Effects of Different Amount of Diammonium Phosphate (DAP) Fertilizer on Growth and Yield of Common Bean

Abstract

This study evaluated the effects of different rates of diammonium phosphate fertilizer on the growth, yield, and yield components of common bean under field conditions at the Faculty of Agriculture Research Farm, Kabul University, during the 2025 growing season. The experiment was conducted using a randomized complete block design with three replications and four fertilizer treatments: 0 (control), 30, 60, and 90 kg ha⁻¹ of diammonium phosphate. Data were collected on vegetative growth traits, including plant height, number of branches, and number of leaves, as well as reproductive traits such as number of pods per plant, grains per pod, pod length, pod width, 100-seed weight, and grain yield. The data were analyzed using analysis of variance, and treatment means were separated using the least significant difference test at the 5% significance level. Fertilizer application significantly affected most growth and yield parameters. The application of 60 kg ha⁻¹ produced the greatest vegetative growth, recording the highest plant height (33.8 cm) and number of branches (4.47), while the unfertilized control produced the highest number of leaves (36.4). The application of 90 kg ha⁻¹ resulted in the highest reproductive performance, including number of pods per plant (12.33), grains per pod (4.00), pod size, 100-seed weight (66 g), and grain yield (1090 kg ha⁻¹). The findings indicate that moderate fertilizer application promotes vegetative growth, whereas a higher application rate maximizes reproductive development and grain yield. Therefore, applying 90 kg ha⁻¹ of diammonium phosphate is recommended to improve common bean productivity under agroecological conditions similar to those of the study area.