A low nitrogen fertiliser rate in oat–pea intercrops does not impair N2 fixation

Abstract

Intercropping is commonly used in low-input systems but could also be a strategy for higher input systems. Three ratios of substitutive oat–pea intercrops were tested on a fertile soil in eastern Austria with application of a low nitrogen (N) fertiliser rate (6 g N m−2) versus an unfertilised control to assess the effect of intercropping and low N fertilisation on dinitrogen fixation (NFIX). The above-ground dry matter (AGDM) and N yield of intercrops increased with N fertilisation, but the increase occurred only in oat, while pea was not affected by N fertilisation. Pure pea stands and intercrops with high pea share resulted in N sparing in the soil at harvest, as the soil mineral N was higher than in pure oat. Half of the applied amount of N was recovered by the AGDM of crops and half remained in the soil at harvest. The NFIX per unit area was highest in pure pea. Intercropping considerably reduced NFIX, especially in intercrops with low pea share. NFIX per unit of AGDM of pea, however, was neither affected by intercropping nor by N fertilisation. Consequently, a low amount of N fertilisation of oat–pea intercrops on a fertile soil can increase overall performance of the system through increasing the performance of oat without impairing that of pea.

Keywords

• avena sativa
• pisum sativum
• dinitrogen fixation
• nitrogen yield
• nitrogen sparing