Potential interaction of soybean-grass intercropping with residual nitrogen for a no-tillage system implementation

Batista, Karina; Giacomini, Alessandra Aparecida; Gerdes, Luciana; Mattos, Waldssimiler Teixeira de; Otsuk, Ivani Pozar

doi:10.4025/actasciagron.v46i1.62944

ABSTRACT.

Combinations between crop intercropping and forage production in a no-tillage system are not well established for environments under low water retention and soil fertility conditions. Our study aimed to evaluate the potential interactions between soybean-grass intercropping with residual nitrogen in a no-tillage system. The experimental design was a randomized block with four replications in a subdivided plot scheme. The main plots in the summer season were: 1) soybean monoculture; 2) soybean - Aruana Guinea grass (Megathyrsus maximus cv. Aruana) intercropping, and 3) soybean - Congo grass (Urochloa ruziziensis cv. Comum) intercropping. The subplots were the nitrogen rates of 0, 50, 100, and 150 kg ha^-1, applied as side-dressing in maize and grasses during the autumn-winter season. Here, the results of the summer seasons are shown. To do so, the parameters evaluated were soybean agronomic traits, dry biomass production, and macronutrient concentrations of plants intercropped. The main effects and interactions were studied. Our findings showed that soybean-Aruana Guinea grass intercropping is an alternative to no-tillage system implementation. Moreover, residual nitrogen from the autumn-winter season directly interfered with the dry biomass production of grasses intercropped with soybeans in the summer season. In short, the systems studied seem suitable for implementing a no-tillage system, which aims to neutralize degraded pastures and produce forage for ensilage. Despite the changes in macronutrient concentrations within the intercropping system and residual nitrogen, and among intercropped crops over the years, Congo grass intercropped with soybeans in the summer season showed great capacity for phosphorus, potassium, and magnesium cycling.

Keywords:
macronutrients in an intercropping system; Megathyrsus; soybean crop system; sustainable agricultural systems; Urochloa

[1] * Author for correspondence. E-mail: batistakarin@gmail.com

Cropping system		Nitrogen rates (kg ha^-1)					F test for regression
		0	50	100	150	Means	Linear	Quadratic
	First season				Second season
Plants height
Soybeans in monoculture	77.75 a	62.25 a	55.50 a	74.50 a	52.38 a	61.16 a	ns	ns
Soybeans intercropped witd Aruana Guinea grass	78.00 a	62.25 a	56.25 a	62.13 a	64.38 a	57.91 a	ns	ns
Soybeans intercropped witd Congo grass	101.75 a	48.88 a	66.00 a	50.00 a	67.63 a	61.47 a	ns	ns
Means		57.79	59.25	62.21	61.46		ns	ns
CV%	10.57^*	19.48^*
First-pod height
Soybeans in monoculture	16.75 a	20.68 a	35.18 a	29.30 a	16.68 a	25.46 a	ns	ns
Soybeans intercropped with Aruana Guinea grass	22.00 a	11.18 a	29.78 a	37.88 a	23.33 a	25.34 a	ns	0.0189
Soybeans intercropped with Congo grass	18.25 a	9.38 a	13.75 a	17.90 a	27.00 a	16.78 a	ns	ns
Means		13.75	26.24	28.36	22.34		ns	ns
CV%	11.52^*	27.33^*
Plant number per meter
Soybeans in monoculture	3.25 a	2.00 a	1.00 a	2.00 a	1.00 a	1.50 a	ns	ns
Soybeans intercropped with Aruana Guinea grass	3.25 a	1.00 a	2.00 a	1.50 a	1.00 a	7.88 a	ns	0.0121
Soybeans intercropped with Congo grass	2.50 a	1.75 a	1.50 a	2.25 a	1.25 a	5.50 a	ns	ns
Means		1.58	1.5	1.92	1.08		ns	ns
CV%	18.23^*	16.17^*

Cropping system		N rates (kg ha^-1)					F test for regression
		0	50	100	150	Means	Linear	Quadratic
Soybean dry biomass production at flowering	First season	Second season
Soybeans in monoculture	181.60 ab	111.11 a	83.33 a	205.56 a	166.67 a	141.67 a	ns	ns
Soybeans intercropped witd Aruana Guinea grass	322.22 a	61.11 a	55.56 a	127.78 a	44.44 a	72.22 a	ns	ns
Soybeans intercropped witd Congo grass	74.66 b	194.44 a	96.30 a	118.52 a	316.67 a	181.48 a	ns	ns
Means		122.22	157.41	140.74	175.93		ns	ns
CV%	22.04^*	26.28^**
Soybean dry biomass production at harvesting for ensiling
Soybeans in monoculture	338.89 a	116.31 a	77.95 a	117.75 a	24.52 a	84.13 a	ns	ns
Soybeans intercropped with Aruana Guinea grass	368.51 a	40.48 a	46.84 a	53.18 a	74.98 a	53.87 a	ns	ns
Soybeans intercropped with Congo grass	216.66 a	47.49 a	165.81 a	60.63 a	79.59 a	88.38 a	ns	ns
Means		68.09	96.87	77.19	59.70		ns	ns
CV%	14.99^*	18.91^**
Grass dry biomass production at flowering
Soybeans intercropped with Aruana Guinea grass	2382.61 a	4394.43 a	4380.92 a	5433.32 a	4132.13 a	4585.20 a	ns	ns
Soybeans intercropped with Congo grass	4466.67 a	3441.76 a	3535.10 a	4659.28 a	4664.95 a	4075.27 a	ns	ns
Means		3482.75	3523.79	4496.71	3926.48		0.0287	ns
CV%	31.44^*	2.13^**
Grass dry biomass production at harvesting for ensiling
Soybeans intercropped with Aruana Guinea grass	4292.45 a	5034.37 a	3868.26 a	5913.28 a	7293.23 a	5527.28 a	ns	0.0011
Soybeans intercropped with Congo grass	5699.96 a	4401.15 a	5847.59 a	5396.64 a	5113.07 a	5189.61 a	ns	ns
Means		4193.56	4323.71	5037.74	5530.58		ns	ns
CV%	16.66^*	2.60^**

Cropping system		N rates (kg ha^-1)					F test for regression
		0	50	100	150	Means	Linear	Quadratic
	First season	Second season
Nitrogen
Soybeans in monoculture	28.00 a	36.24 a	37.20 ab	33.84 a	29.52 a	34.20 a	ns	0.0301
Soybeans intercropped with Aruana Guinea grass	29.75 a	36.00 a	41.76 a	38.34 a	34.08 a	37.55 a	ns	0.0112
Soybeans intercropped with Congo grass	28.70 a	37.08 a	28.80 b	37.44 a	33.84 a	34.29 a	ns	ns
Means		36.44	35.92	36.54 a	32.48		ns	ns
CV%	4.28	9.44
Phosphorus
Soybeans in monoculture	2.64 a	3.40 a	3.77 a	3.10 a	2.70 a	3.24 a	0.0036	ns
Soybeans intercropped with Aruana Guinea grass	2.71 a	3.10 a	3.40 a	3.30 a	3.53 a	3.33 a	ns	ns
Soybeans intercropped with Congo grass	2.73 a	3.13 a	3.07 a	3.46 a	3.23 a	3.22 a	ns	ns
Means		3.21	3.41	3.29	3.16		ns	ns
CV%	3.84	10.37
Potassium
Soybeans in monoculture	22.65 a	22.73 a	19.36 a	18.03 a	15.70 b	18.96 a	0.0010	ns
Soybeans intercropped with Aruana Guinea grass	23.98 a	21.20 a	21.25 a	20.15 a	19.13 ab	20.43 a	ns	ns
Soybeans intercropped with Congo grass	23.05 a	22.17 a	19.57 a	18.05 a	23.67 a	20.86 a	ns	0.0002
Means		22.03	20.06	18.74	19.50
CV%	10.24	11.90
Calcium
Soybeans in monoculture	7.13 a	7.93 b	7.60 a	8.33 a	10.90 a	8.69 a	ns	0.0052
Soybeans intercropped with Aruana Guinea grass	7.50 a	9.80 a	7.60 a	7.45 a	8.23 b	8.27 ab	ns	0.0001
Soybeans intercropped with Congo grass	7.43 a	6.77 b	8.43 a	8.10 a	6.80 c	7.53 b	ns	0.0085
Means		8.17	7.88	7.96	8.64		ns	ns
CV%	6,65^*	10.32
Magnesium
Soybeans in monoculture	5.05 a	6.15 a	5.24 b	5.82 a	4.71 b	5.48 b	0.0241	ns
Soybeans intercropped with Aruana Guinea grass	5.09 a	6.73 a	6.43 a	5.91 a	5.89 a	6.24 a	0.0412	ns
Soybeans intercropped with Congo grass	5.51 a	5.93 a	5.60 ab	5.82 a	5.81 a	5.79 ab	ns	ns
Means		6.27	5.76	5.85	5.47		ns	ns
CV%	9.32	8.15
Sulfur
Soybeans in monoculture	1.85 a	2.13 a	2.30 a	1.63 b	1.30 b	1.84 a	0.0003	ns
Soybeans intercropped with Aruana Guinea grass	2.15 a	1.80 b	2.10 a	1.95 a	1.80 a	1.91 a	ns	0.0009
Soybeans intercropped with Congo grass	1.90 a	1.83 b	1.80 a	1.90 ab	2.03 a	1.89 a	ns	ns
Means		1.92	2.07	1.83	1.71		ns	ns
CV%	8.48	9.18

Cropping system		N rates (kg ha^-1)					F test for regression
		0	50	100	150	Means	Linear	Quadratic
	First crop	Second crop
Nitrogen
Soybeans intercropped with Aruana Guinea grass	16.80 a	17.46 a	14.58 a	16.56 a	18.00 a	16.65 a	ns	ns
Soybeans intercropped with Congo grass	17.50 a	16.38 a	18.00 a	15.30 a	18.54 a	17.06 a	ns	ns
Means		16.92	16.29	15.93	18.27		ns	ns
CV%	9.72	9.44
Phosphorus
Soybeans intercropped with Aruana Guinea grass	1.38 a	1.60 a	1.35 b	1.53 a	1.48 a	1.49 b	ns	ns
Soybeans intercropped with Congo grass	1.78 a	1.75 a	2.10 a	1.88 a	1.83 a	1.89 a	ns	ns
Means		1.68	1.73	1.70	1.65		ns	ns
CV%	9.44	10.37
Potassium
Soybeans intercropped with Aruana Guinea grass	17.05 b	16.55 a	16.20 a	15.73 a	14.68 a	15.79 b	ns	ns
Soybeans intercropped with Congo grass	21.98 a	21.275 a	19.45 b	17.23 a	20.45 a	19.60 a	ns	ns
Means		18.91	17.83	16.48	17.56		ns	ns
CV%	8.30	11.90
Calcium
Soybeans intercropped with Aruana Guinea grass	3.28 a	4.30 a	4.05 b	3.88 a	3.90 a	4.03 a	ns	ns
Soybeans intercropped with Congo grass	3.80 a	3.80 a	5.70 a	4.75 a	4.13 a	4.59 a	ns	0.0009
Means		4.05	4.88	4.31	4.01		ns	ns
CV%	11.81	10.32
Magnesium
Soybeans intercropped with Aruana Guinea grass	4.65 b	5.60 a	5.10 b	4.75 a	5.15 a	5.15 b	ns	ns
Soybeans intercropped with Congo grass	5.59 a	5.39 a	6.42 a	5.95 a	5.56 a	5.83 a	ns	ns
Means		5.49	5.76	5.35	5.36		ns	ns
CV%	6.41	8.15
Sulfur
Soybean + Aruana Guinea	1.63 a	1.78 a	1.30 a	1.25 a	1.08 a	1.35 a	0.0099	ns
Soybeans intercropped with Congo grass	2.13 a	1.40 a	2.10 a	1.60 b	1.45 a	1.64 a	ns	ns
Meanes		1.59	1.70	1.43	1.26		ns	ns
CV%	7.92^*	9.18

Brasil

Brasil

Potential interaction of soybean-grass intercropping with residual nitrogen for a no-tillage system implementation

ABSTRACT.