Use of buffer methods to estimate the potential acidity of Mato Grosso soils

Prado, Marcelo Ribeiro Vilela; Moraes, Milton Ferreira de; Ramos, Fabrício Tomaz; Santos, Carlos Leandro Rodrigues do; Campos, David Vilas Boas de; Barros, Gisele Teixeira

doi:10.1590/1413-7054202044026019

ABSTRACT

Mato Grosso, with a total area of 903357 km², does not have an official methodology for estimating soil potential acidity (H + Al), and determination of H + Al using the standard method is onerous and time consuming. The objective of this study was to compare estimated values of H + Al determined using the standard calcium acetate method with those obtained using three buffer methods, namely, the Shoemaker, McLean, and Pratt (SMP) buffer, Sikora buffer, and Santa Maria buffer (SMB) methods, with samples of the main classes of cultivated soils in the state of Mato Grosso. A total of 196 soil samples were collected from the arable layer (0-20 cm) in agropastoral and adjacent native systems. Statistical models were obtained and compared with models used by laboratories that are hypothetically inadequate because there is no calibration for soils in the state. After laboratory analyses, the paired H + Al and equilibrium pH values corresponding to the equilibrium of each buffer solution (SMP buffer, SMB, and Sikora buffer) were subjected to nonlinear regression analysis (P < 0.05). The SMB method, which does not release pollutant residues into the environment, was better than the Sikora and SMP methods for replacing the standard method used in state laboratories for soil analysis, that is, H + Al (cm³ _c dm^-3) = 51.189 -25.70 ln(pH_SMB) (R² = 0.88, P < 0.0001). Thus, if laboratories use uncalibrated equations to estimate soil potential acidity, the recommended limestone correction will be underestimated or overestimated, which may compromise crop productivity in Mato Grosso.

Index terms:
Limestone; SMP buffer; Sikora buffer; Santa Maria buffer

[1] ^*Corresponding author: fabriciotomazramos@gmail.com

Attribute	Value		Average	Standard deviation	CV (%) ^†
Attribute	Minimum	Maximum	Average	Standard deviation	CV (%) ^†
	--------------------------------------- Dimensionless ---------------------------------------
pH H₂O	4.20	8.00	5.60	0.67	12
pH CaCl₂	3.40	7.08	4.75	0.64	13
pH SMP	5.02	7.38	6.27	0.43	7
pH SMB	4.95	7.35	6.18	0.44	7
pH Sikora	5.63	7.41	6.64	0.32	5
	----------------------------------------- cmol_c dm^-3 -----------------------------------------
H+Al ⁽¹⁾	0.30	12.00	4.50	2.00	44
Al^{3+ (2)}	0.00	2.60	0.30	0.50	173
Ca^{2+ (3)}	0.10	11.70	2.00	1.70	84
Mg^{2+ (4)}	0.10	4.60	0.90	0.70	74
K^{+ (5)}	0.10	2.80	0.20	0.20	124
SB ⁽⁶⁾	0.10	12.60	3.10	2.30	73
CTC ⁽⁷⁾	2.80	21.10	7.60	3.00	40
	------------------------------------------- % -------------------------------------------
V ⁽⁸⁾	2.70	94.80	39.20	20.20	52
	------------------------------------------- g kg^-1 -------------------------------------------
OC ⁽⁹⁾	3.10	29.40	10.40	5.00	48
SOM ⁽¹⁰⁾	5.30	50.70	17.90	8.60	48
Sand	100.00	900.00	581.10	200.70	35
Silt	25.00	325.00	77.60	57.30	74
Clay	75.00	700.00	341.30	168.50	49

Source	State†	Equation	pH SMP††
Source	State†	Equation	4.5	5.0	5.5	6.0	6.5	7.0
			------------- H+Al (cmol_c dm^-3) --------------
Quaggio, Van Raij and Malavolta, (1985QUAGGIO, J. A.; VAN RAIJ, B.; MALAVOLTA, E. Alternative use of the SMP-buffer solution to determine lime requirement of soils. Communications in Soil Science and Plant Analysis, 16(3):245-260, 1985.)	SP	ln(H+Al) = 7.76 - 1.053 pHSMP	20.5	12.1	7.2	4.2	2.5	1.5
Gama et al. (2013GAMA, M. A. P. et al. Potential acidity estimated by SMP pH in soils of the state of Pará. Revista Brasileira de Ciência do Solo , 37(1):199-203, 2013.)	MG	ln(H+Al) = 8.06 - 1.111 pHSMP	21.3	12.2	7.0	4.0	2.3	1.3
Sousa et al. (1989SOUSA, D. M. G. et al. Methods for determining liming needs in cerrado soils. Revista Brasileira de Ciência do Solo , 13(2):193-198, 1989.)	GO	ln(H+Al) = 7.719 - 1.068 pHSMP	18.4	10.8	6.3	3.7	2.2	1.3
Pavan, Oliveira and Miyazawa, (1996PAVAN, M. A.; OLIVEIRA, E. L.; MIYAZAWA, M. Indirect determination of soil extractable acidity (H + Al) by potentiometry with the SMP buffer solution. Brazilian Archives of Biology and Technology, 39(1):307-312, 1996.)	PR	ln(H+Al) = 6.0687 - 0.744 pHSMP	15.2	10.5	7.2	5.0	3.4	2.4
Maeda et al. (1997MAEDA, S. et al. Estimativa da acidez potencial, pelo método do SMP pH, em solos do Mato Grosso do Sul. EMBRAPA, Dourados, Boletim de Pesquisa, n.3, 1997. 25p.)	MS	ln(H+Al) = 8.086 - 1.062 pHSMP	27.3	16.1	9.4	5.6	3.3	1.9
Escosteguy and Bissani (1999ESCOSTEGUY, P. A.; BISSANI, C. A. Estimation of H+Al by SMP pH in soils of the State of Rio Grande do Sul and Santa Catarina. Revista Brasileira de Ciência do Solo , 23(1):175-179, 1999.)	RS/SC	log(H+Al) = 3.914 - 0.391 pHSMP	13.9	8.8	5.6	3.6	2.3	1.5
Moline et al. (2011MOLINE, E. F. V. et al. Estimated value of H+AL by orrelation with soil ph in SMP Rondônia. Enciclopédia Biosfera, 7(12):1-6, 2011.)	RO	H+Al = 31.22 - 8.20 pHSMP + 0.59 pHSMP²	6.3	5.0	4.0	3.3	2.8	2.7
Gama et al. (2013GAMA, M. A. P. et al. Potential acidity estimated by SMP pH in soils of the state of Pará. Revista Brasileira de Ciência do Solo , 37(1):199-203, 2013.)	PA	H + Al = 77.77 + 20.61 pHSMP - 1.435 pHSMP²	14.1	10.6	7.8	5.8	4.4	3.8
Araújo et al. (2014ARAÚJO, D. M. F. et al. Potential acidity of soils in the Amapá State estimated by the potentiometric SMP method. Acta Iguazu, 3(3):57-65, 2014. )	AP	H + Al = 62.08 - 14.394 SMP + 0.8263 pHSMP²	14.0	10.8	7.9	5.5	3.4	1.8
Almeida Júnior et al. (2015)ALMEIDA JUNIOR, A. B.; NASCIMENTO, C. W. A.; BARROS, F. M. R. Potential acidity estimated by the pH SMP method in soils of the State of Paraíba. Revista Brasileira de Ciência do Solo, 39(3):767-773, 2015.	PB	H+Al = 57.108 -13.338 SMP + 0.7637 pHSMP²	12.6	9.5	6.9	4.6	2.7	1.2
Present study - all soils	MT	H+Al = 53.105 - 26.54 ln(pHSMP)	*	10.4	7.9	5.6	3.4	1.5
Present study <350 g kg^-1 clay	MT	H+Al = 49.972 - 24.94 ln(pHSMP)	*	9.8	7.5	5.3	3.3	1.4
Present study ≥ 350 g kg^-1 clay	MT	H+Al = 53.11 - 26.47 ln(pHSMP)	*	10.5	8.0	5.7	3.6	1.6

Source	State	Soil types ⁽¹⁾
Source	State	LVAd	GXd	CXd	CXd	CXd	PVAd	FTXd	RQo	PVAd	LVAd	LVd
		---------------------------------------------------- pH SMP ----------------------------------------------------
		5.28	5.43	5.74	6.03	6.08	6.17	6.22	6.28	6.28	6.91	6.91
		------------------------------------------------------ (t ha^-1) -------------------------------------------------------
Quaggio, Van Raij and Malavolta, (1985QUAGGIO, J. A.; VAN RAIJ, B.; MALAVOLTA, E. Alternative use of the SMP-buffer solution to determine lime requirement of soils. Communications in Soil Science and Plant Analysis, 16(3):245-260, 1985.)	SP	5.25	3.17	4.06	0.00	0.86	0.00	1.63	0.74	0.62	0.00	0.00
Gama et al., (2013GAMA, M. A. P. et al. Potential acidity estimated by SMP pH in soils of the state of Pará. Revista Brasileira de Ciência do Solo , 37(1):199-203, 2013.)	MG	5.21	3.11	3.96	0.00	0.75	0.00	1.51	0.62	0.50	0.00	0.00
Sousa et al. (1989SOUSA, D. M. G. et al. Methods for determining liming needs in cerrado soils. Revista Brasileira de Ciência do Solo , 13(2):193-198, 1989.)	GO	4.64	2.64	3.67	0.00	0.57	0.00	1.38	0.50	0.38	0.00	0.00
Pavan, Oliveira and Miyazawa, (1996PAVAN, M. A.; OLIVEIRA, E. L.; MIYAZAWA, M. Indirect determination of soil extractable acidity (H + Al) by potentiometry with the SMP buffer solution. Brazilian Archives of Biology and Technology, 39(1):307-312, 1996.)	PR	4.94	3.11	4.35	0.19	1.34	0.19	2.15	1.27	1.15	0.30	0.25
Maeda et al. (1997MAEDA, S. et al. Estimativa da acidez potencial, pelo método do SMP pH, em solos do Mato Grosso do Sul. EMBRAPA, Dourados, Boletim de Pesquisa, n.3, 1997. 25p.)	MS	6.98	4.66	5.12	0.50	1.59	0.34	2.26	1.32	1.20	0.44	0.00
Escosteguy and Bissani (1999ESCOSTEGUY, P. A.; BISSANI, C. A. Estimation of H+Al by SMP pH in soils of the State of Rio Grande do Sul and Santa Catarina. Revista Brasileira de Ciência do Solo , 23(1):175-179, 1999.)	RS/SC	3.96	2.14	3.45	0.00	0.54	0.00	1.39	0.53	0.40	0.00	0.00
Moline et al. (2011MOLINE, E. F. V. et al. Estimated value of H+AL by orrelation with soil ph in SMP Rondônia. Enciclopédia Biosfera, 7(12):1-6, 2011.)	RO	2.47	0.99	2.88	0.00	0.43	0.00	1.45	0.65	0.52	0.00	0.37
Gama et al. (2013GAMA, M. A. P. et al. Potential acidity estimated by SMP pH in soils of the state of Pará. Revista Brasileira de Ciência do Solo , 37(1):199-203, 2013.)	PA	5.21	3.44	4.78	0.67	1.84	0.71	2.68	1.81	1.69	0.81	1.06
Araújo et al. (2014ARAÚJO, D. M. F. et al. Potential acidity of soils in the Amapá State estimated by the potentiometric SMP method. Acta Iguazu, 3(3):57-65, 2014. )	AP	5.31	3.51	4.74	0.47	1.60	0.40	2.33	1.41	1.29	0.50	0.00
Almeida Júnior et al. (2015ALMEIDA JUNIOR, A. B.; NASCIMENTO, C. W. A.; BARROS, F. M. R. Potential acidity estimated by the pH SMP method in soils of the State of Paraíba. Revista Brasileira de Ciência do Solo, 39(3):767-773, 2015.)	PB	4.63	2.86	4.15	0.00	1.08	0.00	1.84	0.93	0.81	0.00	0.00
Present study - all soils	MT	5.21	3.46	3.74	0.52	1.65	0.45	2.38	1.45	1.33	0.55	0.00
Present study <350 g kg^-1 clay	MT	4.93	3.21	4.56	0.47	1.51	0.32	2.25	1.34	1.22	0.42	0.00
Present study ≥ 350 g kg^-1 clay	MT	5.28	3.54	4.84	0.60	1.73	0.53	2.46	1.53	1.41	0.63	0.00

Brasil

Brasil

Use of buffer methods to estimate the potential acidity of Mato Grosso soils

Uso de métodos tampões para estimar a acidez potencial de solos de Mato Grosso

ABSTRACT