Biological nitrogen fixation to maximize productivity of intercropped legumes and non‐legumes: Ten years of field experimentations in semi‐arid deserts of egypt

Abstract

A number of field trials was executed in semi‐arid deserts of Ismailia, Egypt, to experiment growth and productivity of sole or mixed canopies of legumes (soybean, leucaena, sesbania, berseem and grasspea) and non‐legumes (corn, Rhodes grass, elephant grass, ryegrass and barley) when inoculated with N₂‐fixing bacteria (diazotrophs) in presence or absence of N fertilizers. An average estimate of > 20 Kg N acre⁻¹ was transferred to neighbouring unfertilized corn, and land equivalent ratio (LER) reached 1.35. Rhodes grass mixed with sesbania or leucaena produced higher biomass yield compared to pure N‐fertilized stands; increases of 66–91% and 22–29% were reported for inoculated and non‐inoculated plants respectively. In mixed canopy with berseem, dry matter yield of the non‐legume partner increased compared to that in pure stands, being higher for barley (120–255%) compared to ryegrass (62–115%). Similar trends were scored with N yield. Response of elephant grass to inoculation with associative diazotrophs was more pronounced when intercropped with leucaena as increases over pure stand in dry matter production approximated 40%. On the other hand, both grasspea and barley were negatively affected by intercropping. Total biomass and N‐yields of barley were more affected than grasspea.

Keywords:

• Forage crops
• Nitrogen‐fixation
• Intercropping
• Desert
• Semi‐arid
• Bio‐fertilization

Notes

Address for correspondence: Environmental Studies and Research Unit (ESRU), Faculty of Agriculture, Cairo University, 12613 Giza, Egypt. Tel/Fax: [phone], e‐mail: [email protected]