The effect of different levels of N, P and K supplies and their combinations on the yield and mineral composition of maize (Mv 380) was examined on calcareous loamy chernozem soil. The soil had a pH(KCl) value of 7.3 and contained 5 % CaCO3,3 % humus, poor supplies of P and Zn, moderate supplies of N and K, and satisfactory supplies of Ca, Mg, Fc, Mn and Cu. The fertiliser was applied in the form of 25% calcium ammonium nitrate, 18% superphosphate and 50% potassium chloride. The factorial experiment consisted of 4N × 4P 4K. = 64 treatments, with 2 replications, giving a total of 128 plots. The N rates were 0, 100, 200 and 300 kg/ha/yr, the P levels 0, 500, 1000 and 1500 kg/ha/10 yr (P2O5) and the K levels also 0, 500, 1000 and 1500 kg/ha/10 yr. This replenishment P and K fertilisation took place when the experiment was set up in 1973. The forecrops used in the experiment were maize, wheat, wheat. Alfalfa was grown on the area for 4 years before the experiment was set up. The main conclusions are as follows: 1. As a result of the fairly wet winter preceding the vegetation period and the lack of hot dry winds in summer, the grain yield in 1977 was double that achieved in 1976, reaching 8.2 t/ha on the unfertilised plots. Nevertheless the total rainfall figures for the whole year and for the vegetation period hardly exhibited any difference in 1976 and 1977. In 1977 the PXK supplies determined the yield of young 6-Icaf shoots and the N×K supply the grain yield. The N1P1 levels and their combinations proved to be optimum. Over-fertilisation with P induced Zn deficiency, leading to a decline in the grain yield of 1.4 t/ha in 1976 and 1.0 t/ha in 1977. 2. The composition of leaf samples taken in the 6-lcaf stage and at the beginning of flowering/tassclling gave a satisfactory indication of the nutritional status of the plant. The optimum values recommended in the literature arc suitable for use in the extension service, since they provide diagnostic information. A P/Zn ratio in excess of 200 in any plant organ is indicative of Zn deficiency. 3. On this soil the Fc, Mn and Cu contents of maize can be modified to a greater extent through NxP interactions than by direct Fe, Mn or Cu soil fertilisation. The stalk responded to the soil supplies with excessive uptake, accumulating 8 times as much P, 7 times as much Cu and 3 times as much Mn at the same stalk mass. The Zn reserves dropped to a third on plots well supplied with P. 4. A yield of 8.8 t/ha grain + 5.8 t/ha air-dry stalks contained a total of 171 kg N, 82 kg K (98 kg K2O), 47 kg P (108 kg P2O5), 40 kg Mg, 31 kg Ca, 1-2 kg Fc, 0.5 kg Mn, 0.24 kg Zn and 0.1 kg Cu on this soil. In 1976, due to the severe drought, the same hybrid produced only 4.9 t/ha grain yield and the specific macroelement quantity taken up by l t grain + the corresponding stalk yield was 10-20% greater than that recorded in 1977. The mean Zn, Mn and Fe contents were 32%, 42% and 223% higher, respectively, in the dry year.
|Number of pages||13|
|Publication status||Published - Dec 1 2000|
ASJC Scopus subject areas
- Agronomy and Crop Science