rate in the NPK and OM treatments were relatively lower than
CK, but producing higher pH values in the NPK and OM
treatments than in the CK (Fig.1), which suggested that chemical
fertilizer and organic manure could alleviate soil acidification to
some extent. It has been reported that the application of alkaline
fertilizer (e.g. calcium magnesium phosphate fertilizer) would
return some alkaline substance to soils and thus increase the soil
pH [42]. In addition, the application of organic manure could
improve soil acidity by increasing the soil organic matter,
promoting the soil maturation, improving the soil structure, and
enhancing the soil base saturation percentage, which is in line with
Zhang [35] and Li [43]. Moreover, studies showed that the soil pH
in CK was lower than the initial value, which indicated that the
acid deposition could have a great influence on the soil
acidification in this trial region [44]. Since a too high or too low
pH is harmful to the crop growth, it might be a practicable
measure to establish the proper range of soil pH through fertilizer