Effect of soil amendments on soil respiration in the midland agroecological environment, Ethiopia

The effects of soil amendments on soil respiration (SR) rate have not yet been fully evaluated. In the Upper Blue Nile Basin, Ethiopia, we investigated seasonal variations in SR rates between and within soil amendments. We set up 24 plots with 8 treatments—polyacrylamide (PAM), gypsum (G), biochar (B), lime (L), control (C), PAM + L, PAM + G, and PAM + B—in 3 replicates. Soil temperature, moisture, and SR data were collected monthly. Data were evaluated by paired t-test and nonparametric repeated-measures ANOVA. The SR rates were significantly lower (P < 0.05) in PAM + B (3.43 ± 0.55 µmol m−2 s−1) than in B (4.23 ± 0.61 CO2 µmol m−2 s−1) and PAM + L (4.14 ± 0.57 µmol m−2 s−1). The SR rate differed significantly in all plots between the wet and dry seasons. The relationships between SR rate and soil properties were not significant, although there was a non-significant positive association with soil organic carbon, total nitrogen, soil pH, and clay content. There was a significant (P < 0.01) association between soil moisture and SR in all treatments. PAM + B offers a practical means of enhancing carbon storage efficiency. Comprehensive studies should be conducted in a variety of agroecological settings to determine optimal techniques to reduce SR emissions.