Content of nitrates in potato tubers depending on the organic matter, soil fertilizer, cultivation simplifications applied and storage
Nitrates naturally occur in plant-based food. Nitrates content in consumable plant organs is small and should not raise concern provided that the recommended fertilization and harvest terms of the original plants are observed. The aim was to determine the effect of the application of various organic matter of soil fertilizer and simplifications in growing potato (Solanum tuberosum L.) on the content of nitrates in the tubers of mid-early cultivar ’Satina’ after harvest and after 6-mo of storage. Introducing cultivation simplification involves limiting mineral fertilization by 50% as well as chemical protection limitation. The soil fertilizer was used: 0.6 (autumn), 0.3 (spring), and 0.3 L ha-1 (during the vegetation period). The content of nitrates, was determined with the use of the ion-selective method (multi-purpose computer device CX-721, Elmetron). The lowest amount of nitrates was recorded in the tubers from the plots without the application of organic matter with a 50% rate of mineral fertilization with soil fertilizer (120.5 mg kg-1 FW). The use of varied organic matter resulted in a significant increase in the content of nitrates in tubers and the lowest effect on their accumulation was reported for straw. The soil fertilizer used significantly decreased the content of nitrates in tubers by 15% for 100% NPK and 10.4% for 50% NPK. After 6-mo storage, irrespective of the experiment factors, the content of nitrates decreased in the fertilization experiment by 26% and in the experiment with a limited protection - by 19.9%.