Over de afbraak van Ca-cyaanamide in den grond

J. Temme

Research output: Thesisinternal PhD, WU


The weed killer calcium cyanamide was also a slowly acting N fertilizer. It released N as urea, which was subsequently converted to ammonium carbonate and nitrate. The first phase was mainly physico-chemical involving hydrolysis to calcium hydroxide and cyanamide, which was then hydrolysed to urea. It was promoted by free H +in the soil and exceeded any possible microbiological action, as application initially caused a decrease in the soil microflora.
The second phase was microbiological; first urea was released. The herbicidal effect was due to the formation of dicyanodiamide and its decomposition products, which were toxic also to most micro-organisms. It formed at high pH (8-10) if the topdressing became moist. Nitrification was depressed in concentrations higher than 10% of total N. But the initial effect perhaps limited the proliferation of pathogens.

Apart from killing weeds, it might injure both crop and microflora, if not incorporated into the soil.

A method was developed of estimating the rate of ammonification and nitrification of calcium cyanamide for different soil samples and, thus, the amount of fertilizer needed for optimum effect.
Original languageDutch
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
  • Smit, J., Promotor, External person
Award date7 Feb 1946
Place of PublicationWageningen
Publication statusPublished - 1946
Externally publishedYes


  • soil
  • calcium
  • nitrification
  • organic compounds
  • soil chemistry
  • derivatives
  • cyanogens

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