The Effect of Rice-hull Mulch on Growth, Carbohydrate Content, and Nitrogen Fixation in Phaseolus vulgaris L.1

Abstract

Mulching ‘Puebla 152’ beans with rice hulls to a depth of 4 cm reduced afternoon soil temperature, soil temperature fluctuation, and slowed the loss of soil moisture. These effects were greatest prior to canopy closure. Fresh weight of nodules, roots, stems, leaves, and total plant increased 50%, 38%, 49%, 24%, and 38%, respectively, with mulching, but pod and final seed weight were unaffected. Mulching had little effect on the concentration of soluble and insoluble carbohydrates. N 2 fixation rates (C 2 H 2 reduction) were low (≤ 0.6 µmole/plant per hr) but were as much as 3 times higher in mulched than unmulched plants.