Influence of Different Types of Organic Manure on Growth and Yield of Slender Leaf (Crotalaria brevidens)

Abstract

Slender leaf (Crotalaria brevidens) is an underutilised leguminous leafy vegetable with potential contributions to food security, dietary diversity and soil fertility. This study evaluated the influence of different organic manure sources on root nodulation, vegetative growth and yield of slender leaf under field conditions at the Meru University of Science and Technology Demonstration Farm, Kenya. The experiment was conducted during September–December 2023 and February–May 2024 using a randomised complete block design with five treatments replicated four times: 4 t ha⁻¹ cattle manure, 4 t ha⁻¹ goat manure, 3 t ha⁻¹ poultry manure, 130 kg ha⁻¹ NPK (17:17:17) fertiliser and an untreated control. Seeds were sown at 30 cm × 30 cm spacing, and data were collected on soil moisture, plant height, chlorophyll index, root nodulation, leaf fresh and dry weight, and seed weight. Manure source significantly affected several growth and yield parameters (p < 0.05). Poultry manure consistently produced the strongest response, including the highest plant height at 63 DAS in both seasons, improved chlorophyll index, greater root nodulation and higher seed weight. It also produced the highest leaf fresh weight, reaching 116.7 g per plant in season one and 135.7 g per plant in season two. Goat and cattle manure improved crop performance compared with the control, although their effects were generally lower than poultry manure. The findings indicate that poultry manure is a promising locally available nutrient source for improving slender leaf productivity under the conditions of this experiment.