Growth, Seed Yield and Quality of Soybean as Affected by Integrated Fertilizer Managements and Zeolite Application

ABSTRACT

Sustainable management approaches should be considered to meet gaps between soybean N demand and biological N fixation in poor nutrient soils. Field studies were laid out in 2015 and 2016 to determine the effect of integrated fertilizer systems and zeolite application on two cultivars of soybean. The experiment design was randomized complete block design with factorial arrangement of treatments and three replications. Treatments comprised of two soybean cultivars (C) (M7 and M9), five fertilization systems (F1, 100% sheep manure; F2, 100% urea; F3, 50%, urea + 50% sheep manure; F4, 75% urea + 25% sheep manure and F5, 25% urea + 75% sheep manure), and four zeolite rates (Z1: 0 Mg ha⁻¹ zeolite application (control) Z2: 4 Mg ha⁻¹, Z3: 8 Mg ha⁻¹, Z4: 12 Mg ha⁻¹). Soybean seed yield and yield components were considerably enhanced by applying integrated treatments (F3-F5), but the impact of their application was potentiated by increasing the level of applied zeolite. Increasing the zeolite from 0 to 12 Mg ha⁻¹ increased M7 seed yield by 55% and 73% in F2 and F4 treatments, respectively. Fertilizer systems did not affect oil content, even though cultivar ×year interaction affected this trait. According to the quadratic model, the maximum seed protein was achieved with the application of 8.4 Mg zeolite ha⁻¹. Nitrogen fertilizer led to a low oil yield and a high protein yield while zeolite improved both traits. The study demonstrates that amending soil by these natural fertilizers manures could be a promising strategy to improve soybean yield and quality.

KEYWORDS:

• Cultivar
• sheep manure
• protein content
• oil content
• soil amending