The study involved two consecutive experiments on the same area at Camden, New South Wales, 34°S. In the first, the intercropping experiment, nitrogen was applied at the rate of 0, 25, 50 and 100 kg N ha −1 to maize alone (M), maize + soybean (MS), and maize + peanut (MP) intercropping patterns. In addition, soybeans alone (S) and peanuts alone (P) were grown without the addition of nitrogen, giving a total of 14 treatments. After harvesting the first experiment, above-ground plant material was removed, plots were rotary hoed and residual nitrogen was measured at sowing and after 15 weeks in a crop of wheat. Intercropping treatments gave relative yield totals as high as 1.4 at 0 kg N ha −1 fertilizer nitrogen. Maize grain yield was not affected by legume intercrop, indicating neither competitive depression nor nitrogen transfer from the legume. Intercropping depressed legume dry matter and grain yields at 0 kg N ha −1. In the residual nitrogen experiment, nitrogen uptake by wheat, considered the best criterion of residual nitrogen availability, was affected by cropping pattern. At 0 kg N ha −1 the values were M = 12, MS and MP = 19, S = 46 and P = 54 kg N ha −1, all significantly different at P × 0.05. Exchangeable soil nitrogen at sowing and at anthesis showed similar rankings although those at anthesis were lower than those at sowing. Fertilizer nitrogen had no effect on maize grain yield, but it increased maize total dry matter yield. There was no significant interaction between cropping pattern and fertilizer nitrogen. Fertilizer nitrogen affected nitrogen uptake by wheat at anthesis and exchangeable soil nitrogen at sowing but not at anthesis. The responses in exchangeable soil nitrogen at sowing, and in wheat nitrogen uptake at anthesis, to fertilizer nitrogen in the M treatments were linear, while those in the MS and MP treatments were quadratic, maximum value being attained by about 50 kg N ha −1. Nitrogen applied to intercropped legumes appeared inhibitory to nitrogen fixation, both directly from increased soil nitrogen and indirectly by stimulation of maize growth and shading of intercropped legumes. The data showed that a subsequent crop would benefit as much from following one of the maize + legume intercropping patterns to which no nitrogen had been applied as from following a maize crop to which 100 kg N ha −1 had been applied.