Effects of integrated fertilizer application on selected soil properties and yield attributes of common bean (Phaseolus vulgaris L.) on different soil types

Abstract

In Ethiopia, common bean (Phaseolus vulgaris L.) productivity remains low because of low soil fertility. However, both plant production and soil fertility benefit from integrated application of fertilizers. Thus, this study investigates the effect of integrated application of inorganic, organic and biofertilizers on selected soil properties and yield components of common bean. A field experiment was conducted at three sites in southern Ethiopia, under two consecutive cropping season (2021 and 2022). The experiment was conducted using a randomized complete block design (RCBD) with three replications. The treatments included three levels of inorganic fertilizer (Triple Superphosphate, TSP), applied at 0, 42.5, and 85 kg TSP ha⁻¹ for Kokate; 0, 29, and 58 kg TSP ha⁻¹ for Hawassa; and 0, 35.5, and 71 kg TSP ha⁻¹ for Alage, tailored to the specific conditions of each site. Additionally, the experiment incorporated three levels of organic inputs 0, 5 t biochar ha⁻¹, and 5 t compost ha⁻¹ as well as Rhizobium inoculation (HB-429) applied at 500 g ha⁻¹. These treatments were designed to assess the combined effects of inorganic, organic and biofertilizers on soil health and crop performance. Results showed that the integrated application of inorganic, and organic fertilizers significantly (p ≤ 0.05) improved soil pH, soil organic carbon, and available P compared with the sole fertilizer application plots. Similarly, the integrated use of inorganic, organic and biofertilizers increased nodule numbers, seed weight, grain yield, and biomass yield. We also found that 23 and 24 % higher grain yield were achieved with integrated applications of TSP fertilizer with compost on Hawassa and Alage sites than sole inorganic fertilizer application. On the other hand, the integrated application of TSP fertilizer with biochar increased by 18 % grain yield on Kokate over the sole application of inorganic fertilizer. The highest economic benefit of 69,460 and 63,250 ETB was obtained from the integrated application of TSP fertilizer with compost at Hawassa and Alage sites, respectively. The highest economic benefit for the Kokate site was 53,583 ETB at TSP fertilizer with biochar application. Overall, the study confirms that site-specific integrated soil fertility management appears to be a prerequisite for sustainable and profitable common bean production over sole fertilizer application in southern Ethiopia.

Keywords: Biochar; Biofertilizer; Compost; Economic benefit; Grain yield; Inorganic fertilizer.