Dry matter production and nutrient uptake of Potato (solanum tuberosum L.) as influenced by N and P application on sitisols of western Ethiopia.

The influence of different levels of N and P on haulm and tuber dry matter production, and nutrient uptake of two potato varieties, Tolcha and Menagesha, were evaluated at Bako Agricultural Research Center, westrern Ethiopia, during the years 2000 and 2002. The experiment was laid out in a split plot design having three replications with the two potato varieties assigned to the main plot while three levels of N (0, 69 and 138 kg N ha-1) and four levels of P (0, 69, 138 and 207 kg P ha-1havingfactorial combination to sub-plots. Soil samples were taken from 0 to 30 cm depth before and after treatment application to determine the selected soil physic-chemical properties. Highly significant (P0.01) differences were noted for haulm and tuber dry matter between the varieties. Increasing N levels from 0 to 69 kg ha-1 significantly increased tuber dry matter on an average by 84%. On the contrary, the effect of P was non-significant (P0.05) with respect to haulm and tuber dry matter. The variety and N interaction effect significantly(P0.01) increased haulm and tuber dry matter. There were highly significant differences (P0.01) between the two potato varieties with respect to haulm and tuber nutrient uptake. Nutrient uptake of the haulm and the tuber was significantly (P0.01) enhanced due to N applications. The soil analyses showed that the soil of the soil of the experimental site was low in organic carbon and total nitrogen. The available P of the acidic Nitisols of Bako soil was estimated to b3 7.48 ppm, which is below the critical level for potato production. The soil available P accounted only 4.3% for the variation of tuber dry matter. It was noted that 69 kg N ha-1 was found to be critical for potato production on Nitisols of western Ethiopia. Further studies on phosphorus nutrition in conjunction with organic amendments to improve phosphorus use efficiency need due consideration.