Effect of soil acidification on regrowth of orchardgrass (Dactylis glomerata) under application of grazing cattle dung, cattle manure compost, and chemical fertilizer

Abstract

Orchardgrass (Dactylis glomerata) persists poorly in acidic soils. Not many studies have looked into the effects of fertilizers in improving orchardgrass persistence within acidic soils. We conducted experiments on 64 individual potted orchardgrass plants, which were defoliated to 5 cm and assigned to one of the following four treatment groups: unfertilized control (CNT), chemical fertilizer (CHE), grazing cattle dung (DNG), and cattle manure compost (CMP). Half the pots in each treatment received aluminum sulfate solution to induce further soil acidification (Al-add), while the others received water (no-Al). On days 20 and 47, after defoliation, soil properties and dry weights of aboveground biomass (AGB) (separated into leaves and stubble) and roots of four pots in each treatment group were measured. Al-add induced soil acidification in all fertilizers across the experiment (p < 0.05). On day 20, AGB and leaves in CHE was increased by acidification (p < 0.05), which was not observed in other fertilizer treatments (p > 0.1). Stubble growth increased following acidification in all fertilizer treatments (p < 0.05). Acidification did not increase AGB on day 47; no effect was seen on root growth at either day 20 or 47 (p > 0.1). On day 20, soil concentrations of inorganic nitrogen (IN), nitrate-nitrogen (NO₃-N), and ammonium-nitrogen (NH₄-N) were significantly elevated in Al-add pots (p < 0.05). The increment was greater in CHE and CMP than in CNT and DNG on day 20, with a similar trend being observed for IN and NH₄-N concentrations at day 47. IN and NH₄-N concentrations in DNG with no-Al increased over the regrowth period. These results indicate that orchardgrass regrowth in acidic soils can be improved by fertilizer addition, depending on fertilizer type. The increased concentration of soil IN, induced by soil acidification, is likely to be one of the factors encouraging growth. This increase of regrowth may favor the persistence of orchardgrass in strongly acidic soils.