Browsing by Subject "jaettu lannoitus"

In Finland, potato is cultivated on more than 22 000 hectares, which makes it one of the most important crops. Potato is considered drought sensitivive because of it´s shallow roots. Thus, irrigation is recommended to improve not only the yield but to ensure good tuber quality. However irrigation is increases production costs. Nitrogen fertilization also affects yield and tuber quality but excess nitrogen can increase costs, nutrient leaching and reduce tuber quality. Thus, the equipment that can be used to estimate nutrient deficiencies have become more common. The effect of irrigation and nitrogen fertilization on growth and tuber yield of potato was investigated during 2001 – 2003 at Potato Research Institute in Lammi, Finland. Irrigation methods were surface irrigation and subsurface drip irrigation. Nitrogen was applied as a single dose when planting or as sidedress. Further interest was to find out whether SPAD values could be used to evaluate both the demand and timing of potato nitrogen fertilization. Irrigation did not affect potato development, tuber yield or starch content. Irrigation methods had no effect on tuber yield either. However, irrigation reduced the yield of marketable tuber yield. The benefit of drip irrigation was the possibility of combined irrigation and fertilizer application. Nitrogen increased tuber yield. The potato stand that received nitrogen as a single dose produced the greatest yield. However, even the potato stand which did not receive nitrogen produced quite large yield, over 30 tn/ha. In 2003, the stands which were given sidedress nitrogen with drip irrigation produced even greater yield than the ones that had been given nitrogen as a single dose. The stands which did not receive nitrogen had highest starch content. The SPAD values were used when estimating the demand of nitrogen fertilization with drip irrigation. SPAD measurements are easily conducted and non-destructive. SPAD values can be used to estimate the demand and timing of fertilization, even though there seems to be slight delay until the values indicate the nutrient deficiency.