Trickle and sprinkler irrigation of potato (Solanum tuberosum L. in the Middle Anatolian Region in Turkey
Abstract The potato Solanum tuberosum L. is widely planted in the Middle Anatolian Region, especially in the Nigde Nevsehir district where 25% of the total potato growing area is located and produces 44% of the total yield. In recent years, the farmers in the Nigde Nevsehir district have been applying high amounts of nitrogen (N) fertilizers (sometimes more than 900 kg N ha 1 and frequent irrigation at high rates in order to get a much higher yield. This situation results in increased irrigation and fertilization costs as well as polluted ground water resources and soil. Thus, it is critical to know the water and nitrogen requirements of the crop, as well as how to improve irrigation efficiency. Field experiments were conducted in the Nigde Nevsehir (arid) region on a Fluvents Entisols soil to determine water and nitrogen requirements of potato crops under sprinkler and trickle irrigation methods. Irrigation treatments were based on Class A pan evaporation and nitrogen levels were formed with different nitrogen concentrations. The highest yield, averaging 47,505 kg ha 1 was measured in sprinkler irrigated plots at the 60 g m 3 nitrogen concentration level in the irrigation treatment with limited irrigation (480 mm) Statistically higher tuber yields were obtained at the 45 and 60 g m 3 nitrogen concentration levels in irrigation treatments with full and limited irrigation. Maximum yields were obtained with about 17% less water in the sprinkler method as compared to the trickle method (not statistically significant) On the loam and sandy loam soils, tuber yields were reduced by deficit irrigation corresponding to 70% and 74% of evapotranspiration in sprinkler and trickle irrigations, respectively. Water use of the potato crop ranged from 490 to 760 mm for sprinkler irrigated plots and 565 830 mm for trickle irrigated treatments. The highest water use efficiency (WUE) levels of 7.37 and 4.79 kg m 3 were obtained in sprinkle and trickle irrigated plots, respectively. There were inverse effects of irrigation and nitrogen levels on the WUE of the potato crops. Significant linear relationships were found between tuber yield and water use for both irrigation methods. Yield response factors were calculated at 1.05 for sprinkler methods and 0.68 for trickle methods. There were statistically significant linear and polynomial relationships between tuber yield and nitrogen amounts used in trickle and sprinkler irrigated treatments, respectively. In sprinkler irrigated treatments, the maximum tuber yield was obtained with 199 kg N ha 1 The tuber cumulative nitrogen use efficiency (NUE cu and incremental nitrogen use efficiency (NUE in were affected quite differently by water, nitrogen levels and years. NUE cu varied from 16 to 472 g kg 1 and NUE in varied from 75 to 1035 g kg 1 depending on the irrigation method. In both years, the NH 4 N concentrations were lower than NO 3 N, and thus the removed nitrogen and nitrogen losses were found to be 19 87 kg ha 1 for sprinkler methods and 25 89 kg ha 1 for trickle methods. Nitrogen losses in sprinkler methods reached 76% which were higher than losses in trickle methods.