MAIZE RESPONSE TO SOIL-APPLIED HUMIC SUBSTANCES AND FOLIAR FERTILIZATION WITH POTASSIUM
M. Szczepanek* and E. Wilczewski
Department of Agrotechnology, Faculty of Agriculture and Biotechnology, UTP University of Science and Technology in Bydgoszcz, Poland
*Corresponding author email: Malgorzata.Szczepanek@utp.edu.pl
Application of some compounds stimulating growth and physiological processes may have favourable effect on maize productivity. The study aimed to assess the response of maize germination and initial growth to soil-applied humic substances, and the effect of these substances and foliar potassium fertilizer on the maize grain yield. The study was based on a single-factorial field experiment conducted over 2006-2008 in Poland, (17o35′ E; 53o09′ N), on soil classified as mesic Typic Hapludalf, in a randomized block design, in four replications. The effect of the following was evaluated: humus preparation Humistar (12% humic acids and 3% fulvic acids), applied pre-sowing into soil, at a rate of 40 dm3 ha-1 (T1), foliar fertilizer Drakar (25.7% K and 3% N), applied at BBCH 16 and 17, at a rate of 2 dm3 ha-1 (T2), combined application of Humistar and Drakar (T3), and the control (T4). Humistar application resulted in an increase in germination energy, but it did not affect germination capacity or seedlings weight of maize. Humistar or Drakar caused an increase in cob weight, grain proportion in the cob weight and grain yield, as compared with the control. The increase in grain yield in individual years of the study after Humistar application ranged from 1.21 to 8.41% (140-620 kg ha-1), whereas after Drakar from 0.35 to 5.8% (40-430 kg ha-1). Combined application of these preparations caused an increase in grain yield on average from the years in relation to control (by 2.1%), but there was no difference in yield as compared with the application of Humistar or Drakar only. Further studies are necessary to evaluate the effect of these preparations in weak soils with low content of organic matter and nutrients.
Key words: maize, grain, germination, humic substances, leaf greenness index, potassium.