Long-Term Organic Manure Retarding Soil Acidity in the Double-Cropping Rice Field of Southern China.

This paper investigates the effects of different long-term (36 years) fertilizer treatments on soil pH, exchangeable acids, exchangeable base cation and cation exchange capacity (CEC) at 0–10 cm and 10–20 cm soil layers in a double-cropping rice field. The following fertilizer treatments were included: chemical fertilizer (MF), rice straw and chemical fertilizer (RF), 30% organic manure and 70% chemical fertilizer (OM), and without any fertilizer input as a control (CK). This result indicated that soil pH at 0–10 cm layer with RF and OM treatments was higher than that of MF and CK treatments. Soil exchangeable acidity content at 0–10 cm and 10–20 cm layers with RF and OM treatments were decreased by 48.4%, 51.6% and 49.2%, 54.2%, compared with CK treatment, respectively. Soil exchangeable calcium (Ca²⁺), magnesium (Mg²⁺) and potassium (K⁺) contents at 0–10 cm and 10–20 cm layers in paddy field with OM and RF treatments were higher than that of CK treatment. Moreover, compared with CK treatment, soil exchangeable base ion content at 0–10 cm and 10–20 cm layers in paddy field with OM treatment were increased by 54.1% and 42.6%, respectively. Soil CEC and effective cation exchange capacity (ECEC) at 0–10 cm and 10–20 cm layers with OM and RF treatments were significantly higher than that of MF and CK treatments. In conclusion, our results indicated that long-term application of crop residue or organic manure can improve soil exchangeable base ion and exchangeable capacity contents, alleviate soil acidity in a double-cropping paddy field. [ABSTRACT FROM AUTHOR]