Using QBS-ar index and A/C ratio for evaluation of soil quality
Paper ID : 1001-IPCA4
Authors:
Sahebeh Ghasemi-Moghadam *1, Ali Ahadiyat2, Yaghoub Fathipour3, Alireza Saboori4
1Department of Plant Protection, Science and Research Branch, Islamic Azad University, Tehran, Iran
2Department of Plant Protection, Science and Research Branch, Islamic Azad University, Tehran, Iran.
3Department of Entomology, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran
4Dept. Plant Protection, Col. Aric., Univ. Tehran
Abstract:
In the recent two decades, assessing soil quality by bioindicators besides the common physical and chemical methods has been given attention. Mites and springtails, due to their roles in the trophic cycles, are important among soil fauna. Their ability to show soil conditions has already been confirmed. Acari/Collembola (A/C) ratio is one of the applied indicators for measuring soil quality, and recently the QBS-ar index has been considered to determine soil biological quality. In this study, the effect of using fertilizers on soil quality was investigated using the QBS-ar index and A/C ratio. The experiment was performed as a randomized complete block design (RCBD), including granular urea fertilizer (46% nitrogen) with two dosages (A = 2 kg and D = 1 kg), poultry manure (B), zinc sludge (C) and control (E) in five blocks. Zinc sludge was selected to simulate the accumulation of zinc sulfate fertilizer in the soil. Soil samples were randomly collected using a quadrat (20 cm × 20 cm) at a depth of 10 cm, during a year (2017–2018) with 10 days intervals. Soil fauna was identified after collection and separation. Each taxon was given an Ecological-Morphological Index (EMI) score of 1 to 20, depending on its adaptation level to the soil. The summation of the EMI scores at each treatment determined the QBS-ar index. Also, the relationship between soil elements and humidity with A/C ratio was evaluated by the Pearson correlation coefficient. Based on the results, the A/C ratio in the treatments A, B, C, D and E were 7.95, 26.4, 2.4, 6.35 and 2.71, respectively, and the QBS-ar indices were 152, 138, 133, 133 and 113, respectively. There was also a significant correlation between lead (P = 0.006; r = −0.538), cadmium (P = 0.012; r = −0.495), and iron (P = 0.004; r = 0.556) with the A/C ratio. Therefore, increasing the concentration of Pb and Cd in soil could reduce soil quality, while increasing the Fe concentration could increase soil quality. The A/C > 1 in all treatments indicates healthy and no degradation in soil. According to the proposed threshold (93.7), the soil of the treatments was undamaged and rich; and this result was similar to the data obtained from the evaluation of the A/C ratio. Furthermore, the QBS-ar and A/C indices were reliable bioindicators for assessing soil quality by farmers due to identification at the taxon level.
Keywords:
Mesostigmata, Prostigmata, Oribatida, edaphic mites, Biomonitoring.
Status : Abstract Accepted (Oral Presentation)