The effect of various levels of NPK supplies and their combinations on the development, yield and yield components of winter rape (cv. Yet Neuj) was examined in the 11th year of a long-term mineral fertilisation experiment set up on calcareous loamy chernozem soil. The ploughed layer of soil at the growing site contained approx. 3% humus, 5% CaCO3 and 20% clay, and was poorly supplied with P and Zn and moderately well with N and K. The experiments involved 4N×4P×4K = 64 treatments in 2 replications, giving a total of 128 plots. The mineral fertiliser was applied in the form of 25% calcium ammonium nitrate, 18% superphosphate and 50% potassium chloride. The groundwatcr was at a depth of 13-15 m, making the area drought-sensitive. The major results were as follows: 1. As the result of the annual application of 0, 100, 200 and 300 kg/ha N the NO3-N reserves in the 0-60 cm soil layer amounted to 66, 123, 204 and 303 kg/ha, respectively, in spring. The application of 0, 1000, 2000 and 3000 kg/ha P2O5 and K2O over the 11 years raised the ammonium lactatc (AL)-solublc P2O5 content of the ploughed layer from 76 to 470 mg/kg and that of K2O from 130 to 263 mg/kg. 2. As the result of improved P×K supplies the mean leaf number per plant in autumn (on Nov. 25th) increased from 3.2 to 5.1, while the percentage of the soil covered by winter rape rose from 31 to 65%. Although the development of the winter rape accelerated, especially due to improved P supplies, the dry autumn prevented the stand from attaining the desirable 6-8-Icaf stage. In spring the mean weed cover was less than 5%. As the result of satisfactory PK supplies the weed cover decreased from 7% on the control soil to 4%, while the mean number of weed species dropped from 7 to 4. Satisfactory nutrient supplies improved the weed-suppressing capacity of the winter rape. Significant N effects could not be demonstrated in the autumn/spring rosette stage even on soil which had not be fertilised for 11 years. 3. By the beginning of ripening the K effects disappeared on this deep-layered loam soil. Moderate P effects were recorded, while the effect of NXP supplies became pronounced. With increasing rates of N and P there was a 30-40% reduction in the plant density, while the number of branches per plant doubled and the number of pods per plant rose by 2-2.5 times. The mean height of the plants surpassed that of unfertilised plants by 25-30%. As the result of N fertilisation the moisture content of winter rape organs rose significantly and the plants matured somewhat later. 4. Depending on the NPK supplies of the soil the following minimum and maximum yields were recorded in the experiment: on Apr. 17th, 2-17 t/ha (fresh) and 0.2-1.6 t/ha (air-dry); at flowering 12-62 t/ha (fresh) and 1.6-7.6 t/ha (air-dry), at the beginning of ripening 20-55 t/ha (fresh) and 5.6-18.6 t/ha (airdry), at complete ripening 5.7-10.5 t/ha straw and 0.7-1.8 t/ha seed (air-dry). The various treatments thus led to 8 x differences in the rosette stage, 5 x at flowering, 3 x at the beginning of ripening and 2 at full maturity (seed, straw) between the unfertilised and optimum NPK treatments. 5. The optimum PK supplies to winter rape can be achieved on this soil with ISO-200 mg/kg ammonium lactate (AL)-solublc P2O5 and K2O, combined with annual applications of around 100 kg/ha N, or NO3-N reserves of 100-150 kg/ha in the 0-60 cm soil layer prior to sowing or in spring. These data could serve as guidelines for the Hungarian extension service.
|Number of pages||15|
|Publication status||Published - Dec 1 2001|
ASJC Scopus subject areas
- Agronomy and Crop Science