Özet:

: Many investigators have focused on the impact of fertilizers on crop yield and ignored fertilizers impact on the plants composition. The impact of seven types of soil treatments (sewage sludge, horse manure, chicken manure, vermicompost, elemental organic fertilizer, inorganic fertilizer, and native soil) and similar seven treatments amended with biochar on the concentrations of NH 3 and NO 3 in the roots and shoots of three commercial varieties of turnips, Brassica rapa was investigated. The three varieties (Purple Top White Globe PTWG, Scarlet Queen Red SQR, and Tokyo Cross TC) varied in concentrations of NH 3 and NO 3 levels. High levels of NO 3 in edible plants is associated with harmful effects on human health, due to the risk of creation of carcinogenic N-nitroso compounds. NO 3 in SQR roots and shoots (edible greens) was greater than varieties PTWG and TC. The concentration of NH 3 averaged 20.2, 12.8, and 8.9 µg g −1 fresh turnip roots, whereas NO 3 values averaged 107.6, 64.1, and 62.9 µg g −1 fresh turnip roots in varieties SQR, PTWG, and TC, respectively. Regardless of soil amendment type, the concentration of NH 3 in the shoots (44.0 µg g −1) was greater than the roots (15 µg g −1). On the contrary, NO 3 was higher in the roots (89.4 µg g −1) compared to the shoots (67.6 µg g −1 fresh tissue). Overall, biochar added to vermicompost amended soil increased NH 3 by 73% compared to vermicompost not amended with biochar. Regarding acceptable daily intake (ADI) for NO 3, none of the three varieties analyzed constitute any NO 3 adverse effects on normal human intake. Similarly, consuming turnips grown in any of the animal manures tested do not represent any hazardous issues.

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