Soil factors that contribute to the abundance and structure of the diazotrophic community and soybean growth, yield, and quality under biochar amendment

Chemical and Biological Technologies in Agriculture

Table 4 Pearson correlation coefficients (r) between soil properties and crop efficiency indexes, and nifH gene copies and microbial diversity indexes

Correlation	nifH gene copies	Chao1	Shannon	Simpson
γ_d	− 0.663 *	0.620 *	0.936 **	0.700 *
θ	0.879 **	0.017	− 0.185	− 0.056
pH	0.890 **	0.143	− 0.153	0.058
TOC	0.870 **	− 0.358	− 0.581 *	− 0.335
AP	0.633 *	− 0.458	− 0.556	0.274
AK	0.379	0.131	0.130	0.364
TN	0.881 **	− 0.294	− 0.542	− 0.331
NH₄⁺-N	− 0.201	0.911 **	0.618 *	0.278
NO₃⁻-N	0.710 **	0.296	0.125	0.140
Palmitic acid	− 0.142	0.192	0.324	0.381
Stearic acid	0.458	0.079	− 0.102	− 0.041
Oleic acid	0.039	0.434	0.563	0.435
Linoleic acid	0.076	− 0.062	0.045	0.398
Linolenic acid	− 0.204	0.308	0.610 *	0.460
Protein	0.639 *	0.606 *	0.390	0.424
Oil	0.025	0.513	0.418	0.218
K (plant)	0.549	− 0.190	0.012	0.166
P (plant)	0.613 *	− 0.100	0.055	0.232
Grain yield	− 0.352	− 0.379	0.257	0.400

B27, 45 t hm⁻² biochar addition; B18, 30 t hm⁻² biochar addition; B9, 15 t hm⁻² biochar addition, B0, no biochar addition. θ, water content; γ_d, soil bulk density; TOC, total organic carbon; AP, available phosphorus; AK, available potassium; TN, total nitrogen. * and ** indicate significant (p < .05) and highly significant (p < .01) difference, respectively