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LITTER AND MACRONUTRIENT DEPOSITION IN A STAND OF BLACK WATTLE (Acacia mearnsii De Wild.) IN THE STATE OF RIO GRANDE DO SUL, BRAZIL

ABSTRACT

This study evaluated litter and macronutrient deposition in a six year-old black wattle (Acacia mearnsii De Wild.) stand, in Butia-RS. Five plots (18mx24m) of litter were systematically allocated, each one with four trap collectors of 1 m2. The litter intercepted was collected monthly between January 2002 and December 2003. After collection, litter was divided into leaves, flowers, fruits and caterpillar (Adeloneivaia subangulata) feces, oven dried, weighed, milled and analyzed for N, P, K, Ca and Mg contents. The average annual litter deposition reached 4.32 Mg ha-1, and was composed of 75.5, 11.1, 11.2 and 2.2% of leaves, flowers, fruits and feces, respectively. Litter deposition was more concentrated in the spring. The higher deposition of nutrients was through the leaf fraction, which contributed annually with a great amount of litter biomass, although not showing the highest nutrient concentrations. The supply of total amount of macronutrients to the soil was of 74.8 of N, 26.8 of K, 23.1 of Ca, 7.9 of Mg and 2.4 of P (kg ha-1).

Keywords:
forest nutrition; nutrient cycling; forest plantation

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