Controlled-release urea combined with potassium chloride improved the soil fertility and growth of Italian ryegrass

Abstract

4A field experiment with a split-plot design was conducted to study the effect of 1 5 nitrogen fertilizer type combined with different potassium fertilizer rates on the 1 6 soil fertility and growth of Italian ryegrass. The main plots were assigned to 1 7 controlled-release urea (CRU) and common urea, while low, moderate and high 1 8 potassium chloride (KCl) rates (150, 300 and 450 kg ha -1 , respectively) were 1 9 assigned to the subplots. The results showed compared with the common urea, 2 0 the CRU significantly increased the SPAD value, plant height, leaf area, and 2 1 photosynthetic index. Moreover, the dry and fresh yields of the CRU increased 2 2 by 10.9-25.3% and 11.8-17.7%, respectively. At the same time, compared with 2 3 the KCl150 and KCl450 treatments, the KCl300 treatment resulted in better 2 4 plant growth. Overall, the CRU×KCl300 maximized the soil inorganic nitrogen 2 5 and different soil potassium forms. The root length, volume, surface area, 2 6 average diameter, tips and branches were also improved, and there was a 2 7 significant N×K interaction effect on the tips. Our analysis corroborated the 2 8 CRU combined with 300 kg ha -1 KCl fertilization enhances crop growth by 2 9 2 improving leaf photosynthesis, soil fertility, and yield and should be 3 0 recommended as the best fertilizer ratio for Italian ryegrass production. 3 1