Two separate trials were carried out on different Northland soil types evaluating the most profitable nitrogen (N) product for use on wet soils. Each trial had three randomly allocated replicates of four treatments. The four treatments included ammonium sulphate nitrate (ASN), sulphate of ammonia (SOA), urea and a control. All treatments received one dressing of 30 kg N/ha in mid winter. On the Wharekohe silt loam trial, SOA was the most profitable product, providing extra feed for 4.2 cents/kg dry matter (DM). Urea provided extra feed for 6.3 cents/kg DM and ASN provided extra feed for 7.3 cents/kg DM. On the marine clay trial, urea was the most profitable product, providing extra feed for 9.6 cents/kg DM, compared with 13.8 cents/kg DM for SOA and 27.5 cents/kg DM for ASN. For both trials it was evident that the ASN product was not as economic to use as either SOA on readily leachable soils or urea on nonsulphur- limiting soils under wet Northland conditions. Keywords: ammonium sulphate nitrate, economic response, marine clay, nitrogen, sulphate of ammonia, urea, wet soils, Wharekohe silt loam
