Effects of tree nursery growing media and farmers' management techniques on seedling quality in Mount Kenya region

Low survival and slow growth rate of trees as a result of poor quality tree seedlings hamper effort by small-scale farmers in development of agroforestry systems. These may be attributed to the chemical and physical properties of the growing media used and the management practices adopted. With the growing demand for quality agroforestry trees, farmers have increasingly attempted to raise planting sock on-farm. However, insufficient technical knowledge has often hindered success. Insufficient growth medium quality has been identified as one of the factors contributing to low seedling qualities. Such growing medium contributes to physical and chemical conditions that may be inappropriate for quality seedling development. Slow growth rate and survival rate lead to extra costs in replacement planting as well as delayed benefits. With this knowledge, this study attempted to find out the effect of growing media chemical and physical properties used by farmers to raise seedlings of Tamarindus indica on-farm and the management practices adopted. This was necessitated by the need to determine parameters that make a good tree nursery growing medium that can be used by farmers on their on-farm nurseries for appropriate seedling quality. The study also monitored the quality of the seedlings during the nursery period. On-farm tree nurseries in two agro-ecological zones in mount Kenya region-main coffee and marginal coffee zones were studied. Samples of the growing media used were analysed for chemical and physical properties. Seedlings were produced in the media and their root diameter and seedling height measured periodically. Data collected were analysed for variance (ANOVA) and tested for correlation. Aeration pore volume, total pore volume and wet bulk density were the physical properties that had greatest influence on seedling quality parameters. These had more effect at initial period of growth. Chemical properties affected seedling growth and quality parameters at later stages of growth. Important nutrients were observed to be nitrogen, organic carbon, magnesium and calcium. From the findings of this study, farmers can curtail nursery period from 130 days to as little as 75 days. There is need for further research to determine the cause of too much phosphorus concentration in the growing media tested and understand ways of ameliorating its negative effect on seedling development.

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