Effects of intercropping of soybean with dragonhead on main nutrient efficiency nourished with organic and inorganic resources

  Intercropping defined as growing two or more crops simultaneously in the same field, considering for its more sustainability and higher yields compared to sole-cropping. More developed and distributed root systems besides efficient architecture may enhance uptake and efficiency of nutrients. Application of organic fertilizers, on the other hand reduces environmental pollution and lead to longer nutrients recycling in agricultural systems. Considering these issues, this study aimed to evaluate nutrient efficiency of dragonhead - soybean intercropping nourished with organic manure and chemical fertilizer. A RCBD factorial experiment with three replications was conducted at Shahrekord University research farm in 2016. Five sowing patterns include: Sole-cropping of soybean (S), sole cropping of dragonhead (D) and three intercropping ratios of them (S:D 2:1, 1:1, and 1:2) as first factor were evaluated at two fertilization sources (chemical fertilizer and broiler litter) as second factor. Dragonhead and soybean were harvested at flowering and maturity stages, respectively. Concentration of nitrogen, phosphorus, potassium, copper, iron, zinc and manganese were determined for each plot. Finally, uptake of nutrients was calculated by multiplying the concentration by yield. The relative crop yield and relative nutrients yield in intercropping were calculated. The analysis of variance for the obtained data was done by statistical analysis system (SAS V.9) software. The mean comparison was done using the least significant difference (LSD) test at the 5% probability level. The result showed that the maximum uptake of nitrogen (10.59 g.m-2) and phosphorus (1.79 g.m-2) were obtained in sole cropped soybean and dragonhead treated with organic manure, did not show significant difference with intercropped ratio of soybean: dragonhead (1:1). The highest uptake of potassium (14 g.m-2), iron (0.253 g.m-2), zinc (0.065 g.m-2) and manganese (0.080 g.m-2) were achieved in sole cropped dragonhead treated with organic manure too. While for copper the highest ones (0.0135 g.m-2) were obtained in sole cropped dragonhead under organic manure, showing no significant difference with soybean: dragonhead (1:2) ratio under organic manure. The highest relative yield of nitrogen (1.04), phosphorus (1.09) and iron (1.03) was obtained in soybean: dragonhead (1:1) under organic manure. The greatest relative yield of potassium (1.07), copper (1.32) and manganese (1.03) was observed in soybean: dragonhead (1:2) under organic manure.
In this study, organic manure showed significant gains in terms of nutrient uptake compared to chemical fertilizer. In addition to, uptake efficiency of nutrient was higher compared with sole cropping. Intercropped patterns especially for organic manure application enhances nutrient efficiency. So, enhancement of uptake efficiency reduces the need for fertilizers in farm, in addition to lower environmental hazards contributes to increasing economic efficiency