Escoamento superficial em Latossolo Amarelo distrófico típico sob diferentes agroecossistemas no nordeste paraense

In the watershed of the Timboteua and Buiuna streams in the State of Para, the effect of land use change and soil management on the runoff rates was evaluated. Eighteen experimental plots (1 m(2)) were established, three in each one of the six evaluated agroecosystems as follows: i) 20 years Secondary vegetation ("Capoeira") (CP), ii) Agroforestry system / slash-and-burn (SQ), iii) Agroforestry system / chop-and-mulch (ST), iv) Cassava crop / chop-and-mulch (RT), v) Cassava crop / slash-and-burn (RQ), vi) Cattle pasture / slash-and-burn (PQ). Nearby these plots two rain gauges and three rainwater collectors for monitoring of precipitation were also installed. Along 2010 rainy season 234 samples were collected on 26 different dates. A strong correlation was found between precipitation and runoff, being the highest value of 54.53% of total volume of superficial flow for Cattle pasture degraded and lowest of 1.11% for Agroforestry system that was under recovery for 7 years after burning. The runoff decreased in agroecosystems with lower percentage of organic material in relation to systems with higher percentage.