INFLUENCE OF AMMONIACAL FERTILIZERS IN THE MAIN ROOT BRANCHING OF CARROT (Daucus carota L.)

Abstract

Misshape of carrot roots can be incited by soil agents, like badly prepared soil and nematodes or by ammonium fertilizers. RALEIGH (Knott), cited by SILVA, found that ammonium fertilizers can kill the root and consequently cause malformation. The preference of sodium nitrate or other non-ammonium fertilizers is widely spread in Brazilian literature about carrot. MALAVOLTA (1967) even recommends only small quantities of manure to prevent root damage. REGINA (1964) advises against use of ammonium sulphate and other ammonium fertilizers for the same reason. CAMARGO (1963) also prefers sodium nitrate but mentions the possibility of substitution by ammonium sulphate, too. Although, it was impossible to find any original experimental information about, in Brazilian literature. The sodium nitrate is imported by Brazil from Chile and is therefore almost five times more expensive than ammonium sulphate, in spite of its lower nitrogen content. This trial investigated four sources of nitrogen: ammonium sulphate, sodium nitrate, urea and manure. The quantities applied were higher than MALAVOLTA recommends for carrot. The results don't show any significant difference between treatments, neither in ramification frequence nor in yield. The variety used was a cone-shaped carrot, named London. Other varieties possibly are susceptible to malformation of root by ammonium fertilizers. This will be investigated in further experiments.