Evaluation of Different Rates of Nitrogen Fertilizer and Chicken Manure on Potato Yield and Its Components (Kurdistan Province, Iran).

Optimal management of potato nutrition, as one of the main challenges for its production is very important. Nitrogen plays a crucial role, because both deficiency and excessive consumption of nitrogen cause to reduce tuber yield and quality. Besides, increasing the use of manures, especially chicken manure in potato farms has caused potential problems to determine the optimal amounts of nitrogen fertilizer. This study was carried out in order to investigate the interaction effects of nitrogen fertilizer and chicken manure on some quantitative traits of potato (Var. Ramos) in Dehgalan plain, the west of Kurdistan province, Iran. The experimental design was split-plot based on randomized complete block design with three replications. Four chicken manure levels (zero, 5, 10 and 15 t.ha-1) and four nitrogen rates (zero, 100, 200 and 300 kg.ha-1) were considered as main-plots and sub-plots, respectively. The results showed that there is no significant relationship between the interaction of nitrogen fertilizer and chicken manure. The number of stem (m-2), tubers (per plant) and total tubers (m-2) were not affected by different amounts of nitrogen fertilizer and chicken manure. With increasing nitrogen fertilizer, the percentage of tubers smaller than 60 g and tubers between 60-90 g decreased, whereas tubers between 90-120 g and larger than 120 g increased. The effect of nitrogen fertilizer on tuber yield was a quadratic shape, increased by 200 kg.ha-1, and then declined. The effect of chicken manure on the percentage of tubers with different weights did not follow a clear trend but the final tuber yield increased linearly in response to chicken manure. The highest (39.4 t.ha-1) and lowest (28.6 t.ha-1) tuber yield were obtained in zero t.ha-1 and 15 t.ha-1 chicken manure consumption, respectively. These results imply that higher rates of nitrogen fertilizer application not only cause to increase yield but also reduces it.