Uplatneni obalovanych ledku a kapalnych kondenzatu mocoviny pri pestovani vybranych zelenin.
1994
Tlustos P. | Pavlikova D. | Balik J. | Matousch O.
Three-year experiments were conducted to study the effect of slow-release nitrogen fertilizers on growth, nitrogen uptake by plants and nitrate concentration in selected vegetables. Two groups of fertilizers were investigated. The first one, consisting of granules of ammonium nitrate and limestone (LAV) coated with ureaform, was characterized by different parameters of solubility (T50) of individual samples (120-620 minutes). The second group, prepared on the basis of urea-formaldehyde condensate and urea, differed by the share of water-insoluble N (0.77 to 4.04 % N). Control variants were treated with ammonium nitrate with limestone and urea. Vegetables were cultivated in pots at two levels of nitrogen rates (0.5 and 1.0 g N per pot). The obtained results did not confirm better effects of slow-release fertilizers compared with non-coated ammonium nitrate and with urea. Application of coated ammonium nitrates was followed by the reduction in yields at lower nitrogen rate and higher accumulation of nitrates in double N fertilizing. Nitrogen from coat, being a part of total nitrogen in a fertilizer, was released very slowly and significantly reduced its uptake by directly fertilized and subsequently cultivated vegetables. N uptake decreased with the increasing T50.
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