Yield components and nitrogen use in cereal-pea intercrops in Mediterranean environment

Intercropping is a cropping practice with the potential to increase the sustainability of the agricultural systems. Field pea has been largely studied in intercrop with wheat and barley in Northern and Central Europe whereas much less research has been carried out in semiarid environments of Southern Europe. A two-year field experiment was conducted in Southern Italy with the aim to assess yields and yield components and N use of field pea and four different cereals – wheat, barley, oat and triticale – grown in additive and replacement intercrop. The cereal was the dominant partner in intercrop, strongly outcompeting pea. Cereal height and biomass yield and intercrop density affected yield component parameters of pea causing a severe reduction of number of pods per plant and death of pea plants. Pea yields were generally lower in intercrop than in sole crop. Consequently, nitrogen accumulation in intercrop and Land Equivalent Ratio (LER) N yields-based values resulted negatively affected. LER values were highest in barley-pea intercrops for both grain and straw nitrogen yields. Cereal grain and straw N content increased in intercrop compared to the sole crop while pea grain N content was reduced. The results of this study indicate that cereal-pea intercropping can be a way of improving the grain and straw quality of the intercropped cereal and reducing N inputs into agricultural systems compared with the sole cropping. The choice of the companion cereal and the intercrop density should, however, be carefully evaluated in drought-prone environments like those of Southern Europe.