Rice yield and soil fertility of an organic paddy system with winter flooding

Figures & data

Table 1. Details of winter flooding and application of cattle manure (CM), fermented organic fertilizer 1–3 (OF1-3), weed suppression material (WS), rice bran (RB), and hairy vetch in every plot and of crops from 2007 to 2016

		Plot No.
Year	Season	1 and 2	3 and 4	5 and 6	7 and 8	Crop (conventional or organic)
2007	winter		flooding		flooding
	spring			CM	CM	Rice (conventional)
	summer
	fall
2008	winter		flooding		flooding
	spring					Soybean (conventional)
	summer
	fall				OF1
2009	winter		flooding		flooding
	spring	OF2, WS (excl. 1plot)	OF2, WS	OF2, WS (excl. 1plot)	OF2, WS	Rice (organic)
	summer	OF3	OF3	OF3	OF3
	fall			RB	RB
2010	winter		flooding		flooding
	spring	OF2, WS	OF2, WS	OF2, WS	OF2, WS	Rice (organic)
	summer	OF3	OF3	OF3	OF3
	fall
2011	winter	hairy vetch	hairy vetch	hairy vetch	hairy vetch
	spring					Soybean (organic)
	summer
	fall			RB	RB
2012	winter		flooding		flooding
	spring	OF2, WS	OF2, WS	OF2, WS	OF2, WS	Rice (organic)
	summer	OF3	OF3	OF3	OF3
	fall			RB	RB
2013	winter		flooding		flooding
	spring	OF2, WS	OF2, WS	OF2, WS	OF2, WS	Rice (organic)
	summer	OF3	OF3	OF3	OF3
	fall
2014	winter	hairy vetch	hairy vetch	hairy vetch	hairy vetch
	spring					Soybean (organic)
	summer
	fall			RB	RB
2015	winter	flooding		flooding
	spring	OF2, WS	OF2, WS	OF2, WS	OF2, WS	Rice (organic)
	summer	OF3	OF3	OF3	OF3
	fall			RB	RB
2016	winter	flooding		flooding
	spring	OF2, WS	OF2, WS	OF2, WS	OF2, WS	Rice (organic)
	summer	OF3	OF3	OF3	OF3
	fall

Application rates: CM, 4 kg m⁻²; OF1, OF2, RB, 100 g m⁻²; WS, 80 g m⁻²; OF3, 17 g m⁻² in 2009, 18 g m⁻² in 2010, and 20 g m⁻² in 2012, 2013, 2015, and 2016.

Figure 1. Time course of monthly mean air temperature and monthly cumulative precipitation after start of organic production

Table 2. Rates (g m⁻²) of N and P applied by organic materials in plots with control treatment, with winter flooding (+WF), with rice bran (+RB), and with rice bran and winter flooding (+RB+WF) in 2012–2016

	2012		2013		2015		2016
Materials	N	P	N	P	N	P	N	P
Rice bran	2.4	1.1	2.5	1.1	2.3	1.6	2.5	2.1
OF2^a	1.8	0.8	1.7	0.7	1.7	1.0	1.7	0.7
WS^b	2.6	1.0	2.8	0.8	2.8	1.0	2.6	1.4
OF3^c	0.5	0.6	0.6	0.7	0.6	0.9	0.7	0.6
Total in Control and +WF	4.8	2.4	5.0	2.1	5.0	3.0	5.0	2.7
Total in +RB and +RB+WF	7.3	3.4	7.5	3.2	7.3	4.6	7.4	4.7

^aFermented organic fertilizers made from rice bran, wheat seeds, crab and shrimp shells, and salt.

^bWeed suppression material.

^cFermented organic fertilizer made from rice bran, soybean curd residue, guano, and rapeseed oil cake.

Table 3. Brown rice yield, plant properties, and N and P contents of aboveground parts of rice plants at harvest in plots with control treatment, with rice bran (+RB), with winter flooding (+WF), and with rice bran and winter flooding (+RB+WF) in 2012 and 2013

		Straw dry matter	Brown rice yield^a	Thousand-kernel-weight^a	Stem length	Ear length	Number of ears	Percentage of ripened grains	Aboveground part
Year	Treatment	(g m^−2)	(g m^−2)	(g)	(m)	(m)	(n m^−2)	(%)	N(g m^−2)	P(g m^−2)
2012	Control	676	448	21.1	0.82	0.19	302	69	7.5	1.4
	+RB	721	473	21.3	0.84	0.19	302	79	10.6	1.9
	+WF	807	532	20.7	0.89	0.19	369	72	10.5	1.6
	+RB+WF	817	493	20.6	0.94	0.19	382	55	14.4	2.1
2013	Control	594	397	20.6	0.76	0.18	255	76	5.1	0.9
	+RB	716	507	20.7	0.83	0.18	306	72	7.3	1.4
	+WF	803	581	20.4	0.89	0.19	352	79	9.5	1.4
	+RB+WF	945	556	19.9	0.94	0.19	450	62	12.1	1.5
ANOVA
	RB	**^b	ns^c	ns	**	ns	**	**	**	*
	WF	***	***	***	***	ns	***	**	***	ns
	Year	ns	ns	***	ns	ns	ns	ns	**	*
	RB×WF×Year	ns	ns	ns	ns	ns	ns	ns	ns	ns
	RB×WF	ns	**	*	ns	ns	ns	***	ns	ns
	RB×Year	*	ns	ns	ns	ns	**	ns	ns	ns
	WF×Year	*	*	ns	ns	ns	*	ns	ns	ns

^a > 1.8 mm thickness grain, at 15% moisture.

^b* P < 0.05; ** P < 0.01; *** P < 0.001.

^c Not significant.

Table 4. Brown rice yield, plant properties, and N and P contents of aboveground parts of rice plants at harvest in plots with control treatment, with rice bran (+RB), with winter flooding (+WF), and with rice bran and winter flooding (+RB+WF) in 2015 and 2016 after switching winter flooding position

		Straw dry matter	Brown rice yield^a	Thousand-kernel-weight^a	Stem length	Ear length	Number of ears	Percentage of ripened grains	Aboveground part
Year	Treatment	(g m^−2)	(g m^−2)	(g)	(m)	(m)	(n m^−2)	(%)	N(g m^−2)	P(g m^−2)
2015	A: Control (after +WF)	689	422	22.0	0.89	0.19	312	68	10.3	2.5
	B: +RB (after +RB+WF)	750	417	22.0	0.93	0.20	313	64	10.3	2.2
	C: +WF (after Control)	743	426	22.0	0.93	0.20	315	70	11.2	2.6
	D: +RB+WF (after +RB)	756	418	22.0	0.95	0.21	285	68	11.6	2.7
2016	A: Control (after +WF)	459	347	21.8	0.80	0.19	210	77	5.9	1.5
	B: +RB (after +RB+WF)	608	451	22.2	0.83	0.19	261	78	5.9	1.4
	C: +WF (after Control)	615	463	22.0	0.84	0.19	270	70	6.5	1.6
	D: +RB+WF (after +RB)	683	487	22.1	0.90	0.20	288	71	10.9	2.1
Difference between average in 2015–16 and in 2012–13
A from +WF in 2012–13		−231	−172	1.37	−0.05	0.00	−99	−3	−1.9	0.5
B from +RB+WF in 2012–13		−202	−91	1.83	−0.06	0.00	−129	13	−5.2	0.0
C from Control in 2012–13		44	22	1.17	0.09	0.01	14	−3	2.6	1.0
D from +RB in 2012–13		1	−37	1.05	0.09	0.02	−18	−6	2.3	0.8

^a > 1.8 mm thickness grain, at 15% moisture.

Table 5. Ratios (%) of applied N and P to ear N and P at harvest in plots with control treatment, with rice bran (+RB), with winter flooding (+WF), and with rice bran and winter flooding (+RB+WF) in 2012–2016

	2012		2013		2015		2016		Average ± SD
Treatment	N	P	N	P	N	P	N	P	N	P
Control	101	285	157	541	82	206	131	279	118 ± 33	328 ± 147
+RB	107	292	159	491	116	363	186	571	142 ± 37	429 ± 125
+WF	78	226	84	325	71	174	115	245	87 ± 20	242 ± 62
+RB+WF	92	282	107	461	108	257	105	361	103 ± 7	340 ± 92

Table 6. Analysis of variance of ammonium-N concentrations in the soil solution from April to July of 2012 and 2013

Souce of variation	2012	2013
Rice bran	ns^a	ns
Winter flood	***^b	***
Time	***	***
Rice bran×winter flood×time	ns	ns
Rice bran×winter flood	ns	ns
Rice bran×time	ns	ns
Winter flood×time	*	***

^aNot significant.

^b* P < 0.05; *** P < 0.001.

Figure 2. Seasonal changes in ammonium-N concentration in the soil solution in plots with control treatment, with rice bran (+RB), with winter flooding (+WF), and with rice bran and winter flooding (+RB+WF) in 2012, 2013, 2015, and 2016. Vertical bars indicate SD (n = 2)

Table 7. Available N in the plow layer in the previous November and in April after winter flooding and available P in the plow layer at maximum tillering stage in plots with control treatment, with rice bran (+RB), with winter flooding (+WF), and with rice bran and winter flooding (+RB+WF) in 2012 and 2013

		Available N (mg kg^−1)		Available P
Year	Treatment	Previous Nov.	April	(mg kg^−1)
2012	Control	91	80	222
	+RB	109	87	204
	+WF	106	106	182
	+RB+WF	106	126	247
2013	Control	156	145	188
	+RB	157	159	237
	+WF	155	188	223
	+RB+WF	169	200	258
ANOVA
	RB	ns^a	**^b	ns
	WF	ns	***	ns
	Year	***	***	ns
	RB×WF×Year	ns	ns	ns
	RB×WF	ns	ns	ns
	RB×Year	ns	ns	ns
	WF×Year	ns	ns	ns

^aNot significant

^b* *P < 0.01; *** P < 0.001.

Table 8. Available N in the plow layer in the previous November and in April after winter flooding in plots with control treatment, with rice bran (+RB), with winter flooding (+WF), and with rice bran and winter flooding (+RB+WF) in 2015 and 2016 after switching winter flooding position

		Available N (mg kg^−1)
Year	Treatment	Previous Nov.	April
2015	A: Control (after +WF)	142	151
	B: +RB (after +RB+WF)	141	155
	C: +WF (after Control)	131	147
	D: +RB+WF (after +RB)	144	163
2016	A: Control (after +WF)	140	137
	B: +RB (after +RB+WF)	152	150
	C: +WF (after Control)	147	173
	D: +RB+WF (after +RB)	145	205
Difference between average in 2015–16 and in 2012–13
A from +WF in 2012–13		11	−3
B from +RB+WF in 2012–13		9	−11
C from Control in 2012–13		15	48
D from +RB in 2012–13		12	61