|Title||Over de afbraak van Ca-cyaanamide in den grond|
|Source||University. Promotor(en): J. Smit. - Wageningen : Veenman - 100|
|Publication type||Dissertation, internally prepared|
|Keyword(s)||bodem - calcium - nitrificatie - organische verbindingen - bodemchemie - derivaten - cyanen - soil - nitrification - organic compounds - soil chemistry - derivatives - cyanogens|
|Abstract||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.