Figure 2. Winter wheat and summer maize yields under different fertilizer treatments in 2018 and 2019.

CK, RSMT, SBMT and CMT represent no organic fertilizer treatment, rapeseed meal treatment, soybean meal treatment and cattle manure treatment, respectively. Data were means ± standard error (n = 3). Different lowercase letters indicate significant differences at P < 0.05 level among the four treatments in the same year. Different capital letters indicate significant difference at P < 0.05 level between 2018 and 2019 in the same treatment.