Grain legumes, especially peas, could play a key role in organic cropping systems. They could provide nitrogen (N) to the system via N2 fixation and produce grain rich in protein while improving soil N for the succeeding crop. Thus, maximising N2 fixation and optimising grain N production together with N contribution to soil is a challenging issue for organic pea crops. However, pest, disease and weed infestation are less easy to control in organic systems than in conventional systems. Therefore, the effects of weed infestation and pea weevil (Sitona lineatus L.) attacks on N nutrition and N2 fixation of organic pea crops were examined by on-farm monitoring over two years. The magnitude of the net contribution of the crops to the soil N balance in relation... |