The influence of different nitrogen forms and application time on winter wheat

The research was carried out at the Experimental Station of Aleksandras Stulginskis University during 2015–2016 on medium textured loamy carbonaceous leached soil – Cal(ca)ri-Epihypogleyic Luvisols. The soil of the experimental field was the following: pHKCl 6.8–7.2; phosphorus (P2O5) – 423– 429 mg kg–1; potassium (K2O) – 157–163 mg kg–1; humus – 2.47–2.82%. The researchers explored the winter wheat crop (Triticum aestivum L.) variety ‘Skagen’ fertilized with amide (N-NH2), ammonium (N-NH4) and nitrate (N-NO3) forms of nitrogen fertilizers in different tillering stages (BBCH 21–29). 7 days after winter wheat was fertilized, the level of mineral nitrogen in the soil was on average 23.9% higher using ammonium–nitrate nitrogen form fertilizers than using amide nitrogen form ones. The index of chlorophyll and the area of leafs were essentially higher when ammonium– nitrate and amide forms of nitrogen fertilizers were used. The biggest effect on the index of chlorophyll and the area of leafs was achieved 16 days after the start of vegetation when plants were fertilized with ammonium–nitrate fertilizers. Plants fertilized with ammonium–nitrate fertilizers gave the biggest yield 4 days after the start of vegetation. Data of the experiment showed strong and statistically reliable bonds of the correlation between the grain yield and the time of fertilization with nitrogen fertilizers (ήamide nitrogen fertilizers = 0.850* and ήammonium–nitrate fertilizers = 0.878*).