Boron uptake by plants as affected by organic matter

Abstract

Boron (B) uptake by plant is controlled by B level in soil solution rather than total B content in soil. The affinity of organic matter for B can affect B uptake by plants due to changing B concentration in soil solution. The role of soil organic matter content on B soil solution concentration and uptake by bell pepper were studied. The organic matter used was mature compost (COM), produced from the solid fraction of separated straw-containing cattle manure. Plants were grown in five soil-sand-COM mixtures containing 0, 1, 3, 6 or 10% COM by weight. Four levels of B were applied. The soil was analyzed for B content at the beginning of the experiment and at harvest. Boron concentration in the leaves was determined 45 d from planting. Boron concentration in the soil solution, at the beginning of the experiment, decreased with increasing levels of COM. This decrease was most prominent at high levels of B application. The effect of COM level on leaf B concentration was also prominent at high B application rates, increasing levels of COM resulting in less B in the leaf tissues. Boron concentration in the leaves was highly significantly correlated (r2=0.88) with the B concentration adjusted in the soil solution. The results presented herein indicate that organic matter plays an important role in controlling B concentration in the soil solution and that it has a prominent effect on reducing B uptake by plants.