of Mount Semeru volcanic ash can disrupt soil properties, one of which is biological properties. The biological soil fertility level can be determined based on the Biological Fertility Index. This research aims to determine the total population of soil microorganisms and the Biological Fertility Index class in areas with monoculture and intercropping cropping patterns with the presence of volcanic ash cover and the absence of volcanic ash cover. Field research was carried out on the slopes of Mount Semeru, namely in Pronojiwa Village, Lumajang Regency, at an altitude of 400-800 meters above sea level. Determination of the Biological Fertility Index class is carried out by laboratory analysis of Soil Organic Matter (SOM) using the walkey and black method, Microbial Biomass Carbon (MBC) using the fumigation extraction method, Basal Soil Respiration (BSR), and Cumulative Soil Respiration (CSR) using the Verstraete method with observation time 25 days, and total microbial population using the agar plate method. The mineralization quotient (qCO2) and metabolic quotient (qM) will be determined using calculations from other parameter values ​​that have been obtained. The results showed that the total population of soil microorganisms on land covered with volcanic ash was 4.8 x 105 CFU/g and 4.1 x 106 CFU/g compared to the total population of soil microorganisms on land not covered by volcanic ash of 6.7 x 106 CFU/g and 5.4 x 107 CFU/g. The Biological Fertility Index results show that the Biological Fertility Index scores on land not covered by volcanic ash are higher at 28 and 25. In contrast, on land covered by volcanic ash, the Biological Fertility Index values ​​are only 18 and 23 for all cropping patterns. The Biological Fertility Index class on all land is high, except for monoculture land covered with volcanic ash, which is medium class.