Quantitative effect of fumigation with 1,3-dichloropropene mixtures and with metham sodium on the soil nitrogen status

Abstract

It is a well-known fact that soil fumigation with 1,3-dichloropropene mixtures and metham sodium influences the nitrogen status of the soil. Fumigation gives a partial sterilization of the soil. Lysis of the killed biomass provides the surviving flora with new substrate which leads to an extra mineralisation, the so-called flush. The gain in nitrogen is approx. 5–10 kg N/ha. The inhibition of the process of nitrification retards the conversion of ammonium nitrogen, which is strongly adsorbed to the soil, to nitrate. In agriculture, soil fumigation normally takes place in autumn. The gain in nitrogen in spring after autumn fumigation can be attributed to a reduction in loss of nitrogen by diminished leaching and diminished denitrification of nitrate. The gain in nitrogen depends on the rate of mineralisation, time of recovery of nitrification and weather conditions during the winter. Important factors are also type of soil and date of fumigation. The differences between 1,3-dichloropropene mixtures and metham sodium can be attributed to their different behaviour towards the nitrifiers.