Growth and nutrient contents in lowland rice due to phosphorus and potassium fertilization

Reis, André Fróes de Borja; Nascente, Adriano Stephan; Almeida, Rodrigo Estevam Munhoz de; Chagas Júnior, Aloísio Freitas

doi:10.1590/1983-40632018v4850666

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Scientific Articles • Pesqui. Agropecu. Trop. 48 (2) • Apr-Jun 2018 • https://doi.org/10.1590/1983-40632018v4850666 copy

Growth and nutrient contents in lowland rice due to phosphorus and potassium fertilization

Crescimento e teores de nutrientes em arroz de terras baixas em razão de adubação com fósforo e potássio

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

In order to reach an optimum and sustainable production, growers must know the fertilizing potassium (K) and phosphorous (P) application rates. The present study aimed to determine the rice development in response to combined rates of P and K, on Plinthaquults (380-400 g kg^-1 of clay), under high and low fertility conditions, in the tropical lowland plain of the Araguaia river, Brazil. Three field experiments were performed, each one consisting of a completely randomized factorial block design, with three replications. Treatments included a combination of six K₂O rates (0 kg ha^-1, 30 kg ha^-1, 60 kg ha^-1, 90 kg ha^-1, 120 kg ha^-1 and 150 kg ha^-1) with six P₂O₅ rates (0 kg ha^-1, 30 kg ha^-1, 60 kg ha^-1, 90 kg ha^-1, 120 kg ha^-1 and 150 kg ha^-1). No interaction effect between P and K rates was observed for the evaluated variables in any fertility level/year. Phosphorous application under low fertility conditions, as well as K under high fertility conditions, affect overall crop nutrition, tillering capacity, yield components and grain yield of lowland rice, though no effects were observed due to the P application in high fertility soils and K in low fertility soils. Under high fertility conditions, the grain yield increment rate due to the K application was 4.04 kg ha^-1, whereas in the low fertility areas, such as recently cleared fields, a maximum yield of 7,161 kg ha^-1 was achieved by applying 140 kg ha^-1 of P.

KEYWORDS:
Oryza sativa; irrigated rice; tropical soil

Soil characteristic	Ca	Mg	H + Al	K	CEC	P	SOM	BS	pH CaCl₂	pH water	Clay	Silt	Sand
Soil characteristic	^{____________________} cmol_ckg^{-1 ____________________}					mg kg^-1	g kg^-1	%	pH CaCl₂	pH water	^__________ g kg^{-1 __________}
2010/2011 growing season
Low fertility	0.5	0.3	4.1	0.01	4.9	3.0	5.8	17	4.5	4.4	390	250	360
2011/2012 growing season
High fertility	4.5	3.4	3.7	0.20	11.8	13.0	6.2	68	6.1	5.5	380	280	340
Low fertility	0.9	0.4	3.8	0.01	5.1	3.1	6.1	26	5.0	4.8	400	250	350

Low soil fertility
Growing season	N	P	K	Ca	Mg	Cu	Fe	Mn	Zn
Growing season	^{_____________________________}g kg^{-1 _____________________________}					^{____________________} mg kg^{-1 ____________________}
2010/2011	23.44 a	1.36	8.60 a	4.42	1.24	7.37	53.53	362	20.07 b
2011/2012	19.29 b	1.08	7.28 b	5.86	0.97	4.78	45.76	445	25.44 a
Factors	Anova (F probability)
Growing season (GS)	< 0.01	< 0.01	< 0.01	< 0.01	< 0.01	< 0.01	< 0.01	< 0.01	< 0.01
Phosphorus rates (P)	< 0.001	< 0.01	< 0.01	< 0.01	< 0.01	< 0.01	0.09	< 0.01	0.02
Potassium rates (K)	0.3307	0.13	0.1195	0.825	0.439	0.149	0.331	0.110	0.301
GS x P	0.8593	< 0.01	0.0965	< 0.01	< 0.01	< 0.01	< 0.01	< 0.01	0.225
GS x K	0.153	0.805	0.942	0.270	0.451	0.168	0.294	0.847	0.067
P x K	0.058	0.785	0.996	0.892	0.063	0.455	0.872	0.678	0.410
GS x P x K	0.293	0.999	0.922	0.960	0.117	0.970	0.970	0.866	0.538
High soil fertility
Factors	Anova (F probability)
Phosphorus rates (P)	0.320	< 0.01	0.09	0.054	0.200	0.953	0.105	< 0.01	0.497
Potassium rates (K)	0.046	0.001	0.001	0.261	0.210	0.005	0.230	0.484	0.124
P x K	0.5751	0.564	0.699	0.757	0.810	0.605	0.491	0.852	0.460

Low soil fertility
Growing season	NT	PD	PB	GY
Growing season	unit	m^-2	g	kg ha^-1
2010/2011	2.5 a	363 a	1.64	6,062 a
2011/2012	1.9 b	280 b	1.73	4,929 b
Factors	Anova (F probability)
Growing seasons (GS)	< 0.01	< 0.01	0.043	< 0.01
Phosphorus rates (P)	< 0.01	< 0.01	< 0.01	< 0.01
Potassium rates (K)	0.331	0.351	0.154	0.078
GS x P	0.482	0.182	< 0.01	0.140
GS x K	0.458	0.176	0.787	0.136
P x K	0.282	0.349	0.858	0.333
GS x P x K	0.311	0.098	0.106	0.077
High soil fertility
Factors	Anova (F probability)
Phosphorus rates (P)	0.373	0.303	0.128	0.353
Potassium rates (K)	0.022	< 0.02	< 0.01	0.023
P x K	0.382	0.078	0.496	0.636

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[TFN1] SOM: soil organic matter; BS: base saturation; CEC: cation exchange capacity.