Effect of soil mulch, phosphorus levels and humic acid spray on the growth and green pods yield of broad bean

A field experiment was carried out in 2019/2020 growing season in Wasit governorate to study the effect of soil mulching with wheat crop residues (control and mulch), three levels of phosphorus (0, 120 and 240 kg ha-1) and four concentrations of humic acid (0, 1000, 2000, and 3000 mg l-1) and their interaction on vegetative growth and green pods yield of broad beans. Split-split plots arrangement within a randomized complete block design with three replications was used. The experimental unit was 6 m2 with a length of 2 m and a width of 3 m. The seeds of broad bean (Semillas Fito variety) were seeded in hills 25 cm apart on lines 50 cm apart, on October 5, 2019. The results showed that soil mulch and the addition of the phosphorus level (240 kg ha-1) led to a significant increase in all characteristics studied (plant height, number of leaves, leaf area, leaf area index, number of branches, pod weight, and green pods yield) compared to the control treatment. Humic acid spraying at 2000 mg l-1 caused a significant increase in plant height, leaf area, and leaf area index. The interaction between the factors also caused a significant increase in leaf area, leaf area index, plant branches number, pod weight, and green pods yield to 2108 cm2, 1.687, 11,300, 17.99 g, and 15.13 t ha-1, respectively, compared to the control treatment.