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Carbon and nitrogen stocks of soils under different land uses in Pernambuco state, Brazil

2019; Elsevier BV; Volume: 16; Linguagem: Inglês

10.1016/j.geodrs.2019.e00205

2352-0094

Mônica da Silva Santana, Everardo Valadares de Sá Barretto Sampaio, V. Giongo, Rômulo Simões Cézar Menezes, Kennedy Nascimento de Jesus, Eliza Rosário Gomes Marinho de Albuquerque, Diego Marcelino do Nascimento, Frans Germain Corneel Pareyn, T. J. F. Cunha, Raquel Menezes Bezerra Sampaio, Dário Costa Primo,

Soil erosion and sediment transport

Acrisols, Ferralsols, Leptosols and Planosols were sampled in layers down to 1 m under dense caatinga, open caatinga, pasture and agriculture. Agricultural Leptosols and Planosols had the lowest C and N concentrations among the land uses, although in some cases differences were not statistically significant. On average, conversion of dense caatinga to agriculture reduced C stocks from 63 to 47 Mg ha−1. Acrisols had the highest concentrations of C and N, and Planosols had the lowest concentrations and stocks. Conversion to pasture did not reduce stocks, but open caatinga also had lower C stocks (50 Mg ha−1) than dense caatinga. Nitrogen stocks did not differ among land uses, implying that losses are greater for C than for N. Despite the fact that the western portion of Pernambuco state covers 3% of the Brazilian semi-arid area, it stocks about 0.20 Pg of C (and 0.019 Pg of N), which represents 2% of the total estimated soil C stock in the semiarid region (8.9 Pg). Therefore, the stock per hectare in the west portion of Pernambuco is about one-third smaller than the stock per hectare in the whole Brazilian semiarid region, probably a consequence of the lower average C concentration in the 20 cm superficial layer, a higher proportion of agricultural fields and shallower depths of some soil classes in western Pernambuco than in the whole semiarid region.