Table 1 Effects of N fertilization and green manure on grain yield, nutrient accumulation, soil available P, and soil enzyme activities in 2012 and 2014.

Treatment	Grain yield (Mg ha⁻¹)	Leaf N concentration (g kg⁻¹)	N accumulation in total above ground biomass (kg ha⁻¹)	Leaf P concentration (g kg⁻¹)	Grain P concentration (g kg⁻¹)	P accumulation in total above ground biomass^a (kg ha⁻¹)	Soil available P^b (mg kg⁻¹)	Dehydrogenase INTF mg kg⁻¹24h⁻¹)	Urease (NH₄⁺-N mg kg⁻¹4h⁻¹)	Acid phosphatase (p-nitrophenol mg kg⁻¹2h⁻¹)	β-glucosidase (p-nitrophenol mg kg⁻¹ 2 h⁻¹)
N fertilizer (F)
0	8.93^b	22.21^b	155.98^b	1.96^a	1.86^a	25.46^b	192.40^a	11.72^a	225.10^b	438.62^b	234.58^a
N	10.45^a	29.75a	249.21a	2.07^a	1.82^a	28.39^a	194.76^a	10.97^b	245.23^a	448.63^a	232.34^a
Green manure (G)
None	8.97^c	23.73^c	162.79^c	1.70^c	1.62^c	20.86^c	160.32^c	10.28^c	213.46^c	422.95^b	197.85^b
alfalfa	10.40^a	28.29^a	237.22^a	2.36^a	2.00^a	32.41^a	218.98^a	12.65^a	255.53^a	458.16^a	251.48^a
broad bean	9.70^b	25.93^b	207.77^b	1.99^b	1.90^b	27.46^b	201.44^b	11.12^b	236.52^b	449.76^a	251.04^a
F	***	***	***	NS	NS	***	NS	*	**	*	NS
G	***	***	***	***	***	***	***	***	***	***	***
F*G	*	*	*	NS	**	***	NS	NS	NS	*	*

^aTotal above ground biomass including yields of grain and straw;
^bSoil available P including soil NaHCO₃-Pi, NaOH-Pi, and NaHCO₃-Po;
Within each main treatment of F and G, means followed by different letters in the same column are significantly different at P < 0.05. *Significant at P < 0.05; **Significant at P < 0.01; ***Significant at P < 0.001; NS, not significant.

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