Using Intercropping to Enhance Micro-Nutrient Concentrations in Crop Grains.

Many studies have confirmed that the intercropping can increase productivity, but few on the micronutrient, especially grain micronutrient concentrations that are closely related to human micro-element nutrition. The objectives of this study was to determine the micronutrient acquisition and grain concentrations in intercropping. A field experiment was established in 2009, which involved phosphorus fertilizer applications (0, 40 and 80 kg P ha^-1) and cropping systems (four intercropping of maize (Zea mays)/turnip (Brassica campestris), maize/faba bean (Vicia faba), maize/chickpea (Cicer arietinum) and maize/soybean (Glycine max), and five corresponding monocultures). The Fe, Mn, Cu and Zn concentrations were measured in grain and other organs of both intercropped and sole cropped species in 2013 and 2014. The results showed that grain Fe and Cu concentrations in the maize intercropped with chickpea were increased by 19.0% and 28.6%, respectively, grain Mn concentrations in the maize intercropped with all associated crops except for faba bean were increased by 14.3 - 25.7%, and grain Zn concentrations in the maize intercropped with turnip were decresed by 10.7-28.6%, compared with that in monocropped maize. The grain Fe, Zn and Cu concentrations in intercropped chickpea were increased by 26.3%, 12.8% and 15.4%, grain Zn and Cu concentrations in intercropped faba bean were increased by 10.6% and 7.5%, respectively, compared with those of corresponding monocultures. Above-ground Fe, Zn, Mn, Cu acquisition of all four intercropping was 30.0% to 32.6% greater than those of the weighted means of corresponding monocultures. Iron, Mn and Cu acquisition across of all cropping systems received P fertilizer applications (40 and 80 kg P ha^-1) was increased by 13.7-16.8%, 13.6-24.2%, 16.7-25.0 %, respectively, but Zn acquisition was decreased by 8.0-31.4%, compared to those without P application. Our findings suggest that intercropping could be a solution for improving human microelement nutrition if proper crops are combined.