The effects of different seeding rates on nitrogen acquisition in pea-wheat intercropping.

Intercropping may improve the use of environmental resources in low-input agricultural systems compared to sole crops and it is possible that risk may be reduced in intercropping, leading to more stable yields and weed control. The aim of the present study was to determine the effect of seeding rate of a normal leafed cultivar and a semileafless pea cultivar (Pisum sativum L.) grown as sole crops, cultivar mixture, and in double and triple intercrops with spring wheat (Triticum aestivum L.) on competitive dynamics, yield and use of nitrogen sources from soil, and symbiotic N2 fixation. A randomized complete blocks experiment design was used. The differences between the treatments were not significant for total grain yield. Land equivalent ratios for grain yield varied between 1.04 (80P/20W) and 1.40 (80D/20W), which showed that plant growth factors are used more efficiently by the intercrops than by the sole crops for grain production. Nitrogen accumulation was higher in pea sole crops compared to pea component crops in the intercrops, due to the decreased pea density and decreased pea growth caused by interspecific competition from wheat. The amount of N2 fixed in pea in the intercrops at the flowering harvest was less than the in the pea sole crop also due to competition from wheat for other growth factors than nitrogen, probably by shading. It was concluded that pea-wheat intercropping can use N resources more efficiently compared to sole crops in sustainable cropping systems. [ABSTRACT FROM AUTHOR]