Atributos físicos de solo arenoso de uma cronossequência lavoura-florestas secundárias na Amazônia Oriental

Abstract

Due to the low availability of resources, much of family agriculture adopts the practice of cutting and burning vegetation for the preparation of agricultural areas in the Amazon. In this system, the soil is grown until the minimum fertility. The fallow has been adoptedfora limited period in many areas of agriculture in the Amazon, which has caused serious damageto the quality of the soil, such as significant reduction (up to 50%) of soil organiccarbonstocks, decreasing its potential agricultural. This problem is even more serious in sandysoils,which are characterized by a weak or nonexistent structure. In order to avoid the degradation of these soils and favor satisfactory productivities, it is essential to carry out adequatemanagement practices. In this context, it was aimed to evaluate the influence of thelandingtime on organic matter and the physical attributes of the sandy soil of an agricultural-forestscropry with different agricultural agricultural agriculture in the periurban region of Bethlehemin the Eastern Amazon. 100 deformed samples and 100 indefined samples were collectedinthe 0-5, 5-10, 10-20 and 20-40 cm of five areas: four areas under secondary forests composedof natural regeneration with different ages (RN02, RN05, RN10 and RN20), and cassavaplanting area (agri-0 years), located in the Red April settlement. The variables were measured:total porosity (PT), macro and microporos (MAC and MIC), soil density (DS), granulometry, organic carbon (CO), and water available (AD) and water retention curves in soil (CRAS) were characterized. The results were compared by Student's t-test with Bonferroni correction.The results of the fringulometric analysis demonstrated that there is a predominanceof sandcontents, with textured classes ranging from frank sand and sand. The organic carboncontentswere not affected by the time of fallow. Physical parameters (DS, PT, Mac, MICandAD)also did not present significant differences in the Test T-test, however as the depths, it is perceived that in the deeper layers there is higher density (DS) and lower total porosity, with decreased Mac and MIC increase, evidencing greater water retention in the subsurfacelayers below 5 cm. In all depths there are low available water contents (AD). The lack of significant differences within the correspondence may be related to the small sample number (n=5) andnon-controlled environmental factors in the area.