Effects of Phosphorous, Iron and Zinc Fertilizers on Quantity and Quality of Turnip (Brassica rapa) Forage

To evaluate the effects of phosphorous, iron and zinc fertilizers on quantity and quality of turnip, a field experiment was conducted in 2009. The experiment treatments arranged as split plot factorial based on a completley randomized design with 4 replications in the research farm of the University of Tehran (Karaj-Iran). The main factor including three levels of phosphorous (super phosphate triple, 0, 150 and 300 kg/ha) and 2 levels of iron fertilizer (Chelate in EDDHA form, 0 and 4 kg/ha) along with three levels of zinc fertilizer (zink sulfate, 0, 20 and 40 kg/ha) were allocated to subplots. Control treatments include plots with no fertilizers. The results indicated that phosphorous had significant effects on dry yield and some quality traits such as crude protein percentage, water soluble carbohydrates, and ash. Also 300 kg/ha phosphorous fertilizer increased dry yield by 42.7% compared to control. The iron fertilizer had positively significant effect on DMD, CP (P≤0.01), ADF, and ASH (P≤0.05). Investigated factors had no significant effect on plant height. Applications of these fertilizeres are necessary for achieving high dry yield along with high quality forage.