Effect of Mineral Fertilization and Humic Acids on Availability of NPK in Soil and Maize Growth

Abstract

 This experiment were conducted to study the effect of NPK fertilizers, humic acid and their interaction on soil N, P, K availability and growth of “Baghdad” Maize (Zea mays L.) variety. This study was conducted in field experiment , College of Agricultural Engineering Sciences, Univ. Baghdad, Al- Jadriya during 2020 growing season, included two treatments: four levels of humic acid application to soil at 0 (H0), 20 kg.H-1(H20) , 40 kg.H-1(H40) and 60 kg.H-1(H60) and three levels of NPK fertilizers, 0 (M0), 50 %(M50) and 100 % (M100) From the fertilizer recommendation (240 kg N H-1, 80 kg P H-1 and 120 kg K H-1) and their interaction. Treatments were replicated three times at factorial experiment in a RCBD. The results showed that, humic acid at 60 kg.H-1(H60) gave highest soil nitrogen content of 125.1 mg.kg-1, highest soil phosphor content of 22.82 mg.kg-1, highest soil potassium content of 327.1 mg.kg-1, highest plant height of 184.28 cm and highest plant dry weight of 182.1 gm. Results also showed that NPK fertilizer at 100 % (M100) gave highest soil nitrogen content of 127.8 mg.kg-1, highest soil phosphor content of 26.29 mg.kg-1 , highest soil potassium content of 326.9 mg.kg-1, highest plant height of 183.44 cm and highest plant dry weight of 198.2 gm. The interactions between NPK and humic acid addition significantly affected in all traits especially the interaction treatment (H60M100).