Cover crops on soil quality and yield of cowpea under no-tillage in the Amazon savanna

Rocha, Paulo Roberto Ribeiro; Maia, Sonicley da Silva; Melo, Valdinar Ferreira; Uchôa, Sandra Cátia Pereira; Batista, Karine Dias; Cavalcante, Luiza Amorim

doi:10.4025/actasciagron.v46i1.62853

ABSTRACT.

Conservation practices such as no-tillage are necessary to maintain, and/or improve agricultural soil quality. However, straw formation and maintenance in tropical regions is a limiting factor to adopting this system. In this sense, this research aimed to study the effect of cover crops on straw formation, soil quality indicators, and cowpea yield under no-tillage in the Amazon savanna. Two experiments were carried out in consecutive years, on a Latossolo Amarelo. The treatments consisted of the straw of cover crops in a single (_S) and intercrop (_I) system, as follows: Urochloa brizantha (UB_S), Pennisetum glaucum (PG_S), Crotalaria juncea (CJ_S), Canavalia ensiformis (CE_S), Mucuna aterrima (MA_S), U. brizantha and C. juncea (UBCJ_I), U. brizantha and C. ensiformis (UBCE_I), P. glaucum and C. juncea (PGCJ_I), P. glaucum and C. ensiformis (PGCE_I), and spontaneous vegetation (SV). Cowpea was cultivated after desiccation of the cover crops. Most of the straw favored soil particle aggregation, except for C. juncea and SV, which negatively influenced this variable. Basal soil respiration, organic carbon content, potassium, base saturation, geometric mean diameter, macroaggregates, and macroporosity at layer of 0-0.10 m were the most sensitive indicators for improving soil quality in a savanna environment. UB_S, UBCJ_I, and UBCE_I were superior to the other treatments in improving soil quality. Almost all treatments increased cowpea yield by up to 29%, except for CJ_S and SV.

Keywords:
soil cover; conservationist system; Vigna unguiculata

[1] * Author for correspondence. E-mail: paulo.rocha@ufrr.br

CC	BSR (mg C-CO₂ kg⁻¹soil h⁻¹)		M	MBC (mg C kg⁻¹soil)		M	qCO₂ (mg C-CO₂ g⁻¹ MBC h⁻¹)		M
CC	1^st cycle	2^nd cycle	M	1^st cycle	2^nd cycle	M	1^st cycle	2^nd cycle	M
UB_S	3.10	2.25	2.67 a	63.74 Aa	72.96 Ab	68.35	0.05 Ab	0.03 Ba	0.04
PG_S	2.69	2.35	2.52 a	43.90 Bb	68.21 Ab	56.05	0.06 Aa	0.04 Ba	0.05
CJ_S	2.62	1.97	2.29 b	62.83 Aa	76.79 Ab	69.81	0.04 Ab	0.03 Ba	0.03
CE_S	2.84	2.08	2.46 a	41.46 Bb	89.14 Aa	65.30	0.07 Aa	0.02 Ba	0.05
MA_S	2.45	2.14	2.29 b	48.83 Bb	89.73 Aa	69.28	0.05 Ab	0.04 Ba	0.04
UBCJ_I	2.73	2.03	2.38 b	53.88 Ba	66.79 Ab	60.34	0.05 Ab	0.03 Ba	0.04
UBCE_I	2.60	2.03	2.31 b	58.22 Ba	85.72 Aa	71.97	0.05 Ab	0.02 Ba	0.04
PGCJ_I	2.65	2.12	2.39 b	55.87 Ba	68.87 Ab	62.37	0.05 Ab	0.03 Ba	0.04
PGCE_I	2.95	2.16	2.56 a	43.86 Bb	84.48 Aa	64.17	0.07 Aa	0.03 Ba	0.05
SV	2.41	1.77	2.09 b	48.65 Ab	55.89 Ab	52.27	0.05 Ab	0.03 Ba	0.04
M	2.70 A	2.09 B		52.12	75.86		0.05	0.03

CC	pH (H₂O)		m	Organic carbon (g kg⁻¹)		m	Phosphorus (mg dm⁻³)		m
CC	1^st cycle	2^nd cycle	m	1^st cycle	2^nd cycle	m	1^st cycle	2^nd cycle	m
UB_S	5.46	5.26	5.36	5.22 Ba	6.53 Aa	5.88	16.17	26.48	21.33 c
PG_S	5.48	5.35	5.41	4.06 Ba	5.42 Ab	4.74	21.67	31.14	26.40 b
CJ_S	5.27	5.11	5.19	4.64 Aa	5.57 Ab	5.10	23.00	24.89	23.94 c
CE_S	5.33	5.08	5.20	4.77 Aa	4.93 Ab	4.85	23.50	35.12	29.31 b
MA_S	5.38	5.09	5.24	4.06 Ba	5.23 Ab	4.65	15.00	18.63	16.82 c
UBCJ_I	5.49	5.32	5.40	4.64 Aa	4.67 Ab	4.66	18.83	25.55	22.19 c
UBCE_I	5.47	5.35	5.41	4.06 Ba	6.43 Aa	5.25	19.25	27.83	23.54 c
PGCJ_I	5.53	5.25	5.39	4.39 Aa	4.93 Ab	4.66	22.50	26.09	24.29 c
PGCE_I	5.49	5.26	5.37	4.83 Aa	5.60 Ab	5.21	24.00	33.09	28.55 b
SV	5.60	5.33	5.46	4.35 Aa	4.85 Ab	4.60	40.54	41.08	40.81 a
M	5.45 A	5.24 B		4.50	5.42		22.45 B	28.9 A
CC	Potassium (mg dm⁻³)		M	Calcium (cmol_c dm⁻³)		m	Magnesium (cmol_c dm⁻³)		m
CC	1^st cycle	2^nd cycle	M	1^st cycle	2^nd cycle	m	1^st cycle	2^nd cycle	m
UB_S	81.90	91.88	86.89 a	1.06	0.97	1.01 a	0.59	0.55	0.57 a
PG_S	58.40	79.44	68.92 c	1.03	0.93	0.98 a	0.54	0.52	0.53 a
CJ_S	72.80	87.50	80.15 a	1.05	0.95	1.00 a	0.60	0.56	0.58 a
CE_S	71.30	84.83	78.07 b	1.05	0.90	0.97 a	0.49	0.38	0.43 b
MA_S	58.01	69.50	63.76 c	0.98	0.92	0.95 a	0.45	0.39	0.42 b
UBCJ_I	80.60	86.71	83.65 a	0.95	0.88	0.92 b	0.50	0.47	0.48 b
UBCE_I	74.91	89.75	82.33 a	0.93	0.89	0.91 b	0.53	0.42	0.47 b
PGCJ_I	65.08	85.00	75.04 b	0.86	0.89	0.87 b	0.50	0.45	0.48 b
PGCE_I	67.51	81.67	74.59 b	0.88	0.82	0.85 b	0.51	0.44	0.48 b
SV	57.53	76.58	67.54 c	1.00	0.98	0.99 a	0.58	0.54	0.56 a
M	68.80 B	83.29 A		0.98 A	0.91 B		0.53 A	0.47 B

SB (cmol_c dm⁻³)				Al (cmol_c dm⁻³)			H + Al (cmol_c dm⁻³)			V (%)
CC	1^st cycle	2^nd cycle	m	1^st cycle	2^nd cycle	m	1^st cycle	2^nd cycle	m	1^st cycle	2^nd cycle	m
UB_S	1.86	1.75	1.80 a	0.04	0.10	0.07	2.2	2.7	2.4	46.5	40.1	43.3
PG_S	1.71	1.65	1.68 a	0.03	0.03	0.03	2.2	2.5	2.4	44.1	39.4	41.8
CJ_S	1.85	1.74	1.79 a	0.09	0.14	0.12	2.5	2.9	2.7	42.9	37.7	40.3
CE_S	1.71	1.49	1.60 b	0.09	0.11	0.10	2.5	2.7	2.6	41.5	35.9	38.7
MA_S	1.57	1.49	1.53 b	0.09	0.11	0.10	2.5	2.2	2.3	38.8	40.9	39.8
UBCJ_I	1.66	1.57	1.62 b	0.01	0.06	0.04	2.2	2.4	2.3	42.9	39.9	41.4
UBCE_I	1.65	1.53	1.59 b	0.03	0.07	0.05	2.2	2.5	2.3	43.4	37.8	40.6
PGCJ_I	1.52	1.55	1.54 b	0.01	0.09	0.05	2.2	2.6	2.4	41.3	38.6	39.9
PGCE_I	1.56	1.47	1.52 b	0.01	0.11	0.06	2.2	2.6	2.4	41.8	35.8	38.8
SV	1.72	1.71	1.72 a	0.00	0.08	0.04	2.1	2.8	2.5	46.1	37.3	41.7
m	1.68 A	1.60 B		0.04 B	0.09 A		2.3 B	2.6 A		42.9A	38.4B

CC	Geometric mean diameter (mm)		Macroaggregates (%)		Microaggregates (%)		Simple particles (%)
CC	0-0.15 m	0.15-0.30 m	0-0.15 m	0.15-0.30 m	0-0.15 m	0.15-0.30 m	0-0.15 m	0.15-0.30 m
UB_S	1.79 Aa	1.56 Ab	85.84 Ab	83.89 Ab	12.53 Aa	14.69 Aa	1.63 Aa	1.42 Aa
PG_S	1.48 Ab	1.42 Ab	82.75 Ab	79.19 Ab	15.66 Aa	18.81 Aa	1.60 Aa	2.00 Aa
CJ_S	2.14 Aa	1.04 Bb	90.57 Aa	78.43 Bb	8.09 Bb	19.69 Aa	1.34 Ba	1.88 Aa
CE_S	2.42 Aa	1.77 Ba	90.73 Aa	88.27 Aa	8.39 Ab	10.70 Ab	0.88 Aa	1.02 Aa
MA_S	2.21 Aa	2.08 Aa	89.60 Aa	89.23 Aa	9.26 Ab	9.67 Ab	1.14 Aa	1.10 Aa
UBCJ_I	2.49 Aa	1.81 Ba	89.83 Aa	86.36 Aa	8.99 Ab	12.29 Ab	1.17 Aa	1.35 Aa
UBCE_I	1.11 Bb	1.64 Ab	79.62 Bb	84.97 Aa	19.08 Aa	13.71 Bb	1.30 Aa	1.32 Aa
PGCJ_I	1.96 Aa	1.56 Ab	84.64 Ab	82.36 Ab	13.62 Aa	15.29 Aa	1.74 Ba	2.36 Aa
PGCE_I	1.48 Bb	2.20 Aa	82.10 Bb	87.90 Aa	15.65 Aa	10.12 Bb	2.25 Aa	1.98 Aa
SV	1.13 Ab	1.43 Ab	81.61 Ab	83.63 Ab	16.57 Aa	15.30 Aa	1.82 Aa	1.07 Ba

CC	DM (kg ha⁻¹)		Mean	CY (kg ha⁻¹)		Mean
CC	1^st cycle	2^nd cycle	Mean	1^st cycle	2^nd cycle	Mean
	^{______________________________________________}kg ha^{−1 ___________________________________________}
UB_S	10689.73	11242.78	10966.25 a	1610.69	2102.39	1856.54 a
PG_S	9838.80	9966.00	9902.40 a	1749.45	1886.46	1817.96 a
CJ_S	8137.95	8427.35	8282.65 b	1404.30	1930.96	1667.63 b
CE_S	5440.70	8998.95	7219.83 b	1752.65	1954.07	1853.36 a
MA_S	6022.10	9608.05	7815.08 b	1713.66	1976.22	1844.94 a
UBCJ_I	9472.85	9922.40	9697.63 a	1904.07	2131.24	2017.66 a
UBCE_I	8487.15	9931.60	9209.38 a	1756.44	2161.77	1959.11 a
PGCJ_I	9449.15	9711.13	9580.14 a	1824.34	1860.58	1842.46 a
PGCE_I	7796.40	9555.25	8675.83 a	1880.59	1888.32	1884.46 a
SV	4841.45	6940.65	5891.05 c	1546.22	1581.56	1563.63 b
Mean	8017.63 B	9430.41 A		1715.01 B	1946.58 A

Brasil

Brasil

Cover crops on soil quality and yield of cowpea under no-tillage in the Amazon savanna

ABSTRACT.