The Use of Apple Pomace as a Soil Amendment Enhances the Activity of Soil Microorganisms and Nitrogen Transformations and Affects Crop Growth

Abstract

Apple pomace (AP) is an abundant waste causing environmental problems. Therefore, the aim of the study was to evaluate the impact of AP on soil and plant growth under optimum and limited water availability. Two laboratory experiments were conducted to evaluate the impact of AP on: (i) hydrophysical properties, respiration, and N transformations in soil aggregates and (ii) the growth of wheat and faba bean in soil with addition of AP under optimum and limited water availability. The soil respiration rate increased rapidly after the introduction of AP, and the effect was dependent on the aggregate size. The reduction of nitrate and the increase in ammonium content in response to the AP addition were more pronounced in the larger aggregates. Reduced growth of wheat was noted in the dry soil supplemented with AP. Faba bean maintained its unchanged rate of growth after the application of AP, irrespective of water availability. An increase in the chlorophyll content was observed in faba bean grown in the AP-enriched soil. The apple pomace reduced the water wetting rate and increased the repellency index but did not affect the tensile strength of the soil aggregates. Disposal of AP as a soil amendment affects many indicators of soil quality. The application of AP to the soil has an impact on respiration and N transformations in the soil aggregates; moreover, it differently influences the growth of spring wheat and faba bean.