Effects of Vermicompost, Fertilizer and Mulch on Plant Growth, Nodulation and Pod Yield of French Bean (Phaseolus vulgaris L.)
Integration of vermicompost and organic mulch as elements of vegetable production system sustain soil fertility and crop productivity. A field experiment was conducted with the objective to investigate the effects of vermicompost, NPK fertilizer and organic mulch on crop growth, nodulation and pod yield of French bean (Phaseolus vulgaris L.) with an ultimate aim of optimizing water and nutrient requirement in mild-tropical climate during dry season. The shoot growth traits, namely shoot length, number of primary branches, shoot fresh weight and shoot dry weight were increased by 28-63% through application of N P2O5 K2O 8:13:10 kg·ha-1 + vermicompost 3.75 t·ha-1 and by 5-50% in organic mulching treatments. Application of vermicompost reduced nodule fresh weight and nodule dry weight by 44.9 and 44.5%, respectively. Likewise, corresponding nodule number, nodule fresh weight and nodule dry weight were reduced by 8.6, 11.1 and 14.1% with organic mulching. Poor nodulations might be due to reduced oxygenation of the soils under vermicompost and organic mulch which is ultimately impeding the nitrogenase activity and biological nitrogen fixation. Mulching of French bean with dried grasses and crop residues are also led to higher single pod weight, pod length, pod weight/plant and pod yield by 10.9, 12.8, 20.1 and 20.2%, respectively. Present study shows that application of N P2O5 K2O fertilizer 8-15:13-25:10-20 kg·ha-1, vermicompost 2.50-3.75 t·ha-1, 4 cm thick mulch of dried crop residues and 50% irrigation is the most suitable and sustainable strategy to improve plant growth, pod formation and pod yield of French bean, and soil health of mild-tropical climate during dry season.