SUPPLY OF NPK ELEMENTS THROUGH PRECIPITATION AND THROUGHFALL IN A COPPICE OF GREEN OAK IN THE EAST OF ALGERIA
Nutrient provisions through precipitation and throughfall represent major factor of the sustainability of the forest ecosystem. Nevertheless, data related to this aspect are non-existent in Algeria. Precipitation and throughfall volumes and their contributions in NPK elements were evaluated between 2012 and 2013, in a green oak coppice at Marconna in Aurès (eastern Algeria). Precipitation volumes were evaluated by the placement of 10 containers in a bare soil. To quantify the throughfall, four containers were installed under the canopy of each tree among 25 selected trees. Water samples taken from previously rinsed plastic bottles with distilled water were kept away from light and transported to the laboratory for volume estimation and chemical analysis, as quickly as possible. After rapid filtration, samples became ready for NPK analysis. Various devices and chemicals were used for the measurements of NPK elements in the laboratory. Kjeldahl's method, colorimetry and flame photometry were used for quantifying total nitrogen, phosphorus and potassium respectively. The results showed that annual rainfall amounts varied between 223,9 and 289,6 mm, whereas the annual throughfall was 127,1 mm for 2012 and 189,8 mm for 2013.Besides, the annual quantities of N, P and K returned to the soil by the rainfall ranged from 5,05 to 7,62 kg/ ha/year. However, the throughfall results showed that the coppice accumulated amounts of N, P and K elements varying between 4,08 and 5,47 kg / ha / year. On average, nitrogen was the most provided element. It represented 47,07%.