BEZERRA, J. M.; http://lattes.cnpq.br/6945041178312614; BEZERRA, Joel Medeiros.
Résumé:
The progress of research contributes to the improvement of management techniques adopted
and, consequently, to a cultivation system with lower environmental impact and greater
sustainability. Accordingly, this research aims to evaluate the impact of the stock of the
temporal dynamics of carbon and nitrogen in a Ultisol cohesive with sugarcane cultivation with
previous straw burning for harvesting on soil properties. The experimental area is located in the
North Forest Zone in Goiana-PE municipality. Soil samples were performed in area
chronosequence cultivated with sugarcane, it is composed of eight plots with different
deployment times: zero time (Mata, strictly speaking), one, two, three, four, five, six and seven
years. 5 samples per field were performed in seven 0-5, 5-10, 10-20, 20-40, 40-60, 60-80 and
80-100 cm. To characterize the quality of soil physical properties were analyzed (particle size
and density), water (hydraulic conductivity, moisture, macro and microporosity) and chemical
(stock of carbon and nitrogen, and fertility). The attributes in the study were initially analyzed
by classical statistics to determine anomalous data and pattern of distribution of knowledge
subsequently applied multivariate analysis of hierarchical clustering and principal component,
allowing the evaluation of similarities and/or differences of the areas studied in addition to the
reduction of dependent variables on the variation of the data. The replacement of forest by
agricultural cultivation system of sugarcane with straw burning for manual harvesting promoted
decrease of about 50% in organic carbon stocks and total soil nitrogen. The largest carbon and
nitrogen stocks in all evaluated layers were statistically pronounced in forest area. The use of
multivariate techniques proved effective in environments of distinction about different times of
deployment of crop cycles of sugarcane in chronosequence, grouping the different times of
management as to the physical water and soil chemical attributes, which refers the importance
of long-term soil sustainability studies. From the sugarcane plant cultivation cycle was found
to change as water physical and chemical attributes of the soil, especially in the surface layers
0-40 cm. After seven years of evaluation of crops observed that soil characteristics tended
gradually to return the initial conditions of forest through lack of mobilization and soil
disturbance as can be seen in soca 5th and 4th year, mainly in layers 60-100 cm deep, to the
chemical and physical water, respectively.