Alluvial soil quality in agroforestry systems and native forest of the Brazilian semiarid region

The agroforestry systems consist of techniques appropriate to local conditions, taking into account the coexistence with the semiarid in Brazil. The objective of the research was to evaluate the soil properties in agroforestry management units (SAFs), and native forest, in Bueno community, city of Iraucuba, CE. Treatments were: (1) Agroforestry management unit SAF 1 in the elevated portion of the landscape (interfluve); (2) Agroforestry management unit SAF 2 in the portion of slope (colluvium), and (3) Native forest. Soil samples were collected: 5 composite samples, derived from 15 sub-samples in areas of study in the layers 0.00-0.10; 0.10-0.20; 0.20-0.30 and 0.30-0.40 m. It was a completely randomized design, with 5 repetitions, treatments (SAF 1, SAF 2 and native forest) and the plots being repetitions. The analysis of variance was applied and means submitted to Tukey test at 5%. There were significant differences for properties analyzed, except to CEes, indicating low concentration of soluble salts, without risks of salinity (0.25 a 0.34 dS m-1). The exchangeable sodium (9.51 a 29.88 mg dm-3), with normal values of PST (0.66 a 1.35%), in the SAF 2 differed from the others. The values of exchangeable sodium considered high are not characterized with restriction according to the normal EST. The units of SAF 1 and SAF 2 contributed to the maintenance of soil quality in top condition to MN, featuring high levels of calcium, magnesium and potassium, with restrictions to the exchangeable sodium SAF 1 and SAF 2 to a lesser extent to the native forest.   Key words: Iraucuba-CE, semiarid, caatinga, agroecology.