Modifying the pore structure of coco-peat as a growing medium for horticultural crops in greenhouse.

Abstract

Soilless culture is a technique for crop production using no soil. It offers earlier growth and higher yield. Lack of suitable soils, disease contamination after repeated use and the desire to apply optimal conditions for plant growth are leading to the worldwide trend of growing plant in media instead of soil. Coco-peat being one of the soilless media is considered as a good growing media component with acceptable pH, electrical conductivity and other chemical attributes but it has been recognized to have high water holding capacity which causes poor air water relationship, leading to low aeration within the medium, thus affecting the oxygen diffusion to the roots Therefore, the main aim of this work is to investigate the physical properties of improved coco-peat that meets the requirement of plant growth. These properties include: moisture content, water holding capacity and porosity (both total and air-filled). The moisture content values ranged from 2.9 to 28.3% for different soilless types, the lowest value of moisture content (2.9 %) was found for pumice and the highest value of moisture content (28.3%) was obtained for coco-peat. The water holding capacity values ranged from 12.7 to 85.1% for different soilless media. The porosity values ranged from 43.0 to 91.0 % for different soilless media. For the mixtures, each material improved the WHC of coco-peat differently and the percentage of WHC for the mix ratio of each combination close to that of soil (52%) was considered the best, 60:40 for both coco-peat to pumice and coco-peat to rice husks with WHC of 53.8% and 56.6% respectively whereas 40:60 for coco-peat to sand gave the desired WHC of 51.0%. The favorable ratio for both coco-peat to pumice and coco-peat to rice husks is 60:40 while that of coco-peat to sand is 40:60 respectively. Based on economic evaluation, coco-peat and pumice combination proved to the best favorable medium with the highest NPV value, followed by coco-peat and sand and then coco-peat and rice husks being the most expensive among the three. Results of this research indicated that certain physical properties of coco-peat can be improved through incorporation of rice husks, pumice and sand.