EFFECT OF HUMIC ACIDS AND THE AMOUNT OF MINERAL FERTILIZER ON SOME CHARACTERISTICS OF SALINE SOIL, GROWTH AND YIELD OF BROCCOLI PLANT UNDER SALT STRESS CONDITIONS

Abstract

A pots experiment was undertaken to determine the combined effect of humic acids and mineral fertilizer on some characteristics of saline soil, growth, and yield components of broccoli. The experiment was conducted in a randomized complete block design with three replications. The first factor consists of two levels of humic acids, namely without humic acid (H0 = 0.00 g L–1) and humic acid application (H1 = 0.35 g L–1), while the second factor included nine fertilizer (92 kg N ha–1, 200 kg P2O5 ha–1, 150 kg K2O ha–1) application rates that were (100, 100, 100%), (120, 120, 120%), (120, 120, 100%), (80, 120, 120%), (100, 100, 120%), (80.100, 100%), (120, 80, 80%), (100, 80, 80%), (80, 80, 80%) which added as a percentage of original fertilizer recommendation taking the symbols of R1 to R9 respectively. The treatment R1 was designated as a control treatment. The results indicated that humic acid application (H1) and increasing the amount of applied mineral fertilizer (R2) reduced the hydraulic conductivity of the soil for different soil depths. Humic acid addition (H1) increased concentrations of calcium and magnesium while reducing sodium concentration compared to control (H0). Contrary to humic acid, increasing the supplied mineral fertilizer led to a reduction in concentrations of calcium and magnesium while increasing sodium concentration in the soil. The sodium adsorption in soil particles in the ground was decreased due to humic acid application while improving the mineral fertilizer. Humic acid (H1) combined with increasing the amount of chemical fertilizer (R2) gave the desirable results in decreasing the sulphate, chloride and bicarbonate in the soil profile. The addition of humic acid (H1) and increasing mineral fertilizer application (R2) led to a significant increase in plant height, leaf area and head weight of broccoli per plant. Similarly, the interaction between humic acids and chemical fertilizers (H1R2) led to a significant increase in plant height, leaf area and head weight of broccoli per plant.