Table 3. N surplus (kg N ha⁻¹) of each crop from October 2010 to September 2013.

Treatment#	Winter wheat				Summer maize				Annual
	2011	2012	2013	Average	2011	2012	2013	Average	2010–2011	2011–2012	2012–2013	Average
N0	−79§	−77	−82	−79	−82	−89	−115	−95	−161	−166	−197	−175
N0+S	−41	−43	−44	−43	−61	−74	−100	−78	−102	−117	−144	−121
Nopt	−48	−15	−48	−37	94	−32	−38	8	46	−47	−86	−29
Nopt+S	−1	26	−16	3	67	−13	−22	11	66	13	−38	14
Ncon	119	138	63	107	131	55	44	77	250	193	107	183
Ncon+S	176	174	143	164	149	111	92	117	325	285	235	282
Mbal+S	125	51	69	81	−3	−22	−7	−11	122	29	62	71
Wbal+S	78	50	69	65	65	−2	9	24	143	48	78	89

^#N₀, N_opt, N_con, M_bal and W_bal represent control, improved N_min test, conventional farming practice, cattle manure with N balance method and waste compost with N balance method, respectively. S represents straw returning.

^§N_surplus = N_{Chemical Fertilizer} + N_Compost + N_Straw − N_uptake.