Results are presented of nitrogen input via bulk precipitation over a two-year period, to coastal fynbos vegetation occurring on soils of low nutrient status. The annual precipitation recorded during the study periods of 1980 -81 and 1981-82 was 381 mm and 466 mm respectively which was below the 40-year mean of 577 mm recorded for the area. Total nitrogen in put during 1980-81 was 1,99 kg N ha -1 y-1 . Of this 1,12 kg N ha -1 y -1 was inorganic nitrogen in the form of N03-N and NH 4 -N.

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... c N input occurred predominantly in the winter rainfall months of June to August. Inorganic N input during 1981-82 was 1,79 kg N ha -1 y -1 with an NH4-N to N03-N quotient of 1. Logarithmic relationships exist between N03-N and NH 4 -N concentrations in bulk precipitation and the vo lume of precipitation co ll ected at weekly intervals. Bulk precipitation col lectors at 1,5 m and 4 m were not suitable to determine the infuence of local recycling of dust aerosols. It is probable that although atmospheric N deposition may contribute a portion of the extra-system N, it alone is not sufficient to replenish N lost by coastal fynbos ecosystems as a result of recurrent short interval fires . Rather the low input of nitrogen to the Pella site reported gives an indication of the levels of N deposition to be expected in the fynbos region where N is derived mainly from oceanic sources and few anthropogenic activities influence precipitation composition. S. A fr. J. Bot. 1986, 52: 273-276 Resultate van stikstoftoevoer deur massa-neerslag oor 'n twee-jaartydperk aan kus-fynbos wat voorkom in grand arm aan voedingstowwe, word aangebied. Die jaarlikse neerslag aangeteken gedurende die studie-periodes van 1980-81 en 1981-82 was 381 mm en 466 mm onderskeidelik en minder as die gemiddelde 577 mm vir die area oor 40 jaar. Die totale stikstoftoevoer gedurende 1980 -81 was 1,99 kg N ha-1 j -1 . Hiervan was 1,12 kg N ha-1 j -1 organiese stikstof in die vorm van N03-N en NH4-N. Anorganiese Ntoevoer het hoofsaaklik gedurende die nat maande van Junie -Augustus plaasgevind. Anorganiese N-toevoer gedurende 1981-82 was 1,79 kg N ha-1 j-1 met 'n NH 4 -N tot N0 3 -N-kwosient van 1. Logaritmiese verhoudings bestaan tussen N03-N-en NH4-Nkonsentrasies in massa-neerslag en die volume van neerslag wat met weeklikse tussenposes versamel is. Massaneerslag-versamelaars by 1,5 men 4 m was nie geskik om die invloed van plaaslike hergebruik van stat-aerosols te bepaal nie. Alhoewel atmosferiese Nneerslag mag bydra tot die buite-sistemiese N, is dit by sigself onvoldoende om die N wat uit kusfynbos-ekosisteme verlore raak deur die gedurige korttermyn-voorkomste van brande, te vervang. Die redelik lae toevoeg in g van stikstof in die Pella-gebied gee 'n aanduiding van die stikstofvlakke wat verwag kan word in die fynbos-gebiede waar N hoofsaaklik van oseaan-bronne afhanklik is en min antropogeniese bedrywighede die samestelling van die neerslag bernvloed . S.-Afr. Tydskr. Plantk. 1986, 52: 273-276