Clean recovery and recycling of seasonal surplus forage grass by microbial driven anaerobic fermentation: a case study of napiergrass

Chemical and Biological Technologies in Agriculture

Table 2 Effects of harvest dates and store time on fermentation quality of fermented napiergrass

Items^C	Treatments^D	Store time (d)						SEM^E	P value^F
Items^C	Treatments^D	1	3	7	15	30	60	SEM^E	G	D	G × D
pH	NN_I	5.31^B	4.63	4.13	3.66^B	3.76	3.99^B	0.142	< 0.001	< 0.001	0.082
pH	NN_II	5.88^A	4.86	4.39	4.19^B	4.00	4.20^A	0.159	< 0.001	< 0.001	0.082
DM (g/kg FM)	NN_I	236^B	232^B	231^B	231^B	230^B	226^B	1.801	< 0.001	0.066	0.760
DM (g/kg FM)	NN_II	267^A	261^A	255^A	254^A	253^A	242^A	2.705	< 0.001	0.066	0.760
LA (g/kg DM)	NN_I	5.51^A	21.2^A	34.5^A	51.1^A	52.0^B	43.2^A	4.153	< 0.001	< 0.001	0.017
LA (g/kg DM)	NN_II	1.99^B	10.1^B	17.6^B	32.8^B	39.2^A	25.6^B	3.142	< 0.001	< 0.001	0.017
AA (g/kg DM)	NN_I	2.78^B	3.60^B	4.83^B	5.39^B	8.19	14.4	1.018	0.047	< 0.001	0.186
AA (g/kg DM)	NN_II	3.67^A	5.99^A	7.43^A	7.67^A	8.11	12.9	0.708	0.047	< 0.001	0.186
LA/AA	NN_I	1.99^A	5.88^A	7.19^A	9.58^A	6.39^A	3.17^A	0.631	< 0.001	< 0.001	< 0.001
LA/AA	NN_II	0.54^B	1.69^B	2.39^B	4.33^B	4.89^B	2.00^B	0.376	< 0.001	< 0.001	< 0.001
PA (g/kg DM)	NN_I	ND	ND	ND	ND	ND	ND	–	–	–	–
PA (g/kg DM)	NN_II	ND	ND	ND	ND	ND	ND	–	–	–	–
BA (g/kg DM)	NN_I	0.34B	1.18	1.38	1.23	1.18	1.45	0.079	0.002	0.005	0.986
BA (g/kg DM)	NN_II	0.66A	1.49	1.63	1.59	1.69	1.84	0.096	0.002	0.005	0.986
WSC (g/kg DM)	NN_I	45.2	24.1	17.9	12.1	10.1	7.41	3.214	0.286	< 0.001	0.288
WSC (g/kg DM)	NN_II	40.6	27.8	23.6	11.2	11.7	10.3	2.756	0.286	< 0.001	0.288
NH₃–N (g/kg TN)	NN_I	36.6^B	42.1^B	53.9^B	64.1^B	92.3^B	98.9^B	6.177	< 0.001	< 0.001	< 0.001
NH₃–N (g/kg TN)	NN_II	47.6^A	68.2^A	119^A	145^A	150^A	187^A	11.87	< 0.001	< 0.001	< 0.001

^A−BMeans with different uppercase in the same row differ at p < 0.05
^CDM dry matter, FM fresh material, LA lactic acid, AA acetic acid, LA/AA the ratio of lactic to acetic acid, PA propionic acid, BA butyric acid, WSC water soluble carbohydrates, NH₃–N ammonia–nitrogen, TN total nitrogen
^DNN_I natural fermentation of napiergrass harvested at the early vegetative stage, NN_II natural fermentation of napiergrass harvested at the late vegetative stage
^ESEM standard error of means
^FG the effect of harvest date, D the effect of store time; G × D the interaction between harvest date and store time