GREENHOUSE GAS EMISSIONS AND CHEMICAL AND PHYSICAL SOIL ATTRIBUTES OF OFF-SEASON AGRICULTURAL PRODUCTION SYSTEMS IN THE SAVANNAH OF MARANHÃO STATE, BRAZIL

Brito, Lucélia de C. R. de; Souza, Henrique A. de; Deon, Diana S.; Souza, Ivanderlete M. de; Santos, Smaiello F. da C. B. dos; Sobral, Amanda H. S.

doi:10.1590/1809-4430-Eng.Agric.v43n2e20220181/2023

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Scientific Paper • Eng. agríc. 43 (2) • May 2023 • https://doi.org/10.1590/1809-4430-Eng.Agric.v43n2e20220181/2023 copy

GREENHOUSE GAS EMISSIONS AND CHEMICAL AND PHYSICAL SOIL ATTRIBUTES OF OFF-SEASON AGRICULTURAL PRODUCTION SYSTEMS IN THE SAVANNAH OF MARANHÃO STATE, BRAZIL

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Management of agricultural production systems interferes with greenhouse gases (GHG) emissions, thereby altering physical, chemical, and biological attributes of soil; therefore, it is important to understand the relationship between soil attributes and GHG emissions. This study evaluated GHG emissions and their relationship with soil attributes in off-season soybean, maize, brachiaria and eucalyptus production systems. The experiment was carried out in Brejo, Maranhão, Brazil, with soybean ( Glycine max ), maize ( Zea mays ), brachiaria ( Urochloa ruzizienses ), and eucalyptus ( Eucalyptus grandis ). Fluxes of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) were evaluated using air samples analyzed by gas chromatography. Soil attributes were ammonium and nitrate contents, total organic carbon, moisture, pH, density, total porosity, and water-filled pore space. N₂O flux was 287.1 µg m^-2 h ^-1 for eucalyptus cultivation, while areas cultivated with soybeans, maize and brachiaria had influxes of 46.7, 7.2, and 13.17 µg m^-2 h^-1, respectively. In the off-season, the highest emissions of N₂O and CO₂ were measured in eucalyptus areas due to soil moisture and porosity conditions provided by accumulation of litter on the soil surface.

Cerrado; Carbon dioxide; Methane; Nitrous oxide

Depth	pH	OM	P	K	Na	Ca	Mg	Al	H+Al	SB	CEC	BS
cm	(H₂O)	g kg^-1	mg dm^-3	---------------------- cmol_c dm^-3 --------------------								%
0-20	5.6	29	17	0.31	0.09	8.7	1.3	0.08	7.8	10.31	18.1	57
20-40	5.4	32	11	0.28	0.09	8.1	1.1	0.10	8.9	9.48	18.4	52

	Cu	Fe	Mn	Zn	Coarse Sand	Fine Sand	Clay	Silt	Classification

	----- mg dm^-3 ----				-------------------- % ------------------
0-20	0.2	22.3	6.9	0.6	25.0	36.1	18.6	20.4		Sandy loam
20-40	0.3	34.0	5.2	0.6	26.4	25.0	20.6	28.1

Management history and description
Soybean ( Glycine max )
In 2017, maize ( Zea mays ) was intercropped with brachiaria ( Urochloa ruziziensis ). The forage was broadcasted at the rate of 5 kg ha^-1. Basal fertilization consisted of 260 kg ha^-1 of 13-33-08 applied to planting furrows and 280 kg ha^-1 of 08-00-36 as topdressing when maize plants had four leaves (four-leaf stage) and 150 kg ha^-1 of polymerized urea, also as topdressing, at eight-leaf stage. After maize harvest, brachiaria plants remained in the area until desiccation in January 2018 for soybean sowing at a spacing of 0.5 m between plant rows for a population of 200,000 plants ha^-1 (cultivar AN 83022 SC Conventional). Following soybean harvest (May 2018), pearl millet seeds were broadcasted at rate of 20 kg ha^-1 of seeds. Basal fertilization in soybeans consisted of 165 kg ha^-1 of 09-46-00 (monoammonium phosphate) and 300 kg ha^-1 of 10-00-30 as topdressing (30 days after planting).
Maize ( Zea mays )
In 2017, the area was cultivated with sorghum ( Sorghum bicolor ) with basal fertilization consisting of 260 kg ha^-1 of 13-33-08 applied to planting furrows and 280 kg ha^-1 of 08-00-36 as topdressing at four-leaf stage and 150 kg ha^-1 of polymerized urea also as topdressing at eight-leaf stage. After harvesting, crop residues were used as straw for the following harvest. In 2018, maize was sown with rows spaced at 0.5 m apart for a stand of 60,000 plants ha^-1. At sowing, 280 kg ha^-1 of NPK 13-33-08 were used, and the first topdressing fertilization was performed at four-leaf stage by applying 280 kg ha^-1 of 10-00-30. The second topdressing fertilization was carried out at four-leaf stage, applying 100 kg ha^-1 of polymerized urea. Maize harvest took place in June 2018.
Brachiaria ( Urochloa ruzizienses )
In 2017, the area was cultivated with sorghum ( Sorghum bicolor ) and basal fertilization consisted of 260 kg ha^-1 of 13-33-08 in planting furrows and 280 kg ha^-1 of 08-00-36 as topdressing at four-leaf stage and 150 kg ha^-1 of polymerized urea as topdressing at eight-leaf stage. In January 2018, desiccant was applied to plants growing on the area. Approximately 20 days after desiccant application, brachiaria was broadcasted using 8 kg ha^-1 of seeds at a cultural value of 30%, without fertilization.
Eucalyptus ( Eucalyptus grandis )
Eucalyptus seedlings were transplanted in January 2017, in triple rows (4 m between rows and 3 m between plants), in the East-West direction. The spacing between rows was 28 m and the row length was 150 m. Between tree rows, soybeans and maize were cultivated. Eucalyptus implantation was accompanied by soil amendment and fertilizer application following recommendations by Sousa and Lobato (2004).

	N₂O	CH₄	CO₂	NO₃ ^-	NH₄₊	Moist	pH	TOC	Ts	Tair	Tch	BD	TP
CH₄	0.01
CO₂	0.87*	0.04
NO₃ ^-	0.0	-0.26	0.12
NH₄⁺	-0.12	-0.15	-0.04	0.61*
Moist	0.38	0.04	0.47*	0.03	0.22
pH	0.35	0.19	0.33	0.13	-0.16	-0.05
TOC	0.01	-0.51*	0.10	0.23	0.51*	0.2	-0.03
Ts	0.38	-0.51*	0.45*	0.09	-0.06	-0.08	0.13	0.29
Tair	-0.01	-0.02	-0.02	-0.25	-0.38	-0.24	0.19	-0.33	0.57*
Tch	0.32	-0.44	0.38	0.02	-0.15	-0.12	0.15	0.17	0.98*	0.72
BD	-0.35	0.39	-0.17	-0.34	-0.35	-0.24	-0.3	-0.12	-0.12	0.01	-0.10
TP	0.29	-0.26	0.06	0.29	0.24	0.25	0.28	-0.11	-0.05	0.02	-0.04	-0.96*
WFPS	0.16	0.16	0.39	-0.04	0.15	0.86*	-0.16	0.27	-0.07	-0.24	-0.12	0.24	-0.25

Attributes	PC1	PC2
N₂O	0.40	0.13
CH₄	0.11	-0.29
CO₂	0.37	0.19
NO₃ ^-	-0.06	0.46
NH₄⁺	-0.21	0.40
Moist	0.33	0.20
pH	0.38	-0.18
TOC	-0.13	0.41
Ts	0.11	0.08
Tair	0.05	-0.33
Tch	0.10	-0.02
BD	-0.40	-0.15
TP	0.38	-0.12
WFPS	0.21	0.32

Eigenvalues	5.62	4.64
Total variance (%)	40.2	33.2
Accumulated variance (%)	40.2	73.4

Associação Brasileira de Engenharia Agrícola SBEA - Associação Brasileira de Engenharia Agrícola, Departamento de Engenharia e Ciências Exatas FCAV/UNESP, Prof. Paulo Donato Castellane, km 5, 14884.900 | Jaboticabal - SP, Tel./Fax: +55 16 3209 7619 - Jaboticabal - SP - Brazil
E-mail: revistasbea@sbea.org.br

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[1] * Corresponding author. Federal University of Piauí/Teresina - PI, Brazil. E-mail: lucelia_cassia@yahoo.com.br | ORCID ID: https://orcid.org/0000.0001.5137.9610