Banca de DEFESA: DIANA VALADARES PESSOA
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.STUDENT : DIANA VALADARES PESSOA
DATE: 25/05/2022
TIME: 14:00
LOCAL: Google meet
TITLE:
DYNAMICS OF LITTER AND ORGANIC SOIL MATTER IN A SILVIPASTORY AND MONOCULTIVE SYSTEM IN AGRESTE DE PERNAMBUCOKEY WORDS:
Intercropping, Mimosa caesalpiniifolia Benth, Urochloa decumbens Stapf., decomposition, soil, nutrients.
PAGES: 83
BIG AREA: Ciências Agrárias
AREA: Zootecnia
SUBÁREA: Pastagem e Forragicultura
SPECIALTY: Manejo e Conservação de Pastagens
SUMMARY:
Silvopastoral systems correspond to the exploitation of trees, swards, and cattle in an integrated way. This study aimed to evaluate the dynamics of litter and soil organic matter in silvopastoral systems composed of palisade grass (Urochloa decumbens Stapf.) and sabiá (Mimosa caesalpiniifolia Benth.), besides their respective monocropping systems during the trees’ establishment phase. Treatments were distributed in randomized complete block design with three repetitions. Litter deposition was assessed in a two-year trial, and leaf decomposition was measured in both legume and grass, until 512 days, in monocropping and silvopastoral systems (between rows, at a 2-m distance). Moreover, the contents and stocks of C and N, besides microbial biomass and soil density and organic matter fractionation were evaluated in the silvopastoral system considering distances of 0, 2, 4, and 6 m from double-rows, and in the monocropping system too. Soil samplings were made at the implantation of silvopastoral system (16 months after tree planting = one year), one year later (two years), and two years later (three years), on soil layers of 0-10, 10-20, and 20-40 cm. The greatest total (531.9; 347.9; 201.6 kg ha-1) and leaf deposition of litter (425.3; 235.9; 130.5 kg ha-1) were observed in monocropping system, between double-rows (0 m) and at a 2-m distance. Greater total deposition and those of leaves, stems, and miscellaneous, besides litter contents of organic and mineral matter, calcium, potassium, and contributions of all nutrients, were verified in the dry season. Conversely, the greatest C content of litter was found in rainy season. The Mg content of litter was greater at a 2-m distance from the tree double-row. Regarding litter decomposition, the remaining biomass from each species was not influenced by cropping systems, but it decreased exponentially during the incubation period. The content of remaining N increased while C/N ratio and C content reduced during the incubation period. About the chemical composition of remaining litter, greater remaining N was verified in palisade grass under the monocropping system (10.13 g kg-1 OM). In the silvopastoral system, contents of C (438.23) and lignin (225.68), and lignin/N ratio (39.77) of palisade grass were greater between tree double-rows while the C/N ratio was higher at 2 m from this double-row. Concerning the chemical composition of remaining litter from sabiá, the N content was greater between double-rows (22.06 g kg-1 OM) and at 2-m distance (22.52 g kg-1 OM) compared to the legume’s monocropping. Conversely, the C/N ratio (21.79) was higher in the monocropping system. Fiber fractions like NDF, ADF, and lignin increased throughout incubation time. Sabiá monocropping displayed greater contents and stocks of N compared to palisade grass pasture, but without differences regarding the silvopastoral system. At the beginning of silvopastoral system implantation, there was a higher content of microbial carbon in the soil (419.09 mg kg-1). Soil density was greater in one-year sampling, while a reduction was verified in the two-year sampling, mainly at the 40-cm soil layer. In the second year of implantation, there were increases in C contents (7.80, 7.57, and 7.22 g kg-1), and C stocks (9.18; 8.38; 14.18 Mg ha-1) compared to the first year, in all soil layers. Intercropping between Mimosa caesalpiniifolia Benth. and Urochloa decumbens Stapf., in silvopastoral systems, can produce more stable organic matter and constant return of soil nutrients because these species provide different compositions to the litter. Furthermore, using sabiá in this system showed the potential to increase both contents and stocks of soil nitrogen, and after two years, to increase considerably carbon stocks.
BANKING MEMBERS:
Presidente - 3514546 - MARCIO VIEIRA DA CUNHA
Interno - 3091000 - VALDSON JOSE DA SILVA
Externa ao Programa - 1929733 - GISELLE GOMES MONTEIRO FRACETTO
Externo ao Programa - 330722 - ALBERICIO PEREIRA DE ANDRADE
Externo à Instituição - JOSÉ DE PAULA OLIVEIRA - IPA